Avian Monitoring in the Lassen National Forest
2009 Report
April 2010
Ryan D. Burnett, Diana Humple, Alissa Fogg, and Tim Guida
PRBO Conservation Science
Sierra Nevada Program
PO BOX 634
Chester, CA 96020
PRBO Contribution #1740
Executive Summary .................................................................................................................. 1 Chapter 1. Landbird Monitoring of Fuel Treatments on the Lassen National Forest ................... 2 Background and Introduction ................................................................................................. 3 Methods...................................................................................................................................... 4 Results ...................................................................................................................................... 12 Discussion................................................................................................................................. 18 Acknowledgements ................................................................................................................. 20 Literature Cited ...................................................................................................................... 21 Chapter 2. Resident and Neotropical Migratory Bird Response to Aspen Enhancement on the
Lassen National Forest ................................................................................................................. 24 Background and Introduction ............................................................................................... 25 Project Area ............................................................................................................................. 25 Methods.................................................................................................................................... 26 Results ...................................................................................................................................... 31 Discussion................................................................................................................................. 41 Conclusions .............................................................................................................................. 45 Acknowledgements ................................................................................................................. 45 Literature Cited ...................................................................................................................... 46 Chapter 3. Resident and Neotropical Migratory Bird Monitoring in Mountain Meadows: 2009
Report ........................................................................................................................................... 48 Background and Introduction ............................................................................................... 49 Methods.................................................................................................................................... 50 Results ...................................................................................................................................... 54 Discussion................................................................................................................................. 62 Conclusions .............................................................................................................................. 65 Acknowledgements ................................................................................................................. 65 Literature Cited ...................................................................................................................... 66 Executive Summary
PRBO Conservation Science (PRBO) has been conducting songbird monitoring in the
Northern Sierra since 1997. In this report we present results from avian monitoring of fuel
treatments and aspen restoration on the Lassen National Forest and from meadows across the
Northern Sierra with updated information from 2009.
Chapter one reports on the first year of our expanded avian monitoring of Herger
Feinstein Quincy Library Group Forest Recovery Act fuel treatments on the Lassen National
Forest. Recently treated sites across the forest were added in 2009 to compliment ongoing work
on the Forest as well as in the Plumas-Lassen study area. Preliminary results suggest the range of
treatments (DFPZ, Group Selection, mastication, fire) have varying effects on the avian
community.
The second chapter discusses results from our sixth year of monitoring landbirds in aspen
habitat on the Lassen National Forest. Results show that treated aspen stands support greater
total abundance of birds and abundance of key species such as Mountain Bluebird, Chipping
Sparrow, and Red-breasted Sapsucker but these initial benefits may be short-lived for some
species. In 2009, avian abundance and richness indices showed a decline at treated sites for the
second consecutive year.
In the third chapter we present results from monitoring of meadows across the Northern
Sierra Nevada, primarily within the Feather River watershed. We compared avian community
indices across sites and where applicable compared treated areas to adjacent reference sites.
Results suggest some Feather River watershed meadows still support diverse and abundant bird
populations including several species of conservation concern. However, a number of sites have
suppressed avian communities - likely a result of over a century of inappropriate management.
Management actions that restore hydrologic and ecological function and minimize the negative
impacts created through past management actions will likely benefit a number of avian species
including several that are of conservation concern.
1
Chapter 1. Landbird Monitoring of Fuel Treatments on the Lassen
National Forest
Diana Humple, Tim Guida, and Ryan D. Burnett
PRBO Conservation Science
2
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Background and Introduction
The Records of Decisions for the Sierra Nevada Forest Plan Amendment and
Herger Feinstein Quincy Library Group (HFQLG) Forest Recovery Act direct the Forest Service
to maintain and restore old forest conditions that provide habitat for a number of plant and
animal species (HFQLG 1999, SNFPA 2001, 2004). Simultaneously, they direct the Forest
Service to take steps to reduce risks of large and severe fire by removing vegetation and reducing
fuel loads in overstocked forests. Striking a balanced approach to achieving these potentially
competing goals is a significant challenge to effectively accomplish the various desired outcomes
of forest management.
Historically, fire was the primary force responsible for creating and maintaining habitat
diversity and landscape heterogeneity in the Sierra Nevada (Skinner and Chang 1996). Over the
past century, fire return intervals have been lengthened and the area affected by wildfire annually
has been dramatically reduced in the interior mountains of California (Taylor 2000, Taylor and
Skinner 2003, Stephens et al. 2007). Thus, there is little doubt fires role in influencing the
composition of the Sierra Nevada landscape has been reduced (Skinner and Chang 1996).
Fire suppression in concert with past silvicultural practices has resulted in increased stand
densities, loss of landscape heterogeneity, and increased fuel loads in Sierra Nevada Forests
(Vankat and Major 1978, Parsons and DeBenedetti 1979, McKelvey and Johnston 1992,
Minnich et al. 1995, Taylor and Skinner 2003). While the ways in which these changes affect
fire patterns and vegetation dynamics are frequently discussed, they also undoubtedly impact the
wildlife species that inhabit these forests.
Mechanical silvicultural treatments have the potential to fill some of fire’s historic
role in maintaining disturbance-dependent habitats (Weatherspoon 1996, Arno and Fiedler
2005). There has been considerable study of silvicultural treatments and their effects on
landbirds in eastern North American forests (Anand and Thompson 1997, King et al. 2001, Fink
et al. 2006, Askins et al. 2007) and the Cascades (Hansen et al. 1995, Hagar et al. 2004,
Chambers et al. 2007), but little published information exists on the effects of mechanical fuel
treatments on the avian community in the Sierra Nevada (but see Siegel and DeSante 2003 and
Garrison et al. 2005).
By monitoring the populations of a suite of landbird species we can measure the
effectiveness of management actions in achieving a sustainable and ecologically functional forest
3
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
ecosystem. Specifically, we are interested in determining the responses of landbirds to
management practices intended to produce forests with larger trees and high canopy cover along
with more open-canopy, smaller size class forest with reduced ladder and ground fuels.
In this report we summarize our efforts in 2009 intended to investigate landbird response
to changes in vegetation structure and composition that occur when forests are managed to
reduce fuels under the Herger Feinstein Quincy Library Group Forest Recovery Act Pilot Project
(HFQLG 1999). We summarize what surveys were completed in 2009, the treatment history at
each site, and some preliminary analysis of bird community indices by treatment type. We
compared community indices and most abundant species among treatment types and between
paired treated and reference sites. Future analyses will be more comprehensive, combining data
with those from the larger HFQLG region in which PRBO is collecting bird data (e.g., Plumas
National Forest). Future analysis will also include analysis of the longer-term effects of fuel
treatments on the avian community.
Methods
Study Location
The study occurred in the Lassen National Forest within the boundaries of the HFQLG
Forest Recovery Act Pilot Project with the exception of the Wiley Ranch sites. The study sites
encompassed portions of Butte, Lassen, Plumas, Shasta and Siskiyou (Wiley Ranch) Counties at
the intersection of the Sierra Nevada and Cascade mountains of Northeastern California, USA
(Figure 1). Survey sites ranged in elevation from 1362 to 2074m with a mean elevation 1628m.
All sites occurred within the mixed conifer, true fir, and yellow pine zones though the actual
habitat structure and dominant tree species varied by site. A total of 519 point count stations
across 49 transects was surveyed in 2009 (Figure 1 and Table 1).
4
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Figure 1. Location of of PRBO’s fuel treatment avian monitoring study sites in the Lassen National Forest. Black dots are point count stations and the
Lassen National Forest is the area in green. Note, Brown’s Ravine study area includes Lower, Middle and Upper Oak Reference transects. Wiley Ranch
is located approximately 20km north of the map on the Shasta Trinity National Forest but is administered by the Lassen National Forest.
5
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Table 1. Fuel treatment point count transects, Lassen National Forest 2009. Summary of transect, number of points per transect, treatment type and
details, if treatment has occurred, and year of treatment.
Transect
Code
# Points
Ranger District
Treatment Type
Treated
Year Treated
Battle
BATL
13
Almanor
DFPZ
yes
2004
Bizz DFPZ
BIZD
7
Eagle Lake
DFPZ
yes
2005
Bizz Reference
BIZR
7
Eagle Lake
Reference
n/a
Black's Ridge DFPZ
BRDZ
12
Hat Creek
DFPZ
yes
2004
Black's Ridge Group Selection
BRGS
12
Hat Creek
Group Selection
yes
2008
Cabin Mastication
CBMA
11
Hat Creek
Plantation/Mastication
yes
2006
Carter Meadow Road
CMRO
12
Almanor
Wildfire
n/a
(2008)
Gray's Peak Central
GPCE
10
Almanor
Plantation/Mastication
no
Gray's Peak East
GPEA
14
Almanor
Plantation/Mastication
no
Gray's Peak West
GPWE
13
Almanor
Plantation/Mastication
no
Hog DFPZ
HOGD
7
Eagle Lake
DFPZ
yes
2004
Hog Reference
HOGR
7
Eagle Lake
Reference
n/a
Harvey Valley DFPZ
HVD
7
Eagle Lake
DFPZ
no
Harvey Valley Reference
HVR
7
Eagle Lake
Reference
n/a
Jonesville DFPZ
JVDZ
12
Almanor
DFPZ
yes
2005/2006/2007
Konos DFPZ
KOND
7
Eagle Lake
DFPZ
yes
2007
Konos Reference
KONR
7
Eagle Lake
Reference
n/a
Lower Oak Reference
LOKR
32
Almanor
Reference
n/a
Middle Oak Reference
MOKR
6
Almanor
Reference
n/a
North Cobble DFPZ
NCDZ
12
Hat Creek
DFPZ/Group Selection
yes
2006
North Cobble Mastication
NCMA
12
Hat Creek
Plantation/Mastication
yes
2007
Brown’s Ravine Oak Stand 1
OAK1
7
Almanor
DFPZ
yes
2005
Brown’s Ravine Oak Stand 2
OAK2
14
Almanor
DFPZ
yes
2005
Brown’s Ravine Oak Stand 3
OAK3
10
Almanor
DFPZ
yes
2005
Brown’s Ravine Oak Stand 4
OAK4
14
Almanor
DFPZ
yes
2006/2007
Brown’s Ravine Oak Stand 5
OAK5
7
Almanor
DFPZ
yes
2006/2007
Brown’s Ravine Oak Stand 6
OAK6
6
Almanor
DFPZ
no
Brown’s Ravine Oak Stand 7
OAK7
8
Almanor
DFPZ
no
Brown’s Ravine Oak Stand 8
OAK8
7
Almanor
DFPZ
no
Brown’s Ravine Oak Stand 9
OAK9
6
Almanor
DFPZ
yes
2006/2007
Peg DFPZ
PEGD
7
Eagle Lake
DFPZ
no
6
Ch. 1. Fuel Treatments
Transect
Peg Reference
Pittville North DFPZ
Pittville South DFPZ
Round DFPZ
Round Reference
Storrie Fire Mastication East
Storrie Fire Mastication West
Stover
Upper Oak Reference
Warner Burn
Warner DFPZ
Wiley Ranch North
Wiley Ranch South
West Shore North DFPZ
West Shore North Reference
West Shore South DFPZ
West Shore South Reference
Young Pine
TOTAL
PRBO Avian Monitoring in the Lassen National Forest – 2009
Code
PEGR
PNDZ
PSDZ
RNDD
RNDR
STME
STMW
STVR
UOKR
WABU
WADZ
WRNO
WRSO
WSND
WSNR
WSSD
WSSR
YOPI
# Points
7
12
12
8
7
10
11
12
36
12
12
16
16
8
6
9
4
8
519
Ranger District
Eagle Lake
Hat Creek
Hat Creek
Eagle Lake
Eagle Lake
Almanor
Almanor
Almanor
Almanor
Almanor
Almanor
Hat Creek
Hat Creek
Almanor
Almanor
Almanor
Almanor
Almanor
7
Treatment Type
Reference
Group Selection/Prescribed Fire
DFPZ/Group Selection
DFPZ
Reference
Plantation/Mastication
Plantation/Mastication
Plantation/Mastication
Reference
Prescribed Fire
DFPZ
DFPZ
DFPZ
DFPZ
Reference
DFPZ
Reference
Plantation/Mastication
Treated
n/a
yes
yes
yes
n/a
no
no
yes
n/a
yes
yes
no
no
yes
n/a
yes
n/a
no
Year Treated
2005/2008
2005
2005
fall 2009
2007
2006
2006/2007
2002/2004
2002/2004
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Site Selection and Treatment History
We combined data across multiple projects on the Almanor, Eagle Lake, and Hat
Creek Ranger Districts of the Lassen National Forest (Table 1) to investigate the effects
of HFQLG treatments on landbirds. Treatments included Defensible Fuel Profile Zones
(DFPZ), Group Selection, Plantation/Mastication, and fire (prescribed and wild) (Table
2). Treatments, and specific treatment histories at given transects and point count
stations, are summarized in Table 1.
Table 2. Forest treatment types in the Northern Sierra Nevada for which the response of landbirds
was investigated in 2009.
Treatment
Defensible Fuel Profile Zones
(DFPZ)
Group Selection
Plantation/Mastication
Burn
Description
Mechanically created shaded fuel break, generally linear in shape;
affects more acres than any treatments in our study area.
Removal of all overstory trees in 0.5 – 2 acre area, sometimes
embedded within a DFPZ network.
Plantings of Ponderosa Pine. Mechanical shredding of shrubs that
sometimes uproots shrubs but often leaves plants alive below ground
to regenerate.
Generally low intensity human ignited burning. Generally consumes
understory fuels and some middle story trees. Some sites
experienced wildfire or backfires set during a wildfire.
DFPZ treatments monitored on the Eagle Lake Ranger District were established
in 2004 after consulting ranger district staff and available GIS layers. We selected 6 sites
that were slated for treatment in the next several years. At each treatment area we
established between 5 to 7 point counts inside of treatment boundaries and 5 to 8 sites in
similar habitat at least 100m outside the treatment but within 500m of the treated area
(see Burnett et al. 2004).
A similar protocol was used for the Brown’s Ravine Black Oak enhancement
DFPZ project in the Almanor Ranger District of the Lassen (Table 1). In this project,
treatment units were larger so we filled each unit with points spaced 220m apart. Each
unit contained between 5 and 14 points. Reference sites were established in adjacent units
where no treatment was planned (Burnett et al. 2004).
In 2009, 21 new transects comprising 261 point-count stations were added to the
project (Table 1) in the Almanor and Hat Creek Ranger Districts. We had already
established six transects in DFPZ’s on the Eagle Lake rangers district in 2004, of which
five had already been treated so we did not add additional sites in that district in 2009.
We used GIS layers of the boundaries of fuel projects that had already been implemented
8
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
to select new monitoring sites in the Almanor and Hat Creek ranger districts. We chose
projects that had been completed in the past five years and were large enough to contain a
minimum of 8 point count stations spaced 250m apart. We also selected projects in order
to obtain a sample of each of the four treatment types described in Table 2 above. In
addition to the previously treated fuel treatment sites, we also established transects within
the proposed Gray’s Peak project area and Storrie Fire mastication units on the ARD. We
used a similar site selection protocol as described above where GIS layers of unit
boundaries were employed to establish points in a way that would maximize the points a
person could sample in one morning while covering the majority of treatment units in the
project. Additionally three plantation study sites where we had already established
monitoring in previous years – Young Pine II, Carter Meadow Road, and Stover (Young
Pine I) – are included in this analysis and there site selection was very similar to that
already described above. For all of these sites we had no prior knowledge of the site
conditions prior to establishing the points. With the exception of the West Shore North
and South DFPZ’s, we did not establish adjacent reference points for any of these new
transects.
For each point count station, we identified the treatment history with respect to
four distinct treatment types (Tables 1 & 2). A given treatment was only considered to
occur at a point if the point fell inside the treatment polygon. Of the 519 points, 277 had
been treated in one or more ways prior to the 2009 point count seasons; the remaining
points were considered a combination of sites that have not yet been treated (but will be)
or were reference sites paired with treated units (Table 3).
Table 3. The number of point count stations by treatment type in each ranger district in PRBO’s
Northern Sierra study area in 2009. Each point was visited twice in 2009.
Treatment Type
Total
DFPZ
Group Selection
Mastication
Burn
Reference
Number of points
Number of points
Number of post-treatment points
Number of points
Number of post-treatment point visits
Number of points
Number of post-treatment point visits
Number of points
Number of post-treatment point visits
Number of reference points
1
21 points were treated fall 2009 (after point count surveys complete,
9
2
Almanor
319
133
108
0
n/a
78
121
24
242
84
Eagle
Lake
85
43
29
0
n/a
0
n/a
0
n/a
42
12 prescribed burn, 12 wildfire (backfire)
Hat
Creek
115
58
26
27
27
23
23
7
7
0
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Survey Protocol
We used a standardized five-minute variable circular plot point count census
(Reynolds 1980, Ralph et al. 1993, Ralph et al. 1995) to sample the avian community in
the study area. In this method, points are clustered in transects, but data were only
collected from fixed stations, not along the entire transect.
In 2009, all birds detected at each station during the five-minute survey were
recorded according to their initial distance from the observer. Detections were recorded
to the nearest meter up to 300 meters. Beyond 300 meters observations were recorded
simply as greater than 300 meters. The method of initial detection (song, visual, or call)
for each individual was also recorded. All observers underwent intensive 14 day training
in bird identification and distance estimation prior to conducting surveys. Laser
rangefinders were used to assist in distance estimation at every survey point.
Counts began around local sunrise, were completed within four hours, and did not
occur in inclement weather. Each transect was visited twice during the peak of the
breeding season from mid-May through the first week of July (Table 4).
Table 4. Dates of point count visits, Lassen National Forest fuel treatment transects 2009.
code
BATL
BIZD
BIZR
BRDZ
BRGS
CBMA
CMRO
GPCE
GPEA
GPWE
HOGD
HOGR
HVD
HVR
JVDZ
KOND
KONR
LOKR
MOKR
NCDZ
NCMA
OAK1
visit 1
6/1/2009
5/14/2009
5/14/2009
6/9/2009
6/9/2009
6/12/2009
6/2/2009
5/30/2009
6/1/2009
5/30/2009
5/15/2009
5/15/2009
5/25/2009
5/25/2009
6/1/2009
5/16/2009
5/16/2009
5/18/2009, 5/19/2009
5/23/2009
6/3/2009
6/3/2009
5/18/2009, 5/19/2009
visit2
6/20/2009
6/21/2009
6/21/2009
6/18/2009
6/18/2009
6/29/2009
6/24/2009
6/15/2009
6/15/2009
6/15/2009
6/21/2009
6/21/2009
6/23/2009
6/23/2009
6/14/2009
6/30/2009
6/30/2009
6/16/2009, 6/17/2009, 6/18/2009
6/25/2009
6/19/2009
6/19/2009
6/16/2009, 6/17/2009
10
Ch. 1. Fuel Treatments
code
OAK2
OAK3
OAK4
OAK5
OAK6
OAK7
OAK8
OAK9
PEGD
PEGR
PNDZ
PSDZ
RNDD
RNDR
STME
STMW
STVR
UOKR
WABU
WADZ
WRNO
WRSO
WSND
WSNR
WSSD
WSSR
YOPI
PRBO Avian Monitoring in the Lassen National Forest – 2009
visit 1
5/18/2009, 5/19/2009
5/18/2009
5/23/2009
5/23/2009
5/21/2009
5/21/2009, 5/22/2009
5/21/2009, 5/22/2009
5/19/2009
5/16/2009
5/16/2009
6/10/2009
6/3/2009
5/16/2009
5/16/2009
5/24/2009
6/11/2009
5/29/2009
5/21/2009, 5/22/2009
6/2/2009
6/2/2009
6/12/2009
6/12/2009
6/8/2009
6/8/2009
6/8/2009
6/8/2009
6/8/2009
visit2
6/16/2009, 6/17/2009
6/16/2009
6/25/2009
6/25/2009
6/26/2009
6/23/2009, 6/25/2009, 6/26/2009
6/23/2009, 6/25/2009
6/17/2009
6/11/2009
6/11/2009
6/18/2009
6/19/2009
6/11/2009
6/11/2009
6/20/2009
6/30/2009
6/24/2009
6/23/2009, 6/25/2009, 6/26/2009
6/27/2009
6/27/2009
6/20/2009
6/20/2009
6/29/2009
6/29/2009
6/24/2009
6/24/2009
6/24/2009
Statistical Analysis
Annual per-point species abundance, richness, and diversity metrics of birds
within 50 meters were summarized for 519 points. We excluded species that are not
adequately sampled using the point count method (e.g., waterfowl, shorebirds, kingfisher,
and raptors), as well as species not breeding in the region (e.g., Rufous Hummingbird).
We also excluded European Starling and Brown-headed Cowbird from analysis of
species richness and total bird abundance because they are invasive species regarded as
having a negative influence on the native bird community. Birds unidentified to species
(e.g., XXWA, Unidentified Warbler) were included in abundance estimates and, if the
only one of that taxa, in richness estimates, but were excluded from diversity indices.
We define species richness as the mean number of species detected within 50
meters of the observer per point across visits. The index of total bird abundance is the
11
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
mean number of individuals detected per point per visit; this number is obtained by
dividing the total number of detections within 50 meters by the number of stations and
the number of visits (2). Species diversity was measured using a modification of the
Shannon-Wiener index (Krebs 1989) introduced by MacArthur (1965), which reflects
combined species richness and equal distribution of the species. Diversity can be
considered as mean species diversity (average diversity per point). The relative
abundance of species is the mean number of detections of a given species per point per
visit within 50 meters of observers.
We determined community indices for each transect. We also compared
community indices (richness and abundance), as well as the abundance within 50 meters
of the ten most common species (at all study sites combined), among treatment types.
Means and confidence intervals were generated with StataIC 10.0 (StataCorp 2007). For
this, we lumped untreated sites with reference sites as “Untreated/Reference”. We
assigned points where group selection had occurred inside of another treatment simply as
group selection; we lumped prescribed burn and wildfire burned points under the
“treatment” category of “Fire”. The ten most abundant species were, in order: Mountain
Chickadee, Audubon’s Warbler, Dusky Flycatcher, Oregon Junco, Red-breasted
Nuthatch, Golden-crowned Kinglet, Hermit Warbler, Chipping Sparrow, Western
Tanager, and Fox Sparrow.
Additionally, we compared these indices for paired reference versus treated
transects using a two-tailed t-test, and included only sites that had been treated prior to
the 2009 breeding season; these included Biz, Hog, Konos, Round, West Shore North,
and West Shore South (DFPZ and Reference transects, respectively).
Results
Community Indices by Transect
Ninety-six species in total were detected across the 49 transects in 2009. Seventynine were used in assessing community indices (17 species were removed because they
were not appropriate to assess via the point count method; see Methods above).
Community index values were highly variable among transects (Table 5).
Diversity values were as low as 0.99 (Wiley Ranch South, untreated DFPZ), with the
most diverse sites having diversity values as high as 7.53 (Carter Meadow Road, hand
12
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
conifer release in 2001 and burned in 2008 Cub fire), 7.63 (Battle, 5 years post DFPZ
treatment), and 8.70 (West Shore South Reference). Abundance values ranged from 0.59
birds per point (Wiley Ranch South) to 7.04 (Battle), 7.06 (West Shore South DFPZ,
treated in 2002 or 2004), and 7.25 (West Shore South Reference) birds per point. Species
richness values ranged from 1.00 (Wiley Ranch South) up to 8.54 (Battle), 8.58 (Carter
Meadow Road), and 9.5 (West Shore South Reference).
Table 5. Point count indices for fuel treatment transects, Lassen National Forest 2009.
Station
BATL
BIZD
BIZR
BRDZ
BRGS
CBMA
CMRO
GPCE
GPEA
GPWE
HOGD
HOGR
HVD
HVR
JVDZ
KOND
KONR
LOKR
MOKR
NCDZ
NCMA
OAK1
OAK2
OAK3
OAK4
OAK5
OAK6
OAK7
OAK8
OAK9
PEGD
PEGR
PNDZ
PSDZ
RNDD
Diversity
(sw)
7.63
3.78
5.40
6.70
3.08
6.20
7.53
5.26
4.91
6.85
3.36
3.48
4.24
3.79
4.96
4.12
5.22
5.88
6.41
5.04
3.42
6.04
6.75
6.46
5.86
4.62
5.84
4.88
4.97
4.84
3.94
5.31
5.74
5.33
2.48
Abundance
(individuals/visit)
7.04
2.71
4.71
6.67
2.00
6.14
6.71
4.35
4.82
5.96
2.57
2.86
3.21
2.71
3.67
3.21
4.07
4.80
4.75
3.79
3.17
4.43
5.36
5.35
4.25
4.07
4.17
3.69
3.93
3.00
3.57
4.14
4.29
4.00
2.00
13
Species
richness
8.54
4.00
6.00
7.58
3.17
7.00
8.58
5.70
5.57
7.54
3.71
3.71
4.71
4.00
5.33
4.43
5.57
6.38
6.83
5.42
3.83
6.57
7.29
7.20
6.29
4.86
6.17
5.25
5.29
5.00
4.43
5.86
6.25
5.75
2.63
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Diversity
(sw)
4.17
6.15
5.24
3.86
6.20
7.31
6.58
2.88
0.99
6.01
5.16
7.18
8.70
5.18
Station
RNDR
STME
STMW
STVR
UOKR
WABU
WADZ
WRNO
WRSO
WSND
WSNR
WSSD
WSSR
YOPI
Abundance
(individuals/visit)
3.07
5.75
4.05
3.25
4.93
4.88
5.21
1.88
0.59
5.06
3.83
7.06
7.25
4.44
Species
richness
4.43
6.80
5.55
4.17
6.75
7.67
7.17
3.00
1.00
6.75
5.50
8.11
9.50
5.75
Community Indices between Treated and Untreated Paired Transects
Comparing indices of abundance and richness between paired transects, a general
pattern was observed of higher community indices at the reference sites than at the
treated DFPZ sites (Figures 2 and 3; Table 5). The mean total bird abundance per point
was significantly higher in the reference transect than the treated transect for BIZ (2.71
versus 4.71 birds/pt; t-statistic = -2.77, P = 0.02). The mean richness per point was
significantly higher in the reference transect than the treated transect for RND (2.63
versus 4.43 species/pt; t-statistic = -2.31, P = 0.04). Differences also approached
significant between treated and reference sites for Bizz, Konos and West Shore South
species richness and for Round total abundance; for all, they were again greater in the
reference site.
Table 5. Comparison between paired treated DFPZ versus reference transects, Lassen National
Forest 2009.
Index of Abundance
DFPZ
Ref
Test
Mean (SE)
Mean (SE) statistic
BIZ
2.71 (0.56) 4.71 (0.45)
-2.77
HOG
2.57 (0.52) 2.86 (0.5)
-0.40
KON
3.21 (0.55) 4.07 (0.32)
-1.34
RND
2.00 (0.37) 3.07 (0.48)
-1.70
WSN
5.06 (0.67) 3.83 (0.75)
1.22
WSS
7.06 (0.44) 7.25 (0.72)
-0.24
*significant at the P < 0.05 level
P
Value
0.02*
0.70
0.20
0.11
0.25
0.82
14
DFPZ
Mean (SE)
4.00 (0.87)
3.71 (0.36)
4.43 (0.48)
2.63 (0.33)
6.75 (0.75)
8.11 (0.39)
Species Richness
Ref
Test
Mean (SE) statistic
6.00 (0.58)
-1.91
3.71 (0.68)
0
5.57 (0.48)
-1.68
4.43 (0.72)
-2.31
5.50 (1.18)
0.94
9.50 (0.65)
-1.92
P Value
0.08
1.00
0.12
0.04*
0.37
0.08
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
In a few cases (e.g., Hog richness and abundance and West Shore South
abundance), indices were similar between paired treated and reference transects.
Although the opposite pattern was observed for West Shore North, the results are not
significant as the confidence intervals overlap.
Figure 2. Index of abundance from paired DFPZ versus reference point count stations, Lassen
National Forest 2009. Error bars represent 95% confidence intervals.
Total Abundance (DFPZ vs. Reference) 12
Mean # birds per visit (<50m) 10
8
DFPZ
6
Ref
4
2
0
BIZ
HOG
KON
RND
WSN
WSS
Community Indices and Species Abundance Among Treatment Types
Figures 3, 4 and 5 summarize community indices among treatment types. The
treatment type with the highest indices overall, and higher than any of the other treatment
types (P<0.05), was burn. DFPZ treatment points overall had the second highest indices;
diversity and richness there were higher (P<0.05) than any other treatment type except
burn. Group selection treatment sites had the lowest community indices.
15
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Figure 3. Mean per point richness values for paired DFPZ versus reference point count stations,
Lassen National Forest 2009. Error bars represent 95% confidence intervals.
Species Richness (DFPZ vs. Reference)
Mean # of species per point (<50m)
14
12
10
8
DFPZ
6
Ref
4
2
0
BIZ
HOG
KON
RND
WSN
WSS
Figure 3. Species diversity (mean diversity per point per visit within 50m) for Lassen National Forest
fuel treatment point counts 2009. Error bars represent 95% confidence intervals.
Untreated/Reference
Plantation/Mastication
Group Selection
DFPZ
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Burn
Mean bird diversity per point
Shannon Index of Diversity
16
Burn
DFPZ
Group Selection
Plantation/Mastication
Untreated/Reference
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Figure 4. Bird abundance (mean number of individual birds per point per visit within 50m) for
Lassen National Forest fuel treatment point counts 2009. Error bars represent 95% confidence
interval.
Untreated/Reference
Plantation/Mastication
Group Selection
DFPZ
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Burn
Mean birds per point (<50m)
Total Bird Abundance Burn
DFPZ
Group Selection
Plantation/Mastication
Untreated/Reference
Figure 5. Species richness (mean number of species per point per visit within 50m) for Lassen
National Forest fuel treatment point counts 2009. Error bars represent 95% confidence interval.
Untreated/Reference
Plantation/Mastication
Group Selection
DFPZ
10.00
9.00
8.00
7.00
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Burn
Mean number of species per point
Species Richness
17
Burn
DFPZ
Group Selection
Plantation/Mastication
Untreated/Reference
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Bird species more associated with trees and canopy (e.g., Mountain Chickadee,
Hermit Warbler, and Western Tanager), as well as those associated with open understory
(Oregon Junco) were most common at the treated DFPZ points. Species associated with a
shrub understory were most common in the burn treatment category.
Table 6. Mean species abundance (and standard error) for top 10 most abundant species (detections
<50m from observer) over the project area, by treatment type, Lassen National Forest 2009. Highest
value of a given index across all treatment levels is shown in bold. Species are listed in taxonomic
order.
Dusky Flycatcher
Mountain Chickadee
Red-breasted Nuthatch
Golden-crowned Kinglet
Audubon’s Warbler
Hermit Warbler
Western Tanager
Chipping Sparrow
Oregon Junco
Fox Sparrow
Burn
n=31
0.62 (0.12)
0.35 (0.07)
0.24 (0.06)
0.24 (0.08)
0.16 (0.04)
0.16 (0.05)
0.19 (0.05)
0.27 (0.11)
0.32 (0.07)
0.45 (0.14)
DFPZ
n=184
0.35 (0.04)
0.58 (0.04)
0.24 (0.03)
0.19 (0.02)
0.51 (0.04)
0.27 (0.03)
0.26 (0.03)
0.23 (0.04)
0.48 (0.04)
0.02 (0.01)
Group
Selection
n=27
0.04 (0.03)
0.28 (0.06)
0 (0)
0 (0)
0.20 (0.06)
0 (0)
0.07 (0.033)
0.46 (0.09)
0.37 (0.07)
0.02 (0.02)
Plantation/
Mastication
n=35
0.47 (0.09)
0.57 (0.10)
0.17 (0.06)
0.14 (0.05)
0.54 (0.11)
0.11 (0.07)
0.17 (0.05)
0.26 (0.08)
0.21 (0.06)
0.13 (0.07)
Untreated/
Reference
n=242
0.50 (0.04)
0.38 (0.03)
0.25 (0.03)
0.24 (0.03)
0.41 (0.03)
0.17 (0.02)
0.13 (0.02)
0.11 (0.02)
0.31 (0.03)
0.25 (0.03)
Discussion
In 2009, PRBO monitored 49 point count transects totaling 519 points as part of
our long-term landbird response to fuel treatments project. Such long-term monitoring is
allowing us to assess how fuel reduction treatments change the composition and
abundance of landbird species over space and time. Along with our Plumas-Lassen study
these two data sets provide us with the most comprehensive study of the response of
landbirds to fuel treatments anywhere in the Sierra Nevada.
Overall, we found that bird community indices were highest at burned sites,
consistent with findings from our Plumas-Lassen study (Burnett et al. 2009). Sites
selected for prescribed fire may be in areas with lower fuel loads which allow for the use
of prescribed fire. The other treatment type with relatively high indices overall were
DFPZ’s. As with fire, it will be important to tease out the effect of time since treatment in
order to truly understand the impacts of DFPZ management practices on landbirds but
our preliminary data and that from the Plumas-Lassen study suggest that the effects of
DFPZ treatments on landbirds are mixed both in terms of species response and site to site
18
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
differences. The pre-existing conditions at a site and the prescription of the DFPZ
treatment are both factors that likely contribute to the response of the avian community to
treatments. We continue to suggest that treatments that retain variable canopy cover and
target areas of lower overall avian diversity (e.g. overly dense 2nd growth white fir forest)
will likely have the greatest positive impact on the landbird community.
The treatment type with the lowest community indices overall was Group
Selection – a treatment that removes all of the overstory of trees in a 1- 2 acre area.
However, the fact that all Group Selection transects were in the Hat Creek Ranger
District may be biasing this result and as with DFPZ’s, the effects of group selections on
the avian community is likely heavily contingent on the pre-existing condition at the site
and landscape context of the treatment. For example, we did not find a significant effect
of group selections on avian diversity in denser west side forest on Plumas National
Forest (Burnett et al. 2009). This may be because our group selection sites often straddled
the edges of treatments since they were established prior to treatments and boundaries
were moved slightly. Whereas in the LNF we established points after treatments had been
implemented and thus were able to place our point count stations in the center of the
group selections and thus surveyed less edge. We would expect lower bird diversity
within group selections immediately following treatments as the vast majority of
vegetation structure has been removed however, few negative effects were found in
group selection treatments in pine-hardwood dominated stands in the central Sierra
Nevada (Garrison et al. 2005).
Of the top ten most abundant species, each treatment type could boast having the
highest abundance of at least one of the species across all five treatments. The two
treatments that had the greatest abundance of the largest number of species were, again,
DFPZ and burn. The species most common in burn varied in life history from species
associated with understory shrub habitat (Dusky Flycatcher, Fox Sparrow) to a species
associated with large trees (Golden-crowned Kinglet), reflecting the diversity in habitats
created after fires, especially when combining sites that burned in different years and
different intensities. The species most common in DFPZ were generalists (Mountain
Chickadee and Oregon Junco) or mature forest associated species (Hermit Warbler and
Western Tanager).
19
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
When we compared indices of abundance and richness between paired transects, a
general pattern was observed of significantly higher community indices at the reference
sites than at the treated DFPZ sites. Because this result differs from the higher indices
observed across all five treatment types at DFPZ than reference sites, when not restricted
to the paired sites, this underscores the usefulness of conducting studies with paired sites
when possible. This also suggests there maybe some at least short-term loss in habitat
quality for the landbird community at sites that have been converted to shaded fuel
breaks. In the northern Sierra Nevada, many species are associated with foliage volume
in the middle and especially understory (Verner and Larson 1989). It is this component
(fuel ladders) of the habitat that is often removed during DFPZ treatments (as well as in
group selection, pre-commercial thinning, and mastication) and could result in short-term
declines of a number of species following fuel reduction treatments. However, in group
selections and mastication understory, foliage volume is likely to return whereas in
shaded fuel breaks (>40% canopy cover retained) it may be less likely to return. It is for
these reasons that we suggest a mosaic design of varying canopy covers in fuel treatments
be prescribed.
Consistent with previous results, our preliminary data from the LNF fuel
treatments suggest that sites treated with low to moderate intensity fire – including
prescribed fire – harbor some of the highest landbird diversity in the Northern Sierra
Nevada. The use of low to moderate intensity fire should be greatly increased in these
forests.
We focused in this report on summarizing 2009 efforts and results, but intend in
the coming years to conduct more comprehensive analyses, both spatially and temporally.
We remain conservative about generalizing patterns thus far, as a more in depth analysis
will take into account time since treatment, pre versus post treatments, and spatial
patterns unrelated to treatment.
Acknowledgements
Funding for this project was provided by the Lassen National Forest and Herger
Feinstein Quincy Library Group Forest Recovery Act monitoring funds. We especially
would like to thank Coye Burnett, Tom Frolli, Karen Harville, Bobette Jones, Tom
Rickman, and Mark Williams of the Lassen National Forest and Colin Dillingham – the
20
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
USFS QLG monitoring coordinator - for their support and assistance with this project.
We also wish to thank Tim Guida, crew leader, and Nathan Fronk and Luke Owens, our
2009 field crew.
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in central hardwood forests. The Journal of Wildlife Management 61, 159-171.
Arno, S.F., and C.E. Fiedler. 2005. Mimicking Nature’s Fire: Restoring Fire Prone
Forests in the West. Island Press, Washington D.C.
Askins, R.A., B Zuckerberg, and L. Novak. 2007. Do the size and landscape context of
forest openings influence the abundance of breeding success of shrubland
songbirds in southern New England? Forest Ecology and Management 250, 137147.
Burnett, R.D., D.Humple, T.Gardali, and M.Rogner. 2004. Avian Monitoring in the
Lassen National Forest. A PRBO report to the USFS. Contribution # 1242.
Burnett, R.D., N.Nur, and C.A.Howell. In prep. Implications of spotted owl management
for landbirds in the Sierra Nevada, CA, USA. Forest Ecology and Management.
Burnett, R.D., D. Jongsomjit, and D. Stralberg. 2009. Avian monitoring in the Plumas
and Lassen National Forest: 2008 Annual Report. PRBO report to the U.S. Forest
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Chambers, C.L., W.C. McComb, and J.C. Tappeiner II. 1999. Breeding bird responses to
three silvicultural treatments in the Oregon Coast Range. Ecological Applications
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ESRI 2000. Arc View GIS 3.2a. Environmental Systems Research Institute. Redlands,
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Fink, A.D., F.R. Thompson III, and A.A. Tudor. 2006. Songbird use of regenerating
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Garrison, B.A., M.L. Triggs, and R.L. Wachs. 2005. Short-term effects of group-selection
timber harvest on landbirds in montane hardwood-conifer habitat in the central
Sierra Nevada. Journal of Field Ornithology 76: 72-82.
Hagar, J., S. Howlin, and L.Ganio. 2004. Short-term response of songbirds to
experimental thinning of young Douglas-fir forests in the Oregon Cascades.
Forest Ecology and Management 199: 333-347.
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PRBO Avian Monitoring in the Lassen National Forest – 2009
Hansen, A.J., W.C. McComb, R. Vega, M.G. Raphael, and M. Hunter. 1995. Bird
habitat relationships in natural and managed forests in the west cascades of
Oregon. Ecological Applications 5: 555-569.
HFQLG (Herger-Feinstein Quincy Library Group Forest Recovery Act) 1999. Final
Environmental Impact Statement, U.S. Department of Agriculture, Forest
Service, Pacific Southwest Region, Vallejo, CA.
http://www.fs.fed.us/r5/hfqlg/publications/1999_feis/TOC.htm
King, D.I., R.M. Degraaf, and C.R. Griffin. 2001. Productivity of early successional
shrubland birds in clearcuts and groupcuts in an eastern deciduous forest. Journal
of Wildlife Management 65: 345-350.
Krebs, C.J. 1989. Ecological Methodology. Harper and Row Publishers, New York, New
York: 654 pp.
MacArthur, R.H. 1965. Patterns of species diversity. Biological Reviews 40:510-533.
Martin, T.E. and G.R. Geupel. 1993. Nest monitoring plots: Methods for locating nests
and monitoring success. J. Field Ornith. 64:507-519.
McKelvey, K.S. and J.D. Johnston. 1992. Historical perspectives on forests of the Sierra
Nevada and the Transever Ranges of Southern California: Forest conditions at the
turn of the century. Pp. 225-246 In The California spotted owl: a technical
assessment of its current status. Tech Coordination by J. Verner, K.S. McKelvey,
B.R. Noon, R.J. Gutierrez, G.I. Gould Jr., and T.W. Beck. Pacific Southwest
Research Station General Technical Report 133. Albany, CA.
Minnich, R.A., M.G. Barbour, J.H. Burk, and R.F. Fernau. 1995. Sixty years of change in
California coniferous forests of the San Bernardino mountains. Conservation
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Parsons, D.J. and S.H. Benedetti. 1979. Impact of fire suppression on a mixed-conifer
forest. Forest Ecology and Management 2: 21-33.
Ralph, C.J., G.R. Geupel, P. Pyle, T.E. Martin, and D.F. DeSante 1993. Field Methods
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General Technical Report PSW-144.
Ralph, C.J., S. Droege, and J.R. Sauer. 1995. Managing and monitoring birds using point
counts: standards and applications. In C. J. Ralph, J. R. Sauer and S. Droege
(eds.), Monitoring Bird Populations by Point Counts. USDA Forest Service
Publication, Gen. Tech. Rep. PSW-GTR-149, Albany, CA .
Reynolds, R.T., J.M. Scott, and R.A. Nussbaum. 1980. A variable circular plot method
for estimating bird numbers. Condor 82:309:313.
22
Ch. 1. Fuel Treatments
PRBO Avian Monitoring in the Lassen National Forest – 2009
Siegel, R.B. and D.F. DeSante. 2003. Bird communities in thinned versus unthinned
sierran mixed conifer stands. Wilson Bulletin 115: 155-165.
Skinner, C.N. and C.Chang. 1996. Fire regimes, past and present. Sierra Nevada
Ecosystem Project: Final Report to Congress. Vol. 2, Assessments and scientific
basis for management options, pp. 1041-1069. University of California Centers
for Water and Wildland Resources, Davis, CA, USA.
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Statement, Record of Decision. United States Department of Agriculture, Forest
Service, Pacific Southwest Region, Vallejo, CA.
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of Agriculture, Forest Service, Pacific Southwest Region, Vallejo, CA.
http://www.fs.fed.us/r5/snfpa/final-seis/rod/
Stata Corp. 2007. Intercooled Stata 10 for Windows. Stata Corp. LP College Station,
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Stephens, R.E. Martin, and N.E. Clinton. 2007. Prehistoric fire area and emissions from
California forests, woodlands, shrublands, and grasslands. Forest Ecology and
Management 251: 205-216.
Taylor, A.H. 2000. Fire regimes and forest changes along a montane forest gradient,
Lassen Volcanic National Park, southern Cascade Mountains, USA. Journal of
Biogeography 27:87-104.
Taylor, A.H. & C.N. Skinner. 2003. Spatial patterns and controls on historical fire
regimes and forest structure in the Klamath Mountains. Ecological Applications
13:704-719.
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California. Journal of Biogeography 5:377-402.
Weatherspoon, C.P. 1996. Fire-silvicultural relationships in Sierra forests. In Sierra
Nevada Ecosystem Project Final Report to Congress, Vol. 2: Assessments and
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Resources, University of California, Davis, pp. 1167-1176.
23
Chapter 2. Resident and Neotropical Migratory Bird Response to
Aspen Enhancement on the Lassen National Forest
Photo by Kevin Cole
Ryan D. Burnett & Alissa Fogg
PRBO Conservation Science
24
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Lassen National Forests - 2009
Background and Introduction
In the Sierra Nevada, with extensive livestock grazing and the absence of regular
fire, aspen are often out-competed by conifers (Mueggler 1985). As a result, the health of
aspen has deteriorated and its extent throughout western North America has been reduced
as much as 96% (Bartos and Campbell 2001). Aspen inventories and assessments on the
Lassen National Forest found the vast majority of aspen stands to be in poor health and in
need of management actions to avoid further degradation or complete stand loss. As a
result, the forest has implemented strategies to restore aspen habitat by removing
competing conifers and excluding livestock grazing (Jones et al. 2005).
Aspen habitat in western North America can support a disproportionately rich and
abundant avian community compared to the surrounding habitats (Flack 1976, Winternitz
1980, Mills et al. 2000, Griffis-Kyle and Beier 2003). Several bird species demonstrate a
strong affinity with aspen, including Northern Goshawk (Accipiter gentilis), Red-naped
and Red-breasted Sapsuckers (Sphyrapicus nuchalis/ruber), Dusky Flycatcher
(Empidonax oberholseri), Warbling Vireo (Vireo gilvus), Swainson’s Thrush (Catharus
ustulatus), and MacGillivray’s Warbler (Oporornis tolmiei) (Salt 1957, Flack 1976,
Finch and Reynolds 1988, Heath and Ballard 2003, Richardson and Heath 2004).
In 2004, PRBO began an adaptive management based project monitoring birds
across aspen habitat on the Eagle Lake and Almanor Ranger Districts of the Lassen
National Forest. The primary objective of this study is to guide and evaluate aspen
restoration treatments by monitoring the response of a suite of landbird species associated
with a broad range of aspen habitat characteristics. In this report we incorporate results
from 2009 into those from 2004 – 2008 and use the knowledge gained from this
additional information to help guide future restoration treatments and long-term
management of aspen habitat on the Lassen National Forest.
Project Area
All avian survey work was conducted on the Lassen National Forest in the Eagle
Lake and Almanor Ranger Districts at the junction of the Sierra Nevada and Cascade
Mountains of California (Lat 400 N, Long 1200 W). Sites ranged in elevation from
approximately 1500 – 2000 meters (Figure 1).
25
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Lassen National Forests - 2009
Methods
Aspen Sampling Design
For all aspen sites we used GIS layers containing polygons of known aspen stands
based upon aspen inventories conducted by Forest Service staff. In the Eagle Lake
Ranger District (ELRD) we selected sites non-randomly that represent the range of
conditions in which aspen are found throughout the District. We limited our selection to
areas that could be covered by one observer in a four-hour morning count window and
that contained enough acres of aspen habitat to fit a minimum of 4 point count stations
with at least 220 meter spacing between points. We attempted to maximize the number of
post-treatment sites, which were limited in number, as they could provide us with
information on bird response to aspen treatments that were already five to nine years old.
The transects with treated stands on the ELRD in 2009 included Harvey Valley, Pine
Creek, Martin Creek, Feather Lake, and Butte Creek.
In the Almanor Ranger District (ARD) we selected sites that were within
proposed aspen enhancement projects (e.g., Minnow – Coon Hollow, Creeks II – Ruffa,
Brown’s Ravine, Feather – West Dusty 1-3, Lott’s – Philbrook/Coon Hollow, and Mini –
Robber’s Creek) and established points with at least 220 meter spacing in delineated
aspen polygons. Two additional transects, Willow Creek and West Dusty 4 were once
part of proposed projects but were dropped for various reasons. A total of 6 points (four
points on the West Dusty 3 transect, one point on the West Dusty 1 transect, and one
point on the Willow Creek transect) were treated as of the 2009 breeding season on the
ARD.
On both districts we attempted to maximize the number of points within the
delineated aspen stands in the areas selected. In some areas where stands were not in high
densities, we limited transect size to allow for the extra time to walk between stands in
order to allow for completion within the limited morning hours allowed by the
standardized protocol. Generally, the first stand chosen was the one closest to the nearest
road. Once the first stand was chosen, the next closest stand that was at least 200 meters
from the previous was selected, and so on. All sites were selected without previous
knowledge of the local micro habitat attributes or condition.
26
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Lassen National Forests - 2009
Survey Protocol
Standardized five minute unlimited distance variable circular plot point count
censuses (Reynolds 1980, Ralph et al. 1993) were conducted at 181 stations along 18
transects in 2009 (Table 1, Figure 1, and Appendix 1). All birds detected at each station
were recorded along with the exact distance from the observer where it was first detected
(to the nearest meter). Birds flying above the station in transit but not observed landing
were recorded separately. The method of initial detection (song, visual or call) for each
individual was recorded. Counts began around local sunrise and were completed within
four hours. Each transect was surveyed twice between 15 May and 1 July in each year,
including 2009 (Table 1). An electronic range finder was used to assist with distance
estimation at each point count station and all observers had previous songbird field work
experience and went through intense three week training on bird identification and
distance estimation.
Table 1. Aspen point count transects, ranger district, number of stations, and dates
surveyed in 2009 in Lassen National Forest.
Site Name Brown’s Ravine Aspen Coon Hollow Aspen Philbrook Aspen Robber’s Creek Aspen Ruffa Aspen West Dusty Aspen 1 West Dusty Aspen 2 West Dusty Aspen 3 West Dusty Aspen 4 Willow Creek Aspen Butte Creek Aspen Crazy Harry Aspen Feather Lake Aspen Harvey Valley Aspen Lower Pine Creek Aspen Martin Creek Aspen Pine Creek Aspen Susan River Aspen # of Stations 4 14 10 16 12 10 6 8 8 9 8 7 5 15 12 11 14 12 Ranger District Almanor Almanor Almanor Almanor Almanor Almanor Almanor Almanor Almanor Almanor Eagle Lake Eagle Lake Eagle Lake Eagle Lake Eagle Lake Eagle Lake Eagle Lake Eagle Lake 27
Date, 1st Survey Date, 2nd Survey 6/14/2009 6/14/2009 6/14/2009 5/28/2009 6/14/2009 5/26/2009 5/28/2009 5/26/2009 5/26/2009 5/28/2009 5/27/2009 5/29/2009 5/29/2009 5/28/2008 5/27/2009 5/25/2009 5/27/2009 5/29/2009 6/26/2009 7/1/2009 7/1/2009 6/23/2009 7/1/2009 6/21/2009 6/24/2009 6/24/2009 6/21/2009 6/21/2009 6/30/2009 6/30/2009 6/30/2009 6/20/2008 6/22/2009 6/29/2009 6/22/2009 6/29/2009 Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Lassen National Forests - 2009
Analyses
Avian community point count analysis was restricted to a subset of the species
encountered. We excluded species that do not breed in the study area as well as those that
are not adequately sampled using the point count method (e.g., waterfowl, kingfisher, and
raptors). We also excluded European Starling and Brown-headed Cowbird from analysis
of species richness and total bird abundance because they are invasive species regarded
as having a negative influence on the bird community. However, we did investigate the
abundance of these two species separately.
Species richness
We present species richness as the average number of species detected within 50
meters per point across visits within a year for the species adequately sampled using the
point count method.
Total Bird Abundance
The index of total bird abundance is the mean number of individuals detected per
station per visit. This number is obtained by dividing the total number of detections
within 50 meters by the number of stations and the number of visits.
Index of Species Abundance
An index of the abundance of species was calculated as the total detections of a
given species within 50m of an observer per point count visit. For sites with multiple
years (most) we summed the detections and then divided by total visits across years
versus averaging the means for each year.
Statistical Tests
We employed a suite of statistical tests in comparing treated aspen to untreated
aspen. Negative binomial regression was used to test for differences in indices of
abundance of individual species between treated and untreated aspen stands; while linear
regression was used to compare the community indices of species richness and total bird
abundance. The test statistic (F for linear & Likelihood Ratio for negative binomial) and
28
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Lassen National Forests - 2009
p-values are presented. For the analysis of trends, linear regression was used with year as
the independent variable and we included a quadratic term for year if the linear fit was
poor. F-tests were used to evaluate the addition of the quadratic term. For all tests
significance was assumed at an α = 0.05 level. Stata 10.0 statistical software was used to
conduct all statistical analyses (Stata Corp 2007).
29
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Figure 1. Location of PRBO Aspen point count stations in the Lassen National Forest surveyed in 2009.
30
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Results
In 2009, total bird abundance in aspen stands monitored across the two ranger
districts ranged from a high of 7.83 at Ruffa Aspen to a low of 2.86 at Crazy Harry, and
species richness ranged from 10.67 at Ruffa Aspen to 4.29 at Crazy Harry (Table 2). The
mean total bird abundance by transect in 2009 was 5.29 while the mean species richness
was 7.23. In comparison, total bird abundance in upland unburned habitat in the PlumasLassen study area in 2009 was 5.08 and species richness was 6.37.
We compared the total bird abundance and species richness at untreated aspen
sites in the ARD to untreated aspen sites in the ELRD in 2009. Species richness was 7.98
in the ARD and 6.60 in the ELRD. Total bird abundance in the ARD was 5.84 compared
to 4.90 in the ELRD (Figure 2); these differences were not statistically significant. When
sites in both ranger districts that have been treated were included, both species richness
and total bird abundance decreased slightly in both districts but these changes were not
statistically significant (Figure 2).
When data from all years were combined, total bird abundance and species
richness were higher at treated sites compared to untreated sites on the Eagle Lake
Ranger District between 2006 and 2009 (Figure 3). Across this four year period, total bird
abundance averaged 5.54 at treated sites and 4.53 at untreated sites (F = 4.25, p = 0.04).
Species richness at treated sites averaged 6.99 compared to 6.33 at untreated sites (F =
0.81; p<0.37).
31
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Table 2. Mean per point total bird abundance (detections/point/visit) and species richness (within 50 m of observers) at aspen sites
surveyed in the Lassen National Forest from 2004 – 2009. Sites not surveyed are represented by double dashes. Coon Hollow and
Philbrook transects were surveyed only once in 2008 due to fire access restrictions, thus they were not included in 2008 figures.
Station
Ruffa Aspen
Brown’s Ravine
Butte Creek
Coon Hollow
Crazy Harry
Feather Lake
Harvey Valley
Lower Pine Creek
Martin Creek
Philbrook
Pine Creek
Robber’s Creek
Susan River
West Dusty 1
West Dusty 2
West Dusty 3
West Dusty 4
Willow Creek
Total
2004
5.72
2.38
4.63
-4.50
4.60
3.47
4.00
3.78
-4.60
-3.67
-----4.16
Total Bird Abundance
2005 2006 2007 2008
7.11 5.92 6.88 6.33
3.25 4.13 3.75 2.75
5.81 7.31 5.69 5.50
4.75
---4.00 5.43 3.64 3.57
7.40 5.30 9.50 8.00
3.03 5.93 4.17 2.43
2.67 4.04 4.67 3.96
4.18 3.91 6.32 5.86
3.65
---4.57 5.90 5.04 4.71
-5.72 5.78 5.09
3.13 3.09 4.92 1.29
-3.75 4.30 3.00
-3.33 3.67 4.08
-3.63 3.81 3.19
-4.75 5.25 4.56
-4.28 5.44 4.61
4.67 5.36 5.32 4.42
Species Richness
2009
7.83
5.63
7.13
6.86
2.86
4.80
4.50
5.21
3.73
6.10
4.36
4.94
5.58
3.80
3.83
4.63
6.56
6.00
5.29
32
2004
7.56
2.75
5.75
-6.43
6.40
4.93
5.75
5.09
-5.93
-4.75
-----5.53
2005
7.33
5.25
8.00
-5.43
7.20
4.47
4.42
5.45
-6.43
-5.00
-----5.90
2006
7.50
6.25
9.63
-8.00
5.80
6.93
5.92
5.27
-7.21
7.63
4.50
5.50
4.00
5.50
6.75
5.33
6.68
2007
8.92
5.00
8.38
6.71
5.85
7.80
4.67
6.83
8.00
5.30
7.00
7.31
6.50
6.80
3.67
5.63
7.88
7.22
6.79
2008
8.42
4.25
7.75
-5.71
7.80
3.47
6.17
8.36
-6.86
7.63
2.25
5.00
5.67
5.38
5.75
6.78
6.08
2009
10.67
7.75
8.63
8.43
4.29
6.20
6.13
7.00
5.27
8.80
6.29
7.12
7.83
5.30
5.50
6.38
8.63
8.44
7.23
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Figure 2. Mean per point species richness (per year) and total bird abundance (per visit)
based on detections within 50 meters of observers at treated and untreated aspen sites on
Almanor and Eagle Lake ranger districts in 2009 with standard error.
Almanor vs. Eagle Lake 2009
9
Almanor Untreated
8
Almanor Total
7
Eagle Lake Untreated
6
Eagle Lake Total
5
4
3
2
1
0
Species Richness
Total Bird Abundance
Figure 3. Mean per point species richness and total bird abundance at treated and
untreated aspen sites on the Eagle Lake Ranger District from 2006 – 2009 compared to
coniferous forest in the Plumas-Lassen study area from 2003 – 2006 with standard error.
Treated vs. untreated aspen
8.00
7.00
6.00
5.00
Treated Aspen
Untreated Aspen
4.00
Conifer Forest
3.00
2.00
1.00
0.00
Species Richness
Total Bird Abundance
33
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Species richness decreases substantially in 2009 at treated sites on ELRD to its
lowest value since the beginning of the study (Figure 4). Including a quadratic term for
year improved model fit (F = 8.2, p = 0.005). Species richness at untreated sites on ELRD
continued to show a significant increasing linear trend (F = 9.6, p < 0.002) between 2004
and 2009. Total bird abundance from 2004 through 2009 at treated sites also decreased
to its lowest value since the beginning of the study and including a quadratic term for
year improved model fit for this metric as well (F = 10.0, p = 0.002). Untreated sites
continued to show a significant increasing linear trend (F = 6.63, p = 0.01).
Figure 4. Mean per point species richness (with standard error) at treated and untreated
aspen sites from 2004 -2009 in Eagle Lake Ranger District (Lassen National Forest) with
standard error and fitted linear and quadratic trend lines.
Species Richness
9
8
# of Species/Point
7
6
5
4
Treated
3
Untreated
2
1
0
2004
2005
2006
2007
34
2008
2009
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Figure 5. Total bird abundance per point count visit (with standard error) by year at
treated and untreated aspen sites from 2004 - 2009 on the Eagle Lake Ranger District
(Lassen National Forest) with standard error and fitted linear and quadratic trends.
Total Bird Abundance
8
# of Individuals/Point/ Visit
7
6
5
4
3
2
Treated
Untreated
1
0
2004
2005
2006
2007
2008
2009
We investigated an index of the abundance of ten of the twelve previously
identified aspen focal species (Burnett in press), at treated aspen, untreated aspen, and
conifer forest across the six-year study period in both ranger districts. We also included
Mountain Chickadee, another potential focal species. There were not adequate detections
of Swainson’s Thrush and Olive-sided Flycatcher – the remaining two focal species – to
include them in the analysis.
Six of the eleven species were significantly more abundant in treated aspen than
untreated aspen; each of these six species were also more abundant in aspen of any kind
compared to coniferous forest in the region (Table 3, Figure 6). Red-breasted Sapsucker,
Hairy Woodpecker, Mountain Bluebird, Tree Swallow, Mountain Chickadee and
Chipping Sparrow were all significantly more abundant in treated aspen than untreated
aspen. Additionally, total bird abundance was significantly greater in treated stands
compared to untreated stands while species richness was similar. Western Wood-Pewee
and Warbling Vireo showed a small non-significant difference between treated and
untreated aspen though these species were far more abundant in aspen stands than conifer
35
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
forest. Only two focal species, Dusky Flycatcher and MacGillivray’s Warbler, remained
more abundant in untreated than treated aspen, with a significant difference for
MacGillivray’s Warbler, and both were similarly abundant in conifer forest as in aspen.
Table 3. Species Richness, total bird abundance, and an index of the abundance of ten
aspen focal species at treated and untreated sites across the Lassen National Forest, 20062009. P-value is from linear (species richness & total bird abundance) or negative
binomial regression (all other metrics) comparing treated to untreated aspen. Means from
conifer forest in the Plumas-Lassen Administrative Study from 2003-2006 are also
presented for comparison.
Species Richness
Total Bird Abundance
Red-breasted Sapsucker
Hairy Woodpecker
Western Wood-Pewee
Dusky Flycatcher
Warbling Vireo
Tree Swallow
Mountain Chickadee
Mountain Bluebird
Oregon Junco
Chipping Sparrow
MacGillivray's Warbler
Treated
Aspen
6.94
5.48
0.22
0.15
0.17
0.16
0.52
0.42
0.62
0.11
0.50
0.20
0.07
Untreated
Aspen
6.63
4.76
0.15
0.08
0.16
0.20
0.50
0.03
0.44
0.00
0.49
0.07
0.14
P
0.23
<0.01
0.03
0.01
0.66
0.29
0.75
<0.01
<0.01
<0.01
0.82
<0.01
0.01
Conifer
Forest
5.47
4.08
0.03
0.03
0.02
0.26
0.09
0.01
0.28
0.00
0.36
0.01
0.11
We investigated the effect of time since treatment on total bird abundance and
species richness during 2004-2009 for all aspen sites on the Lassen National Forest while
controlling for year. When all treated and untreated sites are included (with those that
have not been treated coded as zero) there is a significant positive effect (F = 15.0,
p<0.01) of time since treatment on total bird abundance (Figure 7). When untreated sites
were not included there was no effect of time since treatment (F = 0.07, p = 0.79) on total
bird abundance. For species richness, the effect of time since treatment was positive and
significant when untreated sites were included (F = 4.96, p = 0.03; Figure 8), but was not
when they were excluded (F = 1.41, p = 0.24). This pattern is consistent with what we
have observed in previous years.
36
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Figure 6. Abundance per point count visit ± standard error for the seven aspen focal
species with a significant difference in abundance (p<0.05) between treated and untreated
aspen stands in the Lassen National Forest from 2006-2009. Conifer habitat indices are
shown for comparison using data from the Plumas-Lassen Administrative Study from
2003 – 2006.
0.80
Treated Vs. Untreated Aspen
0.70
Treated Aspen
Untreated Aspen
Detections per visit
0.60
Conifer Forest
0.50
0.40
0.30
0.20
0.10
0.00
Red-breasted
Hairy
Tree Sw allow
Sapsucker Woodpecker
Mountain
Chickadee
Mountain
Bluebird
Chipping
Sparrow
MacGillivray's
Warbler
The time since aspen stands had been treated had a significant effect on the
abundance of six of the ten focal species (Figure 9). For Red-breasted Sapsucker and
Chipping Sparrow the effect was positive and the best fit was linear. For each of the other
five species the effect was more complex. For Hairy Woodpecker, Tree Swallow,
Mountain Bluebird, and Dusky Flycatcher, the best fit model was one with a quadratic
effect of treatment. For all of these except Dusky Flycatcher there was an increasing
trend peaking in the four to five year post treatment period followed by a significant
decrease after that. Dusky Flycatcher was the only species to show a negative effect of
time since treatment; it decreased in the years immediately following treatment but
showed an increase in abundance in the longest time since treatment interval.
MacGillivray’s Warbler also showed a weakly significant (p = 0.06) negative linear trend
with time since treatment.
37
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Figure 9. The mean abundance per point count visit with standard error and predicted
values for the six focal species showing a significant effect of time since treatment from
2004 - 2009. Graphs show time since treatment in intervals for illustrative purposes but
regression was conducted with all data. All aspen sites surveyed on the Lassen National
Forest are included. All untreated sites were coded as zero years post treatment.
Hairy Woodpecker
Detections/Point Count
Visit
Detections/Point Count
Visit
Red-breasted Sapsucker
0.4
0.3
0.2
0.1
0
0
1 to 2
3 to 4
5 to 6
0.4
0.3
0.2
0.1
0
0
>6
1
0.8
0.6
0.4
0.2
0
3 to 4
5 to 6
0
>6
Detections/Point Count
Visit
Detections/Point Count
Visit
>6
Chipping Sparrow
0.4
0.3
0.2
0.1
0
3 to 4
1 to 2 3 to 4 5 to 6
Years Post Treatment
Dusky Flycatcher
1 to 2
>6
0.3
0.25
0.2
0.15
0.1
0.05
0
Years Post Treatment
0
5 to 6
Mountain Bluebird
Detections/Point Count
Visit
Detections/Point Count
Visit
Tree Sw allow
1 to 2
3 to 4
Years Post Treatment
Years Post Treatment
0
1 to 2
5 to 6
>6
0.4
0.3
0.2
0.1
0
0
Years Post Treatment
1 to 2
3 to 4
5 to 6
Years Post Treatment
38
>6
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
In Harvey Valley, species richness and total bird abundance increased following
treatment (Figure 10). Species richness increased at treated sites 19% over pre-treatment
levels while untreated sites increased 11%. Total bird abundance increased 14% at treated
sites following treatment while it decreased 11% at untreated sites. Due to relatively
small sample size (15 total points) none of these differences were statistically significant.
Figure 10. Species richness and total bird abundance at six reference and nine treated
sites before (2004-2007) and after (2009) treatment with 95% confidence intervals for the
Harvey Valley Aspen transect. All treatments were implemented in the winter of 2008
but not completed until after the breeding season, so 2008 was excluded from analysis.
Species/Point Per Year
Harvey Valley Species Richness
9
8
7
6
5
4
3
2
1
0
Reference
Reference
Treated
Treated
Before
After
Before
After
Harvey Valley Total Bird Abundance
7
Detections/Visit
6
5
4
3
2
1
0
Reference
Reference
Treated
Treated
Before
After
Before
After
39
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Similar to Harvey Valley, treated stands in the Feather aspen project on the ARD
showed a modest increase in 2009 the first year after treatment was implemented (Figure
11). Species richness increased at treated sites 17% while it declined 4% at untreated
sites. Total bird abundance increased 24% at treated sites while it increased 11% at
untreated sites. Again, with small sample sizes none of these differences were statistically
significant.
Figure 11. Species richness and total bird abundance at nine treated aspen sites and five
untreated aspen sites in the Feather aspen restoration project with 95% confidence
intervals. All sites were treated in the fall of 2008.
Species/Point per Year
Species Richness West Dusty 3
10
9
8
7
6
5
4
3
2
1
0
Reference
Reference
Treated
Treated
Before
After
Before
After
Total Bird Abundance West Dusty 3
Individuals/Point Visit
8
7
6
5
4
3
2
1
0
Reference
Reference
Treated
Treated
Before
After
Before
After
40
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
At the Pine Creek aspen site, the trends in species richness and total bird
abundance have been decreasing in the last three years from highs recorded in 2006 and
in 2009 were at similar levels to those recorded in 2004 (Figure 12). The inclusion of a
quadratic term in the model did significantly improve the fit compared to a linear model.
Figure 12. Mean per point species richness and total bird abundance (<50m from
observers) at the Pine Creek Aspen transect from 2004 – 2009 with 95% confidence
intervals. The majority of treatment was implemented in the winter of 2003/2004, fall
2006, and winter 2007/2008.
Pine Creek Aspen
10
Species Per Point or
Individuals/Visit
9
8
7
6
5
4
3
2
Species Richness
1
Total Bird Abundance
0
2004
2005
2006
2007
2008
2009
Year
Discussion
Aspen habitat on the Lassen National Forest harbors greater total bird abundance,
species richness, and abundance of almost all of the aspen focal species compared to
conifer-dominated forest in the region. On average, aspen habitat on the ARD harbored
greater species richness and total bird abundance compared to the ELRD, though there
continues to be considerable site to site and annual variation in these indices as well as in
the abundance of individual species.
Treated vs. Untreated
In the ELRD, the short term response of the avian community to aspen treatments
has been decidedly positive. From 2004 - 2009 species richness and total bird abundance
41
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
showed a significant increase at both treated and untreated aspen. However, in 2009 these
consistent increasing trends showed a downturn at treated sites while they continued to
increase at untreated sites. The fit of the trend at untreated site is not as good as that for
treated sites with considerable annual variation. The untreated sites used as reference
sites have almost all been released from livestock grazing pressure which has been shown
to result in an increase in bird species richness and the abundance of many of our aspen
focal species (Earnst et al. 2006). Thus they may be undergoing passive restoration
resulting in the observed increasing trends. As for the decline in richness and abundance
at treated sites in 2009, it appears as though the short-term benefits of aspen treatments
may be rather short-lived. However, due to potential bias in how treated sites were
selected and the lack of true controls (untreated sites have been switching into the treated
sample as more sites get treated) and the potential bias in how sites are selected for
treatment by the Forest Service (selecting poorer quality sites with unhealthier aspen), we
continue to advise some caution in interpreting these trends.
However, based on several recently treated sites, the pattern of an immediate
increase following treatment followed by a slow but steady declines remains consistent.
For example, Harvey Valley, treated in winter 2007-2008 showed an increase in richness
and abundance in 2009 compared to the mean from the four years prior to treatment as
did West Dusty 3 (part of the Feather project treated in 2008) on the Almanor Ranger
district. However, Pine Creek showed a substantial decrease in 2009 from previous years.
The decline at this site may be a result of the riparian areas being treated in 2007, further
reducing the habitat for conifer associated species; but we also observed a decline here in
many of the focal species in 2009. We also observed decreases in these metrics at Feather
Lake in 2009. We had originally hypothesized treatments would result in a decrease in
species richness and abundance in the lag between the loss of foliage volume and
structural diversity from conifer removal and the time it takes for aspen to regenerate. As
the Pine Creek and Feather Lake represent 45% of our treated sample and the majority of
our older sites, the decreases observed here in 2009 appear to be driving the overall
trends. Continued monitoring will help provide greater insight into these patterns in order
to more fully determine the response of the avian community to treatments over time.
42
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
While we documented declines of many focal species in treated stands in 2009,
the overall abundance of most of the focal species from 2006 – 2009 are still higher at
treated sites than at untreated. All of the seven focal species that were significantly more
abundant in treated aspen compared to untreated aspen were also significantly more
abundant in treated aspen than conifer forest. Chipping Sparrow, declining at a rate of
3.4% per year from 1968-2007 in the Sierra Nevada (Sauer et al. 2008) have been
increasing significantly in treated aspen stands and that patterned continued to hold in
2009. This species often nests in understory trees in areas with a substantial herbaceous
layer where it forages on insects and seeds (Middleton 1998). Thus, treated aspen stands
appear to be ideal habitat for this species, which is very rare in conifer-dominated forest
in the region. Likewise, Mountain Bluebird and Tree Swallow are all but absent from
conifer forest and untreated aspen, but are fairly common to abundant (respectively) in
treated aspen. Mountain Bluebird has been declining over the past 40 years in the Sierra
Nevada at a rate of 2.5% per year, though due most likely to their rarity this trend is not
significant (Sauer et al. 2008).
All of the aspen focal species are more abundant or as abundant in treated aspen
compared to untreated aspen with the exception of MacGillivray’s Warbler. Restoring
dense willow and alder cover in riparian habitat within aspen stands will be key to
improving habitat for MacGillivray’s Warbler – as they are rarely found in aspen stands
away from riparian areas. They are quite abundant at Martin Creek in the treated and
fenced stand with a dense understory. Removing conifers from riparian zones that can
support deciduous riparian vegetation and reducing the grazing in order to allow a dense
understory to return will benefit this species and likely a number of bird species that rely
on this unique but limited habitat.
Aspen habitat often supports a diverse and abundant guild of cavity nesting
species, with many studies showing cavity nesters disproportionately select aspen trees
for nesting (Li and Martin 1991, Dobkin et al. 1995, Martin and Eadie 1999, Martin et al.
2004). While aspen often contain relatively high numbers of natural cavities, secondary
cavity nesting species have been found to nest predominantly in woodpecker created
holes in both live aspen and aspen snags (Li and Martin 1991, Dobkin et al. 1995, Martin
and Eadie 1999). Both Red-breasted Sapsucker and Hairy Woodpecker continued to be
43
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
significantly more abundant in treated aspen than untreated aspen or conifer forest in the
region. At numerous treated aspen – including those at Feather Lake, Butte Creek, Pine
Creek, and Martin Creek – we confirmed active woodpecker nest cavities within treated
stands. In 2008 we documented seven species of woodpecker present during one visit to
the Pine Creek transect (Hairy, Downy, White-headed, Black-backed, Pileated, Northern
Flicker, and Red-breasted Sapsucker). Removing encroaching conifers from within and
surrounding aspen stands, resulting in the expansion of stands and increased density of
large diameter aspen stems over time, should increase habitat for woodpeckers. There is
little doubt that aspen supports far greater abundance of woodpeckers than coniferous
forest and that treating aspen results in even greater increases in these species of
management interest. In turn, woodpeckers are a critical component of the aspen
community as the source of cavities for an abundant and diverse group of secondary
cavity nesting birds, many of which use these aspen areas in relatively high numbers
(e.g., Mountain Bluebird, Tree Swallow, and Mountain Chickadee).
Time Since Treatment
The time since aspen stands had been treated continued to show a generally
positive but complex effect on many of the focal species once 2009 data, including five
treated sites on the ARD were added. The best fit models for four of the six species
showing a significant effect of time since treatment included a quadratic term. For three
of these species their abundance peaked in the three to four years post-treatment time
period and then declined in the following time intervals. This suggests the immediate
positive increase after aspen treatments may be relatively short-lived for at least some
species and mimics the general pattern observed with species richness and total bird
abundance. However, it is important to remember that that the post-treatment sample is
relatively small (42 sites in 2009) and any inherent biases in how sites were chosen for
treatment could easily be magnified in this analysis.
These patterns suggest that no one aspen condition or post-treatment time period
is ideal for all species. The conditions created immediately following aspen treatments
may be mimicking the structure found in natural post-disturbance habitat that often
supports greater numbers of some of these species (Raphael et al. 1987). Though Hairy
44
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Woodpecker, Tree Swallow, and Mountain Bluebird showed marked declines at sites
over four years post-treatment, each was more abundant in these older sites than they
were in untreated aspen. These results continue to support the notion that management of
aspen habitat should consider the importance of disturbance and the early successional
habitat in which it results.
Conclusions
Our results from 2009 continue to suggest that aspen treatments employed on the
LNF are having a positive effect on the aspen breeding bird community. Key species
such as Red-breasted Sapsucker, Mountain Bluebird, and Chipping Sparrow all appear to
have had a short-term positive response to treatment. Based on these and previous results,
we believe that treatments that increase the size and health of aspen stands will be highly
beneficial to aspen focal bird species in the Lassen National Forest in the long-term and
should be a top priority of land managers here. We also recognize the value of continuing
the monitoring of landbird communities in treated aspen habitat in order to better
understand the complex patterns we have observed in recent years as treated stands
mature.
Acknowledgements
Funding for our Aspen project was provided by the Lassen National Forest and
Herger Feinstein Quincy Library Group Forest Recovery Act monitoring funds. We
especially would like to thank Coye Burnett, Tom Frolli, Bobette Jones, Tom Rickman,
and Mark Williams of the Lassen National Forest - for their support and assistance with
this project. We also wish to thank Tim Guida, crew leader, and Nathan Fronk and Luke
Owens, our 2009 field crew.
45
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
Literature Cited
Bartos, D.L. and R.B. Campbell, Jr. 2001. Landscape dynamics of aspen and conifer
forest. In Sustaining aspen in Western Landscapes: Symposium Proceedings.
Grand Junction, CO: Rocky Mountain Research Station. USDA Forest Service.
RMRS -18:5-14.
Burnett, R.D. In press. Integrating Avian Monitoring into Forest Management: Pine-Oak
and Aspen Enhancement on the Lassen National Forest. USFWS Technical
Report.
Dobkin, D. S., A. C. Rich, J. A. Pretare, and W. H. Pyle. 1995. Nest-site relationships
among cavity-nesting birds of riparian and snowpocket aspen woodlands in the
northwestern Great Basin. Condor 97:694-707.
Earnst, S.L., J.A. Ballard, and D.S. Dobkin. 2005. Riparian songbird abundance a decade
after cattle removal on Hart Mountain and Sheldon National Wildlife Refuges.
PSW-GTR 191:550-558.
Finch, D.M. and R.T. Reynolds. 1987. Bird response to understory variation and conifer
succession in aspen forests. Pages 87-96, In J. Emmerick et al. eds. Proceedings
of issues and technology in the management of impacted wildlife. Thorne
Ecological Institute, Colorado Springs, CO.
Flack, J.A. Douglas. 1976. Bird populations of aspen forests in western North America.
Ornithological Monographs No. 19. The American Ornithologist’s Union.
Heath, S.K. and G. Ballard. 2003. Patterns of breeding songbird diversity and occurrence
in riparian habitats of the Eastern Sierra Nevada. In California Riparian Systems:
Processes and Floodplain Management, Ecology, and Restoration. 2001 Riparian
Habitats and Floodplains Conf. Proc. (P. M. Faber, ed.). Riparian Habitat Joint
Venture, Sacramento, CA.
Jones, B.E., T.H. Rickman, A. Vasquez, Y. Sado, K.W. Tate. In press. Removal of
invasive conifers to regenerate degraded aspen stands in the Sierra Nevada.
Restoration Ecology 13:373-379.
Li, P., and T. E. Martin. 1991. Nest-site selection and nesting success of cavity-nesting
birds in high elevation forest drainages. Auk 108:405-418.
Martin, K., K. E. H. Aitken, and K. L. Wiebe. 2004. Nest-sites and nest webs for cavitynesting communities in interior British Columbia: nest characteristics and niche
partitioning: Condor. 106 5–19.
Martin, K. and J.M. Eadie. 1999. Nest webs: A community wide approach to the
46
Chapter 2. Aspen Enhancement
PRBO Avian Monitoring in the Plumas & Lassen National Forests - 2008
management and conservation of cavity nesting forest birds. Forest Ecology and
Management 115:243-257.
Mueggler, W.F. 1985. Forage. In Aspen: Ecology and management in the Western
United States. USDA Forest Service General Technical Report RM-119:129-134.
Middleton, Alex L. 1998. Chipping Sparrow (Spizella passerina), The Birds of North
America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved
from the Birds of North America Online:
http://bna.birds.cornell.edu/bna/species/334
Ralph, C. J., G. R. Geupel, P. Pyle, T. E. Martin, & D. F. DeSante. 1993. Field Methods
for Monitoring Landbirds. USDA Forest Service Publication, PSW-GTR 144,
Albany, CA.
Raphael, M.G., Morrison, M.L., Yoder-Williams, M.P. 1987. Breeding bird populations
during twenty five years of post-fire succession in the Sierra Nevada. The Condor
89, 614-626.
Reynolds, R.T., J.M. Scott, and R.A. Nussbaum. 1980. A variable circular plot method
for estimating bird numbers. Condor 82:309:313.
Richardson, T.W. and S.K. Heath. 2005. Effects of conifers on aspen breeding bird
communities in the Sierra Nevada. Transactions of the Western Section of the
Wildlife Society 40: 68 – 81.
Sauer, J. R., J. E. Hines, and J. Fallon. 2008. The North American Breeding Bird Survey,
Results and Analysis 1966 - 2007. Version 10.13.2007. USGS Patuxent Wildlife
Research Center, Laurel, MD.
Stata Corp. 2007. Intercooled Stata 10.0 for Windows. Stata Corp. LP College Station,
TX.
47
Chapter 3. Resident and Neotropical Migratory Bird Monitoring in
Mountain Meadows: 2009 Report
Ryan D. Burnett
PRBO Conservation Science
48
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Background and Introduction
Mountain meadows are among the most important habitats for birds in California
(Siegel and DeSante 1999, Burnett and Humple 2003, Burnett et al. 2005); they support
several rare and declining species and are utilized at some point during the year by almost
every bird species that breeds in or migrates through the Sierra Nevada. Meadows also
perform a vital role as watershed wetlands that store and purify drinking water for
millions of Californians. And yet, most of these meadows are in a degraded state and
their value for water storage and as critical habitat for birds and other wildlife has been
dramatically reduced.
In the Sierra Nevada, meadows have been heavily degraded or lost due to well
over a century of human activities including flooding, diversions, vegetation removal,
and overgrazing (SNEP 1996, Siegel and DeSante 1999). As far back as 1869, John Muir
lamented about the destruction of Sierra meadows by man, “….but as far as I have seen,
man alone, and the animals he tames, destroy these gardens.” Indeed few, if any,
meadows in the Sierra remain unaltered by human activities. The meadows that do
remain are in a compromised state and they are owned by a diverse set of interests
including private industry and utilities, state and federal agencies, and private ranches.
Though they have been altered, a number of meadows in the Feather River
watershed support populations of many declining and threatened riparian meadow bird
species, including Sandhill Crane, Swainson’s Thrush, Yellow Warbler, and Willow
Flycatcher. The area also supports breeding populations of 11 of the 16 California
Partners in Flight Riparian Focal Species (Humple and Burnett 2004, RHJV 2004). With
its high diversity and abundance of meadow bird species, including the largest population
of Willow Flycatcher in the Sierra Nevada region (Humple and Burnett 2004), the
Feather River watershed is a conservation hotspot for meadow birds.
Meadow conservation and management in the Feather River watershed and
throughout the Sierra Nevada will require a collaborative effort between different land
management agencies, county government, non-governmental organizations, and private
landowners. In order to manage for breeding bird populations, especially listed meadowdependent species such as Willow Flycatcher and Sandhill Crane, the Forest Service
49
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
needs to with the other meadow landowners in the area in order to ensure the long-term
viability of these and other bird species.
In this chapter we summarize results from point count surveys from meadows in
the Feather River watershed in 2009, including three new sites in the Last Chance Creek
watershed and one new site on the Eagle Lake Ranger District (ELRD). We use a suite of
meadow focal species to compare abundance and richness metrics between meadows and
provide recommendations for improving habitat for these and other species. We also
briefly report on our breeding and post-breeding mist-netting efforts at wet meadow sites
in the region.
Methods
Site Selection
Several considerations went into selecting meadow sites we sampled. Following
an inventory of 16 meadows in the Almanor Ranger District (ARD) of the Lassen
National Forest (LNF) between 2000 and 2001 we selected a subset of those sites to
continue long-term meadow monitoring within. We were interested in surveying sites that
supported or could support a riparian deciduous shrub (willows/alders) bird community
and especially those sites that had recently undergone management changes (e.g. active
restoration and/or removal of grazing). With these two considerations in mind we
attempted to choose sites that represented a range of elevations and habitat conditions.
With this strategy, we believe the sites selected are not totally representative of the range
of meadow conditions in the ARD area but represent some of the higher quality riparian
meadow bird habitat in the area. Sites within the Last Chance Watershed were added
within areas that have been restored or are slated to be restored in the next couple of
years. The Pine Creek Valley transect was established at the request of the ELRD in order
to investigate the difference in the avian community within and outside of a grazing
exclosure.
Point Count Censuses
Point count data allow us to measure secondary population parameters such as
relative abundance of individual bird species and species richness. This method is useful
for making comparisons of bird communities across time, locations, habitats, and land50
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Figure 1. PRBO Northern Sierra meadow point count sites surveyed in 2009.
51
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
use treatments. Standardized five-minute multiple distance band point count censuses
(Reynolds et al. 1980, Ralph et al. 1995) were conducted at each of 94 stations along nine
transects in 2010 within the greater ARD area, 54 points in the Last Chance Creek
Watershed in eastern Plumas County, and 15 points in the Pine Creek Valley on the
ELRD for a total of 162 point count stations (Table 1). Point count stations were a
minimum of 50 meters from meadow edges where feasible; if the riparian corridor was
less than 100 meters wide, points were placed equidistant from each edge, and in most
cases points were located within 50 meters of stream channel (where they existed). At
each site points were spaced between 200 and 250 meters apart and were configured in a
manner that maximized spatial coverage of sites.
Table 1. PRBO Northern Sierra meadow point count transects with transect codes, year established,
and dates surveyed in 2009.
Transect
Alkali Flat
Carter Meadow
Clark’s Creek
Fanani Meadow
Gurnsey Creek
Humbug Valley
Lower Last Chance Creek
Pine Creek Valley
Robber’s Creek
Soldier Meadow
West Shore Lake Almanor
Yellow Creek Riparian
Yellow Creek PG&E
Total
Code
ALFL
CAME
CKCR
FAME
GUCR
HUVA
LLCH
PCVA
ROCR
SOME
WSLA
YCRI
YCPGE
# of
points
18
7
18
8
10
17
18
15
14
7
13
12
6
163
Year
2009
2009
established 1st Visit 2nd Visit
2009
19-Jun 27-Jun
2004
16-Jun 30-Jun
2009
29-May 20-Jun
2003
28-May 17-Jun
1997
1-Jun
16-Jun
2003
10-Jun 26-Jun
2009
13-Jun 25-Jun
2009
13-Jun 22-Jun
2004
12-Jun 29-Jun
2001
28-May 17-Jun
2004
2-Jun
18-Jun
2001
5-Jun
19-Jun
2008
5-Jun
19-Jun
All birds detected at each station during the five-minute survey were recorded.
Detections were placed within one of six categories based on the initial detection distance
from observer: less than 10 meters, 10-20 meters, 20-30 meters, 30-50 meters, 50-100
meters, and greater than 100 meters. Birds flying over the study area but not observed
using the habitat were recorded separately, and excluded from all analyses. The method
of initial detection (song, visual or call) for each individual was also recorded. Counts
began around local sunrise and were completed within four hours. Each transect was
visited twice each year between late May and the end of June. With the exception of
52
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Lower Last Chance Creek, Alkali Flat, and Clark’s Creek, all surveys were conducted by
the author who has been conducting point counts in the Sierra Nevada for over a decade.
The three other sites were surveyed by two experts in Northern Sierra bird identification
that passed a double observer field test with the author prior to conducting counts. An
electronic range finder was used by all observers to assist with distance estimation at each
point count station.
Statistical Analysis
Point count analysis was restricted to a subset of the species encountered. We
excluded species that do not breed in the study area as well as those species that are not
adequately sampled using the point count method (e.g., shorebirds, waterfowl, raptors,
and swallows). For a number of the analyses we used a suite of meadow focal species
that represent a range of meadow bird habitat conditions and as a group are likely to
provide a better measure of the quality of meadow habitat than all species (Chase and
Geupel 2005; Table 2).
Table 2. Avian focal species (listed in taxonomic order) for meadow monitoring in the ARD and their
conservation status. California Partners in Flight Riparian Focal species are noted in bold (RHJV
2004).
Conservation Status1
Species
Sandhill Crane
State Threatened
Red-breasted Sapsucker
Declining in the Sierra2; NTMB
State Endangered, USFS Sensitive, NTMB
Willow Flycatcher
NTMB, Declining in the Western U.S.
Warbling Vireo
USFS Priority Land Bird Species, NTMB
Swainson’s Thrush
NTMB
Black-headed Grosbeak
State Species of Special Concern, NTMB
Yellow Warbler
MacGillivray's Warbler
NTMB
Significant Decline in Sierra2, NTMB
Wilson's Warbler
None
Song Sparrow
Lincoln's Sparrow
NTMB
1
NTMB = Neotropical Migratory Bird
2
from Sauer et al. 2008.
53
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Species richness
The species richness index used here was obtained by summing the species detected
within 50 meters of the observer across both visits to each point count station and then averaged
across all points in the transect. Similarly, focal species richness is the same calculation but
limited to the list of species in table 2. Presenting the mean species richness, as is done herein,
allows for comparisons between transects or habitats consisting of different numbers of point
count stations but does not provide a measure of the total number of species across an entire
transect.
Indices of Abundance
An index of total bird abundance, defined as the mean number of individuals detected per
station per visit, was calculated for each transect. This number is obtained by dividing the total
number of detections within 50 meters of the observer by the number of stations and the number
of visits. The same method was employed for creating focal species abundance (the total number
of individuals of all focal species combined) and for each individual focal species. Note that
Sandhill Crane was did not occur within 50m of observers but would not have been included in
these indices if it had as it is not adequately sampled using point counts (large territories and
shy).
Results
Song Sparrow was the most abundant meadow bird focal species detected from 2003 –
2009 at the Almanor area meadows with and index of abundance of 1.17, followed by Yellow
Warbler at 1.04 (Figure 2). In the Last Chance Creek watershed these two species were also the
most abundant focal species with indices of abundance of 0.97 and 0.74 respectively (Figure 3).
Willow Flycatcher, a Forest Service sensitive and state threatened species, had an index of
abundance of 0.08 in the Almanor area while this species along with Wilson’s Warbler and
Lincoln’s Sparrow were not detected in the Last Chance watershed.
54
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Figure 2. The mean abundance (+/- standard error) of nine meadow focal species per point count visit from
2003 – 2009 across all sites combined in wet riparian meadows in the Almanor Ranger District.
Focal Species Abundance (Almanor Area)
Black-headed Grosbeak
Red-breasted Sapsucker
Willow Flycatcher
Lincoln's Sparrow
Wilson's Warbler
Warbling Vireo
MacGillivray's Warbler
Yellow Warbler
Song Sparrow
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
Detections/Point Count Visit
Figure 3. The mean abundance (+/- standard error) of nine meadow focal species per point count visit in 2009
across all sites combined in the Last Chance Creek watershed. Note Willow Flycatcher, Lincoln’s Sparrow,
and Wilson’s Warble were not detected here in 2009.
Focal Species Abundance (Last Chance Watershed)
Willow Flycatcher
Lincoln's Sparrow
Wilson's Warbler
Red-breasted Sapsucker
Warbling Vireo
MacGillivray's Warbler
Black-headed Grosbeak
Yellow Warbler
Song Sparrow
0
0.2
0.4
0.6
0.8
Detections per Point Count Visit
55
1
1.2
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Meadow Comparison
I compared species richness, total bird abundance, focal species richness, and focal
species total abundance across all sites in 2009. The mean species richness for all sites combined
was 6.09. Carter Meadow had the highest avian species richness with 8.86 species per point
(Figure 4). Carter Meadow was followed closely by Robber’s Creek and Yellow Creek at 8.79
and 8.75, respectively. All three of these sites had overall species richness significantly higher
than the average for all sites combined. The lowest species richness was for Yellow Creek PG&E
with 1.5 species per point. Other sites with significantly lower species richness than the average
for all sites combined were Pine Creek Valley, Lower Last Chance Creek, Soldier Meadow, and
Alkali Flat. The mean total bird abundance in 2009 for all sites combined was 6.02. Total bird
abundance was highest at Carter Meadow with 9.14 detections per point per visit (Figure 5). The
only other site with significantly higher total bird abundance than the mean for all sites combined
was West Shore Lake Almanor at 8.35. Sites with significantly lower total bird abundance than
the 2009 average were Yellow Creek PG&E at 1.5, Soldier meadow at 2.71, Pine Creek Valley
at 3.20, and Lower Last Chance Creek at 3.64.
Figure 4. Avian species richness (per point per year detections <50m) at 12 meadow sites in the Northern
Sierra Nevada in 2009 with 95% confidence intervals. The dashed line represents the mean for all sites
combined. Four letter site codes are defined in Table 1.
Species/Point/Year
Species Richness
12
11
10
9
8
7
6
5
4
3
2
1
0
CAME FAME GUCR HUVA ROCR SOME WSLA YCRI YCPGE ALFL CKCR LLCH PCVA
56
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Figure 5. Total bird abundance (per point per visit detections <50m) at 12 meadow sites in the Northern
Sierra Nevada in 2009 with 95% confidence intervals. The dashed line represents the mean for all sites
combined. Four letter site codes are defined in Table 1.
Total Bird Abundance
12
Individuals/Point/Visit
10
8
6
4
2
0
CAME FAME GUCR HUVA ROCR SOME WSLA YCRI YCPGE ALFL CKCR LLCH PCVA
The mean focal species richness for all sites combined in 2009 was 2.38. Focal species
richness was highest at Fanani Meadow with 4.38 species per point (Figure 6). The only other
sites with focal richness significantly higher than the 2009 average were Gurnsey Creek with 4.0
and Carter Meadow at 3.43. Lower Last Chance Creek (1.72), Alkali Flat (1.17), Yellow Creek
PG&E (0.0), and Pine Creek Valley (0.0) all had focal richness significantly lower than the
average.
The mean focal species abundance for all sites combined in 2009 was 2.81. Focal species
abundance was highest at Gurnsey Creek with 4.55 detections per point per visit followed by
West Shore Lake Almanor with 4.19 (Figure 7). These meadows were the only two with
significantly higher focal species abundance than the average from all sites combined. The
meadows with significantly lower focal species abundance than the 2009 average were Lower
Last Chance Creek (1.75), Alkali Flat (1.56), Soldier Meadow (0.93), Yellow Creek PG&E (0.0),
and Pine Creek Valley (0.0).
57
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Figure 6. Avian meadow focal species richness (per point per year detections <50m) at 12 meadow sites in the
Northern Sierra Nevada in 2009 with 95% confidence intervals. The dashed line represents the mean for all
sites combined. Four letter site codes are defined in Table 1.
Focal Species Richness
7
Species/Point/Year
6
5
4
3
2
1
0
CAME FAME GUCR HUVA ROCR SOME WSLA YCRI YCPGE ALFL CKCR LLCH PCVA
Figure 7. Meadow focal species abundance (per point per visit detections <50m) at 12 meadow sites in the
Northern Sierra Nevada in 2009 with 95% confidence intervals. The dashed line represents the mean for all
sites combined. Four letter site codes are defined in Table 1.
Focal Species Abundance
7
Individuals/Point/Visit
6
5
4
3
2
1
0
CAME FAME GUCR HUVA ROCR SOME WSLA YCRI YCPGE ALFL CKCR LLCH PCVA
58
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
PG&E and its partners have been considering restoring a portion of Yellow Creek where
it enters the valley floor in Humbug Valley. We have been monitoring birds upstream of this area
on Yellow Creek since 2003. In 2008, an additional six point count stations were added at the
downstream end of the existing transect in order to sample the project area (YCPGE). Using data
from 2008 and 2009, I compared several avian metrics between the project area and the Forest
Service land immediately above the proposed project area (Figure 8). Species richness, total bird
abundance, focal richness, and the abundance of six focal species were all significantly lower in
the project area. In fact, we did not detect a single focal species in two years within the project
area. The primary species detected in the project were Horned Lark and Savannah Sparrow, two
species associated with drier grassland habitat.
Figure 8. Avian indices along Yellow Creek comparing the proposed Feather River CRM-PG&E restoration
reach with Forest Service land upstream in 2008 and 2009. Error bars are 95% confidence intervals. Note no
meadow bird focal species were detected in the proposed project area in either year.
10
9
8
Project Area
7
Upstream
6
5
4
3
2
1
0
Species
Richness
Total Bird
Abundance
Focal
Richness
Yellow
Warbler
Song
Sparrow
Warbling
Vireo
MacGillivray's
Warbler
Wilson's
Warbler
Red-breasted
Sapsucker
Pine Creek Valley Grassland Grazing Exclosure
At the Pine Creek Valley site, species richness was slightly higher outside of the grazing
exclosure and total bird abundance was greater inside the exclosure, although neither of these
differences was statistically significant (Figure 10). Only the abundance of Willet and Brewer’s
Blackbird – more abundant outside the exclosure - and Savannah Sparrow – more abundant
inside the exclosure - were statistically significant. Wilson’s Phalarope were more than four
59
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
times more abundant inside of the exclosure than outside though due to the relatively limited
sample size (n=15) this difference was not quite statistically significant.
Figure 10. Species richness, total bird abundance, and an index of the abundance of five species per point
count station in the Pine Creek Valley grassland within and outside of a grazing exclosure in 2009. Error bars
represent the 95% confidence interval.
Pine Creek Valley
6
No Grazing
5
Grazing
4
3
2
1
0
Species
Richness
Total Bird
Abundance
Brewer's
Blackbird
Red-winged
Blackbird
Savannah
Sparrow
Willet
Wilson's
Phalarope
Last Chance Creek Restored vs. Unrestored
I compared species richness, focal species richness, total bird abundance, and focal
species abundance at restored and untreated sites in the Last Chance Creek watershed in 2009.
Along the Alkali Flat transect, eleven point count stations were within areas that have been
treated while five points fell within treated areas on the Clark’s Creek transect. Seven of the
restored sites at Alkali Flat were restored in 2003 with the remaining three restored in 2007. All
five of the restored points at Clark’s Creek were restored in 2001. All four metrics were higher at
untreated sites along the Alkali Flat transect, with species richness, focal species richness, and
focal abundance significantly so (Figure 9). For Clark’s Creek, species richness, focal species
richness, and focal species abundance were all higher at untreated sites while total bird
abundance was higher at treated sites. Only focal species richness and abundance were
significantly different between restored and un-restored points at Clark’s Creek in 2009. When
all sites in the watershed were combined - including the 18 untreated points along the Lower Last
Chance Creek transect - focal species richness and abundance were significantly higher at
untreated sites. Species richness was higher at untreated sites while total bird abundance was
higher at treated sites but these differences were not significant.
60
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Figure 9. Per point species richness, total bird abundance, meadow focal species richness and meadow focal
species abundance at restored and un-restored point count stations at Alkali Flat, Clark’s Creek, and all sites
combined in the Last Chance Creek watershed in 2009 with 95% confidence intervals.
# per Point
Alkali Flat
9
8
7
6
5
4
3
2
1
0
Treated
Untreated
Species Richness
Focal Species
Richness
Total Bird
Abundance
Focal Species
Abundance
# per Point
Clark's Creek
10
9
8
7
6
5
4
3
2
1
0
Treated
Untreated
Species Richness
Focal Species
Richness
Total Bird
Abundance
Focal Species
Abundance
Last Chance Watershed Total
# per Point
8
7
Treated
6
Untreated
5
4
3
2
1
0
Species
Richness
Focal Species
Richness
Total Bird
Abundance
61
Focal Species
Abundance
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Post-breeding Meadow Use
During the 2009 breeding season, we continued bird banding at the Gurnsey Creek mistnet station, the 13th consecutive year this site has been monitored (Appendix A). Single visit
post-breeding mist-netting also continued at four meadows in the ARD: Hay, Swain, Spenser,
and Carter. Capture rates at these meadows in 2009 were very high with between 3.21 – 5.97
captures per net hour compared to 1.15 captures per net hour, the breeding season average at
Gurnsey Creek suggesting a relatively good productivity year for a number of species in the area.
Discussion
Wet meadows with extensive riparian deciduous vegetation support rich and abundant
breeding bird populations and are used extensively following the breeding season by the majority
of upland breeding species in the Sierra. Since wet meadows represent less than 1% of National
Forest land in the Sierra Nevada, and have been heavily degraded over the past century, meadow
restoration and conservation should be among the highest priorities of land mangers in the Sierra
Nevada. As meadows are arguably the single most important habitat for birds in the Sierra
Nevada (Siegel and DeSante 1999), and birds are a cost-effective tool to help guide ecological
restoration, avian monitoring and the management recommendations generated from it should be
seen as a integral tool to achieving meadow restoration in the Sierra Nevada.
The ARD area meadows support higher bird abundance than any other habitat type in the
Lassen region we have surveyed. Only aspen habitat (see Chapter 2) has slightly higher species
richness. Meadows in the greater ARD area are among the most important for meadow birds in
the Sierra Nevada. Yellow Warbler, a California Bird Species of special concern, reaches its
greatest reported density in the state here (RHJV 2004, Heath 2008). The area also harbors more
Willow Flycatcher than any other similarly sized area of the Sierra Nevada as well as a breeding
population of the state threatened Greater Sandhill Crane. With a wealth of mountain meadows
and many in a degraded state, the Feather River watershed should be considered an ideal location
to focus restoration actions to benefit these and other meadow dependent bird species.
Though many of our meadows sites, especially in the ARD, support relatively diverse
and abundant bird populations, it appears that many meadow sites (including a number we
surveyed) could benefit from some additional restoration actions. For many of the sites
(Robber’s Creek, Gurnsey Creek, Soldier Meadow), removal of encroaching conifers and
62
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
planting of willows could ensure the long-term health of these sites. Both Humbug Valley and
Yellow Creek have sections of stream channel that have been isolated from their floodplains and
may benefit from more significant restoration actions that restore a wet meadow condition. An
increase in riparian deciduous vegetation (e.g. Salix, Populus, and Alnus spp.) at many of these
sites would greatly enhance their value to meadow birds (e.g. Soldier Meadow, Last Chance
Creek restored sites).
There is currently little habitat value for wet meadow bird species within the Yellow
Creek proposed project area. In fact, the site had the lowest avian indices of any meadow site we
surveyed in 2009. In contrast, the 2 kilometers of meadow upstream from the project area
support a diverse and abundant meadow bird community, including recent detections of
Swainson’s Thrush and Willow Flycatcher – the two rarest meadow birds in the Sierra Nevada.
Additionally, this area supports an abundant population of Yellow Warbler, a California Bird
Species of Special Concern (Shuford and Gardali 2008). On Humbug Creek, 1 kilometer across
the valley from the project area, there are approximately eight Willow Flycatcher territories as
well as a large number of Yellow Warbler territories. Restoring Yellow Creek within the
proposed project area to a wet meadow with a substantial willow component is likely to have
substantial benefits to all of these meadow species of conservation interest as well as a host of
other meadow dependent focal species.
Unlike Yellow Creek, unrestored areas within the Last Chance Creek watershed do
support populations of several meadow focal species, especially Song Sparrow and Yellow
Warbler. Interestingly, we found that most avian metrics were higher at unrestored sites than
restored sites in the watershed in 2009. The higher total bird abundance at restored sites is
primarily due to Red-winged Blackbird being 28 time more abundant at restored sites, the
species that has clearly benefited the most from restoration actions thus far. Since we do not have
pre-treatment data for the areas that have been restored, it is difficult to determine how
restoration has affected the rest of the avian community at these sites. However, with some of the
lowest avian indices of any meadow sites we surveyed in 2009 and the fact that restored sites
have lower indices than unrestored sites, it appears that additional restoration actions (e.g. willow
planting) should be considered at restored sites to improve habitat for wet meadow dependent
birds. Where appropriate conditions exist to support riparian deciduous shrubs and trees, creating
dense clumps of these plants should improve habitat for meadow birds. Existing willow clumps
63
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
within the watershed that support Yellow Warbler and Song Sparrow could be used as a template
for creating suitable habitat in restored meadow areas. Alkali Flat sites 1-4 and Clark’s Creek
sites 10 and 11 had the highest density of these two species on these two transects. Additional
considerations during the design phase of restoration projects may also help improve habitat for
meadow birds in the first 10 years after restoration.
The Pine Creek Valley grassland is a distinctly different meadow than most of the sites
we have surveyed. Indeed it is more of a wetland with ponded water in many years well into
June with an undefined stream channel. Thus, the habitat is more suitable for bird species such as
waterfowl, shorebirds, and Sandhill Crane. We documented relatively large numbers of both
Wilson’s Phalarope and Willet at this site, both of which we believe breed here based on timing
of their occupancy and behaviors. Additionally, a pair of Sandhill Crane was observed on both
visits within and outside of the grazing exclosure. A complete list of species and their breeding
status is presented in Appendix B. In 2009 the majority of the wetland area we surveyed in Pine
Creek was inundated with water and therefore not actively being grazed by cattle. Thus, the
differences in habitat inside and outside of the grazing exclosure did not appear great. However,
we did find that Wilson’s Phalarope, Savannah Sparrow, and Red-winged Blackbirds were all
substantially more abundant inside of the exclosure while Willet and Brewer’s Blackbird were
more abundant outside of the exclosure. The Willets were primarily associated with the small
hummocks that provided upland islands within the flooded wetland. This feature was unique to
the area outside of the exclosure and may explain why the majority of Willet were found outside
of the exclosure and species richness was higher here.
A priority for meadow bird conservation in the Feather River watershed should be
protecting and enhancing the largest wet meadows, especially for Sandhill Crane, Willow
Flycatcher, and Yellow Warbler. However, our results also show that species such as Lincoln’s
Sparrow, Wilson’s Warbler, and Warbling Vireo are much more abundant in smaller and higher
elevation meadows, such as Carter. Several other higher elevation meadow sites such as
Robber’s Creek, Hay Meadow, and Spenser Meadow (where we have conducted post-breeding
banding), also support breeding Lincoln’s Sparrow. Thus, we recommend managing the larger
meadow complexes at lower elevations (3500 – 5500 feet) for species such as Sandhill Crane,
Willow Flycatcher, and Yellow Warbler (Childs Meadow, Battle Creek Meadow, Deer Creek
Meadow, Humbug Valley, West Shore Lake Almanor) while also protecting and, where
64
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
necessary, enhancing higher elevation sites to support species such as Lincoln’s Sparrow and
Wilson’s Warbler as well as provide critical post-breeding habitat for the majority of migratory
birds that breed in the Sierra Nevada. Additionally, wetland habitats which generally support far
lower abundance and diversity of meadow birds are important as they provide unique habitat for
uncommon species such as Sandhill Crane, shorebirds, and waterfowl.
Conclusions
With the loss and degradation of riparian meadow habitat and it disproportionate
importance to birds, restoration and prudent management of meadows in the Feather River
watershed should be among the highest priorities of land mangers here. Increasing the function
and resiliency of wet willow-filled meadows should result in improved meadow bird habitat;
however, active measures such as willow planting is likely necessary to ensure habitat is
provided sooner rather than later. Meadow restoration in the Feather River watershed requires
partnerships between the U.S. Forest Service, local government agencies (e.g. Feather River
Coordinated Resource Management Group.), and non-profit organizations (e.g. The Nature
Conservancy, Feather River Land Trust, PRBO Conservation Science). Working together these
groups have the potential to dramatically increase the value of meadow habitats for birds in this
region.
Acknowledgements
Funding for our meadow bird project is provided through Lassen National Forest wildlife
monitoring funds and a grant from the Resources Legacy Family Foundation. I wish to thank
Colin Dillingham and David Arsenault for their many hours of volunteering to collect all of the
bird data for the three Last Chance Creek transects. Additionally I would like to thank Tom
Frolli, Bobette Jones, Tom Rickman, and Mark Williams from the Lassen National forest and
Leslie Mink, Kara Rockett, and Jim Wilcox of the Feather River Coordinated Resource
Management Group for their assistance and support of this project.
65
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
Literature Cited
Burnett, R. D., and D. L. Humple. 2003. Songbird monitoring in the Lassen National Forest:
Results from the 2002 field season with summaries of 6 years of data (1997-2002). PRBO report
to the U.S. Forest Service.
Burnett, R.D., D.L. Humple, T. Gardali, and M. Rogner. 2005. Avian Monitoring in the Lassen
National Forest. 2004 Annual Report. PRBO report to the U.S. Forest Service.
Chase, M.K. and G.R. Geupel. 2005. The use of avian focal species for conservation planning in
California. In Proceedings of the 3rd International Partners in Flight Conference. USDA Forest
Service Gen. Tech. Rep. PSW-GTR-191.
Heath, S.K. 2008. Yellow Warbler (Dendroica petechia) In Shuford, W.D. & T. Gardali (eds.),
California Bird Species of Special Concern. Studies of Western Birds 1. Western Field
Ornithologists, Camarillo, CA and California Department of Fish and Game, Sacramento.
Humple, D.L. and R.D. Burnett 2004. Songbird monitoring in Meadow and Shrub habitats
within the Lassen National Forest: Results from the 2003 Field Season. A PRBO progress report
to the USDA Forest Service. PRBO Contribution # 1173.
Muir, J. 1911. My first summer in the Sierra. The Riverside Press, Cambridge, MA.
Ralph, C.J., Droege, S., Sauer, J.R., 1995. Managing and monitoring birds using point counts:
standards and applications. In: C. J. Ralph, J. R. Sauer and S. Droege (Eds.), Monitoring bird
populations by point counts. USDA Forest Service, General Technical Report PSW-GTR 149,
161-169.
Reynolds, R.T., J.M. Scott, and R.A. Nussbaum. 1980. A variable circular plot method for
estimating bird numbers. Condor 82:309:313.
RHJV (Riparian Habitat Joint Venture). 2004. Version 2.0. The riparian bird
conservation plan: a strategy for reversing the decline of riparian associated birds in
California. California Partners in Flight. http://www.prbo.org/calpif/pdfs/riparian.v2.pdf.
Shuford, W.D., Gardali, T. (Eds.), 2008. California Bird Species of Special Concern. Studies of
Western Birds No. 1. Western Field Ornithologists, Camarillo, CA and California Department of
Fish and Game, Sacramento.
Siegel, R.B. and D.F. DeSante. 1999. Version 1.0 The draft avian conservation plan for
the Sierra Nevada Bioregion: conservation priorities and strategies for safeguarding Sierra bird
populations.
SNEP (Sierra Nevada Ecosystem Project) 1996. Sierra Nevada Ecosystems. Volume 1,
chapter 1. Regents of the University of California.
http://ceres.ca.gov/snep/pubs/web/PDF/v1_ch01.pdf
66
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
APPENDIX A. Summary of 2009 meadow mist-netting in the Almanor Ranger District
with dates, net hours, captures, and capture rates.
Site
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek Total
(Summer)
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek
Gurnsey Creek Total (Fall)
Hay Meadow
Swain Meadow
Carter Meadow
Spenser Meadow
Date
5/20/2009
5/30/2009
6/9/2009
6/20/2009
6/27/2009
7/9/2009
7/17/2009
7/29/2009
8/5/2009
8/17/2009
8/24/2009
9/1/2009
9/8/2009
9/15/2009
9/22/2009
9/28/2009
7/30/2009
7/31/2009
8/3/2009
8/4/2009
Net
Hours
45
40
45
43.92
44.5
43.5
45
45
45
45
441.92
Captures
44.5
45
45
45
45
42
266.5
36
36
33
34
35
31
27
30
64
123
310
215
209
166
109
67
50
49
37
52
63
78
62
33
58
21
503
Captures/
net hour
1.11
1.23
0.82
1.18
1.42
1.79
1.38
0.73
1.29
0.47
1.14
0.79
0.69
0.60
0.67
1.42
2.93
1.16
5.97
5.81
5.03
3.21
Chapter 3. Mountain Meadows
PRBO Avian Monitoring in the Lassen National Forests - 2009
APPENDIX B. Breeding status of all bird species detected during two visits to the Pine
Creek Valley wetland in 2009. Breeding status codes: 1 = confirmed breeder, 2 = likely
breeder, 3 = no suitable nesting habitat within the wetland for this species probably just
foraging here.
Common Name
American Robin
Barn Swallow
Brewer's Blackbird
Brewer's Sparrow
Cliff Swallow
Common Raven
Horned Lark
Killdeer
Mallard
Mountain Bluebird
Mourning Dove
Northern Pintail
Northern Shoveler
Red-winged Blackbird
Sandhill Crane
Savannah Sparrow
Spotted Sandpiper
Vesper Sparrow
Western Meadowlark
Willet
Wilson's Phalarope
Yellow-headed Blackbird
Scientific Name
Turdus migratorius
Hirundo rustica
Euphagus cyanocephalus
Spizella breweri
Petrochelidon pyrrhonota
Corvus corax
Eremophila alpestris
Charadrius vociferus
Anus mallardi
Sialia currucoides
Zenaida macroura
Anas aculta
Anas clypeata
Agelaius phoeniceus
Grus canadensis
Passerculus sandwichensis
Actitis macularia
Pooecetes gramineus
Sturnella neglecta
Catoptrophorus semipalmatus
Phalaropus tricolor
Xanthocephalus xanthocephalus
68
Breeding Status
3
1
2
2
1
3
2
2
2
2
2
2
2
1
2
2
2
2
2
2
1
2