BREEDING BIRD RESPONSE TO FOREST CANOPY REDUCTION ON THE MIDCUMBERLAND PLATEAU IN NORTHERN ALABAMA
A THESIS
by
BRANDIE K. STRINGER
Submitted in partial fulfillment of the requirements
for the degree of Master of Science
in the Department of Biological and Environmental Sciences
in the College of Agricultural, Life, and Natural Sciences
Alabama A&M University
Normal, AL 35762
December 2014
Submitted by BRANDIE K. STRINGER in partial fulfillment of the requirements
for the degree of MASTER OF SCIENCE in PLANT AND SOIL SCIENCE.
Accepted on behalf of the Faculty of the Graduate School by the Thesis
Committee:
Callie Jo Schweitzer, PhD____________
Paul Hamel, PhD___________________
Yong Wang, PhD__________________ Major advisor
Ken Ward, PhD____________________
_________________________________Dean of the Graduate School
_________________________________Date
ii
Copyright by
BRANDIE K. STRINGER
2014
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BREEDING BIRD RESPONSE TO FOREST CANOPY REDUCTION ON THE MIDCUMBERLAND PLATEAU IN NORTHERN ALABAMA
Stringer, Brandie, M.S., Alabama A&M University, 2014. 102 pp.
Thesis Advisor: Yong Wang, Ph.D.
Understanding forest bird response to silvicultural practices is crucial to bird
conservation, as many declining forest bird species are dependent upon periodic
disturbance for their habitat needs. As the continuation of a study initiated in 2002, I
examined the effects of canopy reduction treatments (shelterwoods) on breeding forest
bird communities with respect to species composition and species richness. The study
areas were on the southern end of the mid-Cumberland Plateau in northern Jackson
County, Alabama. As part of a randomized complete-block design with three
replications, fifteen 4 ha stands were treated in 2001-2002 with one of five target
overstory retention (percentage) treatments: 0 (clearcut), SW25, SW50, SW75, and
SW100 (control). In 2011, residual trees in all but clearcut stands were harvested; three
new controls were added. Using territory mapping, territory density of birds was
quantified by species during the breeding season (April-July) of 2002, 2003, 2010 and
2012. Compared to controls and clearcuts, shelterwoods held highest richness in all years
except for 2003, when SW75 richness was slightly below that of clearcut stands.
Immediately following treatment, clearcut stands had lowest richness and abundance of
forest interior and interior-edge species. However, most of these species rebounded by
2010. Interior-edge species were most abundant in SW50 in 2002 and 2003, but no
effects were seen by 2010. Open-edge species abundance was highest in SW25/SW50 in
all years. Habitat mosaics resulted which supported all primary habitat association
iv
guilds, but treatment effects have expiration dates, especially for management of openedge species.
KEY WORDS: forest management, disturbance ecology, oak regeneration, Neotropical
migrants, community ecology, shelterwood, clearcut
v
TABLE OF CONTENTS
ABSTRACT AND KEY WORDS .................................................................................... iv
TABLE OF CONTENTS ................................................................................................... vi
LIST OF TABLES ........................................................................................................... viii
LIST OF FIGURES .............................................................................................................x
LIST OF ABBREVIATIONS ......................................................................................... xvii
ACKNOWLEDGMENTS ............................................................................................... xix
CHAPTER ONE - INTRODUCTION.................................................................................1
Objective ......................................................................................................................... 5
Literature Review............................................................................................................ 5
Clearcut Harvesting .................................................................................................... 6
Shelterwood Harvesting .............................................................................................. 7
Hypotheses ...................................................................................................................... 9
CHAPTER TWO - METHODOLOGY .............................................................................10
Study Sites .................................................................................................................... 10
Experimental Design ..................................................................................................... 10
Experimental Treatments .......................................................................................... 12
Tree and Canopy Cover Measurements`................................................................... 14
Forest Bird Assessment................................................................................................. 16
Bird Territory Mapping............................................................................................. 16
Territory Delineation ................................................................................................ 17
Guild Categories ....................................................................................................... 17
Geographic Information System Applications.......................................................... 18
Statistical Analyses ....................................................................................................... 20
Treatment and Year Effect on Canopy Cover........................................................... 20
vi
Treatment and Year Effect on Birds ......................................................................... 21
CHAPTER THREE - RESULTS .......................................................................................22
Tree Measurements ....................................................................................................... 22
Canopy Cover ........................................................................................................... 22
Live Basal Area and Density .................................................................................... 23
Bird Community Response ........................................................................................... 27
Species with Low Territory Densities....................................................................... 27
Other Detections ....................................................................................................... 28
Territory Density....................................................................................................... 28
CHAPTER FOUR - DISCUSSION ...................................................................................75
Bird Community and Habitat ........................................................................................ 75
CHAPTER FIVE - CONCLUSIONS ................................................................................84
Management Implications ............................................................................................. 84
REFERENCES ..................................................................................................................86
APPENDIX ........................................................................................................................92
Territory Density Tables ............................................................................................... 92
VITA
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LIST OF TABLES
Table
1.
Page
Scientific name, common name, and guild memberships of all forest songbird
species that held territories on the study sites in any of the years 2002, 2003,
2010, and 2012 at Jack Gap and Miller Mountain in Jackson
County, Alabama.. ................................................................................................ 19
2.
Percent canopy cover means ± (SE) in 2002, 2003, 2009, and 2012 at Jack Gap
and Miller Mountain in Jackson County, Alabama.. ............................................ 23
3.
Mean ± (SE) basal areas (BA = m2/ha; all live trees ≥ 14.2 cm DBH) in 2002,
2003, 2009, and 2011 at Jack Gap and Miller Mountain in Jackson County,
Alabama.. .............................................................................................................. 25
4.
Mean ± (SE) stems per hectare (SPH; all live trees ≥ 14.2 cm DBH) in 2002,
2003, 2009, and 2011 at Jack Gap and Miller Mountain in Jackson County,
Alabama. . ............................................................................................................ 27
viii
5.
Appendix A.1. Mean ± SE and mixed model analysis (SPSS v20) results for
territory densities [(territories/4 ha)*100] for breeding bird communities in
2002, 2003, 2010, 20111, and 2012 at Jack Gap and Miller Mountain in
Jackson County, Alabama. .................................................................................... 92
6.
Appendix A.2. Mean ± SE and mixed model analysis (SPSS v20) results for
aggregated sum of territory densities [(territories/4 ha)*100] for breeding bird
guilds in 2002, 2003, 2010, 20111, and 2012...................................................... 100
ix
/
LIST OF FIGURES
Figure
1.
Page
Study site location for Jack Gap (JG) and Miller Mountain (MM), Jackson
County, Alabama. ................................................................................................. 11
2.
Topographic map of complete block replicate one, showing treatments at Miller
Mountain, Jackson County, Alabama.. ................................................................. 13
3.
Topographic map of complete block replicates two and three, showing treatments
at Jack Gap, Jackson County, Alabama.. .............................................................. 15
4.
Mean basal areas (BA = m2 / ha) ± SE for all live trees ≥ 14.2 cm DBH in 2002,
2003, 2009, and 2011 at Miller Mountain and Jack Gap in Jackson County,
Alabama.. .............................................................................................................. 24
5.
Mean stems per hectare (SPH) ± SE for all live trees ≥ 14.2 cm DBH in 2002,
2003, 2009, and 2011 at Miller Mountain and Jack Gap in Jackson County,
Alabama. . ............................................................................................................ 26
6.
Overall mean territory density [(territories/4-ha)*100] ± SE for all species that
held ≥10 territories displaying treatment*year interaction in 2002, 2003, 2010,
and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama.. ............ 31
x
7.
Mean species richness ± SE including all species that held ≥10 territories
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 32
8.
Mean territory density [(territories/4 ha)*100] ± SE of the Black-and-white
Warbler displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. ................................ 33
9.
Mean territory density [(territories/4 ha)*100] ± SE of the Blue-gray Gnatcatcher
displaying treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and
Jack Gap, Jackson County, Alabama.. .................................................................. 34
10.
Mean territory density [(territories/4 ha)*100] ± SE of the Blue-gray Gnatcatcher
displaying year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama.. .......................................................................... 35
11.
Mean territory density [(territories/4 ha)*100] ± SE of the Carolina Wren
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 36
12.
Mean territory density [(territories/4 ha)*100] ± SE of the Downy Woodpecker
displaying treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and
Jack Gap, Jackson County, Alabama.. .................................................................. 37
13.
Mean territory density [(territories/4 ha)*100] ± SE of the Downy Woodpecker
displaying year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama.. .......................................................................... 38
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14.
Mean territory density [(territories/4 ha)*100] ± SE of the Eastern Towhee
displaying treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and
Jack Gap, Jackson County, Alabama.. .................................................................. 39
15.
Mean territory density [(territories/4 ha)*100] ± SE of the Eastern Towhee
displaying year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama.. .......................................................................... 40
16.
Mean territory density [(territories/4 ha)*100] ± SE of the Eastern Wood-Pewee
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 41
17.
Mean territory density [(territories/4 ha)*100] ± SE of the Hooded Warbler
displaying year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama.. .......................................................................... 42
18.
Mean territory density [(territories/4 ha)*100] ± SE of the Indigo Bunting
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 43
19.
Mean territory density [(territories/4 ha)*100] ± SE of the Kentucky Warbler
displaying treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and
Jack Gap, Jackson County, Alabama.. .................................................................. 44
20.
Mean territory density [(territories/4 ha)*100] ± SE of the Kentucky Warbler
displaying year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama.. .......................................................................... 45
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21.
Mean territory density [(territories/4 ha)*100] ± SE of the Mourning Dove
displaying year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama.. .......................................................................... 46
22.
Mean territory density [(territories/4 ha)*100] ± SE of the Northern Cardinal
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 47
23.
Mean territory density [(territories/4 ha)*100] ± SE of the Red-bellied
Woodpecker displaying year effect in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 48
24.
Mean territory density [(territories/4 ha)*100] ± SE of the Red-eyed Vireo
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 49
25.
Mean territory density [(territories/4 ha)*100] ± SE of the Scarlet Tanager
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 50
26.
Mean territory density [(territories/4 ha)*100] ± SE of the Summer Tanager
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 51
27.
Mean territory density [(territories/4 ha)*100] ± SE of the Tufted Titmouse
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 52
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28.
Mean territory density [(territories/4 ha)*100] ± SE of the White-breasted
Nuthatch displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama.................................. 53
29.
Mean territory density [(territories/4 ha)*100] ± SE of the White-eyed Vireo
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 54
30.
Mean territory density [(territories/4 ha)*100] ± SE of the Worm-eating Warbler
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 55
31.
Mean territory density [(territories/4 ha)*100] ± SE of the Yellow-breasted Chat
displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama............................................. 56
32.
Mean territory density [(territories/4 ha)*100] ± SE of the Yellow-throated Vireo
displaying treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and
Jack Gap, Jackson County, Alabama.. .................................................................. 57
33.
Mean territory density [(territories/4 ha)*100] ± SE for all bark foraging species
that held ≥10 territories.. ....................................................................................... 58
34.
Mean territory density [(territories/4 ha)*100] ± SE for all foliage gleaning
species that held ≥10 territories.. .......................................................................... 59
35.
Mean territory density [(territories/4 ha)*100] ± SE for all ground foraging
species that held ≥10 territories.. .......................................................................... 60
36.
Mean territory density [(territories/4 ha)*100] ± SE for all hawking forager
species that held ≥10 territories.. .......................................................................... 61
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37.
Mean territory density [(territories/4 ha)*100] ± SE for all forest interior species
that held ≥10 territories.. ....................................................................................... 62
38.
Mean territory density [(territories/4 ha)*100] ± SE for all interior-edge species
that held ≥10 territories.. ....................................................................................... 63
39.
Mean territory density [(territories/4 ha)*100] ± SE for all open-edge species that
held ≥10 territories.. .............................................................................................. 64
40.
Mean territory density [(territories/4 ha)*100] ± SE for all Neotropical migrant
species that held ≥10 territories.. .......................................................................... 65
41.
Mean territory density [(territories/4 ha)*100] ± SE for all resident species that
held ≥10 territories. ............................................................................................... 66
42.
Mean territory density [(territories/4 ha)*100] ± SE for all temperate migrant
species that held ≥10 territories.. .......................................................................... 67
43.
Mean territory density [(territories/4 ha)*100] ± SE for all canopy nesting species
that held ≥10 territories.. ....................................................................................... 68
44.
Mean territory density [(territories/4 ha)*100] ± SE for all cavity nesting species
that held ≥10 territories.. ....................................................................................... 69
45.
Mean territory density [(territories/4 ha)*100] ± SE for all ground nesting species
that held ≥10 territories.. ....................................................................................... 70
46.
Mean territory density [(territories/4 ha)*100] ± SE for all ground nesting species
that held ≥10 territories.. ....................................................................................... 71
47.
Mean territory density [(territories/4 ha)*100] ± SE for all low-shrub nesting
species that held ≥10 territories.. .......................................................................... 72
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48.
Mean territory density [(territories/4 ha)*100] ± SE for all midstory-subcanopy
nesting species that held ≥10 territories.. .............................................................. 73
49.
Mean territory density [(territories/4 ha)*100] ± SE for all midstory-subcanopy
nesting species that held ≥10 territories.. .............................................................. 74
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LIST OF ABBREVIATIONS
ANOVA – Analysis of Variance
BA – Basal Area
CLEAR – Clearcutting, a silvicultural treatment
DBH – Diameter at Breast Height
GIS – Geographic Information System
HSD – Honestly Significant Difference
IBCC – International Bird Census Committee
JG – Jack Gap, location of blocks two and three of study site
LSD – Least Significant Difference
MM – Miller Mountain, location of block one of study site
PIF – Partners in Flight
SAS – Statistical Analysis System
SE – Standard Error
SPH – Stems per Hectare
SPSS – Statistical Package for the Social Sciences
SW25 – Shelterwood treatment with target overstory retention level of 25% in 2001
SW50 – Shelterwood treatment with target overstory retention level of 50% in 2001
SW75 – Shelterwood treatment with target overstory retention level of 75% in 2001
xvii
SW100 – Shelterwood treatment with target overstory retention level of 100% (control)
in 2001
USDAFS – United States Department of Agriculture Forest Service
xviii
ACKNOWLEDGMENTS
I thank my committee members: Dr. Yong Wang, Dr. Callie Schweitzer, Dr. Paul
Hamel, and Dr. Ken Ward for their invaluable time and effort. This study was financially
and/or technically supported by the Forestry, Ecology, and Wildlife Program at Alabama
A&M University, the USDA Forest Service Southern Research Station, the Stevenson
Land Company, the Alabama Department of Conservation and Natural Resources, the
Birmingham Audubon Society’s Walter F. Coxe Research Fund, the Alabama
Experimental Program to Stimulate Competitive Research (ALEPSCoR) Graduate
Research Scholars Program (GRSP) fellowship, and National Science Foundation. Many
other individuals contributed to this project; their efforts are appreciated.
xix
CHAPTER ONE
INTRODUCTION
The importance of songbird conservation has received much attention in the
ecological community, as many species are declining (Sauer et al., 2011; Askins, 2000).
Particularly vulnerable are Neotropical migrants that breed during summer months in
North America and overwinter in South and Central America, the Caribbean, and Mexico
(Cornell Lab of Ornithology, 2007). A smaller subset of these migrants is in danger of
becoming threatened. Partners in Flight (PIF), an international bird conservation
organization, has included these species on the conservation concern list (Partners in
Flight Science Committee, 2012; Rich et al., 2004. Due to population declines, extensive
conservation efforts have focused on the Cerulean Warbler (Setophaga cerulea;
Carpenter et al., 2011; Hamel, 2000; Hamel et al., 2004; Sheehan et al., 2014). Research
has suggested that habitat alteration or loss is a major contributor in the decline of this
species and other Neotropical migratory songbirds (Askins, 2000; Sauer et al., 2011).
Also contributing to declines is brood parasitism by cowbirds (Molothrus spp.), a process
in which female cowbirds lay their eggs in nests of other host species (Robinson et al.,
1995).
Some forest songbirds that breed in the southeastern United States have been
vulnerable to the agricultural clearing in the late nineteenth and early twentieth centuries.
1
This was followed by pine plantation reforestation and coupled with fire suppression
during most of the twentieth century. Forestry practices have decreased periodic
disturbance and contributed to the loss of forest understory (Owen, 2002), which is
necessary to maintain populations of many bird species (Rich et al., 2004). Despite
numerous studies focusing on forest bird breeding grounds (Carpenter et al., 2011; Gram
et al., 2003; King & DeGraaf, 2000; Lesak et al., 2004; Newell & Rodewald, 2012;
Robinson & Robinson, 1999; Thompson & Fritzell, 1990), it is still not clear how
anthropogenic disturbance affects community and population dynamics (Rich et al.,
2004). It has been suggested that conservation efforts should include the production and
maintenance of early successional habitat, particularly by land managers of both publiclyand privately-owned land (Hunter et al., 2001; Rich et al., 2004).
Land managers of southern upland hardwood forests face multiple challenges.
Oak (Quercus spp.) is considered to be one of the most economically important groups of
these forest systems (Hicks et al., 2004). Oaks are of mostly intermediate to low shade
tolerance (Loftis, 1990; Schweitzer & Dey, 2011; Stringer, 2006). Oak saplings expend
more energy in root development than they do in height growth (Hicks et al., 2004); this
causes them to be overtopped by shade-tolerant species such as sugar maple (Acer
saccharum) and light-responsive species such as yellow-poplar (Liriodendron tulipifera;
Schweitzer & Dey, 2011). Under the right conditions, oaks thrive from a regime of
periodic disturbance from surface fires (Brose et al., 1999; Van Lear & Brose, 2001).
However, there is much dispute about fire's role in oak forests, especially on mesic or
productive sites (Brose et al., 2013). Fire suppression during the twentieth century and
an increasing abundance of browsing deer have been major culprits in decreased oak
2
reproduction in southern upland hardwood forests (Hicks et al., 2004). The resultant
mature, even-aged forests with closed canopies do not provide adequate light conditions
that are required for oak reproduction (Larsen & Johnson, 1998). With this decline in
oak reproduction, the goal of managing forests to meet increasing demand for oak and
other hardwoods that are wildlife-dependent (Van Lear & Brose, 2002) and
economically-valuable has become the focus of some forest researchers (e.g. Loftis,
1990; Rathfon, 2011; Schweitzer, 2004; Schweitzer & Dey, 2011).
To manage for advanced reproduction by insufficiently competitive oaks,
managers are altering regeneration techniques to facilitate the development of sustainable
levels of oak stocking. One such technique is the oak-shelterwood method that involves
culling the forest midstory of undesirable, shade-tolerant species such as sugar maple and
American beech (Fagus grandifolia); this allows more light penetration to the forest
understory and encourages oak seedling development (Loftis, 1990; Stringer, 2006).
Some studies have shown successful oak advanced reproduction from shelterwood
harvests aimed in oak regeneration (Loftis, 1990; Rathfon, 2011).
Forest birds contribute to forest ecosystem function in many ways. Insectivorous
songbirds, especially those of the Paridae family, help control populations of potentially
dangerous arthropods and their larvae (Connor et al., 1999). Frugivorous birds contribute
to seed dispersal, as well as gastrointestinal scarification and germination heterogeneity
through digestion (Traveset et al., 2001). It has also been suggested that these fruiteating birds contribute to increased germination rates (Greenberg et al., 2001).
Hummingbirds (Trochilidae) and other nectar-feeding species act as pollinators (Brown
3
& Gibson, 1983). The breakdown of snags and coarse woody debris is facilitated by bark
excavators (Lesak et al., 2004) such as woodpeckers (Picidae) and nuthatches (Sittidae).
Alabama has the third largest commercial forest industry and the second largest
private forest landholdings in the USA (Alabama Forestry Commission, 2009). It is
important that land managers, particularly those in this state, are equipped with the proper
tools for lucrative timber management and for effective forest bird management. Partners
in Flight (PIF), an international bird conservation agency, has specified the need to
require examination of the effects of silvicultural practices on forest birds (Rich et al.,
2004). Studies that observed the long-term effects of shelterwood treatments on forest
birds are limited (e.g. Augenfeld et al., 2008). No study has examined bird response
through multiple stages of shelterwood treatments. Studying forest bird response to
silvicultural treatments can help managers to formulate strategies that will balance
economic needs with ecological needs of healthy populations of forest birds.
To test the effectiveness of the shelterwood treatment for oak regeneration in the
mid-Cumberland Plateau region, the USDA Forest Service (USDAFS) Southern
Research Station initiated a study in conjunction with the Mead Corporation in 2001: the
‘Mead Study’ (C. J. Schweitzer, pers. comm.). Alabama A&M University took this
unique opportunity and implemented several projects. Responses of wildlife species to
oak regeneration treatments were examined in partnership with, and under partial
support, of the USDAFS in 2002 (e.g. Felix et al., 2008; Lesak, 2004; Wang et al., 2006).
This study continued the initial avian study (Lesak 2004) and examined the bird
communities immediately before and following the second cut in the two-cut shelterwood
sequence of this long-term study.
4
Objective
The objective of this study was to examine the temporal responses of forest bird
communities to oak regeneration treatments through a before-after control-treatment field
experiment. The sequential treatments of shelterwood: initial partial removal of
midstory, enhanced understory development, and final removal of all harvestable canopy,
created dynamic forest habitat changes. This study aimed to examine the forest bird
response to these sequential habitat changes. Breeding forest bird richness, abundance,
as well as guild-level and overall community structure were examined before (in 2010)
and after (in 2011 and 2012) removal of residual merchantable tree canopies in 20102011; these data were compared with the results from 2002 and 2003 after initial
treatments in 2001-2002.
Literature Review
Certain forest management prescriptions can create early successional habitat that
may be essential for some early successional and forest edge avian species (Askins, 2000;
Lesak et al., 2004) such as the Prairie Warbler (Setophaga discolor) and Yellow-breasted
Chat (Icteria virens; Robinson & Robinson, 1999). Yet other species, such as the Wormeating Warbler (Helmitheros vermivorum), may suffer immediate decline due to the loss
of mature forest habitat (Askins, 2000). These prescriptions may also increase mortality
risk due to higher predation and parasitism in open-canopy forests (Pease & Grzybowski,
1995). However, with sufficient re-growth of the forest vegetation and subsequent
changes in structure, silvicultural disturbance may eventually provide sustainable
resources for mature forest bird species (Lesak et al., 2004; Newell & Rodewald, 2012).
5
Silvicultural treatments vary according to the goals of a land manager. Clearcut
harvesting involves the removal of the entire overstory in one treatment; this is designed
to regenerate even-aged, single-cohort stands, and usually favors somewhat shadeintolerant tree species (Hicks et al., 2004). Also included in even-aged management are
the aforementioned shelterwood harvests. Uneven-aged management includes single-tree
selection and group selection. Single-tree selection is used to develop a stand that has
many cohorts of shade-tolerant species. Group selection involves removing trees and
establishing new age classes in small groups (Hicks et al., 2004).
Clearcut Harvesting
Clearcut harvesting often abruptly changes species composition and provides
habitat for early successional species (Costello et al., 2000; Lesak et al., 2004). Studies
examining forest bird response to silvicultural treatments have often compared clearcut
stands with untreated stands (e.g. Conner & Adkisson, 1975; Thompson & Fritzell, 1990;
Thompson et al., 1992). Costello et al. (2000) compared bird species richness and
abundance between clearcuts, group selection openings, and mature forest stands. Their
(Costello et al., 2000) study found higher species richness in clearcuts and higher
abundance of species that require or prefer the habitat on the edge or the interior of
clearcuts.
Relatively short-term studies have revealed that clearcuts often create habitat for
the open-edge nesting Indigo Bunting (Passerina cyanea), Prairie Warbler, and Yellowbreasted Chat (Annand & Thompson, 1997; Conner & Adkisson, 1975; Lesak et al.,
2004; Wallendorf et al., 1992), but negatively impact the forest interior nesting Acadian
6
Flycatcher (Empidonax virescens; Wallendorf et al., 2007), Worm-eating Warbler
(Conner & Adkisson, 1975; Gram et al., 2003; Thompson et al., 1992; Wallendorf et al.,
2007) and Ovenbird (Seiurus aurocapilla; Conner & Adkisson, 1975; King & DeGraaf,
2000; Wallendorf et al., 2007). The interior-edge nesting Kentucky Warbler (Geothlypis
formosa) was less sensitive to clearcut treatments and re-inhabited these stands in a
relatively short amount of time (Thompson et al., 1992). Long-term assessments of forest
bird responses to clearcut harvesting have been limited (e.g. McDermott & Wood, 2009).
Shelterwood Harvesting
Shelterwood harvests are often used to regenerate oak and involve a sequential
forest canopy removal. Partial removal of forest canopy initially allows light to penetrate
to the forest floor to promote oak regeneration, followed by final removal of all
harvestable trees (Loftis, 1990; Stringer, 2006). Studies of shelterwood harvesting effects
on forest bird species have been mostly short-term and limited, and few have compared
shelterwood with other treatments such as clearcut (e.g. Annand & Thompson, 1997;
King & DeGraaf, 2000; Lesak et al., 2004).
Studies of songbird response to silvicultural treatments are often short-term or
non-experimental, ex post facto, involving the examination of forest stands with variation
in treatment history. Even less studied are the responses of conservation priority species
(Rich et al., 2004) to both shelterwood and clearcut treatments in the Cumberland Plateau
Region (e.g. Lesak et al., 2004), especially in multiple stages of sequential treatments.
During the second year after initial shelterwood harvests, Lesak (2004) noticed favorable
response to all shelterwood treatments by the Kentucky Warbler; responses of the Prairie
7
Warbler and Worm-eating Warbler populations to treatments of 25% overstory retention
were also positive. Annand and Thompson (1997) compared the effects of stands treated
using the shelterwood method to clearcuts, group selection, single-tree selection, and
uncut stands and found higher species richness in shelterwoods than uncut stands.
Augenfeld et al. (2008) tested the effects of shelterwood harvesting (24-57% removal) in
oak-hickory forests of Kentucky and Tennessee on the bird community. Compared to
unharvested controls, shelterwoods held lower densities of interior-edge species such as
the Kentucky Warbler and Wood Thrush (Hylocichla mustelina) and interior species such
as the Worm-eating Warbler. King and DeGraaf (2000) found the highest richness in
shelterwoods, compared to clearcuts (three to five years post-harvest) and uncut sites.
Newell and Rodewald (2011) examined short-term response of bird community to
shelterwoods (50% stocking) compared to unharvested stands in oak-hickory forests of
southeastern Ohio. They found higher densities of canopy- and shrub-nesting species,
and lower densities of late-successional midstory- and ground-nesters after harvests. In
the central Appalachians, Sheehan et al. (2014) studied effects of a medium shelterwood
harvest compared to a light single-tree selection, a heavy even-aged harvest with
residuals (similar to clearcut), and an unharvested control. Their results indicated that
species richness was negatively correlated with increased residual basal area. Open-edge
species, such as the Yellow-breasted Chat, were positively associated with low residual
basal area; interior species, such as the Worm-eating Warbler, were positively associated
with higher residual basal area. Substantial gaps remain in our knowledge of short- and
long-term temporal response patterns of forest bird species to silviculture on the
Cumberland Plateau.
8
Hypotheses
Based on previous research conducted at the site (Lesak, 2004) and from the
literature review, I tested the following hypotheses (Ha):
Ha: 1. Bird community responses will display treatment and year effects of oak
regeneration treatments in 2010 (ninth year response to clearcuts and entry one of
shelterwood harvests): A. Interior and interior-edge species abundance will be higher in
controls (SW100), SW75, and clearcuts than in other shelterwoods (SW25 and SW50),
and overall abundance and species richness will increase compared to 2003 (Lesak et al.,
2004; Schweitzer & Dey, 2011). B. Open-edge species abundance will decrease
compared to 2003 (Gram et al., 2003; Robinson & Robinson, 1999). C. Species richness
and abundance will decrease compared to 2003 in shelterwood stands (from here on
referred to as shelterwoods) and clearcuts (Costello et al., 2000), as canopies close.
Ha: 2. Bird community responses will show treatment and year effects of oak
regeneration treatments in 2012 (eleventh year response to clearcuts and second year
response to the second entry of shelterwood harvests): A. In shelterwoods, interior and
interior-edge species abundance will decrease compared to controls (Lesak et al., 2004)
and clearcuts, and will decrease compared to 2010. B. Open-edge species abundance will
increase compared to 2010 in shelterwoods. C. Overall species richness and abundance
in shelterwoods will increase compared to 2010. D. Species richness and abundance in
clearcuts will not be different than 2010.
9
CHAPTER TWO
METHODOLOGY
Study Sites
The study was conducted on the southern end of the mid-Cumberland Plateau in
northern Jackson County, Alabama (Fig. 1). The average temperature in this region is
approximately 13° C and average annual precipitation is 149 cm (Smalley, 1982). Two
sites were used, one located at Miller Mountain (MM) [Fig. 2. (34” 58’ 30” N, 86” 12’
30” W)], and one at Jack Gap (JG) [Fig. 3. (34” 56’ 30” N, 86” 04’ 00” W)] (Lesak,
2004). Miller Mountain has a southern to southwestern aspect and JG has a northern
aspect (Schweitzer, 2004). Elevation for both sites varies between 260 to 520 m, with
slopes ranging from 15 to 30%. Upland hardwood was the primary forested land cover
type, composed mainly of oak and hickory (Carya spp.) with yellow-poplar, sugar maple,
red maple (A. rubrum), and American beech (Schweitzer, 2004).
Experimental Design
A complete randomized block design was initially established with five
treatments of varying basal area retention and replicated within three blocks in 2000.
Two blocks of ten stands were established at JG and one block of five stands at MM.
Each stand was approximately square in shape and 4 ha in size. Each block was
10
approximately 20 ha, for a total study area (in 2010) of 60 ha. All stands were arranged
adjacently within each block (Schweitzer, 2004). In 2011, three new stands (two at JG
and one at MM) were added to the study as new control stands (because the initial
controls were harvested) for a total of eighteen stands comprising a 72 ha study site (C. J.
Schweitzer, personal comm.).
Figure 1. Study site location for Jack Gap (JG) and Miller Mountain (MM), Jackson County, Alabama.
11
Experimental Treatments
The five treatments consisted of forest stands with the following target overstory
retention percentages: 0 (clearcut), 25, 50, 75, and 100 (control, no harvest for at least the
prior forty years), and were blocked by location (see Fig. 2 and 3). Trees in the 25% and
50% retention stands (SW25 and SW50) were marked and retained according to species
(preference was given to oak, ash, and persimmon), vigor, class, and crown position
(Schweitzer, 2004). Initial tree harvesting was accomplished by chain saw felling and
grapple skidding. Stands of 75% retention (SW75) were treated with an herbicide
injection (Arsenal®, containing active ingredient imazapyr) in 2001 to remove the
midstory. The stands of 25-75% retention were initiated as shelterwood stands
(Schweitzer, 2004) to investigate the relationship between varying levels of overstory
retention and oak regeneration. For comparisons with shelterwood treatments, stands of
0% retention were treated with a single clearcut prescription, which was completed in
2002 (Schweitzer, 2004). The study guidelines stated that no clearcut stands greater than
4 ha were allowed (C. J. Schweitzer, pers. commun.), which necessitated smaller
treatment stands than would be desirable for bird research. Although these stands were
not of ideal sizes to fully address all bird questions, the existing infrastructure permitted
me to do this work with an opportunity for considerable insight into bird responses.
All fifteen original forest stands were allowed to grow for approximately ten years
for advance regeneration of oaks to develop, and in 2011, residual harvestable trees in the
initial overstory stands of 25, 50, 75, and 100 (control) were removed during the second
phase shelterwood harvest using chainsaw felling and grapple skidding. Because the
initial control stands (100% retention) were harvested, three previously unstudied and
12
unharvested stands were added as controls for bird surveys and assessments in 2011.
After 2011 treatments were completed and new controls were established, there were
approximately five forest stand cohorts: (1) mature or 'new' control), (2) ten-year-old
regenerating clearcut, (3) released regeneration from the first phase harvest (25 and 50%
retentions); this cohort differed due to treatment, and included a well-established mid and
understory in conjunction with the residual canopy trees and with more vertical structure
due to either persistence of these under and midstory stems through the second harvest,
and/or from new sprouts on midstory trees and from overstory trees that were harvested,
Figure 2. Topographic map of complete block replicate one, showing treatments at Miller Mountain,
Jackson County, Alabama. One new control stand was added for 2011-2012 surveys.
13
(4) released regeneration from the 75% retention, which did not have a well-developed
midstory (mostly small-diameter sugar maple) because the midstory was killed with the
herbicide during the first treatment phase, which also prevented resprouting, and leaving
a much more herbaceous-to-shrubby layer than the 25 and 50% retention treatments
immediately after final harvest, and (5) new "clearcut," which was formerly the 100%
retention, and due to lack of prior treatments, this was essentially a clearcut, the same as
the first phase 0% retention treatments, but 10 years younger.
Tree and Canopy Cover Measurements`
Pre-treatment basal area data were collected from five measurement plots (0.08
ha) that were systematically located within each stand (Schweitzer, 2004). At these
locations, all overstory trees ≥ 14.2 cm in diameter at breast height (DBH; 1.4 m) were
measured prior to treatment in 2001 to estimate initial basal area (BA); these locations
were revisited in mid- to late-summer of 2002, 2003, 2004, 2005, 2006, 2009 (Schweitzer
& Dey, 2011), and 2011 (C. Schweitzer pers. comm.). These measurements were used to
calculate initial BA, residual BA, stem density, measured as stems per hectare (SPH), and
the percentage of overstory retention. These locations were also used for measuring
canopy cover with a handheld spherical densitometer at 1.4 m above the forest floor
surface; these measurements were taken at plot center and at 3.7 m in each cardinal
direction from plot center (Schweitzer & Dey, 2011).
In 2012, I used a hand-held spherical densiometer (Model-A, Forest
Densiometers, Rapid City, SD) to measure canopy cover at 1.4 m above the forest floor
surface. All monitored nest sites (unpublished data) that were located within the stands
14
were used for habitat measurements. Canopy cover was measured at the center of nests
and at 11.3 m from center in each cardinal direction. Comparison sites were used for
each nest at 35 m from nest center at a randomly selected bearing. The same canopy
cover measurements were collected at comparison sites; these data were used if the
comparison sites were located within study stands.
Figure 3. Topographic map of complete block replicates two and three, showing treatments at Jack Gap,
Jackson County, Alabama. Two new control stands were added for 2011-2012 surveys.
15
Forest Bird Assessment
Bird Territory Mapping
Bird surveys were conducted during the breeding season (late April to July) in
2002 and 2003 by Lesak (2004) and in 2010, 2011, and 2012 by my team. In 2002, three
transects were established in each stand. Transects ran parallel with the slope and were
spaced ≤ 50 m apart and from stand boundaries (Lesak, 2004). Each transect was marked
for reference at approximately 25 m intervals. The territory mapping technique followed
Williams (1936), the International Bird Census Committee (IBCC, 1970), and Ralph et
al. (1993). Each stand was surveyed nine to ten times per year, the appropriate amount of
sampling effort needed to reliably estimate territory data (Ralph et al., 1993; Lesak,
2004). Surveys took place in the morning between 0530 and 1030. An entire block of
replicates was covered within a single day to reduce temporal bias. To reduce observer
bias, surveys were conducted independently by one to two observers for each breeding
season. All three blocks were visited in a rotation before the next rotation began. In each
rotation, the order of visits within blocks was prearranged to ensure that all stands were
visited equal amounts at all possible morning times. Each survey in each stand lasted
forty-five minutes to one hour. Stand entrance and exit locations were also rotated.
During surveys, territorial defense displays (e.g. songs, calls, distraction displays) and
other behaviors indicative of an active territory were recorded on topographic maps.
Behaviors were then transposed onto transparency films and manually traced in 2002 and
2003 for territory determination (Lesak, 2004). Displays from all other years (2010,
2011, and 2012) were digitized in ArcMap (ArcGIS 10.0) for territory determination.
16
Territory Delineation
Data from surveys were used to delineate territories using criteria suggested by
IBCC (1970). To constitute a territorial cluster, a species must have been recorded on
three or more visits, two of which must have been 10 days apart or more, and two or
more must have included a song or other display of high territorial significance.
Territories were delineated by examining the stands that contained them, but also
adjacent stands. If approximately half of a territory’s registrations (observations)
occurred within a stand, a one-half of a territory was assigned. Existence of multiple
territories was determined to occur when one or more simultaneous registrations or an
individual or breeding pair was observed along with other supportive observations, and/or
two or more pairs of non-simultaneous registrations were made, and/or one or more nonsimultaneous registrations was coupled with knowledge of territory size for species with
low detection probabilities or few valid visits (late breeders) were observed. A few
exceptions to these criteria were accepted on the basis of strong evidence of breeding
(e.g. nest, nest building, food carrying).
Guild Categories
Bird species were assigned to guilds (Table 1) by Lesak (2004). These guilds
were based on migration, nesting, foraging, and habitat preference. Migrant guilds
(Imhof, 1976; Sauer et al., 1996) consisted of (1) Neotropical, species that migrate to
Central or South America in the fall, (2) Temperate, species that spend at least part of
their winter in the southern part of the United States and/or northern Caribbean Islands,
17
and (3) Resident species. Five nesting location guilds (Ehrlich et al.,1988) were used:
(1) Ground, (2) Low- shrub, (3) Midstory-subcanopy, (4) Canopy, and (5) Cavity.
Birds were assigned to four foraging guilds based on foraging behavior and substrate
(Ehrlich et al., 1988): (1) Foliage gleaners, which mostly feed on insects located on
vegetation, (2) Ground foragers, which feed from low vegetation, soil, and leaf litter, (3)
Bark gleaners, and (4) Hawking (aerial) foragers. Primary habitat association of
each bird species was based on categories suggested by Blake and Karr (1987), Freemark
and Collins (1992), and Lesak (2004), which included: (1) Open-edge, also known as
early successional, edge-, and field-dwelling species, (2) Interior-edge, species that
prefer forest interiors but are believed to be less disrupted by forest disturbance, and
forest edge inhabitants, and (3) Forest interior, species that require mature forests with
closed canopies, and usually require a minimum forest area.
Geographic Information System Applications
Geographic Information System (GIS) applications were used to enhance this
study continuation. Spot-mapping data were recorded and summarized with the use of
ArcMap. Topographic maps of each treatment stand and the territorial behavior
registrations detected within said stand for each survey in 2010, 2011, and 2012 were
scanned and saved as jpg files. These files were georeferenced, and data points were onscreen digitized in ArcMap; observations for each species on each stand were used for
quantifying territory density per stand.
18
Table 1. Scientific name, common name, and guild memberships of all forest songbird species that held
territories on the study sites in any of the years 2002, 2003, 2010, and 2012 at Jack Gap and Miller
Mountain in Jackson County, Alabama. Species classified by: fall migratory destination (N=Neotropical
migrant; T=temperate migrant; R=resident), nest location (G=ground; L/S=low-shrub; M/S=midstory and
subcanopy; CN=canopy; CV=cavity; P=parasite), foraging strategy (F=foliage glean; G=ground glean;
B=bark glean; H=hawking),and habitat association (O/E= open-edge; I/E=interior-edge; I=interior).
Species
Antrostomus vociferus, Eastern Whip-poor-will
Archilochus colubris, Ruby-throated Hummingbird
Baeolophus bicolor, Tufted Titmouse
Cardinalis cardinalis, Northern Cardinal
Coccyzus americanus, Yellow-billed Cuckoo
Contopus virens, Eastern Wood-Pewee
Cyanocitta cristata, Blue Jay
Dryocopus pileatus, Pileated Woodpecker
Empidonax virescens, Acadian Flycatcher
Geothlypis formosa, Kentucky Warbler
Geothlypis trichas, Common Yellowthroat
Hylocichla mustelina, Wood Thrush
Icteria virens, Yellow-breasted Chat
Icterus spurius, Orchard Oriole
Meleagris gallopavo, Wild Turkey
Melanerpes carolinus, Red-bellied Woodpecker
Melanerpes erythrocephalus, Red-headed Woodpecker
Mniotilta varia, Black-and-white Warbler
Myiarchus crinitus, Great Crested Flycatcher
Passerina caerulea, Blue Grosbeak
Passerina cyanea, Indigo Bunting
Picoides pubescens, Downy Woodpecker
Picoides villosus, Hairy Woodpecker
Pipilo erythrophthalmus, Eastern Towhee
Piranga olivacea, Scarlet Tanager
Piranga rubra, Summer Tanager
Poecile carolinensis, Carolina Chickadee
Polioptila caerulea, Blue-gray Gnatcatcher
Sayornis phoebe, Eastern Phoebe
Seiurus aurocapilla, Ovenbird
Setophaga citrina, Hooded Warbler
Setophaga discolor, Prairie Warbler
Sialia sialis, Eastern Bluebird
Sitta carolinensis, White-breasted Nuthatch
Spinus tristis, American Goldfinch
Spizella passerina, Chipping Sparrow
Spizella pusilla, Field Sparrow
Thryothorus ludovicianus, Carolina Wren
Toxostoma rufum, Brown Thrasher
Tyrannus tyrannus, Eastern Kingbird
Vireo flavifrons, Yellow-throated Vireo
Vireo griseus, White-eyed Vireo
Vireo olivaceus, Red-eyed Vireo
19
Migrant
Guild
T
N
R
R
N
N
R
R
N
N
T
N
N
N
R
R
R
T
N
N
N
R
R
R
N
N
R
T
R
N
N
T
R
R
R
R
R
R
T
N
N
T
N
Nest
Location
Guild
G
M/S
CV
L/S
M/S
CN
CN
CV
M/S
G
L/S
M/S
L/S
M/S
G
CV
CV
G
CV
L/S
L/S
CV
CV
G
CN
M/S
CV
M/S
G
L/S
L/S
CV
CV
L/S
L/S
G
L/S
L/S
CN
CN
L/S
M/S
Foraging
Guild
H
F
G
F
H
G
B
H
G
F
G
F
F
G
B
B
B
H
G
F
B
B
G
F
F
F
F
H
G
F
F
H
B
F
G
G
G
G
H
F
F
F
Habitat
Guild
O/E
O/E
I/E
I/E
I/E
I/E
I/E
I
I
I/E
I/E
I/E
O/E
O/E
O/E
I/E
I/E
I
I/E
O/E
O/E
I/E
I
I/E
I
I/E
I/E
I/E
I/E
I
I
O/E
O/E
I
O/E
O/E
O/E
O/E
O/E
O/E
I/E
O/E
I/E
Statistical Analyses
Treatment and Year Effect on Canopy Cover
Canopy cover measurement data collected by USDAFS in 2002, 2003, and 2009
(Schweitzer & Dey, 2011) were used for this study. These canopy cover data from 2009
were used to compare with bird data from 2010. Schweitzer and Dey (2011) used twoway factorial analysis of variance (ANOVA) to test the treatment and year effects while
controlling the block effect. Tukey’s Honestly Significant Difference (HSD) tests were
used for mean separation (SAS, 2000). When an interaction occurred between year and
treatment, they analyzed year separately using ANOVA with treatment and block as main
factors. They reported means and standard errors. Statistical tests were declared
significant when the probability of Type I error was ≤ 0.05.
I used one-way ANOVA and Tukey's HSD test (SPSS v20) to examine the effect
of treatment on my canopy cover measurements for 2012. I reported Schweitzer and Dey
(2011) means and standard errors for 2002 (first-year response), 2003 (second-year
response), and 2009 (used for ninth-year response in 2010), as well as my results for
means and standard errors for 2012 (second-year response to shelterwood removal
harvests and eleventh-year response to clearcuts).
20
Treatment and Year Effect on Birds
Bird data from 2002, 2003, 2010, and 2012 were analyzed using mixed model
(SPSS v20), with year as the repeated variable and treatment as the between-subjects
factor. Data from 2011 were excluded due to insufficient replications. Normality and
homogeneity of variance assumptions of the data were tested with Shapiro-Wilk and
Levene test, respectively. Data transformations such as log and arcsine were used if these
assumptions were not met. I tested the effects of treatment, year, and their interactions on
the bird community measurements such as territory density, richness, and pooled mean
territory density of guilds. Because of a low sample size and the desire to interpret
possible treatment effects, treatment/year interactions were deemed significant if p ≤
0.10. If there was no interaction between year and treatment, I directly examined the year
and treatment main effect; LSD tests followed at the significance level of p ≤ 0.10. If
there was an interaction between year and treatment, I examined treatment effect by each
year separately, followed by LSD tests. Territory density was used to quantify species
richness via the "recode into different variables" function (SPSS v20). For all species
that held territory values of > 0 in a stand, a new value of 1 was assigned to those species
in each relative stand. This allowed each species that held territories to have a single
value for each stand. These values were used to measure species richness.
21
CHAPTER THREE
RESULTS
Tree Measurements
Canopy Cover
Amount of canopy cover (Table 2) could be grouped into three levels in 2001
after initial treatments (Schweitzer & Dey, 2011). Closed (near 100%) canopy was
observed in SW75 and in SW100 (control), 75% cover was observed in SW50 and
SW25, and 31% cover was observed in clearcuts. By the second year post-initial
treatment, canopy was relatively unchanged in SW75 and SW100, but had dropped to
just under 50% in SW25 and SW50, and 5% in clearcuts. Eighth-year response in 2009
showed nearly full canopy closure in all stands and mean separations revealed no
difference among stands with different treatments. In 2012, two years after final
shelterwood removal harvests, canopy cover was highest in controls, followed closely by
2002 clearcuts, which had mostly closed (almost 90%) canopies. Shelterwoods varied
between 19% (SW75) and 78% (SW50); mean separations revealed no statistical
difference between SW75 and SW100, or between SW 25, SW50, clearcuts, and controls.
22
Table 2. Percent canopy cover means ± (SE) in 2002, 2003, 2009, and 2012 at Jack Gap and Miller
Mountain in Jackson County, Alabama. Data from 2002, 2003, and 2009 were collected by USDAFS and
reported by Schweitzer and Dey (2011). Sample sizes for 2012 were unequal between treatments and
lower compared to all other years. Treatments were: clear=clearcut in 2002; control=control installed for
2012 bird surveys; SW100=shelterwood with 100% target overstory retention level in 2001, used as bird
survey control for 2002, 2003, and 2010; SW25=shelterwood with 25% target overstory retention level in
2001; SW50=shelterwood with 50% target overstory retention level in 2001; SW75=shelterwood with 75%
target overstory retention level in 2001.
Treatment
2002
2003
2009
Clear
31.0 (28.6)B
5.4 (9.8)C
92.0 (11.5)A
SW25
76.0 (14.3)A
48.0 (16.3)B
95.4 (4.1)A
A
B
SW50
74.9 (11.9)
44.7 (14.2)
93.3 (7.0)A
A
A
SW75
98.3 (2.2)
94.6 (4.1)
93.4 (3.7)A
SW100
99.7 (0.3)A
96.8 (3.2)A
97.5 (1.3)A
Control
.
.
.
F
19.26
86.23
1.02
P-value
0.0004
<0.0001
0.4503
Columns with unique letters were significantly different at the 0.05 level.
2012
86.4 (1.6)A
68.1 (6.4)A
78.5 (7.4)A
19.0 (7.4)B
24.8 (3.3)B
88.7 (3.8)A
70.86
0.0000
Live Basal Area and Density
Mixed model analyses for both live basal area (BA; Table 3; Fig. 4) and density
(SPH; Table 4; Fig. 5) detected a treatment / year interaction, indicating treatment effects
shifted among years. Mean separations with LSD test showed that initial treatment
application resulted in a gradient of three different live BA (Table 3; Fig. 4), and the
differences were detected through year eight (2009). The clearcut stands held the lowest
live BA of trees ≥ 14.2 cm in diameter for all years examined, and was significantly
different than all other treatments. The herbicide treatment (SW75) contained the highest
live BA in years one and two and was not statistically different than SW100. Basal areas
in SW25 and SW50 were statistically different than other levels and were between
highest and lowest. These treatments (SW25 and SW50) were predominately populated
with new stump sprouts, many of which did not meet the criterion of ≥ 14.2 cm in
diameter in order to be measured.
23
Initial harvest
Final harvest
Figure 4. Mean basal areas (BA = m2 / ha) ± SE for all live trees ≥ 14.2 cm DBH in 2002, 2003, 2009, and
2011 at Miller Mountain and Jack Gap in Jackson County, Alabama. Vertical (y-axis) scale is different
than other figures due to variable value variations. Initial treatments were completed in 2001-2002:
clear=clearcut; SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with
50% target overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
24
For years one and two, tree density or number of live SPH of trees ≥14.2 cm in
diameter was split into two distinct statistical groups (Table 4; Fig. 5). Lowest SPH was
seen in clearcuts, SW50, and SW25; highest was seen in SW100 and SW75. By year
eight, there was a third group containing SW25 and SW75 that was detected in the
middle of highest and lowest live SPH. Residual harvest in only one block of stands was
completed prior to tree surveys in 2011, when there were insufficient replications for
testing treatment effect. Following residual harvests, all merchantable stems were
removed from the SW25, SW50, SW75, and SW100, resulting in considerably lower
SPH and BA in all but SW25 and control stands In year one following final harvest
(2011), live SPH was highest in control stands, followed by SW100. Lowest values were
seen in clearcut and SW75. Live BA was highest in the newly added controls and lowest
in SW75. This was reflective of the missing midstory that was deadened nine years prior.
Table 3. Mean ± (SE) basal areas (BA = m2/ha; all live trees ≥ 14.2 cm DBH) in 2002, 2003, 2009, and
2011 at Jack Gap and Miller Mountain in Jackson County, Alabama. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW
stands were harvested after 2010 bird surveys.
Treatment
2002
2003
A
1
2009
A
2011
A
Clear
2.0 (2.2)
2.1 (2.4)
2.7 (2.8)
SW25
10.1 (2.2)B
11.0 (2.4)B
11.5 (2.8)B
SW50
11.9 (2.2)B
12.4 (2.4)B
13.2 (2.8)B
C
C
SW75
24.1 (2.2)
24.6 (2.4)
25.0 (2.8)C
C
C
SW100
23.1 (2.2)
23.6 (2.4)
25.7 (2.8)C
Control
.
.
.
F
17.58
15.88
12.28
P-value
0.0002
0.0002
0.0007
Columns with unique letters were significantly different at P < 0.05.
1
Due to insufficient replications (one), data from 2011 were not tested for effect.
25
1.0 (0.7)
4.7 (0.7)
4.0 (0.7)
1.5 (0.7)
6.1 (0.7)
22.9 (0.7)
.
.
Initial harvest
Final harvest
Figure 5. Mean stems per hectare (SPH) ± SE for all live trees ≥ 14.2 cm DBH in 2002, 2003, 2009, and
2011 at Miller Mountain and Jack Gap in Jackson County, Alabama. Vertical (y-axis) scale is different
than other figures due to variable value variations. Initial treatments were completed in 2001-2002:
clear=clearcut; SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with
50% target overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
26
Table 4. Mean ± (SE) stems per hectare (SPH; all live trees ≥ 14.2 cm DBH) in 2002, 2003, 2009, and
2011 at Jack Gap and Miller Mountain in Jackson County, Alabama. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW
stands were harvested after 2010 bird surveys.
Treatment
2002
2003
2009
Clear
50.2 (28.9)A
48.8 (29.5)A
60.6 (28.4)A
A
A
SW25
132.3 (28.9)
135.1 (29.5)
143.7 (28.4)AB
A
A
SW50
103.1 (28.9)
103.6 (29.5)
109.2 (28.4)A
B
B
SW75
235.1 (28.9)
231.0 (29.5)
202.2 (28.4)BC
B
B
SW100
275.4 (28.9)
273.7 (29.5)
288.1 (28.4)C
Control
.
.
.
F
10.49
9.78
9.56
P-value
0.0013
0.0017
0.0019
Columns with unique letters were significantly different at P < 0.05
1
Due to insufficient replications (one), data from 2011 were not tested for effect.
1
2011
22.9 (44565.8)
117.8 (44565.8)
59.3 (44565.8)
17.3 (44565.8)
141.7 (44565.8)
328.0 (44565.8)
.
.
Bird Community Response
Species with Low Territory Densities
Species that held territories with low density values (<10 per year across all study
years) and were thus excluded from analyses included: the Acadian Flycatcher, Blue
Grosbeak (Passerina caerulea), Blue Jay (Cyanocitta cristata), Brown Thrasher
(Toxostoma rufum), Chipping Sparrow (Spizella passerina), Common Yellowthroat
(Geothlypis trichas), Eastern Bluebird (Sialia sialis), Eastern Kingbird (Tyrannus
tyrannus), Eastern Phoebe (Sayornis phoebe), Eastern Whip-poor-will (Antrostomus
vociferus), Field Sparrow (Spizella pusilla), Great Crested Flycatcher (Myiarchus
crinitus), Hairy Woodpecker (Picoides villosus), Orchard Oriole (Icterus spurius),
Ovenbird (Seiurus aurocapilla), Pileated Woodpecker (Dryocopus pileatus), Red-headed
Woodpecker (Melanerpes erythrocephalus), Ruby-throated Hummingbird (Archilochus
colubris), Wild Turkey (Meleagris gallopavo), Wood Thrush (Hylocichla mustelina), and
27
Yellow-billed Cuckoo (Coccyzus americanus). Several of these were found nesting
(some successfully) in or around the stands.
Other Detections
Individuals of other species were detected, but did not hold territories in the
stands. Many species were found only during spring migration. Species that were found
all three years of my study were the American Crow (Corvus brachyrhynchos), American
Redstart (Setophaga ruticilla), Barred Owl (Strix varia), Red-shouldered Hawk (Buteo
lineatus), Veery (Catharus fuscescens), and Yellow-throated Warbler (Setophaga
dominica). Species that were found only in 2012 and 2011 were the Chimney Swift
(Chaetura pelagica), Cerulean Warbler (Setophaga cerulea), and Swainson’s Thrush.
The Gray Catbird (Dumetella carolinensis) was found only in 2012 and 2010. The
Black-throated Green Warbler (Setophaga virens) and Broad-winged Hawk (Buteo
platypterus) were found only in 2012. The Cooper’s Hawk (Accipiter cooperii), Eastern
Screech Owl (Megascops asio), Magnolia Warbler (Setophaga magnolia), and Palm
Warbler (Setophaga palmarum) were found only in 2011. The Red-tailed Hawk (Buteo
jamaicensis) and Yellow Warbler (Setophaga petechia) were found only in 2010.
Territory Density
Overall response. Density value data for 2010 and 2012 were combined with data from
2002 and 2003 (Lesak, 2004). From four samples taken over the course of eleven years,
46 species held 1,380 territories on the study sites. Total number of species encountered
28
and territories maintained for each year were as follows: 2002, 32 species held 255
territories; 2003, 34 species held 357 territories; 2010, 30 species held 332 territories;
2012, 43 species held 436 territories.
Overall year and block effects by treatment. Pooling the interpreted territories for all
species yielded a total territory density for each treatment. Mixed model analysis
revealed an overall treatment / year interaction, suggesting the pattern of territory density
related to the treatments shifted between years (Fig. 6; F12 = 2.46, Ptreat*year = 0.003).
Clearcut density was highest in 2003 (second year response), which was similar to
clearcut density in 2012 and 2010, and lowest in 2002 (first year response), which was
similar to density values in 2012. Overall density in SW25 stands was highest in 2003
and lowest in 2002, although mean separations revealed no difference between years.
For SW50 stands, density was highest in 2003, which was statistically different than all
other years, and lowest in 2010, which was statistically similar to 2002 and 2012 (F2,2 =
17.19, Pyear = 0.055). No year effects were seen in SW75, but density was highest in
2010 and lowest in 2003. Density in SW100 stands was highest in 2012 and lowest in
2010, which held values similar to those observed in 2003 and 2002.
Overall treatment effects by year. Mixed model analysis with LSD test revealed an
interaction between treatment and year, indicating density values shifted between years
(Fig. 6; F12 = 2.46, Ptreat*year = 0.003). In 2002, overall density was highest in SW50 and
lowest in clearcuts. In 2003, abundance was highest in SW25, which was similar to
SW50, and lowest in SW100, which held density values similar to SW75 stands; clearcut
29
stands had densities just higher than SW75. In 2010 (the ninth year of the study), there
were three overlapping groups of density values; highest was in SW25, SW75, and
SW50, and lowest was in SW100 and clearcuts; in between these extreme groups were
values from stands of clearcuts, SW50, and SW75. In 2012, which was second-year
response to residual shelterwood harvests, density was highest in SW50 and lowest in
controls. Controls and clearcuts as a group were statistically lower in density than all
shelterwoods (F5,10 = 5.73, Ptreat = 0.009).
Species richness. Mixed model analysis with LSD test revealed an interaction between
year and treatment for species richness, indicating the values shifted between years (Fig.
7; F12,21 = 3.77, Ptreat*year = 0.004). In 2002, clearcuts were significantly lower in richness
than all other treatments (F4,8 = 1.92, Ptreat = 0.003). No difference was detected between
SW100 (control) and SW75, which were between highest and lowest richness levels, or
between SW75, SW25, and SW50, which held highest richness. In 2003, richness was
significantly higher in SW25 and SW50 than all other treatments and controls (F4,8 =
12.49, Ptreat2003 = 0.002). In 2010, richness was lower in SW100 (control) than treated
stands (F4,8 = 4.68, Ptreat2010 = 0.031). In 2012, after all residual harvests were made, all
shelterwoods including SW100 held higher richness than clearcuts and 'new' controls
(F5,10 = 12.20, Ptreat2012 = 0.001).
30
Initial harvest
Final harvest
Figure 6. Overall mean territory density [(territories/4-ha)*100] ± SE for all species that held ≥10
territories displaying treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack
Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other figures due to density
variations. Initial treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25%
target overstory retention level; SW50=shelterwood with 50% target overstory retention level;
SW75=shelterwood with 75% target overstory retention level; SW100=shelterwood with 100% target
overstory retention level, used as bird survey control for 2002, 2003, and 2010; control=control installed
for 2012 bird surveys. Initial harvests were completed before bird surveys in 2002, as denoted by the solid
red arrow. Residuals in SW stands were harvested after 2010 bird surveys, as denoted by the red-lined
arrow.
31
Initial harvest
Final harvest
Figure 7. Mean species richness ± SE including all species that held ≥10 territories displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
Individual species response. Overall treatment effects were observed in five species and
overall year effects were seen in eight species (Table 5). Treatment / year interactions
(Table 5) were detected in thirteen species.
32
The Black-and-white Warbler (Mniotilta varia) had a year-by-treatment
interaction (Table 5; Fig. 8; F12,23 = 1.92, Ptreat*year = 0.086). However, there were no
treatment effects in any given year.
Effects of treatment (Table 5; Fig. 9; F4,34 = 8.81, Ptreat = 0.000) and year (Fig. 10;
F3,21 = 15.48, Pyear = 0.000) were detected for the Blue-gray Gnatcatcher (Polioptila
caerulea), which was most abundant in SW50 and least abundant in clearcuts.
Initial harvest
Final harvest
Figure 8. Mean territory density [(territories/4 ha)*100] ± SE of the Black-and-white Warbler displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
33
Figure 9. Mean territory density [(territories/4 ha)*100] ± SE of the Blue-gray Gnatcatcher displaying
treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County,
Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial treatments
were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention
level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in all
SW stands were harvested after 2010 bird surveys.
Carolina Wren (Thryothorus ludovicianus) mean density had an interaction (Table
5; Fig.11; F12,18 = 5.66, Ptreat*year = 0.001). In 2002, density was highest in SW50 and
lowest in SW75 (F4,10 = 6.35, Ptreat2002 = 0.008). Second-year (2003) density was highest
in SW50 and clearcuts; lowest density was in SW100 and SW75 (F4,10 = 8.29, Ptreat2003 =
0.003). In 2010, density was highest in SW75 and lowest in clearcuts.
34
Initial harvest
Final harvest
Figure 10. Mean territory density [(territories/4 ha)*100] ± SE of the Blue-gray Gnatcatcher displaying
year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama.
Vertical (y-axis) scale is different than other figures due to density variations. Initial treatments were
completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in all SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
During the second year (2012) after residual harvests, Carolina Wren density was highest
in SW75 and lowest in clearcuts, which were statistically different than all other
treatments (F4,10 = 9.80, Ptreat2012 = 0.002).
35
Initial harvest
Final harvest
Figure 11. Mean territory density [(territories/4 ha)*100] ± SE of the Carolina Wren displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
The Downy Woodpecker (Picoides pubescens) displayed effects of treatment
(Table 5; Fig. 12; F4,36 = 4.36, Ptreat = 0.006) and year (Table 5; Fig. 13; F3,20 = 3.10, Pyear
= 0.049). Overall abundance was highest in SW75, which was similar in density to
SW50, and lowest was in clearcuts. Overall abundance was highest in 2002, which was
similar to density in 2010, and was lowest in 2003, which was similar to 2012.
36
Figure 12. Mean territory density [(territories/4 ha)*100] ± SE of the Downy Woodpecker displaying
treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County,
Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial treatments
were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention
level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW
stands were harvested after 2010 bird surveys.
37
Initial harvest
Final harvest
Figure 13. Mean territory density [(territories/4 ha)*100] ± SE of the Downy Woodpecker displaying year
effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical
(y-axis) scale is different than other figures due to density variations. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
Effects of treatment (Table 5; Fig. 14; F4,30 = 5.06, Ptreat = 0.003) and year (Table
5; Fig. 15; F3,22 = 4.30, Pyear = 0.016) were observed for the Eastern Towhee (Pipilo
erythrophthalmus). Overall density was highest in SW50, which was similar to clearcuts
and SW25, and was lowest in SW100. Overall density was highest in 2012 and lowest in
2002.
38
Figure 14. Mean territory density [(territories/4 ha)*100] ± SE of the Eastern Towhee displaying treatment
effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical
(y-axis) scale is different than other figures due to density variations. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in all
SW stands were harvested after 2010 bird surveys.
The Eastern Wood-Pewee (Contopus virens) had an interaction of treatment and
year (Table 5; Fig. 16; F12,20 = 2.43, Ptreat*year = 0.038). First-year response (2002) saw
highest density in SW25, which was similar to SW50; this group was statistically
different than SW100, clearcuts, and SW75, which held lowest density (F4,10 = 3.37,
Ptreat2002 = 0.054).
39
Initial harvest
Final harvest
Figure 15. Mean territory density [(territories/4 ha)*100] ± SE of the Eastern Towhee displaying year
effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical
(y-axis) scale is different than other figures due to density variations. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
After nine years of forest growth (in 2010) following initial treatments, density was
highest in SW75, which was statistically similar to SW25 and SW50; lowest density was
found in the statistically different group of clearcuts and SW100 (F4,10 = 4.31, P treat2010 =
0.028). In second-year (2012) response to final harvests density was highest in SW100
and SW25; these stands had statistically higher density than clearcuts and SW50, which
had lowest density (F4,10 = 4.51, P treat2012 = 0.024).
40
Initial harvest
Final harvest
Figure 16. Mean territory density [(territories/4 ha)*100] ± SE of the Eastern Wood-Pewee displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
The Hooded Warbler (Setophaga citrina) displayed a year effect (Table 5; Fig.
17; F3,14 = 36.47, Pyear = 0.000). Overall density was highest in 2010, which was different
than all other years; lowest density was in 2012.
41
Initial harvest
Final harvest
Figure 17. Mean territory density [(territories/4 ha)*100] ± SE of the Hooded Warbler displaying year
effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical
(y-axis) scale is different than other figures due to density variations. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in all SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
The Indigo Bunting (Passerina cyanea) showed different treatment effects in
different years (Table 5; Fig. 18; F12,18 = 11.62, Ptreat*year = 0.000). In first year response
(2002), density was highest was in SW50 and SW25; lowest was in SW100 (F4,10 =
11.56, Ptreat2002 = 0.001). After two growing seasons (in 2003), density was highest in
SW25 and clearcuts; lowest was found in SW100 and SW75 (F4,10 = 30.77, Ptreat2003 =
0.000). By the ninth year (2010) following initial treatments, density was highest in
42
SW25, which was similar to SW50 and SW75, and lowest was found in SW100, which
was different compared to all other treatments (F4,10 = 4.48, Ptreat2010 = 0.025). Almost
two years after residual harvests, density was highest in SW75 and lowest in controls
(F4,10 = 4.87, Ptreat2012 = 0.019). Clearcuts held next lowest density and were different
compared to all other treatments.
Initial harvest
Final harvest
Figure 18. Mean territory density [(territories/4 ha)*100] ± SE of the Indigo Bunting displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
43
The Kentucky Warbler had a treatment effect (Table 5; Fig. 19; F4,34 = 7.98, Ptreat
= 0.000). In all four study years, overall abundance was highest in SW50, which was
statistically similar to SW25; lowest abundance was in SW100, which was similar to
clearcut. Overall density was highest in 2012, which was similar to 2010; lowest density
was in 2002 (Fig. 20; F3,16 = 12.83, Pyear = 0.000).
Figure 19. Mean territory density [(territories/4 ha)*100] ± SE of the Kentucky Warbler displaying
treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County,
Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial treatments
were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention
level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW
stands were harvested after 2010 bird surveys.
44
Overall abundance for the Mourning Dove (Zenaida macroura) was highest in
2012 and lowest in 2002; density values in 2012 and 2010 were statistically higher than
values found in 2002 and 2003 (Table 5; Fig. 21; F3,16 = 7.52, Pyear = 0.002).
Initial harvest
Final harvest
Figure 20. Mean territory density [(territories/4 ha)*100] ± SE of the Kentucky Warbler displaying year
effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical
(y-axis) scale is different than other figures due to density variations. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
45
Initial harvest
Final harvest
Figure 21. Mean territory density [(territories/4 ha)*100] ± SE of the Mourning Dove displaying year
effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical
(y-axis) scale is different than other figures due to density variations. Initial treatments were completed in
2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
The Northern Cardinal (Cardinalis cardinalis) displayed a treatment by year
interaction (Table 5; Fig. 22; F12,20 = 2.47, Ptreat*year = 0.036). In the first year (2002)
following initial harvests, density was highest in SW50, which was statistically different
than all other treatments; lowest density was in clearcuts, SW25, and SW100 (F4,10 =
4.69, Ptreat2002 = 0.022). In the following year (2003), density was highest in SW50 and
clearcuts and lowest in SW75. No treatment effects were observed in any other years.
46
Initial harvest
Final harvest
Figure 22. Mean territory density [(territories/4 ha)*100] ± SE of the Northern Cardinal displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
The Red-bellied Woodpecker (Melanerpes carolinus) displayed an effect of year
(Table 5; Fig. 23; F3,19 = 3.88, Pyear = 0.026). Overall density was highest in 2012, which
was statistically similar to 2010; lowest density was in 2003, which was statistically
similar to 2002 and 2010.
47
The Red-eyed Vireo (Vireo olivaceus) had treatment effects that changed by year
(Table 5; Fig. 24; F12,19 = 2.11, Ptreat*year = 0.072). In 2002, density was highest in SW100
and SW75 and lowest in clearcuts, which were statistically different from all other
treatments (F4,10 = 9.54, Ptreat2002 = 0.002). In second-year (2003) response to initial
harvests, abundance was still greatest in SW75 and least in clearcuts; clearcuts and SW25
were statistically lower than all other treatments (F4,10 = 3.60, Ptreat2003 = 0.046). The
same pattern continued for the ninth year (2010; F4,10 = 2.81, Ptreat2010 = 0.084). In second
year (2010) response to final harvests, all treatments were statistically similar.
Initial harvest
Final harvest
Figure 23. Mean territory density [(territories/4 ha)*100] ± SE of the Red-bellied Woodpecker displaying
year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County, Alabama.
Vertical (y-axis) scale is different than other figures due to density variations. Initial treatments were
completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention level;
SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests
were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands
were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
48
Initial harvest
Final harvest
Figure 24. Mean territory density [(territories/4 ha)*100] ± SE of the Red-eyed Vireo displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
A treatment by year interaction was found for the Scarlet Tanager (Piranga
olivacea; Table 5; Fig. 25; F12,18 = 3.84, Ptreat*year = 0.005). First year response to initial
treatments had highest abundance in SW75 and SW50, which was similar to SW100;
lowest abundance was detected in clearcuts and SW25 (F4,10 = 7.61, Ptreat2002 = 0.004).
49
Initial harvest
Final harvest
Figure 25. Mean territory density [(territories/4 ha)*100] ± SE of the Scarlet Tanager displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
By the second year (2003), density was still highest in SW75 and lowest in clearcuts and
SW25 (F4,10 = 4.67, Ptreat2003 = 0.022). There were no treatment effects seen in years nine
(2010) or eleven (2012, which was also second-year response to residual harvests)
following initial treatments.
50
The Summer Tanager (Piranga rubra) displayed treatment effects that varied
according to year (Table 5; Fig. 26; F12,23 = 2.93, Ptreat*year = 0.013). In 2003 (second-year
response), density was highest in SW50; lowest was in the group of SW100 and SW75
stands (F4,10 = 8.75, Ptreat2003 = 0.003). Eleven years after initial treatments and almost
two years after final harvests, Summer Tanager abundance was highest in SW75 and
lowest in clearcuts; clearcuts were different than all other treatments (F4,10 = 4.02,
Ptreat2012 = 0.034).
Initial harvest
Final harvest
Figure 26. Mean territory density [(territories/4 ha)*100] ± SE of the Summer Tanager displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
51
The Tufted Titmouse (Baeolophus bicolor) displayed a treatment by year
interaction (Table 5; Fig. 27; F12,20 = 3.03, Ptreat*year = 0.014). In first-year (2002)
response, density was split into three distinct groups; highest was in SW100, SW75, and
SW50; lowest was in clearcuts; in between highest and lowest were SW25 and SW75
(F4,10 = 14.07, Ptreat2002 = 0.000). No treatment effects were found in any other years.
Initial harvest
Final harvest
Figure 27. Mean territory density [(territories/4 ha)*100] ± SE of the Tufted Titmouse displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
52
A treatment by year interaction was observed for the White-breasted Nuthatch
(Sitta carolinensis; Table 5; Fig. 28; F12,20 = 2.74, Ptreat*year = 0.022). After initial
harvests, density was highest in SW75 and lowest in clearcuts (F4,10 = 3.31, Ptreat2002 =
0.057). In second-year response (in 2003), density was highest in SW100, SW75, and
SW50 and lowest in clearcuts (F4,10 = 8.50, Ptreat2003 = 0.003). After nine years of forest
growth, density was still highest in SW75 and lowest in SW50, SW100, and clearcuts
(F4,10 = 3.72, Ptreat2010 = 0.042).
Initial harvest
Final harvest
Figure 28. Mean territory density [(territories/4 ha)*100] ± SE of the White-breasted Nuthatch displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
53
Initial harvest
Final harvest
Figure 29. Mean territory density [(territories/4 ha)*100] ± SE of the White-eyed Vireo displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
The White-eyed Vireo (Vireo griseus) had an interaction of treatment and year,
but treatment effects were only found in the ninth year (2010) after initial treatments
(Table 5; Fig. 29; F4,10 = 16.50, Ptreat2010 = 0.000). During that year, density was highest
in SW25 and clearcuts; density was lowest in SW75 and SW100.
54
A treatment by year interaction was detected for the Worm-eating Warbler (Table
5; Fig. 30; F12,23 = 3.92, Ptreat*year = 0.002). During first-year response, density was
highest in SW100 and SW75; lowest was in clearcuts and SW25 (F4,10 = 6.17, Ptreat2002 =
0.009). No treatment effects were discovered in 2003 or 2010. In second-year (2012)
response to final shelterwood harvests, density was found highest in controls and lowest
in SW75, SW100, and SW25 (F4,10 = 5.58, Ptreat2012 = 0.013).
Initial harvest
Final harvest
Figure 30. Mean territory density [(territories/4 ha)*100] ± SE of the Worm-eating Warbler displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
55
The Yellow-breasted Chat displayed unique treatment effects in almost every year
(Table 5; Fig. 31; F12,18 = 7.63, Ptreat*year = 0.000). No treatment effects were found in
first-year response. By the second-year (in 2003), highest density was in SW25 and
clearcuts; lowest density was in SW75 and SW100 (F4,10 = 12.77, Ptreat2003 = 0.001). In
2010, density was highest in clearcuts, SW25, and SW50; lowest was in SW100 and
SW75 stands (F4,10 = 3.59, Ptreat2010 = 0.046). In 2012, density was highest in SW50;
lowest density was in controls and clearcuts, which were different from all other
treatments (F4,10 = 3.85, Ptreat2012 = 0.038).
Initial
harvest
Final
harvest
Figure 31. Mean territory density [(territories/4 ha)*100] ± SE of the Yellow-breasted Chat displaying
treatment*year interaction in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson
County, Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial
treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory
retention level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with
75% target overstory retention level; SW100=shelterwood with 100% target overstory retention level, used
as bird survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Initial
harvests were completed before bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red-lined arrow.
56
The Yellow-throated Vireo (Vireo flavifrons) displayed an overall treatment effect
for all years studied (Table 5; Fig. 32; F4,36 = 6.22, Ptreat = 0.001). This species was most
abundant overall in SW75 and SW25; lowest abundance was in clearcuts.
Figure 32. Mean territory density [(territories/4 ha)*100] ± SE of the Yellow-throated Vireo displaying
treatment effect in 2002, 2003, 2010, and 2012 at Miller Mountain and Jack Gap, Jackson County,
Alabama. Vertical (y-axis) scale is different than other figures due to density variations. Initial treatments
were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25% target overstory retention
level; SW50=shelterwood with 50% target overstory retention level; SW75=shelterwood with 75% target
overstory retention level; SW100=shelterwood with 100% target overstory retention level, used as bird
survey control for 2002, 2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW
stands were harvested after 2010 bird surveys, as denoted by the red arrow.
57
Foraging guilds. Bark foragers displayed an overall treatment effect for all years
examined; they were most abundant in SW75 and least abundant in clearcuts (Table 6;
Fig. 33; F4,33 = 3.96, Ptreat = 0.010). Clearcuts were significantly different than all other
treatments.
Figure 33. Mean territory density [(territories/4 ha)*100] ± SE for all bark foraging species that held ≥10
territories. As a group, these displayed a treatment effect in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other figures
due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW stands were harvested
after 2010 bird surveys.
58
Foliage gleaners had an interaction (Table 6; Fig. 34; F12,17 = 5.74, Ptreat*year =
0.001). During 2002, first-year response, abundance was highest in SW50 and SW75 and
lowest in clearcuts (F4,8 = 12.20, Ptreat2002 = 0.002). After two years of forest growth,
foliage gleaners had highest density in SW25 and SW50; lowest density was in SW100
and SW75 (F4,8 = 16.00, Ptreat2003 = 0.001). In 2010, nine years after initial treatments,
density was highest in SW25; density was lowest in SW100 (F4,8 = 3.42, Ptreat2010 =
0.066). After final harvests were made, no treatment effects were seen.
Initial
harvest
Final
harvest
Figure 34. Mean territory density [(territories/4 ha)*100] ± SE for all foliage gleaning species that held
≥10 territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
59
Treatment effects on ground foragers varied by year (Table 6; Fig. 35; F12,19 =
3.60, Ptreat*year = 0.007). After initial treatment, abundance was highest in SW50; lowest
was SW100, SW75, and clearcuts (F4,8 = 22.68, Ptreat2002 = 0.000). Second-year density
was highest in SW50, SW25, and clearcuts; lowest was in SW100 and SW75 (F4,8 =
17.85, Ptreat2003 = 0.000) After nine years of forest succession, abundance was highest in
clearcuts, SW25, and SW50; lowest was in SW100 stands (F4,8 = 3.34, Ptreat2010 = 0.069).
Initial harvest
Final harvest
Figure 35. Mean territory density [(territories/4 ha)*100] ± SE for all ground foraging species that held
≥10 territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
60
Hawking foragers had treatment effects that were different by year (Table 6; Fig.
36; F12,20 = 2.43, Ptreat*year = 0.038). First-year density was highest in SW25 and SW50;
lowest was in SW100, clearcuts, and SW75 (F4,8 = 4.54, Ptreat2002 = 0.033) . Ninth-year
density was highest in SW25, SW50, and SW75; lowest was in clearcuts (F4,8 = 4.00,
Ptreat2010 = 0.045).
Initial harvest
Final harvest
Figure 36. Mean territory density [(territories/4 ha)*100] ± SE for all hawking forager species that held
≥10 territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
61
Habitat guilds. Initial response of forest interior species had highest density in SW100,
which had no treatment applied, and SW75; lowest density was in clearcuts and SW25
stands (Table 6; Fig. 37; F4,8 = 5.89, Ptreat2002 = 0.016). Second-year response revealed a
similar trend (F4,8 = 4.52, Ptreat2003 = 0.033). After nine years of forest succession, no
treatment effects were observed. In 2012, almost two years following final harvests,
abundance was highest in SW50; lowest was in SW75 (F4,8 = 2.83, Ptreat2012 = 0.099).
Initial harvest
Final harvest
Figure 37. Mean territory density [(territories/4 ha)*100] ± SE for all forest interior species that held ≥10
territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
62
Density of interior-edge species in first-year response to treatments was highest in
SW50, SW25, and SW75; lowest density was in clearcuts (Table 6; Fig. 38; F4,8 = 13.56,
Ptreat2002 = 0.001). Second-year density was highest in SW50 and SW25; lowest density
was in clearcuts, SW100, and SW75 (F4,8 = 5.34, Ptreat2003 = 0.022).
Initial harvest
Final harvest
Figure 38. Mean territory density [(territories/4 ha)*100] ± SE for all interior-edge species that held ≥10
territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow
63
Open-edge species density in first-year response was highest in SW50 and SW25;
lowest density was in SW100 and SW75 (Table 6; Fig. 39; F4,8 = 12.56, Ptreat2002 =
0.002). Second-year density was highest in SW25 and clearcuts; lowest was in SW100
and SW75 stands (F4,8 = 56.44, Ptreat2003 = 0.000). In ninth-year response, abundance was
highest in SW25, SW50, and clearcuts; lowest abundance was in SW100 and SW75 (F4,8
= 5.69, Ptreat2010 = 0.018). Almost two years following final harvests, in 2012, density
was highest in all shelterwoods and lowest in clearcuts (F4,8 = 9.39, Ptreat2012 = 0.004).
Initial harvest
Final harvest
Figure 39. Mean territory density [(territories/4 ha)*100] ± SE for all open-edge species that held ≥10
territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
64
Migratory guilds. In first-year response to initial treatments, density of Neotropical
migrants was highest in SW50, SW25, and SW75; lowest density was in clearcuts (Table
5; Fig. 40; F4,8 = 8.02, Ptreat2002 = 0.007). Second-year density was highest in SW25 and
SW50; lowest was in SW100 (F4,8 = 20.83, Ptreat2003 = 0.000). Following nine years of
successional growth, highest was in SW75, SW50, and SW25; lowest was in SW100 and
clearcuts (F4,8 = 2.88, Ptreat2010 = 0.095). Two years post-residual shelterwood harvests,
all shelterwoods had highest density; clearcuts had lowest (F4,8 = 2.86, Ptreat2010 = 0.096).
Initial harvest
Final harvest
Figure 40. Mean territory density [(territories/4 ha)*100] ± SE for all Neotropical migrant species that held
≥10 territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow
65
During first-year response, resident species had highest density in SW50; lowest
density was in clearcuts (Table 5; Fig. 41; F4,8 = 10.38, Ptreat2002 = 0.003). Approximately
two years following treatments, density was still highest in SW50; lowest density was in
SW100, SW75, and clearcuts (F4,8 = 4.18, Ptreat2003 = 0.041). No effects occurred in year
nine or eleven following initial harvests.
Initial harvest
Final harvest
Figure 41. Mean territory density [(territories/4 ha)*100] ± SE for all resident species that held ≥10
territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow
66
Temperate migrants showed no treatment response in first-year (Table 5; Fig. 42).
By second-year, density was highest in SW50, clearcuts, and SW25; lowest density was
in SW75 and SW100 (F4,8 = 12.14, Ptreat2003 = 0.002). After nine years, density was
highest in SW25 and SW50; lowest density was in SW100 and SW75 (F4,8 = 7.03,
Ptreat2010 = 0.010). No effects were detected two years after final harvests.
Initial harvest
Final harvest
Figure 42. Mean territory density [(territories/4 ha)*100] ± SE for all temperate migrant species that held
≥10 territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
67
Nesting guilds. In first-year response to initial treatments, canopy nesters held highest
density in SW50, SW25, and SW75; lowest density was in clearcuts and SW100 stands
(Table 5; Fig. 43; F4,8 = 5.28, Ptreat2002 = 0.022). After two years of successional growth,
density was highest in SW75; lowest density was in clearcuts (F4,8 = 14.09, Ptreat2003 =
0.001). No treatment effects were found in 2010 or 2012.
Initial harvest
Final harvest
,
Figure 43. Mean territory density [(territories/4 ha)*100] ± SE for all canopy nesting species that held ≥10
territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
68
Cavity nesters showed a treatment effect (Fig. 44; F4,29 = 6.35, Ptreat = 0.001).
This nesting guild was most abundant overall in SW75 and SW50; lowest abundance was
in clearcut stands.
Figure 44. Mean territory density [(territories/4 ha)*100] ± SE for all cavity nesting species that held ≥10
territories. As a group, these displayed a treatment effect in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other figures
due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW stands were harvested
after 2010 bird surveys.
69
The ground nesting guild displayed overall effects of both treatment (Fig. 45; F4,31
= 5.01, Ptreat = 0.003) and year (Fig. 46; F3,21 = 13.11, Pyear = 0.000). Overall density in
all years examined was highest in SW50 and SW25; lowest density was in SW100,
clearcut, and SW75 stands. Ground nesters had highest density in 2010 and 2012; lowest
density was in 2002.
Figure 45. Mean territory density [(territories/4 ha)*100] ± SE for all ground nesting species that held ≥10
territories. As a group, these displayed a treatment effect in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other figures
due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW stands were harvested
after 2010 bird surveys.
70
Density of low-shrub nesters varied by treatment and year (Fig. 47; F12,20 =
16.00). In year one, density was highest in SW50; lowest density was in SW100 and
SW75 (F4,8 = 11.87, Ptreat2002 = 0.002). One year later, highest density was in SW25 (F4,8
= 56.04, Ptreat2003 = 0.000). After nine years of forest succession, density was highest in
SW25 and SW50 stands; lowest density was in SW100 (F4,8 = 5.66, Ptreat2010 = 0.018). In
2012, density was highest in SW25 and lowest in clearcut (F4,8 = 8.06, Ptreat2012 = 0.007);
density in all shelterwoods was found to be statistically similar for that year.
Initial harvest
Final harvest
Figure 46. Mean territory density [(territories/4 ha)*100] ± SE for all ground nesting species that held ≥10
territories. As a group, these displayed a year effect in 2002, 2003, 2010, and 2012 at Miller Mountain and
Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other figures due to density
variations. Initial treatments were completed in 2001-2002: clear=clearcut; SW25=shelterwood with 25%
target overstory retention level; SW50=shelterwood with 50% target overstory retention level;
SW75=shelterwood with 75% target overstory retention level; SW100=shelterwood with 100% target
overstory retention level, used as bird survey control for 2002, 2003, and 2010; control=control installed
for 2012 bird surveys. Initial harvests were completed before bird surveys in 2002, as denoted by the solid
red arrow. Residuals in SW stands were harvested after 2010 bird surveys, as denoted by the red-lined
arrow.
71
Initial harvest
Final harvest
Figure 47. Mean territory density [(territories/4 ha)*100] ± SE for all low-shrub nesting species that held
≥10 territories. As a group, these displayed a treatment*year interaction in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
72
Species in the midstory-subcanopy nesting guild displayed overall effects of
treatment (Fig. 48; F4,38 = 15.13, Ptreat = 0.000) and year (Fig. 49; F3,18 = 13.09, Pyear =
0.000). In all years examined, this guild was most abundant in SW50 and SW75; lowest
abundance was in clearcuts. Abundance for this group was highest in 2003; lowest
abundance was in 2012 and 2002.
Figure 48. Mean territory density [(territories/4 ha)*100] ± SE for all midstory-subcanopy nesting species
that held ≥10 territories. As a group, these displayed a treatment effect in 2002, 2003, 2010, and 2012 at
Miller Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other
figures due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Residuals in SW stands were harvested
after 2010 bird surveys.
73
Initial harvest
Final harvest
Figure 49. Mean territory density [(territories/4 ha)*100] ± SE for all midstory-subcanopy nesting species
that held ≥10 territories. As a group, these displayed a year effect in 2002, 2003, 2010, and 2012 at Miller
Mountain and Jack Gap, Jackson County, Alabama. Vertical (y-axis) scale is different than other figures
due to density variations. Initial treatments were completed in 2001-2002: clear=clearcut;
SW25=shelterwood with 25% target overstory retention level; SW50=shelterwood with 50% target
overstory retention level; SW75=shelterwood with 75% target overstory retention level;
SW100=shelterwood with 100% target overstory retention level, used as bird survey control for 2002,
2003, and 2010; control=control installed for 2012 bird surveys. Initial harvests were completed before
bird surveys in 2002, as denoted by the solid red arrow. Residuals in SW stands were harvested after 2010
bird surveys, as denoted by the red-lined arrow.
74
CHAPTER FOUR
DISCUSSION
Bird Community and Habitat
Response of bird communities varied temporally or between between treatments.
Overstory removal created early successional habitat, which changed rapidly and
included a dramatic turnover in bird species composition. This was noted in years two
and three (Lesak, 2004), when species such as the Indigo Bunting increased in abundance
in clearcuts and in shelterwoods that had lower values of residual BA and higher
percentages of overstory removed. By year nine, abundance was still higher in clearcuts
and SW25 / SW50 for species such as the Yellow-breasted Chat and White-eyed Vireo,
yet interior-edge species such as the Kentucky Warbler were provided habitat in the
closed canopies of regenerating clearcuts.
As hypothesized, bird community responses in ninth year (2010) following
clearcut and entry one of shelterwood harvests varied according to primary habitat guilds.
Compared to stands treated with SW50, interior species were more abundant in SW75
and control (SW100) stands. Contrary to my predictions, interior species were less
abundant in the regenerating clearcuts as well as controls than SW50 and SW25. This is
most likely due to the increased vertical and horizontal structure that was created by the
logging activity that occurred in these stands. Interior-edge species showed a similar
75
pattern; abundance was highest in SW75, followed closely by SW25 and SW50. Lowest
values were seen in clearcuts and controls (SW100), opposite to how I predicted.
Between second (2003) and ninth (2010) years, overall abundance increased only in
SW75 stands, while species richness increased in all treatments. Open-edge species
abundance decreased in all but the herbicide (SW75) and control (SW100).
Bird community responses showed treatment and year effects of clearcuts in
eleventh-year (2012) response, as well as effects of shelterwood treatments in secondyear (2012) response to residual harvests. Compared to ninth-year (2010) response,
interior species abundance decreased only in SW25, SW75, and SW100. For interioredge species abundance, values decreased in all but SW100 and controls. As predicted,
open-edge species abundance increased in all shelterwoods. Overall abundance increased
only in SW50 and SW100, while species richness increased in all but clearcut and SW25.
It is important to consider the differences between treatment prescription and
execution. For example, stand 15 was originally a SW100, which was used as a control
through 2010, but roughly half of the stand was not logged during the residual harvest.
Therefore, in 2012 this stand appeared similar to a SW25 stand in that there were many
young trees with noticeably smaller diameters and dense understory and midstory layers,
which possibly helps explain why bird diversity was higher in this stand compared to
other SW100 stands. In the same year and stand, species from open-edge, interior-edge,
and interior guilds were observed. Understories in other SW100 stands were not thick
and well-developed prior to final harvest. Because of this, conditions similar to that of a
commercial clearcut were found after final harvest. There were also differences between
initial SW100, which was used as control for bird surveys prior to 2011, and ‘new’
76
controls, installed after 2010 bird surveys. For example, Blue-gray Gnatcatcher density
in SW100 was slightly higher than in controls in 2012. ‘New’ controls were not
evaluated prior to the second silvicultural entry of the study; bird density / diversity in
these stands prior to 2011 was unknown.
Using data from the 0.08 ha plots for determining BA and density values may
have excluded important data, especially for early successional species. These plots only
examined trees that were ≥ 14.2 cm at DBH, a criterion that left out many of the young
stems that were prevalent in clearcut, SW25, and SW75. These smaller stems are not
only important for providing nest cover and protection from predators, but they also more
properly describe tree species composition. Future analyses will examine data from 0.01
ha plots, from which the USDAFS collected diameter for all trees ≥ 3.8 cm DBH. In
addition, understory and overstory vegetation data from 2012 (which were not available
yet for these analyses) will be examined. Tree data from 2011 (block one only) were not
tested for effects due to insufficient replications.
Block effects were expected due to differences in aspect between the two study
sites. Aspect can be used as a predictor for vegetative growth and thus bird response.
Jack Gap was more mesic compared to MM. If humidity is low, soil moisture decreases,
which changes vegetation growth and thus bird response. In addition, there was a
temporal gap between the residual harvests of block one, which was harvested mostly in
winter 2010, and blocks two and three, harvested mostly in summer 2011. It was visually
obvious that vegetation growth was advanced in block one. Blocks two and three had
less dense understory development during 2012 bird surveys. Future studies will
77
examine soil moisture indices for blocks. Block effects will be correlated with shrub
density values and understory plant species composition.
Foraging location guilds were affected differently according to treatment and
year. Bark foragers, which held higher densities in all years in all shelterwoods
compared to clearcuts, were the only foraging location guild to show an overall treatment
response pattern. Throughout the study, shelterwoods provided standing trees, whether
dead or living, whereas all merchantable trees were removed from clearcut stands.
Foliage gleaning, ground, and hawking foragers, as well as all migratory and primary
habitat guilds, showed temporal- and treatment-dependent response patterns.
Nest-site displayed general patterns in cavity, ground, and midstory/subcanopy
nesters. Cavity nesters were most abundant across all years in SW75, which had 48% of
its residual trees in the 5 to 10 cm DBH category (C.J. Schweitzer, pers. comm.) and in
SW50. Cavity nester abundance did not vary between years in SW75, most likely
because logged trees were left lying on the ground and continued to provide foraging
opportunities even after final harvests were completed in 2011. Bark foragers (which
mostly nest in cavities) utilize dead trees, whether they are standing or are down. Ground
nesters were most abundant in SW25 and SW50, most likely attributed to the dense
understories that were provided by the shelterwood treatments. Ground nesters were also
most abundant in years nine and eleven, which illustrates the temporal effects of the
logging activities. This guild responded most favorably to the SW25 and SW50
treatments. The treatment effect seen in these stands is explained by the vertical and
horizontal structure that was created by these treatments, i.e. a more open canopy resulted
with a higher density of smaller diameter trees, thicker layers of herbaceous cover,
78
shrubs, and other understory components, and a well-developed midstory; these
structures are essential for protection of bird nests from predators and weather.
Midstory/subcanopy nesters preferred SW75 and SW50 and were highest in abundance in
year two. Low-shrub nesting species density was highest in SW50 for first year response,
but was highest in clearcut and SW25 during the second year. By year nine, density was
highest in SW25 and SW50. In year eleven, after final harvests, this guild preferred all
shelterwoods to clearcuts. Low-shrub nesting composition most likely evolved in two
steps: (1) colonization, where birds immigrated to the stands after initial treatments when
areas were opened and new nesting habitat was provided, and (2) reproduction, where
younger birds colonized and older individuals returned. The sole species of the parasite
nesting guild was the Brown-headed Cowbird (Molothrus ater). This species generally
requires a different criterion for calculating density, which is number of females detected
per unit. These data will be examined in future manuscripts.
Abundance of interior species guild showed no treatment effects in 2010, which is
most likely due to canopy closure in all treated stands. In 2012, interior species
abundance in SW100, SW25, and SW50 was not different from clearcuts, which was
interesting. Canopy cover for that year in SW100 and SW75 was statistically different
from SW25, SW50, controls, and clearcuts. One possible explanation is that shelterwoods
may provide sufficient canopy habitat for mature forest species if some (<50%) overstory
is retained for several years after an initial harvest (Dickson et al., 1995). Some interior
species, such as the Worm-eating Warbler, are foliage gleaners, and have shown longterm positive response to shelterwoods and their resultant increased complexity in forest
structure (Augenfeld et al., 2008).
79
Black-and-white Warbler density values were different in first-year response
(2002) to clearcuts than first-year response (2011) to residual harvests in SW25, SW50,
and SW75. Second-year response to these residual harvests was similar. Because 2011
results were not analyzed due to insufficient replication, it is hard to draw conclusions
from data in that year, but it may still be worth considering. Canopy cover data in
clearcuts immediately post-harvest were different compared to those of SW25 and SW50
following residual harvests. These shelterwoods (SW25 / SW50) had a prominent
midstory, tending to intermediate crown position trees. These trees were not harvested in
the second harvest, and most likely provided the structure and canopy cover to which
these birds responded. Shelterwoods have caused long term increases in understory
shrub and tree density (Augenfeld et al., 2008). Despite this species' preference for
mature, open forests with closed canopies, abundance was positively correlated with
understory shrubs and trees in even-aged stands in Pennsylvania (Yahner, 1986).
Analysis of microhabitat, rainfall, and other environmental variable data may help to
further explain my results.
Abundance of open-edge species was significantly higher in clearcuts, SW50, and
SW25 than SW100 and SW75 in all years except for 2012, which was after residual
shelterwood harvests. Overstory retention was not found to be different between SW100
(untreated until 2011) and SW75 by second-year post-treatment (Schweitzer & Dey,
2011), which most likely explains why open-edge abundance was not different between
these stands in all years but 2012. During 2012, densities were higher in all shelterwoods
compared to clearcuts, most likely attributed to increased shrub density, higher
herbaceous cover (Augenfeld et al., 2008) and sapling regeneration, which have been
80
positively correlated to abundance of some open-edge species (Newell & Rodewald,
2012). Understory growth was huge for SW25 / SW50, which held lots of small trees
(>550 SPH of all trees ≥ 3.8 cm DBH; C. J. Schweitzer, pers. commun.); this probably
explains why many open-edge species were abundant in these stands. Contrary to
findings of Newell and Rodewald (2012), Prairie Warbler density did not respond to
treatment or year, nor did it have a treatment / year interaction. Fables (1939) found
denser populations in burned compared to unburned habitat, so lack of burn in these
study sites may have contributed to its lack of response. Another possibility is that shrub
density, which has been positively correlated to Prairie Warbler density (Nolan, 1978),
was not adequately developed in test years, leading to no response. This is unlikely, as
shrub layers were quite dense. Analysis of microhabitat data collected may help to
explain these results. Higher densities of this species have been found in xeric
communities compared to those that are mesic (Nolan, 1978). Although all study sites
were considered mesic, blocks two and three were more mesic than block one (C. J.
Schweitzer, pers. commun.). The Prairie Warbler should have responded but may have
been constrained by the size of the treatment units, which were perhaps too small to have
attracted the species into them in the larger matrix of continuous forest (Johnston &
Odum, 1956; Nolan et al., 2014; P. Hamel, pers. commun.). In contrast, the Yellowbreasted Chat responded favorably to overstory removal and basal area reduction because
it is less intolerant of small stands (Eckerle & Thompson, 2001). Future studies of this
nature should ideally have larger stands, ~10-30 ha in closed habitat and 40-100 ha in
open habitat (IBCC).
81
Interior-edge species were more abundant in SW25, SW50, and SW75 compared
to clearcuts and controls (SW100) in year one. By the second year post-initial treatment,
abundance of this guild was not different between clearcuts, SW100, which received no
treatment, or SW75, which had the midstory deadened with an herbicide and no other
disturbance. These results are similar to those of Newell and Rodewald (2012), which
found the Kentucky Warbler breeding in shelterwoods in second and third years after
shelterwood harvests. Also included in this guild is the Eastern Wood-Pewee, which
continued to decline across the entire study.
Richness fluctuated between treatments and study years which were examined
over an eleven-year-period. In 2010 (ninth year response to clearcuts and initial
shelterwood harvests, and one year prior to residual shelterwood harvests), richness was
higher in all treated stands compared to SW100 (control for those years). There were no
differences found in canopy cover between any treatments or controls by the eighth year
(2009) following treatments (Schweitzer & Dey, 2011). Lesak (2004) found no
difference between clearcuts and shelterwoods in second-year (2003) response to
clearcuts and initial shelterwood harvests. Also similar were shelterwoods in first-year
(2002) response, and these stands had higher richness than clearcuts. In second year
(2012) after residual shelterwood harvests, richness was higher in all shelterwoods
compared to clearcuts and controls. The only shelterwood that showed a new pattern
compared to 2010 was SW100. This was expected as the initial treatment for these
stands was to do nothing, then complete a total harvest in 2011, so that canopies were
removed in these stands following 2010 surveys. However, examination of year effects
by clearcut showed no difference between 2003, 2012 (eleventh year response), and
82
2010, years that held higher richness than 2002. This demonstrated that the trees in the
clearcut stands quickly reached stem initiation, and just as fast succeeded into stem
exclusion, where they currently remain (C. J. Schweitzer, pers. commun.). Year effects
for SW75 showed 2012 and 2003 held similar richness and were lower than 2002 and
2010. Richness was higher in year eleven than all other years in SW100, SW25, and
SW50. This is somewhat different than a similar upland hardwood study in Kentucky
and Tennessee, which showed no difference in richness between treatments in any years
(Augenfeld et al., 2008).
When measuring bird response to silvicultural treatments, using territory density
and richness results alone may be misleading. Breeding success (Vickery et al., 1992)
and microhabitat correlations should be taken into consideration in order to form an
accurate prescription for many species. Future analyses will include these bird density
and diversity values and their correlations (if any) to tree species composition, understory
composition, canopy cover, and shrub density.
83
CHAPTER FIVE
CONCLUSIONS
Management Implications
My results combined with those of Lesak (2004) indicate that a wide variety of
basal areas and canopy cover levels are recommended to maintain the species
composition of these and other upland mixed hardwood forest bird communities along
the Cumberland Plateau. Temporal response effects revealed that overall density was
highest in clearcuts in the second, ninth, and eleventh years following treatments, which
suggested that these stands treated with a commercial clearcut may provide adequate
habitat after several years of succession. There was a territory density decline in these
stands, beginning in 2003, which was second-year response; this indicates that some
treatments have an expiration date for many species, and should be repeated at certain
intervals to increase or maintain overall density or richness. Stands of SW100, which
were control stands for all years except years ten (2011) and eleven (2012), held highest
overall density in year eleven after a commercial clearcut harvest was administered.
These results demonstrate the need for increasing shrub density and herbaceous cover to
provide habitat for many open-edge species (Augenfeld et al., 2008). The commercial
clearcut harvests in SW100 stands during year eleven caused significant canopy and basal
area reduction, thereby allowing light to penetrate the forest floor and understory
84
vegetation to grow. Overall bird density values in stands treated with SW25 and SW75
were not different between any years. When compared to control stands, we can assume
that effects from both of these treatments continued throughout the duration of the study.
In SW50 stands, density was highest in second-year response (2003); all other years were
statistically the same.
Many Neotropical migrants are of concern to wildlife researchers. My results
indicate that the BA and canopy reduction that occurred in SW25 and SW50 provided
breeding habitat for many species in this guild across all years of the study. However,
because species from this migratory guild are found in three unique, primary habitat
guilds, it is important that to consider these guild-level responses to the treatments in this
study.
All three primary habitat guilds were represented in the habitat mosaics that were
created under the treatments in this study. Forest interior species density was low in firstand second-year response to shelterwoods and clearcuts, but appeared to rebound by year
nine. Interior species re-inhabited small clearcuts in eight to ten years. Species that are
mostly found along the interior-edge of the forest appeared even less impacted by the
changes in stand composition and structure following the logging activity; this interioredge guild used shelterwoods even after removal of residual trees. This indicates that
interior-edge species are quite resilient to shelterwood and clearcut treatments. Openedge species benefited most from immediate habitat created by clearcut, SW25, and
SW50 treatments. However, these prescriptions need to be repeated often in order to
provide ongoing habitat and help sustain population growth of species within this group.
85
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91
APPENDIX
TERRITORY DENSITY TABLES
Appendix A.1. Table 5. Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 2011 1, and 2012 at
Jack Gap and Miller Mountain in Jackson County, Alabama.
Treatments
Species
Year
92
PBlock
PTreat
PYear
PT*Y
Treat/Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Acadian
2002
0.0±5.153
0.0±5.15
0.0±5.15
8.3±5.15
8.3±5.15
-Flycatcher2
2003
0.0±5.15
0.0±5.15
0.0±5.15
8.3±5.15
8.3±5.15
-Empidonax
2010
0.0±5.15
0.0±5.15
0.0±5.15
8.3±5.15
8.3±5.15
-virescens
2011
0.0±5.89
0.0±10.21
0.0±10.21
0.0±10.21
0.0±10.21
8.3±5.89
2012
0.0±3.63
0.0±3.63
0.0±3.63
0.0±3.63
8.3±3.63
12.5±7.22
4
American
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-1.000
0.164
0.136
Goldfinch
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-(0, 4)
(4,10)
(2,18)
(8,18)
Spinus tristis
2010
0.0±3.73
16.7±3.73
0.0±3.73
0.0±3.73
0.0±3.73
-2011
0.0±0.00
0.0±0.00
25.0±0.00
25.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Black-and2002
0.0±6.10
8.3±6.10
0.0±6.10
8.3±6.10
8.3±6.10
-0.001
0.096
0.000
0.086
white Warbler
2003
8.3±4.24
0.0±4.24
0.0±4.24
0.0±4.24
8.3±4.24
-(2,30)
(4,29)
(3,23)
(12,23)
Mniotilta varia
2010
25.0±8.22
41.7±8.22
25.0±8.22
8.3±8.22
8.3±8.22
-2011
25.0±5.31
25.0±9.20
25.0±9.20
25.0±9.20
6.3±9.20
14.6±5.31
2012
12.5±4.12
16.7±4.12
20.8±4.12
2.1±4.12
10.4±4.12
4.2±4.17
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects due to insufficient
treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
93
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 20111, and 2012 at Jack
Gap and Miller Mountain in Jackson County, Alabama.
Treatments
Species
Year
PBlock
PTreat
PYear
PT*Y
Treat/Year
1
Clear
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Blue-gray
2002
0.0±9.87
29.2±9.87
41.7±9.87
25.0±9.87
16.7±9.87
-Gnatcatcher
2003
41.7±10.86
58.3±10.86
83.3±10.86
25.0±10.86
33.3±10.86
-Polioptila
2010
16.7±9.42
50.0±9.42
50.0±9.42
62.5±9.42
20.8±9.42
-caerulea
2011
12.5±7.22
25.0±12.50
25.0±12.50
0.0±12.50
25.0±12.50
37.5±7.22
2012
4.2±6.12
20.8±6.12
25.0±6.12
12.5±6.12
16.7±6.12
25.0±0.00
2
Blue Jay
2002
0.0±4.17
0.0±4.17
0.0±4.17
4.2±4.17
8.3±4.17
-Cyanocitta
2003
0.0±4.61
0.0±4.61
0.0±4.61
16.7±4.61
4.2±4.61
-cristata
2010
8.3±6.12
8.3±6.12
8.3±6.12
0.0±6.12
0.0±6.12
-2011
20.8±2.95
0.0±5.10
12.5±5.10
0.0±5.10
0.0±5.10
0.0±2.95
2012
25.0±5.99
12.5±5.99
4.2±5.99
8.3±5.99
8.3±5.99
0.0±0.00
Brown Thrasher2
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Toxostoma rufum
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2010
0.0±3.73
0.0±3.73
8.3±3.73
0.0±3.73
0.0±3.73
-2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Carolina
2002
0.0±10.52
16.7±10.52
16.7±10.52
25.0±10.52
12.5±10.52
-0.783
0.796
0.451
0.765
Chickadee
2003
16.7±7.84
8.3±7.84
16.7±7.84
8.3±7.84
12.5±7.84
-(2,27)
(4,32)
(3,16)
(12,16)
Poecile
2010
33.3±11.39
25.0±11.39
25.0±11.39
20.8±11.39
4.2±11.39
-carolinensis
2011
25.0±5.89
50.0±10.21
25.0±10.21
6.2±10.21
18.8±10.21
8.3±5.89
2012
22.1±6.02
15.3±6.02
13.8±6.02
20.8±6.02
16.7±6.02
19.4±5.58
Carolina Wren
2002
25.0±5.84AB
33.3±5.84B
54.2±5.84C
16.7±5.84A
20.8±5.84AB
-0.766
0.000
0.174
0.001
Thryothorus
2003
41.7±7.45BC
25.0±7.45B
50.0±7.45C
4.2±7.45A
0.0±7.45A
-(2,27)
(4,31)
(3,18)
(12,18)
A
AB
BC
C
A
ludovicianus
2010
4.2±9.36
16.7±9.36
37.5±9.36
41.7±9.36
12.5±9.36
-2011
8.3±7.80
25.0±13.50
0.0±13.50
50.0±13.50
37.5±13.50
37.5±7.80
2012
0.0±4.60A
29.2±4.60B
25.0±4.60B
33.3±4.60B
25.0±4.60B
12.5±7.22
Chipping
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Sparrow2
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Spizella
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-passerina
2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects due to insufficient
treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
94
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 2011 1, and 2012 at Jack
Gap and Miller Mountain in Jackson County, Alabama.
Treatments
Treat/Year effects3
Species
Year
PBlock
PTreat
PYear
PT*Y
Clear1
Control5
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Common
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Yellowthroat2
2003
8.3±5.27
8.3±5.27
0.0±5.27
0.0±5.27
0.0±5.27
-Geothlypis
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-trichas
2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Downy
2002
0.0±5.88
29.2±5.88
20.8±5.88
37.5±5.88
8.3±5.88
-0.274
0.006
0.049
0.132
ClearASW100B
Woodpecker
2003
0.0±7.15
8.3±7.15
16.7±7.15
16.7±7.15
8.3±7.15
-(2,34)
(4,36)
(3,20)
(12,20)
SW25BSW50BC
Picoides
2010
16.7±6.58
16.7±6.58
20.8±6.58
16.7±6.58
25.0±6.58
-SW75C
pubescens
2011
16.7±7.86
12.5±13.61
12.5±13.61
8.3±13.61
8.3±13.61
11.1±7.86
2003A2012AB
2012
4.2±4.84
4.2±4.84
12.5±4.84
20.8±4.84
16.7±4.84
25.0±0.00
2010BC2002C
Eastern Bluebird2 2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Sialia sialis
2003
0.0±3.73
8.3±3.73
0.0±3.73
0.0±3.73
0.0±3.73
-2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Eastern
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Kingbird2
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Tyrannus
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-tyrannus
2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Eastern Phoebe2
2002
0.0±3.73
8.3±3.73
0.0±3.73
0.0±3.73
0.0±3.73
-Sayornis phoebe
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Eastern Towhee
2002
12.5±7.68
25.0±7.68
37.5±7.68
12.5±7.68
0.0±7.68
-0.000
0.003
0.016
0.273
SW100ASW75B
Pipilo
2003
41.7±12.83
41.7±12.83
50.0±12.83
16.7±12.83
0.0±12.83
-(2,30)
(4,30)
(3,22)
(12,22)
ClearBCSW25C
erythrophthalmus 2010
25.0±9.96
37.5±9.96
29.2±9.96
25.0±9.96
8.3±9.96
-SW50C
2011
29.2±2.95
50.0±5.10
37.5±5.10
37.5±5.10
37.5±5.10
0.0±0.00
2002A2010AB2003B
2012
33.3±6.48
37.5±6.48
29.2±6.48
33.3±6.48
33.3±6.48
0.0±0.00
2012B
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects due to insufficient
treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
95
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 2011 1, and 2012
at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Species
Year
PBlock
PTreat
PYear
PT*Y
Treat/Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Eastern Whip-poor2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-will2
2003
0.0±0.00
0.0±0.00
0.0±0.0
0.0±0.00
0.0±0.00
-Antrostomus
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-vociferus
2011
0.0±5.89
0.0±10.21
0.0±10.21
0.0±10.21
0.0±10.21
8.3±5.89
2012
0.0±0.00
0.0±0.000
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Eastern Wood2002
12.5±9.64A
50.0±9.64C
41.7±9.64BC
16.7±9.64AB
8.3±9.64A
-0.403
0.004
0.017
0.038
pewee
2003
16.7±13.86
50.0±13.86
33.3±13.86
41.7±13.86
16.7±13.86
-(2,24)
(4,24)
(3,20)
(12,20)
Contopus virens
2010
4.2±6.72A
20.8±6.72AB
20.8±6.72AB
37.5±6.72B
4.2±6.72A
-2011
8.3±6.59
37.5±11.41
12.5±11.41
8.3±11.41
16.5±11.41
20.8±6.59
2012
0.0±5.64A
19.4±5.64CD
5.5±5.64AB
12.5±5.64BC
25.0±5.64D
12.5±7.22
Field Sparrow2
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Spizella pusilla
2003
8.3±3.73
0.0±3.73
0.0±3.73
0.0±3.73
0.0±3.73
-2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Great Crested
2002
0.0±4.91
12.5±4.91
16.7±4.91
0.0±4.91
8.3±4.91
-2
Flycatcher
2003
0.0±7.34
8.3±7.34
8.3±7.34
8.3±7.34
8.3±7.34
-Myiarchus crinitus
2010
8.3±3.49
0.0±3.49
0.0±3.49
0.0±3.49
0.0±3.49
-2011
0.0±0.00
12.5±0.00
0.0±0.00
0.0±0.00
25.0±0.00
0.0±0.00
2012
0.0±2.78
0.0±2.78
0.0±2.78
4.2±2.78
4.2±2.78
0.0±0.00
Hairy Woodpecker2
2002
0.0±5.28
12.5±5.28
8.3±5.28
0.0±5.28
4.2±5.28
-Picoides villosus
2003
0.0±6.98
16.7±6.98
8.3±6.98
8.3±6.98
0.0±6.98
-2010
0.0±5.19
0.0±5.19
0.0±5.19
8.3±5.19
8.3±5.19
-2011
8.3±6.21
12.5±10.75
12.5±10.75
8.2±10.75
8.3±10.75
2.8±2.75
2012
0.0±6.23
16.7±6.23
4.2±6.23
12.5±6.23
16.7±6.23
16.7±8.33
4
Hooded Warbler
2002
0.0±3.23
0.0±3.23
0.0±3.23
0.0±3.23
12.5±3.23
-0.393
0.000
0.260
2012A2003A
Setophaga citrina
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-(0, 4)
(4,13)
(3,14)
(11,13)
2002A2010B
2010
25.0±6.72
37.5±6.72
25.0±6.72
37.5±6.72
29.2±6.72
-2011
25.0±5.89
25.0±10.21
25.0±10.21
25.0±10.21
0.0±10.21
33.3±5.89
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
16.7±4.17
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects due to insufficient
treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
96
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 2011 1, and 2012
at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Species
Year
PBlock
PTreat
PYear
PT*Y
Treat/Year
1
Clear
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
C
CD
D
B
A
Indigo
2002
50.0±9.13
70.8±9.13
75.0±9.13
25.0±9.13
0.0±9.13
-0.035
0.000
0.000
0.000
Bunting
2003
141.7±11.54BC
158.3±11.54C
116.7±11.54B
16.7±11.54A
16.7±11.54A
-(2,35)
(4,10)
(3,18)
(12,18)
B
C
BC
BC
A
Passerina
2010
25.0±8.05
50.0±8.05
29.2±8.05
37.5±8.05
0.0±8.05
-cyanea
2011
29.2±2.95
75.0±5.10
62.5±5.10
62.5±5.10
75.0±5.10
0.0±2.95
2012
25.0±9.45A
75.0±9.45B
58.3±9.45B
83.3±9.45B
66.7±9.45B
0.0±0.00
Kentucky
2002
0.0±5.44
8.3±5.44
12.5±5.44
0.0±5.44
0.0±5.44
-0.001
0.000
0.000
0.198
SW100AClearAB
Warbler
2003
16.7±4.85
33.3±4.85
29.2±4.85
8.3±4.85
0.0±4.85
-(2,34)
(4,34)
(3,16)
(12,16)
SW75BSW25C
Geothlypis
2010
16.7±6.15
25.0±6.15
33.3±6.15
29.2±6.15
4.2±6.15
-SW50C
formosa
2011
29.2±9.77
37.5±16.93
25.0±16.93
0.0±16.93
0.0±16.93
16.7±8.33
2002A2003B
2012
14.6±7.49
25.0±7.49
41.7±7.49
25.0±7.49
27.1±7.49
16.7±8.33
2010BC2012C
Mourning
2002
0.0±3.59
8.3±3.59
0.0±3.59
0.0±3.59
0.0±3.59
-0.364
0.226
0.002
0.909
2002A2003AB
Dove
2003
0.0±4.80
8.3±4.80
8.3±4.80
0.0±4.80
0.0±4.80
-(2,23)
(4,26)
(3,16)
(12,15)
2010BC2012C
Zenaida
2010
8.3±9.28
25.0±9.28
8.3±9.28
0.0±9.28
8.3±9.28
-macroura
2011
16.7±5.89
25.0±10.21
25.0±10.21
0.0±10.21
0.0±10.21
0.0±0.00
2012
16.7±7.40
16.7±7.40
25.0±7.40
20.8±7.40
12.5±7.40
0.0±0.00
A
A
B
A
A
Northern
2002
8.3±6.98
8.3±6.98
41.7±6.98
12.5±6.98
8.3±6.98
-0.001
0.000
0.000
0.036
Cardinal
2003
33.3±4.96C
25.0±4.96BC
33.3±4.96C
0.0±4.96A
16.7±4.96B
-(2,28)
(4,31)
(3,20)
(12,20)
Cardinalis
2010
25.0±7.23
33.3±7.23
20.8±7.23
25.0±7.23
12.5±7.23
-cardinalis
2011
37.5±10.21
50.0±17.68
50.0±17.68
50.0±17.68
25.0±17.68
12.5±7.22
2012
41.7±4.07
37.5±4.07
37.5±4.07
25.0±4.07
20.8±4.07
16.7±8.33
Orchard
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Oriole2
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Icterus
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-spurius
2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2
Ovenbird
2002
0.0±11.79
0.0±11.79
0.0±11.79
8.3±11.79
25.0±11.79
-Seiurus
2003
0.0±3.73
0.0±3.73
0.0±3.73
0.0±3.73
8.3±3.73
-aurocapilla
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75%
retention, SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects due
to insufficient treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
97
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 20111, and
2012 at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Species
Year
PBlock
PTreat
PYear
PT*Y
Treat/Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Pileated
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Woodpecker2
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Dryocopus
2010
16.7±6.45
8.3±6.45
0.0±6.45
16.7±6.45
0.0±6.45
-pileatus
2011
0.0±5.10
0.0±8.84
25.0±8.84
0.0±8.84
12.5±8.84
12.5±5.10
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
16.7±8.33
4
Prairie Warbler
2002
0.0±9.06
0.0±9.06
0.0±9.06
0.0±9.06
0.0±9.06
-0.408
0.138
0.821
Setophaga
2003
8.3±5.27
8.3±5.27
0.0±5.27
0.0±5.27
0.0±5.27
-(0,4)
(3,35)
(3,14)
(11,13)
discolor
2010
8.3±6.18
8.3±6.18
12.5±6.18
0.0±6.18
0.0±6.18
-2011
0.0±2.95
62.5±5.10
37.5±5.10
25.0±5.10
0.0±5.10
4.2±2.95
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Red-bellied
2002
0.0±5.99
12.5±5.99
8.3±5.99
12.5±5.99
8.3±5.99
-0.130
0.471
0.026
0.843
2003A2002A
Woodpecker
2003
8.3±6.85
0.0±6.85
0.0±6.85
8.3±6.85
8.3±6.85
-(2,30)
(4,34)
(3,19)
(12,19)
2010AB
Melanerpes
2010
0.0±7.19
16.7±7.19
8.3±7.19
16.7±7.19
8.3±7.19
-2012B
carolinus
2011
16.7±7.09
0.0±12.29
25.0±12.29
8.3±12.29
8.3±12.29
19.4±5.58
2012
16.7±4.37
12.5±4.37
16.7±4.37
19.4±4.37
15.3±4.37
19.4±5.58
Red-eyed Vireo
2002
0.0±9.72A
45.8±9.72B
62.5±9.72BC
83.3±9.72C
83.3±9.72C
-0.038
0.000
0.007
0.072
A
AB
B
B
B
Vireo olivaceus
2003
4.2±13.91
41.7±13.91
58.3±13.91
83.3±13.91
75.0±13.91
-(2,36)
(4,36)
(3,19)
(12,19)
2010
29.2±12.03A
29.2±12.03A
37.5±12.03AB
70.8±12.03C
66.7±12.03BC
-2011
25.0±0.00
0.0±0.00
0.0±0.00
25.0±0.00
50.0±0.00
50.2±0.00
2012
25.0±11.23
33.3±11.23
25.0±11.23
29.2±11.23
33.3±11.23
50.0±0.00
Ruby-throated
2002
0.0±5.27
8.3±5.27
0.0±5.27
0.0±5.27
8.3±5.27
-Hummingbird2
2003
16.7±9.13
16.7±9.13
16.7±9.13
0.0±9.13
0.0±9.13
-Archilochus
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-colubris
2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Scarlet Tanager
2002
0.0±6.73A
12.5±6.73A
41.7±6.73B
41.7±6.73B
37.5±6.73B
-0.213
0.002
0.363
0.005
A
AB
BC
C
BC
Piranga
2003
0.0±9.51
16.7±9.51
37.5±9.51
58.3±9.51
33.3±9.51
-(2,36)
(4,36)
(3,18) (12,18)
olivacea
2010
12.5±7.74
25.0±7.74
33.3±7.74
20.8±7.74AB
8.3±7.74A
-2011
20.8±4.17
0.0±7.22
25.0±7.22
25.0±7.22
25.0±7.22
29.2±4.17
2012
37.5±7.79
29.2±7.79
25.0±7.79
10.4±7.79
27.1±7.79
25.0±0.00
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75%
retention, SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects
due to insufficient treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
98
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 20111, and
2012 at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Species
Year
PBlock
PTreat
PYear
PT*Y
Treat/Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Summer
2002
20.8±9.29
41.7±9.29
37.5±9.29
29.2±9.29
12.5±9.29
-0.282
0.000
0.012
0.013
Tanager
2003
20.8±5.59BC
33.3±5.59C
50.0±5.59D
16.7±5.59AB
4.2±5.59A
-(2,32)
(4,31)
(3,23) (12,23)
Piranga rubra
2010
16.7±6.62
20.8±6.62
20.8±6.62
16.7±6.62
4.2±6.62
-2011
12.5±7.22
33.3±12.50
16.5±12.50
25.0±12.50
25.0±12.50
12.5±7.22
2012
0.0±4.87A
18.8±4.87B
16.7±4.87B
22.9±4.87B
20.8±4.87B
8.3±8.33
Tufted
2002
4.2±5.23A
29.2±5.23B
45.8±5.23C
41.7±5.23BC
50.0±5.23C
-0.784
0.007
0.056
0.014
Titmouse
2003
16.7±7.34
41.7±7.34
25.0±7.34
41.7±7.34
41.7±7.34
-(2,32)
(4,33)
(3,20)
(12,20)
Baeolophus
2010
29.2±8.08
20.8±8.08
29.2±8.08
20.8±8.08
16.7±8.08
-bicolor
2011
25.0±5.89
25.0±10.21
25.0±10.21
25.0±10.21
25.0±10.21
33.3±5.89
2012
20.8±4.87
33.3±4.87
29.2±4.87
25.0±4.87
29.2±4.87
25.0±0.00
White2002
0.0±5.75A
12.5±5.75AB
16.7±5.75B
25.0±5.75B
20.8±5.75B
-0.019
0.000
0.001
0.022
breasted
2003
0.0±3.51A
16.7±3.51B
25.0±3.51B
25.0±3.51B
25.0±3.51B
-(2,33)
(4,35)
(3,20)
(12,20)
Nuthatch
2010
8.3±4.77AB
20.8±4.77BC
0.0±4.77A
25.0±4.77C
4.2±4.77A
-Sitta
2011
8.3±11.79
8.3±20.41
16.5±20.41
25.0±20.41
0.0±20.41
25.0±11.79
carolinensis
2012
0.0±4.50
0.0±4.50
11.1±4.50
12.5±4.50
5.5±4.50
8.3±8.33
White-eyed
2002
0.0±1.89
0.0±1.89
4.2±1.89
0.0±1.89
0.0±1.89
-0.103
0.000
0.000
0.001
Vireo
2003
8.3±4.70
8.3±4.70
0.0±4.70
0.0±4.70
0.0±4.70
-(2,13)
(4,24)
(3,16)
(12,16)
Vireo griseus
2010
41.7±6.13BC
54.2±6.13C
37.5±6.13B
0.0±6.13A
0.0±6.13A
-2011
29.2±8.33
50.0±14.43
50.0±14.43
0.0±14.43
0.0±14.43
8.3±4.17
2012
41.7±8.68
39.6±8.68
31.3±8.68
16.7±8.68
25.0±8.68
8.3±4.17
Wild Turkey2
2002
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Meleagris
2003
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-gallopavo
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2011
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Wood Thrush2
2002
0.0±7.45
0.0±7.45
0.0±7.45
0.0±7.45
16.7±7.45
-Hylocichla
2003
0.0±8.12
0.0±8.12
0.0±8.12
0.0±8.12
29.2±8.12
-mustelina
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-2011
8.3±8.33
0.0±14.43
0.0±14.43
0.0±14.43
0.0±14.43
8.3±8.33
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
4.2±4.17
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were not tested for effects due to insufficient
treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
Table 5 (continued). Mean ± SE and mixed model analysis (SPSS v20) results for territory densities [(territories/4 ha)*100] for breeding bird communities in 2002, 2003, 2010, 20111,
and 2012 at Jack Gap and Miller Mountain, Jackson County, Alabama
Treatments
Species
Year
99
PBlock
PTreat
PYear
PT*Y
Treat/Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Worm-eating
2002
0.0±5.15A
8.3±5.15AB
16.7±5.15B
33.3±5.15C
37.5±5.15C
-0.002
0.007
0.039
0.002
Warbler
2003
0.0±11.14
16.7±11.14
8.3±11.14
16.7±11.14
41.7±11.14
-(2,31)
(4,27)
(3,23)
(12,23)
Helmitheros
2010
12.5±6.87
16.7±6.87
20.8±6.87
33.3±6.87
37.5±6.87
-vermivorum
2011
33.3±2.95
0.0±5.10
0.0±5.10
0.0±5.10
0.0±5.10
47.8±2.95
2012
25.0±6.04B
8.3±6.04A
20.8±6.04B
0.0±6.04A
4.2±6.04A
50.0±0.00
Yellow2002
0.0±3.23
8.3±3.23
4.2±3.23
16.7±3.23
12.5±3.23
-billed
2003
0.0±6.72
16.7±6.72
8.3±6.72
4.2±6.72
8.3±6.72
-2
Cuckoo
2010
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
-Coccyzus
2011
2.8±1.94
8.3±3.37
8.3±3.37
0.0±3.37
0.0±3.37
0.0±0.00
americanus
2012
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
0.0±0.00
Yellow2002
16.7±5.58
4.2±5.58
0.0±5.58
0.0±5.58
0.0±5.58
-0.026
0.000
0.000
0.000
C
C
B
A
A
breasted
2003
91.7±11.67
100.0±11.67
50.0±11.67
0.0±11.67
0.0±11.67
-(2,27)
(4,31)
(3,18)
(12,18)
Chat
2010
33.3±8.20B
25.0±8.20B
25.0±8.20B
4.2±8.20A
0.0±8.20A
-Icteria virens 2011
12.5±5.89
62.5±10.21
25.0±10.21
50.0±10.21
25.0±10.21
4.2±4.17
2012
0.0±9.01A
41.7±9.01B
54.2±9.01B
50.0±9.01B
45.8±9.01B
0.0±0.00
Yellow2002
0.0±6.65
16.7±6.65
25.0±6.65
33.3±6.65
8.3±6.65
-0.095
0.001
0.383
0.582
ClearASW100B
throated
2003
0.0±8.83
33.3±8.83
25.0±8.83
33.3±8.83
8.3±8.83
-(2,36)
(4,36)
(3,20)
(12,20)
SW50BCSW25CD
Vireo
2010
8.3±8.11
16.7±8.11
8.3±8.11
25.0±8.11
12.5±8.11
-SW75D
Vireo
2011
0.0±11.79
25.0±20.41
25.0±20.41
0.0±20.41
0.0±20.41
16.7±11.79
flavifrons
2012
0.0±6.62
16.7±6.62
8.3±6.62
16.7±6.62
16.7±6.62
16.7±8.33
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention,
SW75=75% retention, SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Data from 2011 were
not tested for effects due to insufficient treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
Appendix A.2. Table 6. Mean ± SE and mixed model analysis (SPSS v20) results for aggregated sum of territory densities [(territories/4 ha)*100] for breeding bird guilds in 2002, 2003, 2010,
20111, and 2012 at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Guilds
Year
PBlock
PTreat
PYear
PT*Y
Treat / Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
Bark
2002
0.0±12.71
62.5±12.71
45.8±12.71
83.3±12.71
45.8±12.71
-0.616
0.010
0.117
0.218
ClearASW100B
Foragers2
2003
16.7±13.69
25.0±13.69
41.7±13.69
50.0±13.69
50.0±13.69
-(2,35)
(4,33)
(3,20)
(12,20) SW50B
2010
50.0±20.39
95.8±20.39
54.2±20.39
66.7±20.39
45.8±20.39
-SW25BSW75B
2011
66.7±25.08
45.8±43.44
79.0±43.44
66.5±43.44
22.8±43.44
70.1±25.08
2012
33.3±13.12
33.3±13.12
61.1±13.12
54.8±13.12
47.8±13.12
56.9±13.11
Foliage
2002
91.7±30.60A
275.0±30.60B
366.7±30.60C
337.5±30.60BC
270.8±30.60B
-0.020
0.000
0.000
0.001
Gleaning
2003
350.0±27.78B
525.0±27.78C
470.8±27.78C
300.0±27.78AB
266.7±27.78A
-(2,33)
(4,34)
(3,17)
(12,17)
AB
B
B
B
A
Foragers
2010
291.7±41.04
395.8±41.04
354.2±41.04
350.0±41.04
200.0±41.04
-2011
250.0±26.02
433.3±45.07
366.5±45.07
306.3±45.07
268.8±45.07
287.5±26.02
2012
226.3±43.48
398.6±43.48
378.4±43.48
354.2±43.48
393.8±43.48
240.3±38.81
Ground
2002
45.8±9.95A
83.3±9.95B
145.8±9.95C
41.7±9.95A
29.2±9.95A
-0.000
0.000
0.000
0.007
B
B
B
A
A
Foragers
2003
133.3±16.38
133.3±16.38
170.8±16.38
29.2±16.38
16.7±16.38
-(2,23)
(4,33)
(3,19)
(12,19)
2010
116.7±21.85AB 170.8±21.85B
158.3±21.85B
145.8±21.85B
70.8±21.85A
-2011
137.5±29.76
212.5±51.54
162.5±51.54
162.5±51.54
150.0±51.54
75.00±29.76
2012
122.9±17.84
166.7±17.84
179.2±17.84
170.8±17.84
152.1±17.84
62.5±17.84
100
2002
12.5±8.79A
50.0±8.79B
41.7±8.79B
16.7±8.79A
8.3±8.79A
-0.403
0.004
0.017
0.038
2003
16.7±9.86
50.0±9.86
33.3±9.86
41.7±9.86
16.7±9.86
-(2,24)
(4,24)
(3,20)
(12,20)
A
AB
AB
B
A
2010
4.2±6.97
20.8±6.97
20.8±6.97
37.5±6.97
4.2±6.97
-2011
8.3±6.59
37.5±11.41
12.5±11.41
8.3±11.41
16.5±11.41
20.8±6.59
2012
0.0±5.08A
19.4±5.08B
5.5±5.08A
12.5±5.08AB
25.0±5.08B
12.5±5.25
A
AB
BC
C
C
Interior
2002
0.0±19.94
41.7±19.94
75.0±19.94
108.3±19.94
116.7±19.94
-0.136
0.006
0.015
0.012
Habitat
2003
8.3±19.03A
50.0±19.03AB
70.8±19.03BC
100.0±19.03C
108.3±19.03C
-(2,38)
(4,38)
(3,17)
(12,17)
2010
83.3±21.63
141.7±21.63
104.2±21.63
125.0±21.63
87.5±21.63
-2011
112.5±17.37
58.3±30.08
91.5±30.08
75.0±30.08
31.3±30.08
152.1±17.37
2012
95.8±17.70B
75.0±17.70AB
106.9±17.70B
29.2±17.70A
76.3±17.70B
91.7±15.66
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Density values from 2011 and controls were not tested for
effects due to insufficient treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
Hawking
Foragers
101
Table 6. (continued). Mean ± SE and mixed model analysis (SPSS v20) results for aggregated sum of territory densities [(territories/4 ha)*100] for breeding bird guilds in 2002, 2003, 2010, 2011 1,
and 2012 at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Guilds
Year
PBlock
PTreat
PYear
PT*Y
Treat / Year
1
Clear
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
A
C
C
C
B
Interior /
2002
58.3±35.26
312.5±35.26
391.7±35.26
329.2±35.26
216.7±35.26
-0.043
0.000
0.113
0.035
Edge
2003
216.7±39.01A
375.0±39.01BC
420.8±39.01C
300.0±39.01AB
225.0±39.01A
-(2,36)
(4,36)
(3,19)
(12,19)
Habitat
2010
220.8±45.00
312.5±45.00
304.2±45.00
366.7±45.00
187.5±45.00
-2011
237.5±33.48
345.8±57.98
279.0±57.98
193.5±57.98
239.3±57.98
238.8±33.48
2012
182.5±36.48
274.3±36.48
261.0±36.48
263.2±36.48
271.5±36.48
243.0±31.78
B
BC
C
A
A
Open /
2002
91.7±13.60
116.7±13.60
133.3±13.60
41.7±13.60
20.8±13.60
-0.001
0.000
0.000
0.000
Edge
2003
291.7±19.14C
308.3±19.14C
225.0±19.14B
20.8±19.14A
16.7±19.14A
-(2,27)
(4,30)
(3,19)
(12,19)
Habitat
2010
158.3±29.36 BC
229.2±29.36 C
179.2±29.36 BC
108.3±29.36AB
45.8±29.36A
-2011
112.5±24.47
325.0±42.39
250.0±42.39
275.0±42.39
187.5±42.39
62.5±24.47
2012
104.2±25.33A
268.8±25.33B
256.3±25.33B
300.0±25.33B
270.8±25.33B
37.5±22.95
Neotropical
2002
100.0±28.70A
258.3±28.70BC
312.5±28.70C
262.5±28.70BC
200.0±28.70B
-0.001
0.000
0.000
0.002
Migrants
2003
291.7±25.02B
483.3±25.02D
408.3±25.02C
275.0±25.02B
195.8±25.02A
-(2,34)
(4,35)
(3,16)
(12,16)
AB
BC
ABC
C
A
2010
183.3±35.70
266.7±35.70
254.2±35.70
312.5±35.70
166.7±35.70
-2011
195.8±23.75
295.8±41.14
216.5±41.14
233.2±41.14
216.5±41.14
233.3±23.75
2012
147.9±34.35A
288.2±34.35B
284.7±34.35B
254.2±34.35B
295.8±34.35B
191.7±34.35
A
B
C
B
B
Residents
2002
50.0±22.17
175.0±22.17
241.7±22.17
183.3±22.17
129.2±22.17
-0.046
0.000
0.001
0.036
2003
158.3±22.19AB
175.0±22.19B
225.0±22.19B
120.8±22.19AB
112.5±22.19A
-(2,33)
(4,34)
(3,16)
(12,16)
2010
187.5±35.70
262.5±35.70
208.3±35.70
216.7±35.70
125.0±35.70
-2011
200.0±33.32
270.8±57.70
266.5±57.70
260.3±57.70
210.3±57.70
155.5±33.32
2012
172.1±23.03
231.9±23.03
237.4±23.03
269.4±23.03
241.6±23.03
143.0±22.03
Temperate
2002
0.0±12.60
37.5±12.60
45.8±12.60
33.3±12.60
25.0±12.60
-0.001
0.000
0.000
0.021
Migrants
2003
66.7±6.97B
75.0±6.97B
83.3±6.97B
25.0±6.97A
41.7±6.97A
-(2,21)
(4,30)
(3,18)
(12,18)
BC
D
CD
AB
A
2010
91.7±18.21
154.2±18.21
125.0±18.21
70.8±18.21
29.2±18.21
-2011
66.7±15.66
162.5±27.12
137.5±27.12
50.0±27.12
31.3±27.12
64.6±15.66
2012
62.5±14.99
97.9±14.99
102.1±14.99
68.8±14.99
81.3±14.99
37.5±19.02
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for 2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Density values from 2011 and controls were not tested for
effects due to insufficient treatment replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
102
Table 6. (continued). Mean ± SE and mixed model analysis (SPSS v20) results for aggregated sum of territory densities [(territories/4 ha)*100] for breeding bird guilds in 2002, 2003, 2010, 20111,
and 2012 at Jack Gap and Miller Mountain, Jackson County, Alabama.
Treatments
Guilds
Year
PBlock
PTreat
PYear
PT*Y
Treat / Year
Clear1
Control5
effects3
SW25
SW50
SW75
SW100
(df)
(df)
(df)
(df)
A
BC
C
BC
AB
Canopy
2002
12.5±16.24
79.2±16.24
108.3±16.24
91.7±16.24
54.2±16.24
-0.031
0.000
0.014
0.054
Nesters
2003
16.7±11.90A
100.0±11.90C
95.8±11.90C
133.3±11.90D
58.3±11.90B
-(2,36) (4,36)
(3,15)
(12,15)
2010
25.0±17.48
62.5±17.48
62.5±17.48
83.3±17.48
25.0±17.48
-2011
29.2±11.02
62.5±19.09
62.5±19.09
33.2±19.09
41.5±19.09
66.7±11.02
2012
37.5±12.08
65.3±12.08
38.8±12.08
39.6±12.08
68.8±12.08
54.2±11.16
Cavity
2002
4.2±17.50
100.0±17.50
108.3±17.50
141.7±17.50
100.0±17.50
-0.351
0.001
0.565
0.120
ClearASW100B
Nesters
2003
41.7±10.03
75.0±10.03
83.3±10.03
100.0±10.03
95.8±10.03
-(2,28) (4,29)
(3,20)
(12,20)
SW25BSW50BC
2010
87.5±26.17
100.0±26.17
83.3±26.17
100.0±26.17
58.3±26.17
-SW75C
2011
91.7±27.10
95.8±46.94
104.0±46.94
72.8±46.94
60.3±46.94
97.2±27.10
2012
63.8±12.62
65.3±12.62
83.3±12.62
98.6±12.62
83.3±12.62
97.2±16.33
Ground
2002
12.5±11.93
50.0±11.93
66.7±11.93
54.2±11.93
45.8±11.93
-0.000
0.003
0.000
0.269
SW100AClearA
Nesters
2003
66.7±12.71
91.7±12.71
87.5±12.71
41.7±12.71
50.0±12.71
-(2,31) (4,31)
(3,21)
(12,21)
SW75ASW25B
2010
79.2±17.33
120.8±17.33
108.3±17.33
95.8±17.33
58.3±17.33
-SW50B
2011
116.7±13.58
112.5±23.52
87.5±23.52
62.5±23.52
43.8±23.52
81.3±13.58
2002A2003B
2012
85.4±11.35
87.5±11.35
112.5±11.35
60.4±11.35
75.0±11.35
58.3±18.04
2012BC2010C
Low /
2002
100.0±15.73B
125.0±15.73B
175.0±15.73C
54.2±15.73A
41.7±15.73A
-0.000
0.000
0.000
0.000
Shrub
2003
325.0±20.75C
333.3±20.75C
258.3±20.75B
20.8±20.75A
33.3±20.75A
-(2,31) (4,32)
(3,20)
(12,20)
B
C
BC
B
Nesters
2010
170.8±31.26
266.7±31.26
195.8±31.26
145.8±31.26
62.5±31.26A
-2011
158.3±29.46
375.0±51.03
300.0±51.03
300.0±51.03
162.5±51.03
100.0±29.46
2012
150.0±23.44A
306.3±23.44B
302.1±23.44B
295.8±23.44B
287.5±23.44B
54.2±26.84
Midstory /
2002
20.8±16.98
116.7±16.98
141.7±16.98
137.5±16.98
112.5±16.98
-0.107
0.000
0.000
0.107
ClearASW100B
Subcanopy
2003
66.7±16.82
133.3±16.82
191.7±16.82
125.0±16.82
112.5±16.82
-(2,38) (4,38)
(3,18)
(12,18)
SW25BCSW75CD
Nesters
2010
62.5±17.18
100.0±17.18
108.3±17.18
150.0±17.18
91.7±17.18
-SW50D
2011
50.0±14.43
58.3±25.00
41.5±25.00
50.0±25.00
100.0±25.00
100.0±14.43
2012A2010B
2012
29.2±17.53
72.9±17.53
66.7±17.53
64.6±17.53
70.8±17.53
91.7±15.02
2002B2003C
1
Territory density values listed as mean±SE for each treatment originally administered in 2001: Clear=clearcut (0% retention), SW25=25% retention, SW50=50% retention, SW75=75% retention,
SW100=100% retention/controls for
2002, 2003, 2010 bird data. Control=controls added for 2011-12 surveys, after harvest of SW100. Density values from 2011 and controls were not tested for effects due to insufficient treatment
replications.
2
Species with <10 territories per year for entire study period were not tested for effects.
3
Estimates with same letters or no letters do not differ significantly for each year.
4
No value was detected.
5
Control data were analyzed separately from all other treatments, and were omitted from mean separations pairwise comparisons treatment grouping.
VITA
Brandie K. Stringer, daughter of Richard (late) and Lyris Stringer, is a native of
Mobile, Alabama. She obtained her Bachelor of Science degree in Biology, with a
concentration in Environmental Science and a minor in Chemistry, from the University of
South Alabama in 2006. After three years of assisting in research on the various fauna
and flora of the United States, she began conducting her master’s thesis research at
Alabama A&M University. She received her Master of Science degree in Plant and Soil
Science in 2014.