SNPLMA RESEARCH PROPOSAL ROUND 10
I. Title Page
Project title: Ecological succession in the Angora fire: Forest management effects on
woodpeckers as keystone species
Primary Science Theme # 1: Forest Health
Subtheme 1a: Understanding long term ecological effects of forest management
Secondary Science Theme# 2: Watershed, Water Quality, and Habitat Restoration
Subtheme 2b: Special status species and communities and priority invasive species
Team members: Gina Tarbill (Sacramento State University), Dr. Patricia Manley (USFS Pacific
Southwest Research Station)
Gina Tarbill
Graduate Student
Sacramento State University
1860 Point View Dr.
Placerville, CA 95667
Phone: (925) 408-3684
Email: gtarbill@gmail.com
Dr. Patricia Manley
US Forest Service
Pacific Southwest Research Station
Sierra Nevada Research Center
1731 Research Park Dr.
Davis, CA 95618
Phone: (530) 759-1719
Fax: (530) 747-0241
Email: pmanley@fs.fed.us
Grants contact:
Bernadette Jaquint
bjaquint@fs.fed.us
ph: (510) 559-6309
fax: (510) 559-6440
Total funding requested: $64,000
In-kind contributions:
$29,700
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II. Project Description
a. Abstract
Woodpeckers are considered keystone species, due in part to their important role as cavity
excavators. Woodpeckers may have especially strong effects on ecosystem processes after fires, when
cavity excavation, drilling, and bark peeling provide cover and foraging areas for other species. These
activities may be limited or enhanced by fire severity and restoration treatments, with cascading impacts
to secondary cavity users. We will investigate the role of primary cavity excavators in the facilitation of
colonization of secondary cavity users. Nest webs illustrate the interrelationships between species that
exhibit sequential use of substrates for nesting, resting, or roosting. Nest webs will be created to
investigate how secondary cavity users utilize woodpecker cavities in burned and areas under various
restoration treatments. These nest webs illustrate where interrelationships between and among species are
strongest, and it will allow predictions on both direct and indirect effects of fire severity and post-fire
restoration practices on woodpeckers and secondary cavity users. These predictions can guide future
management decisions in terms of how best to enhance habitat conditions to promote the restablishment
of bird and small mammal communities in burned areas, and enhance conservation strategies of species of
special concern in the Lake Tahoe Basin.
b. Justification Statement
Cavity nesting communities are often used as indicators for forest health, largely due to their reliance
on snags and decaying trees (Power, et. al., 1996; Hutto, 2006). Snags are important to all taxa: two thirds
of all wildlife species rely on snags at some point in their life cycle (Brown, 2002). Woodpeckers, as
primary cavities excavators, may mediate snag use by secondary cavity users, species dependent on
cavities that are unable to excavate them (Aitken and Martin, 2007). The most abundant primary cavity
excavators in the Lake Tahoe Basin are Hairy (Picoides villosus), Black-backed (P. arcticus), and Whiteheaded woodpeckers (P. albolarvtus) (Table 1). These species are recognized by the US Forest Service
and other agencies as unique indicator species or species of concern. Hairy and Black-backed
woodpeckers are considered indicator species for snag habitat in green and burned forests, respectively
(USFS, 2008). The White-headed woodpecker, relatively common in the Basin, is listed as a species of
concern in Idaho, Oregon, and the U.S. Forest Service in the intermountain and northern regions of the
west. It is proposed for listing in Washington and is nationally listed as endangered in British Columbia
(Garrett, et. al., 1996). Secondary cavity users of the Tahoe Basin include several sensitive species:
American martens (Martes americana), Northern flying squirrels (Glaucomys sabrinanus), and California
spotted owls (Strix occidentalis) (Table 2) (USDA, 2007).
This study will provide crucial data on interdependencies in these communities and resource use by
individual special status members. Creating nest webs for cavity-using communities in the Lake Tahoe
Basin will determine the relative importance of different primary cavity users species to the recovery of
bird and small mammal communities in burned forests, and the recovery of special status species in post
burn, salvage logged or unlogged habitats. Understanding interactions and dependencies among cavity
users will identify the most important habitat and community factors to maintain or increase the
abundance of individual species and recover the diversity of bird and small mammal communities in
burned forests. This study may also provide opportunistic information on the use of cavities by
carnivores of special interest and concern, including American marten, California spotted owl, and an
invasive species, the barred owl (Strix varia). Understanding how burn severity and restoration treatments
affect habitat for species of interest can influence management strategy, aid in conservation, and
potentially track the invasion of a nonnative species.
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c. Background and problem statement
Keystone species are organisms that exert a disproportional effect on the structure or function of
their community by virtue of life history traits or interactions with other species (Paine, 1969). Keystone
species may affect ecosystems by influencing productivity, nutrient cycling, species richness, or the
abundance of one or more dominant species or functional groups of species (Power et al. 1996).
Keystone species are particularly important in terms of conservation and management because the loss of
these species from a community can have catastrophic effects on those organisms that rely upon them to
drive ecosystem processes (Estes and Palmisano, 1974). Focusing conservation efforts on keystone
species preserves their large influence on ecosystem function and may also have direct and indirect
benefits at the community level (Simberloff, 1998; Power et al. 1996).
Keystone species may impact the community by modifying ecosystem structure (Mills et. al.,
1993). Lawton and Jones (1995) identified these species as keystones that modify, maintain, and/or
create habitat, directly or indirectly, by modulating resource availability to other species through physical
changes in biotic or abiotic materials. Interestingly, some keystone species have also been shown to
influence ecological succession (Andersen and MacMahon, 1985; Dangerfield et al., 1998; Rossell et al.,
2005). Ecological succession is defined as the change in community composition over time. Secondary
succession describes the compositional change of a community after a disturbance such as fire, flood,
logging, or overgrazing (Connell and Slatyer, 1977). The outcome of succession is affected by both the
severity of disturbance and the ability of colonizers to disperse and establish. The path of ecological
succession is unpredictable, and depends on both abiotic factors, such as moisture and light availability,
and biotic factors, including the facilitative and inhibitory effects of animals. Facilitative activities of
animals include seed dispersal, soil aeration through burrowing, and cavity creation in snags. These
activities may accelerate the rate of secondary succession by increasing recruitment or creating habitat in
previous unsuitable areas for other organisms (Kelm, et al. 2008; Andersen and MacMahon, 1985;
Dangerfield et al., 1998; Rossell et al., 2005). Keystone species that create habitat and colonize disturbed
areas may accelerate succession for other organisms relying on their facilitative effects.
Woodpeckers have recently been identified as keystone species in forest habitats, largely due to
habitat modification and creation with their unique foraging and nesting activities (Lawton and Jones
1995; Simberloff 1998; Martin and Eadie, 1999; Bonar, 2000; reviewed in Aubrey and Raley, 2002;
Martin et al 2004; Bednarz et al., 2004), and may act as facilitators of succession. By scaling bark and
pecking and drilling into dead and decaying trees, woodpeckers create foraging areas for other species
(Bull et al., 1986; Conner, 1981), accelerate decomposition and nutrient cycling (Farris et al., 2002 and
2004), and mediate insect populations (Otvos, 1970 and 1979). Additionally, as primary cavity
excavators, woodpeckers create cavities for nesting and roosting. These cavities are later used by
secondary cavity users, species dependent on cavities but unable to excavate them. Cavities in snags and
live trees provide nesting, roosting, denning, and resting sites for secondary cavity users (Bull et al.,
1997). Natural (non-excavated) cavities are limited in most habitats and secondary cavity users are
dependent on primary cavity excavators for cavity creation (Aitken and Martin, 2007). Competition for
cavities has been shown to limit population growth of secondary cavity users (Holt and Martin, 1997).
This creates a guild structure in the community with strong secondary cavity user dependence on primary
cavity excavators (Martin and Eadie, 1999). In terms of secondary succession, this indicates that
secondary cavity users may be reliant on primary cavity excavators to re-colonize and modify disturbed
habitat to facilitate occupation by secondary cavity users.
These interactions and dependence may be best-investigated using nest webs. Nest webs have
been used to study direct and indirect effects of woodpeckers on secondary cavity users and the
community at large (Martin and Eadie, 1999; Aitken et al., 2002; Martin et al., 2004; Blanc and Walters,
2007; Gentry and Vierling, 2008). Nest webs are analogous to food webs, with trees/snags as the
fundamental “producers”, primary cavity excavators (PCEs) as the “manufacturers”, and secondary cavity
users (SCUs) as the “consumers” of cavities (Fig. 1; Martin and Eadie, 1999). Nest webs can also be
created at the species level to determine the relative ecological importance of specific excavators on the
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community (Fig. 2). Nest webs can be used to identify which tree species, decay class or DBH category is
selected by the most cavity users, which PCEs create the most cavities, and which SCUs then utilize these
cavities. This allows identification of potential keystone species and habitat generalists and specialists,
and the relationships between them. Predictions may be made on community responses to changes in the
system, such as increases in the number of snags, decreases in snags with large DBH, or decreases in a
particular PCE population.
Although woodpecker nest-site selection and nest re-use has been well-studied (Martin and Eadie,
1999; Aitken et al., 2002; Martin et al., 2004; Blanc and Walters, 2007 and 2008; Gentry and Vierling,
2008), there is a lack of knowledge on the impact of fire to these systems (but see Gentry and Vierling,
2008). Fire is a natural and regular disturbance in mixed conifer forest and may create snags, alter
arthropod communities, and change forest structure (Kotliar, 2002). Woodpeckers are generally early
colonizers of burned areas, likely due to abundance of food (arthropods) and nest (snag) resources (Hutto,
1995). Their unique foraging and nesting strategy may allow them to utilize and exploit resources
unavailable to other organisms, while facilitating the recolonization and occupation of other species by
creating suitable habitat. Woodpeckers have been shown to select nest sites based on habitat features,
including burn severity and presence of bark beetles, and tree features including height, diameter at breast
height (DBH), decay class, and species (Saab et. al, 2004). Cavity use by SCUs is also driven by both
habitat conditions, including burn severity, and cavity characteristics including height, DBH, decay class,
species, cavity height, diameter, and orientation (Aitken et al., 2002; Saab et al. 2004; Gentry and
Vierling, 2008; Czeszczewik, et al., 2008). SCUs may prefer cavities excavated by a particular PCE due
to similar preferences in habitat or cavity characteristics and therefore presence may be positively
correlated between these species. This suggests that different species of woodpeckers may facilitate the
recolonization and occupation of different SCUs in areas of different burn severity. The Angora Fire of
Lake Tahoe provides an ideal system for investigating the facilitative effects woodpeckers may have on
ecological succession through the colonization of disturbed areas by secondary cavity users.
The Angora Fire burned approximately 1,255 hectares in South Lake Tahoe, California in June
and July 2007 (Fig. 1). The California Tahoe Conservancy (CTC) owns 229 urban parcels (42 ha) within
the fire perimeter, and 177 of them were affected by the fire (~36 ha). The fire occurred in an area with a
high level of private and public land intermixed and adjacent to large expanses of undeveloped public
land. The severity of the burns varied within the area, resulting in a mosaic of post-fire conditions. The
primary post-fire treatments have been to minimize erosion through a variety of measures including
mulching, and removing dead and dying trees to reduce risk they pose to human life and property. There
are many PCEs and SCUS in the Tahoe Basin, creating the ideal system for investigating the facilitative
effects of woodpeckers on colonization by SCUs and the response of this community to restoration
efforts.
Table 1. Primary cavity excavators.
Common Name
Black-backed Woodpecker
Downy Woodpecker
Hairy Woodpecker
Northern Flicker
White-headed Woodpecker
Pileated Woodpecker
Williamson's Sapsucker
Red-breasted Sapsucker
Code
BBWO
DOWO
HAWO
NOFL
WHWO
PIWO
WISA
RBSA
Scientific Name
Picoides arcticus
Picoides pubescens
Picoides villosus
Colaptes auratus
Picoides albolarvatus
Dryocopus pileatus
Sphyrapicus thyroideus
Sphyrapicus ruber
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Table 2. Secondary cavity users.
Birds
Common Name
Brown Creeper
Scientific Name
Certhia americana
European Starling
Sturnus vulgaris
House Wren
Mountain Chickadee
Mountain Bluebird
Pygmy Nuthatch
Troglodytes aedon
Poecile gambeli
Sialia currucoides
Sitta pygmaea
Red-breasted Nuthatch
White-breasted Nuthatch
Tree Swallow
Western Bluebird
American Kestrel
Flammulated Owl
Barred Owl
Northern Pygmy Owl
Northern Saw-whet Owl
Sitta canadensis
Sitta carolinensis
Tachycineta bicolor
Sialia mexicana
Falco sparverius
Otus flammeolus
Strix varia
Glaucidium gnoma
Aegolius acadicus
Mammals
Common Name
Scientific Name
Douglas squirrel
Tamiasciurus
douglasii
Flying squirrel
Glaucomys
sabrinus
Western gray squirrel
Sciurus griseus
Yellow-pine chipmunk
Tamias amoenus
Least chipmunk
Tamias minimus
Long-eared chipmunk
Tamias
quadrimaculatus
Shadow chipmunk
Tamias senex
Lodgepole chipmunk
Tamias speciosus
Bushy-tailed woodrat
Neotoma cinerea
Porcupine
Erethizon dorsatum
Pine marten
Martes americana
Short-tailed weasel
Mustela erminea
Long-tailed weasel
Mustela frenata
d. Goals and objectives
The goal of this study is to understand the how primary cavity nesters drive ecological succession
following a wildfire and how restoration activities affect the recovery of bird and small mammal
communities as a function of its effects on ecological succession. Understanding how primary cavity
excavators (PCE) and secondary cavity users (SCU) respond to disturbance is crucial because they drive
ecosystem processes and recovery. Disturbances that have positive effects on cavity excavators, such as
forest fires that create nesting and foraging habitat for woodpeckers may also benefit species that depend
on cavity excavators. Because keystone species, by definition, have great impacts on other identifying
these keystone species and understanding their response to disturbance will allow predictions on the
community as a whole. These predictions can guide future research, influence management decisions, and
enhance conservation practices.
Objectives
1) Understand how woodpecker colonization and modification of burned forest contributes to SCU
occupation
2) Determine if management activities affect PCE and/or SCU in a manner that changes the pace or
character of ecological succession and recovery of bird and small mammal communities after fire
Hypotheses
1) Secondary cavity use by species is correlated with particular excavator due to similarities in nest
site selection
i) Secondary cavity use is determined by habitat characteristics that correlate with a PCE
ii) Secondary cavity use is determined by cavity characteristics that correlate with a PCE
2) Keystone species in this system will create cavities used by greatest diversity of SCUs
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3) Keystone species in this system will have cavities occupied the greatest proportion of the time
4) Habitat specialist will utilize cavities of few species of PCE
5) Habitat generalist will utilize cavities of many species of PCE
e. Approach, methodology, and location
Study Area
The study will take place in and around the Angora Fire (2007) in South Lake Tahoe, California
(Fig. 1). As a mixed conifer forest, pre-fire dominant tree species included Pinus jeffreyii, P. contorta, P.
lambertiana, Abies concolor, A. magnifica, Populus tremuloides, and Calecedrus decurrens and dominant
shrub species included Artemesia spp, Artostaphylos spp., and Ceanothus spp.
Site selection
Sites were selected that represented a range of burn intensity and post-fire treatment, with
emphasis on land with a combination of treatments. The burn intensity grid map created for multi-agency
use was utilized to assign sites to different burn intensities. Salvage logging treatment was designated
using maps created by the United States Forest Service (USFS). Burn severity and salvage logging was
also evaluated on the ground at potential sites to ensure proper designation. The USFS established a
systematic grid of points spaced 400-m apart across the fire area to monitor post-fire vegetation response.
This grid was used to systematically select sample points to reflect different treatment types and sites
were centered around these points. The relatively small size of the burned area and the heterogeneity of
burn severity, salvage logging, and habitat conditions precluded a randomized approach. Differing
treatments were clustered whenever possible to minimize non-treatment effects. We attempted to obtain
an unbiased sample of sites that represented all combinations of burn intensity (no burn, <50% mortality,
>50% mortality) and post-fire treatment (none, thin, salvage). Many of the unburned and unlogged
sampling points were outside the fire perimeter and systematically selected from CTC monitoring points.
A total of 72 sample points were selected for nest searching efforts.
Primary cavity nests – Existing data
Nests were located as part of the SNPLMA funded research project “Biodiversity response to
burn intensity and post-fire restoration” (Manley et al. Round 9). Nest searching methodology largely
followed protocol described in Martin and Geupel (1993). Birds were observed and followed from a
distance to avoid altering their behavior and nests were found during construction, egg laying, incubation,
or nestling stages. Observers attempted to find nests of all primary excavators in the study area (Table 1).
Once an active nest was confirmed, the bird species, location of the nest and stage of nest
development were recorded, along with the UTM coordinates of the nest site. Nest habitat protocols
largely follow the BBIRD protocol (Martin et al. 1997). Habitat data was collected to analyze nest site
selection of secondary cavity users. The following characteristics were recorded for each nest at the time
of discovery: nest height; nest orientation; substrate species, height, diameter at breast height, decadence,
vigor (live or dead), decay, and percent scorch (blackened); distance from and direction to roads, trails,
and development within 30 meters; canopy cover at the nest; and percent slope. Additionally, relative
cavity size was estimated by standing ten meters from cavity tree and “covering” the cavity with different
sized cardboard cut outs held at arm’s length. Distance to roads, trails, and development will be merged
into a single averaged value. Decay class will be analyzed as a ranked ordinal variable. These variables
will be utilized to determine nest site selection of primary cavity excavators and subsequent secondary
cavity users using cavity and tree characteristics.
Forest structure was described in the vicinity of the cavity tree within an 11.3-meter radius circle
(adaptation of Martin et al. 1997). The plot boundaries were delineated using four line transects laid out
in each cardinal direction, delineating one quarter of the circular plot. Within each quarter plot, the
following data was collected: tree (>12.5-cm dbh) species, dbh, vigor, decadence, percent scorch, decay
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class (if snag) and height (if snag); absolute percent cover of shrubs, forbs, grasses and grass-like plants,
litter, bare ground, and trees. For downed wood, the first 0.3 m of each transect at the center of the plot
was not sampled. Along the remaining 11 m, data on logs (>10-cm diameter at small end) that intersect
the transect line was recorded: small-end diameter, large-end diameter, length, decay class, and species (if
possible). If the same log intersects two or more transects, it was only be recorded once. Finally, a 20factor prism was used to tally trees and snags; the species, DBH, vigor, decadence, decay (snags only),
and height (snags only) was recorded for all trees tallied. All quarter plot data will be averaged to
determine structure in total area.
Secondary cavity use data collection
All nest cavities located in 2009 and 2010 with positively identified excavators will be monitored
to determine occupancy by secondary cavity users (Table 2). Remote-triggered digital cameras will
monitor cavities for four-day sessions. The use of cameras allows for detection of elusive, diurnal, and
nocturnal organisms. Cameras will be set on a tree facing the cavity at the appropriate height and angle to
maximize detections. If no tree is available, a post will be set. Cameras will be tested to ensure
functionality and loaded with fresh batteries and empty camera cards. After four days of monitoring,
cameras will be collected and photos from cards will be downloaded. All photos will be analyzed, and if
detections are observed, photos will be labeled and detections will be recorded in a database. All
organisms will be identified to species whenever possible. Additionally, on days when cameras are
pulled, contents of cavities will be viewed using a Treetop Peeper (Sandpiper Technologies Manteca,
CA). Cavity size will also be re-estimated to determine if cavity enlargement has occurred. If enlargement
has occurred, observers will make an effort to determine the species (or appropriate taxon) that enlarged
the cavity and this data will be included in nest webs. Cameras will be set several times per year to
determine use during breeding (April-July) and nonbreeding seasons (October-November, JanuaryFebruary).
Each cavity will be considered an independent data point, although some may be the result of renesting efforts of pairs. Any known re-nesting attempts will be removed from the study. Data will be used
to create nest webs for each woodpecker species following Martin and Eadie (1999). Correlations
between species of primary excavators and secondary cavity users will be analyzed at both the guild and
species level using simple and partial correlation analyses. Relative contributions of cavity substrate (tree
species, decay class, and DBH) and cavity excavators will be obtained by determining the proportions of
trees/cavities used by primary cavity excavators and secondary cavity users. Relationships will be
summarized and any keystone species, habitat generalists, and habitat specialists will be identified (Figure
1 and 2).
Secondary cavity use will also be analyzed by habitat and cavity characteristics, and primary
excavator using multiple logistic regression to develop the best model describing nest selection for each
species. Variables will be tested for covariance using Spearman rank correlations. A global model
utilizing all variables, and reduced models with different combinations of variables will be analyzed.
Additionally, to minimize effects of covariance, Akaike’s Information Criterion (AIC) will be calculated
for all models. Models with lowest AIC value are most parsimonious. Akaike weights will be calculated
to determine the model with greatest support relative to other models.
f. Relationship of the research to previous and current relevant research, monitoring, and
management
There are several wildlife studies in the Angora Fire area that will be complemented by this
research. The Angora Wildlife Monitoring Project (AWMP) was a 2-year multi-species investigation of
the effects of fire and post-fire management practices on birds and small mammals. The SNPLMA
funded project, “Biodiversity response to burn intensity and post-fire restoration” expanded this effort to
include a larger number of sites (from 42 to 72), invertebrates, and nest-site selection by woodpeckers.
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The data obtained in this study will complement and enhance the existing study by investigating the
process by which cavity excavators facilitate the recovery of bird and small mammal communities in
burned areas, and in what ways management activities help or hinder the restoration process. Agency
monitoring efforts include a focus on special status species: willow flycatchers, Northern goshawks, and
California spotted owls. This study has the potential to also complement these monitoring efforts because
we may locate roost sites in the burned area (Bond et. al., 2009).
Many nest re-use studies have been conducted in the other regions, but few have investigated
interactions and dependence of secondary cavity users in the Sierra Nevada (Martin et. al, 2004; Blanc
and Walters, 2008) Additionally, the effects of fire and salvage logging on nesting woodpeckers has
largely focused on the Rocky Mountains, with little attention to woodpeckers in the Sierra Nevada (Saab
and Dudley, 1998; Saab et. al., 2007 and 2009). Understanding how cavity communities are structured in
the Lake Tahoe Basin is needed to improve management of snag habitats and conservation of cavitydependent species.
g. Strategy for engaging with managers and obtaining permits
Because this project is linked with an already established post-fire monitoring project by the US
Forest Service, appropriate permits have been obtained and managers have been contacted for permission.
Presentations to staff and leadership at the primary agencies involved in forest management (e.g., NDSL
Nevada Tahoe Resource Team, US Forest Service LTBMU, California Tahoe Conservancy, California
State Parks) will be conducted to disseminate results and engage managers in discussion of importance of
cavity communities and effects of fire and post-fire management of these communities
h. Description of deliverables and products
Deliverables will be in the form of a draft report, a final report, a minimum of one peer-reviewed
publication, and multiple presentations at local and regional agency, public, and scientific forums,
including at least one national scientific meeting. In addition, we will develop a web page that describes
the project and its progress.
Symposia, conference, workshop presentations:
Lake Tahoe Science Symposium
The Wildlife Society National Conference
Local and regional forest management and fire conferences
Progress and completion reports and presentations:
Draft report and Final Report
Presentations to staff and leadership at the primary agencies involved in forest
management (e.g., NDSL Nevada Tahoe Resource Team, US Forest Service LTBMU,
California Tahoe Conservancy, California State Parks)
Website:
Information on the study background, objectives, study area, methods, results,
conclusions, and photos will be available on PSW-supported public web site for the
project.
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III. Schedule of major milestones/deliverables
Milestone/Deliverables
Spring/summer cavity
monitoring
Start Date
May 1,
2010
Data entry and analysis
August 1,
2010
Fall/winter cavity
monitoring and data
entry
Data analysis and
reporting
October 1,
2010
April 1,
2011
End Date
Description
July 31, Monitor cavities
2010
September Submit year-end interim report
30 1, 2010
March 30, Monitor cavities
2011
June 30, Analyze data, produce final report, submit
2011 manuscripts for publication
IV. Literature cited
Aitken, K.E.H and Martin, K. (2007) The importance of excavators in hole-nesting communities:
availability and use of natural tree holes in old mixed forests of western Canada. Journal of
Ornithology 148: S425-S434.
Aitken, K.E.H., Wiebe, K.L., and Martin, K. (2002) Nest-site reuse patterns for a cavity-nesting bird
community in interior British Columbia. The Auk 119: 391-402.
Andersen, D.C. and J.A. MacMahon (1985) Plant Succession Following the Mount St. Helens Volcanic
Eruption: Facilitation by a Burrowing Rodent, Thomomys talpoides. The American Midland
Naturalist. 114: 62-69.
Aubrey, K.B. and Raley, C.M. (2002) The pileated woodpecker as a keystone habitat modifer in the
Pacific Northwest. General Technical Report. PSW-GTR-181. Pacific Southwest Research
Station, Forest Service, U.S. Department of Agriculture.
Bednarz, J.C., Ripper, D., and Radley, P.M. (2004) Emerging concepts and research directions in the
study of cavity-nesting birds: keystone ecological processes. The Condor 106:1-4.
Blanc, L.A. and Walters, J.R. (2007) Cavity-nesting community webs as predictive tools: where do we go
from here? Journal of Ornithology 148: S417-423.
Blanc, L.A. and Walters, J.R. (2008) Cavity-nest webs in a longleaf pine ecosystem. The Condor 110: 8092.
Bonar, R.L. (2000) Availability of pileated woodpecker cavities and use by other species. Journal of
Wildlife Management 64:52-59.
Bond, M.L., Lee, D.E., Siegel, R.E., and Ward, J.P. (2009) Habitat Use and Selection by California
Spotted Owls in a Postfire Landscape. Journal of Wildlife Management 73: 1116-1124.
Brown, T.K. (2002) Creating and maintaining wildlife, insect, and fish habitat structures in dead wood.
General technical report PSW-GTR-181:883-892. US Department of Agriculture Forest Service,
Albany, CA.
Bull, E.L., Parks, C.G., Torgersen (1997) Trees and logs important to wildlife in the interior Columbia
River Basin. USDA Forest Service General Technical Report PNW-GTR-391.
Bull, E.L., Peterson, S.R., Thomas, J.W. (1986) Resource partitioning among woodpeckers in
northeastern Oregon. USDA Forest Service Research Note PNW-RN-474.
Connell, J.H. and R.O. Slatyer (1977) Mechanisms of Succession in Natural Communities and Their Role
in Community Stability and Organization. American Naturalist 111: 1119-1144.
Conner, R.N. (1981) Seasonal changes in woodpecker foraging patterns. The Auk 98: 562-570.
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Czeszczewik, D., Walankiewicz, W., and Stanska, M. (2008) Small mammals in nests of cavity-nesting
birds: why should ornithologists study rodents? Canadian Journal of Zoology 86: 286-293.
Dangerfield, J.M., McCarthy, T.S. & Ellery, W.N. (1998). The mound-building termite Macrotermes
michaelseni as an ecosystem engineer. Journal of Tropical Ecology 14: 507-520.
Estes, J.A. and Palmisano, J.F. (1974) Sea otters: Their role in structuring near shore communities
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185:1058-60.
Farris, K.L., Garton, E.O., Heglund, P.J., Zack, S., and Shea, P.J. (2002) Woodpecker foraging and the
successional decay of ponderosa pine. USDA Forest Service General Technical Report. PSWGTR-181.
Farris, K.L., Huss, M.J., and Zack, S. (2004) The role of foraging woodpeckers on the decomposition of
Ponderosa pine snags. The Condor 106:50-59.
Garrett, K. L., M. G. Raphael, and R. D. Dixon. 1996. White-headed Woodpecker (Picoides
albolarvatus). In The Birds of North America, No. 252 (A. Poole and F. Gill, eds.). The Academy
of Natural Sciences, Philadelphia, PA, and The American Ornthologists' Union, Washington,
D.C.
Gentry, D.J. and Vierling, K.T. (2008) Reuse of woodpecker cavities in the breeding and non-breeding
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V. Figures
Figure 1. Angora Fire Area
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Figure 2. Nest Web Structure
modified from Martin and Eadie (1999)
Solid lines represent nest cycling or flow; dotted lines represent non-nest interactions
Secondary cavity user
Weak cavity excavator
Non-cavity user
Primary cavity excavator
Cavity substrate
Figure 3. Nest Web by Species
modified from Martin and Eadie (1999)
SCU1
SCU2
PCE 1
Nest Use (proportion)
<0.10
0.10-0.49
0.50-1.0
SCU3
PCE 2
SCU4
PCE 3
Tree 1
SCU5
SCU6
PCE 4
Tree 2
Tree 3
13