2012 Abundance and Productivity of Long

2012 Abundance and Productivity of Long-billed Curlews (Numenius
americanus) in the Long-Billed Curlew Area of Critical Environmental
Concern of Southwest Idaho
Photos by Liz Urban and Jessica Pollock
2012 Annual Report
Prepared for:
US Fish and Wildlife Service Region 6, BLM Four Rivers Field Office,
and Idaho Department of Fish and Game,
(Boise State University Admin. Code 006G106652)
Prepared by:
Jessica Pollock, Liz Urban and Jay Carlisle
Idaho Bird Observatory
Department of Biological Sciences
Boise State University
November 22, 2012
1
ABSTRACT
This report summarizes 2012 efforts to study long-billed curlews (Numenius americanus) in the
Long-billed Curlew Area of Critical Environmental Concern (ACEC) on the BLM Four Rivers
Field Office in southwest Idaho. This includes a continued, intensive abundance survey as well
as nest monitoring efforts. Long-billed curlews are identified as a ‘Species of Greatest
Conservation Need’ in the Idaho State Wildlife Action Plan and as ‘Watch List Species’ by
BLM, and are thus of particular interest to wildlife management agencies. During 2012, we
detected an average of 1.28 long-billed curlews per point/survey; markedly higher than the 0.86
curlews detected per point during surveys within the ACEC during 2011. As with prior years,
curlews were not distributed evenly throughout the study area, and curlews were most abundant
in the eastern half of the ACEC. The estimated 2012 population size of adult curlews within the
ACEC was 132, slightly lower than the 2011 estimate of 148 birds. Relative to 2009 and 2010,
when we located 17 and 20 nests, respectively, results in 2011 were far fewer and only 3 nests
were located. In 2012 we located 10 nests, all of which failed. As with past years, the low nest
success rate is reason for concern. During the 2012 field season, we found three dead curlews,
two of which appeared to be from natural causes and one appeared to be the result of a shooting.
These initial results indicate that the ACEC curlew population continues to decline and several
issues and threats need to be addressed.
2
TABLE OF CONTENTS
LIST OF TABLES .......................................................................................................................... 4
LIST OF FIGURES ........................................................................................................................ 4
LIST OF APPENDICES ................................................................................................................. 5
ACKNOWLEDGMENTS .............................................................................................................. 5
INTRODUCTION .......................................................................................................................... 6
METHODS ..................................................................................................................................... 7
RESULTS ..................................................................................................................................... 12
CURLEW ABUNDANCE ON THE ACEC ...................................................................................... 12
CURLEW PRODUCTIVITY ON THE ACEC ................................................................................... 18
TERRITORY MAPPING ............................................................................................................... 24
VEGETATION AT CURLEW NESTS ............................................................................................. 28
SENSITIVE SPECIES AND POTENTIAL CURLEW PREDATORS ON THE ACEC .............................. 28
DISCUSSION AND RECOMMENDATIONS ............................................................................ 33
LITERATURE CITED ................................................................................................................. 36
APPENDICES .............................................................................................................................. 38
3
LIST OF TABLES
Table 1. Long-billed curlews detected per survey route in the ACEC during spring surveys
2007-2012…………………………………………………………………………………..
13
Table 2. Long-billed curlew densities and population estimates within the ACEC, 20072012…………………………………………………………………………………………
17
Table 3. Productivity and fate of long-billed curlew nests on the ACEC, 2012 …………..
18
Table 4. GPS coordinates for all long-billed curlew nests, probable nest/chick locations, and
fledged chicks on the ACEC, 2012……………………………………………………….
20
Table 5. Broad-scale vegetation characteristics along each survey route in the Long-billed
Curlew ACEC, 2012………………………………………………………………………..
29
Table 6. Differences between “2012 and 2011” and “2011 and 2009” in broad-scale vegetation
characteristics along each survey route in the Long-billed Curlew ACEC……………….
29
Table 7. Vegetation coverage characteristics around 2012 long-billed curlew nests …......
30
Table 8. Vegetation coverage characteristics at random, unoccupied sites that served
as paired sites for 2012 long-billed curlew nests ……………………………………….....
31
Table 9. Vegetation height characteristics around 2012 long-billed curlew nests …………
31
Table 10. Vegetation height characteristics at random, unoccupied sites that served
as paired sites for 2012 long-billed curlew nests …………………………………………..
32
LIST OF FIGURES
Figure 1. Long-billed curlew survey routes in the ACEC, southwest Idaho ………………
11
Figure 2. Locations of 2012 long-billed curlew detections (red points) along standardized survey
routes in the ACEC, southwest Idaho....................................................................................
15
Figure 3. Mean number of long-billed curlew detections (orange circles) per survey for 20072012 surveys along standardized survey routes in the ACEC, Southwest Idaho……………
16
Figure 4. Locations of confirmed long-billed curlew nests, probable nest/chick locations, and
fledged chicks of long-billed curlews on the ACEC in 2012……..……………………
23
4
Figure 5. Map showing approximate territories of male curlews observed in the south-central
portion of the Emmett A survey route during 2012…………………………………………
25
Figure 6. Map showing approximate territories of male curlews observed in the vicinity of the
Sandhollow and Emmett B survey routes during 2012 ……………………………………..
26
Figure 7. Map showing approximate territories of male curlews (mostly paired) observed in the
vicinity of the Sandhollow and Emmett B survey routes during 1979 (from Redmond et al.
1981)…………………………………………………………………………………………
27
LIST OF APPENDICES
Appendix A. Average number and range of long-billed curlews detected per survey at each
survey point within the ACEC 2007-2012……………………………………….……….
38
Appendix B. Observations of other ‘sensitive’ species, including avian Species of Greatest
Conservation Need as well golden eagles, on the ACEC in spring/summer 2012................
42
ACKNOWLEDGMENTS
We thank Ben Wright and Lauren Lapinel for their valuable assistance with surveys and nest
searching/monitoring within the ACEC. Some volunteers aided the 2012 crew in nest-searching
and we thank Alessia Cantaboni, Sandy Vistine-Amdor, Shannon and Bill Lind, Tricia
Howerton, Patty McGrath, Brian Leavell, and Christa Braun for their help. Thanks to Bruce
Ackerman (IDFG) for his help in producing density estimates of curlews on the ACEC and to
Nikki Wade for data processing. Financial support for this project in 2012 was provided by the
U.S. Fish and Wildlife Service Region 6 office.
5
INTRODUCTION
The long-billed curlew (Numenius americanus) occupies grassland, open shrubsteppe, and/or
agricultural habitats for breeding from parts of south-west Canada, south to parts of California
Nevada, Utah, Nevada, Utah, New Mexico, Texas, and east to parts of North Dakota, South
Dakota, Nebraska, and Kansas. In Idaho, this species forages predominately in grasslands, but
also uses wet meadows and agricultural habitats including plowed and active crop fields (Jenni
et al. 1982). Curlews nest on the ground and generally place their nests in open habitats with
patchy vegetation (Pampush and Anthony 1993). Curlews are strictly carnivorous, feeding on
terrestrial insects, benthic invertebrates, and some small vertebrates (Dugger and Dugger 2002).
The largest threat to curlews in Idaho, and throughout their range, is loss and degradation of
habitat, especially grassland habitats (Dugger and Dugger 2002). The conversion of native
grasslands to agricultural fields and residential communities, and the increase in recreational use
are resulting in the loss and degradation of suitable habitat in Idaho (Jenni et al. 1982).
Disturbance from excessive off-road vehicles and other recreational use can be a substantial
problem for nesting curlews, particularly during brood-rearing (Jenni et al. 1982). Currently,
threats to curlews on lands west of Boise, including the Long-billed Curlew Area of Critical
Environmental Concern (ACEC), are greater than the time of ACEC establishment. There is
increased off-road activity (trucks, ATVs and dirt bikes) which endanger the ground-nesting
birds and their offspring. Recreational shooting is rampant and the 2012 crew had to leave the
study area many times due to the danger of multiple shooters pointing in all directions. The
sheer abundance of ground squirrel carcasses from recreational shooting likely contributes to the
high nest failure rates due to increased numbers of scavengers/nest predators (especially ravens
and coyotes) foraging in the area.
Curlews are classified as a Species of Greatest Conservation Need (SGCN) in the Idaho State
Wildlife Action Plan (SWAP; Idaho Department of Fish and Game (IDFG) 2005). Designation
as an SGCN establishes these species as “highest conservation priority eligible” for funding
under the State Wildlife Grants program. One of the key recommended actions for the curlew in
the SWAP is to contribute to the regional monitoring effort established by the U.S. Fish and
Wildlife Service and U.S. Geological Survey (Jones et al. 2003) to assess population sizes and
trends, both locally and rangewide.
In 2003, the long-billed curlew was downgraded from a Bureau of Land Management (BLM)
sensitive species in Idaho to a Type 5 species (Watch List: species that are not considered Idaho
BLM sensitive species, but current populations or habitat information suggests that species may
warrant sensitive species status in the future). However, since 2003, it has become increasingly
apparent that the species is not secure throughout its range. Curlews are believed to be declining,
especially within the Great Plains region (Brown et al. 2001). Breeding Bird Survey (BBS) data
indicate slight declines overall in the U.S. (-1.9% per year; not statistically significant) during
the period 1966–2004, but do not indicate any population changes in the western BBS region
(Sauer et al. 2008). During this same analysis period, BBS data indicate an increase of curlews in
Idaho of +2.05% per year. However, it has been suggested that BBS data do not cover trends for
curlews very well (J. Bart, USGS, pers. comm.), and this suggestion, combined with lack of
population size information, resulted in the establishment of a rangewide survey for the species
(Jones et al. 2003).
6
By the early 1970s, BLM personnel began to recognize that an unusually large population of
curlews nested on the short-grass rangeland within the Black Canyon Planning Unit of the Four
Rivers Field Office (Jenni et al. 1982). As a result, a study was contracted by BLM with the
University of Montana to examine behavioral ecology and habitat relationships of curlews in the
area. Following the study, a Habitat Management Plan was written for the Black Canyon Curlew
Area which established management actions to preserve and enhance habitat characteristics
favorable to nesting curlews. After the importance of the area was recognized and several land
management threats were identified to include land development, the 1988 Cascade
Resource Management Plan established the ground as an Area of Critical Environmental
Concern. The aforementioned study concluded that nearly 1,000 breeding pairs of curlews
nested within the Black Canyon area (Jenni et al. 1982). This population represented a
significant portion of the only 3,000–5,000 pairs estimated to be nesting in all of southern Idaho
(Pampush 1980). Since the Jenni et al. (1982) study, monitoring in the ACEC has been
conducted only sporadically using techniques that have generally lacked scientific rigor. In
2006, IDFG began to address this monitoring issue by conducting pilot curlew surveys on the
ACEC following the nationally accepted protocols outlined by Jones et al. (2003), with routes
based on historical survey routes to the extent possible. This effort continued to expand in 2007
with surveys throughout the ACEC and these surveys have continued annually from 2008-2012.
Population density estimates from 2007-12 surveys on the ACEC (132-306 birds) suggest a
substantially reduced breeding population from the 1970s estimates (~1,000 breeding pairs;
Jenni et al. 1982). Here we report on 2012 abundance and nest monitoring results with reference
to historic results.
STUDY AREA
The Long-billed Curlew ACEC is approximately 61,000 acres ranging from 20-40 miles
northwest of Boise, Idaho. The ACEC is located between the Boise, Payette, and Snake River
valleys characterized by rolling hills of cheatgrass and open sage communities sprinkled with
agricultural fields. Historically the habitat was largely native bunchgrass/sage communities, but
has been highly modified over the years due to livestock grazing, wildfires, and the introduction
of cheatgrass, resulting in a drastic decrease of native perennial grasses. Annual rainfall is
approximately 11 inches, largely falling in winter and spring. Livestock grazing is common as is
recreational use (off-road vehicles and recreational shooting). Curlews are migratory and arrive
to the study area in late March. In late summer 2011, the Goody Fire burned around 3,000 acres
through part of the Emmett A curlew focal area in the ACEC.
METHODS
In 2012, field crews surveyed from April 1 until June 30.
CURLEW ABUNDANCE ON THE ACEC
Curlews were surveyed within the ACEC in April 2007-2012 using the nationally accepted
standardized protocol for counting curlews with a team of two observers (Jones et al. 2003).
These protocols were recently developed to establish a rangewide survey for the species. Survey
7
routes on the ACEC were built upon historic routes. All routes were surveyed by a team of two
observers who stopped at points spaced 0.8-km apart to record all curlews seen or heard within 5
minutes. Surveys began ½ hour after sunrise and continued for 4–5 hours. Data on curlews seen
or heard at each point were collected so that detection probabilities could be estimated from the
count data. Specifically, at each stop there was a primary observer and a secondary observer, and
the individuals in these roles alternated between stops. The primary observer was responsible for
detecting curlews by sight or sound, determining by laser rangefinder the distance band (0–400
m, 400–800 m, >800 m) in which the bird occurred, and communicating this information to the
secondary observer. The secondary observer recorded the information, including the 1-minute
time interval in which each curlew was detected, and recorded all curlews that were not detected
by the primary observer (including the distance band in which such birds were detected). The
time of detection was based on the first observation, regardless of whether the first or second
observer saw it. Collecting data in this manner allows estimation of detection probabilities and
population sizes using two distinctly different methods: the double-observer approach of Nichols
et al. (2000) and the removal-model approach of Farnsworth et al. (2002). Furthermore, because
the data were collected by distance band, total area sampled along a route can be calculated so
the population size estimate for the route can be converted to a density estimate. For this report,
the data collected were analyzed using the Double Observer Sightability probability method
used by Stanley and Skagen (2007) to assess the regionwide population of long-billed curlews.
Within the ACEC, six survey (two-track) routes were established using the criteria specified in
Saunders (2001; Fig. 1). To the extent possible, routes were based upon historical survey routes
which currently exist in the ACEC, and along which curlews have been intermittently counted
since approximately 1977. To bring historical survey routes up-to-date with the modern protocol,
existing routes were shortened, extended, and/or combined, depending on availability of suitable
habitat and original route length. Once routes were modified, points were designated for
sampling curlews at 0.8-km intervals along each route. Routes were surveyed in a manner
coinciding with the relatively narrow time window (2–4 weeks) corresponding to the arrival and
pre-incubation period of curlews, when males are most conspicuous in their aerial display flights
(Redmond et al. 1981). For the ACEC, this sampling window essentially coincides with the
month of April (i.e., 3–27 April; Jones et al. 2003). Surveys were conducted twice along each
route in April of each year. In 2009-2012, we modified the protocol slightly by giving actual
estimates of distance to each detected curlew (i.e., 250m) as opposed to simply identifying the
distance band (i.e., 0-400m) within which a detection occurred.
CURLEW PRODUCTIVITY AND TERRITORY MAPPING ON THE ACEC
ACEC Nest Searching, Monitoring and Territory Mapping: In May-June 2012, we focused at
least 700 hours of effort on locating curlew nests within the ACEC and this effort included a
small community volunteer component. Searches were conducted along all six ACEC abundance
survey routes mentioned above. However, we particularly focused nest-searching efforts along
portions of the Emmett A, Emmett B, and Sand Hollow transects (where curlews were known to
be more numerous based on abundance surveys). We tried to visit each area a minimum of eight
times to get a good sense of territory boundaries, but no birds were color banded so territories are
an approximation only and not absolute. On each visit, we mapped observations of curlews (e.g.,
territorial flights, male disputes) onto topographic maps and later digitized these maps using GIS
in order to approximate territorial boundaries and the number of territories within two focal
8
areas: Emmett A and Sandhollow/Emmett B.
Curlews were initially located visually or aurally from a vehicle or on foot. Once located, an
individual curlew or pair of curlews was watched through binoculars or a spotting scope until
an individual curlew settled on the nest (generally curlews were watched in this manner for no
longer than two hours and curlews that had not settled on a nest within this period of time were
then searched for/monitored during subsequent visits to an ACEC route). We largely used male
behavior to locate nests during the egg-laying period. While the female is egg laying (about one
egg every 24-48 hours) the male guards the nest and even returns to the nest multiple time
throughout the day to ensure the egg(s) are protected. We would follow suspected mated males
(males we saw close to a female or one that we observed grooming a female or copulating) and
typically within an hour or two they would lead us right to the nest. May was a key month for
locating nests during this egg laying period. Once the clutch is complete and the female is
incubating, it is more difficult to locate nests. We then approached the nest and, depending on
suspected status, we flushed the curlew off of the nest in order to count eggs. We recorded a
GPS location of each nest. On subsequent visits, we viewed each nest from as far away as
possible. Nesting status was checked in this way until the nest was known to have failed or had
produced chicks. The area around a nest that had likely produced chicks was scanned for adult
curlews. Once found, adult curlews were watched until chicks, that were usually close by, were
found (adult curlews typically gave loud alarm calls and showed other anti-predator behavior
when chicks were nearby). The minimum number of chicks produced from a nest was then
recorded. Because broods quickly disperse from natal areas, chicks were not monitored beyond
this point, unless not all of the eggs present in the nest had hatched. In addition, we attempted
to locate other broods (i.e., not from nests we had located) by driving and/or walking through
the survey routes (the best way to access the ACEC study area) in search of chicks and/or
especially aggressive adults during June.
VEGETATION
Survey route vegetation: We collected vegetation data along long-billed curlew survey routes on
the ACEC following the recommendations of Fellows (2004) for the range-wide survey (Jones et
al. 2003). We focused our efforts on collecting the ‘primary habitat codes’ described by Fellows
(2004) in each quadrant (NE, NW, SW, and SE) within 400m of each survey point. On the
ACEC, the most frequent primary habitat types included percent cover of short (<12 cm) grasses,
medium (12-38 cm) grasses, tall (>38 cm) grasses, sage-steppe, cropland, and other (largely rural
structures and canals; Fellows 2004). Survey route vegetation was collected early in the season
(April), while vegetation was still in the early green-up phase. This standardized timing allows
for comparison of general vegetation categories among and between years to document how
broad vegetation classes are changing over time.
Nest site vegetation: We followed Pampush (1980) and Pampush and Anthony (1993) in
recording a suite of vegetation characteristics at long-billed curlew nest sites. This methodology
consists of running four, 100-m transects in each of the cardinal directions from the nest cup and
establishing a random subsample within each 10-m interval such that 10 subsamples were
measured along each transect and 40 subsamples were measured at each nest. Vegetation
variables included:
9
percent cover of annuals, perennials, forbs, shrubs, bare ground, and litter (using a
Daubenmire frame)
vertical density of grasses, forbs, and shrubs at 0-25 cm, 26-50 cm, and >50 cm intervals
(number of touches of plant parts on a 6-mm diameter vertical rod)
shrub cover (using the line-intercept method along each transect)
We also measured the same suite of variables at unused sites, which were 250m in a randomlyselected direction from known nest sites (where territory size/overlap allowed us to have a
unused site), with the goal of comparing differences between nest sites and paired, unused sites
using paired t-tests and a P value of 0.05 (but in 2012 sample size was not large enough).
OBSERVATIONS OF SENSITIVE SPECIES AND POTENTIAL CURLEW PREDATORS ON THE ACEC
In conjunction with standardized surveys and nest-searching/monitoring, we also recorded
observations of a suite of ‘sensitive’ species, including avian Species of Greatest Conservation
Need and BLM-listed species as well golden eagle and loggerhead shrike, on the ACEC in
spring/summer 2012. Similarly, we kept track of locations of other predators potentially
important in the life history of long-billed curlews, including coyote (Canis latrans), American
badger (Taxidea taxus), long-tailed weasel (Mustela frenata), and common raven (Corvus
corax). These observations are listed/shown in Appendix B.
POPULATION AND DENSITY ESTIMATES
Population and density estimates were conducted by the Idaho Department of Fish and Game
using only detections in the 0-400m distance band.
10
Figure 1. Long-billed curlew survey routes in the ACEC, southwest Idaho.
11
RESULTS
CURLEW ABUNDANCE ON THE ACEC
Relative to values in prior years, 2012 curlew detection rates decreased overall, and especially on
the Sandhollow and Emmett B routes (Table 1). Curlew detections on Emmett A (survey 2)
increased from 2011. Although curlews were detected along each survey route in 2012, very few
curlews were detected in the northwest corner of the ACEC, and the western half of the ACEC
continues to have lower curlew abundance than the eastern half (refer to Figure 1). In particular,
the highest numbers of curlews in 2007-2012 have been found along the Emmett A, Emmett B,
and Sand Hollow transects (Table 1, Figs. 2, 3). This reflects a possible change in relative
abundance since the comprehensive survey effort in 1977–1979, when low numbers of curlews
were found along Emmett B and high and moderate numbers were found along New Plymouth
(Jenni et al. 1982). Densities of curlews along routes within the ACEC in 2012 varied from 0.17
birds/sq km (Parma route) to 1.32 birds/sq km (Emmett A route). As densities were not uniform,
we also calculated population estimates for 3 sections within the ACEC: Eastern (Emmett A,
Emmett B, and Sandhollow), Central (Letha), and Western (New Plymouth and Parma).
Densities in the ACEC west of I-84 averaged 0.21 birds/sq km, while densities in the eastern half
of the ACEC were notably higher (1.07 birds/sq km; Table 2). Extrapolating these density
estimates to the rest of the ACEC, the overall population estimate for adult curlews in 2012 was
132 (Table 2). Estimated population size between 2007 and 2010 has varied minimally from 276
to 306 curlews; however, the 2011 estimate was substantially lower (142 curlews) and the 2012
estimate is even lower at 132 birds (Table 2). In all six years, the majority (70% - 80%) of the
ACEC curlew population was in the eastern section (Table 2, Fig. 3).
12
Table 1. Long-billed curlews detected per survey route in the ACEC during
spring surveys, 2007-2012.
Survey 1
Curlews/Point
3.6
2.8
2
1.3
1.6
1.4
Survey 2
Curlews/Point
3.4
2.6
2
1.9
1.1
2.4
Route Name
Emmett A
Year No. Points
2007
33
2008
33
2009
34
2010
34
2011
34
2012
34
Emmett B
2007
2008
2009
2010
2011
2012
9
9
8
8
8
8
3
2.6
3.1
3.3
1.5
1.5
4.1
2.7
3
3.6
1.3
1.7
Letha
2007
2008
2009
2010
2011
2012
29
0.9
0.9
0.2
0.6
0.4
0.4
1.1
0.7
0.5
0.2
0.4
0.5
New Plymouth
2007
2008
2009
2010
2011
2012
23
0.3
0.2
0.4
0.4
0.4
0.1
0.4
0.3
0.0
0.3
0.1
0.6
Parma
2007
2008
2009
2010
2011
2012
24
1.0
0.9
0.3
0.2
0.2
0.3
1.3
0.8
0.4
0.6
0.2
0.2
Sandhollow
2007
13
3.9
5.4
13
2008
2009
2010
2011
2012
4.5
2.6
3.0
1.6
0.9
3.2
1.8
2.7
1.6
0.6
14
Figure 2. Locations of 2012 long-billed curlew detections (red points) along standardized survey routes in the ACEC, Southwest
Idaho.
15
Figure 3. Mean number of long-billed curlew detections (tan circles) per survey for 2007-2012 surveys along standardized survey
routes in the ACEC, Southwest Idaho.
16
Table 2. Long-billed curlew densities and population estimates within the ACEC, 2007-2012.
2007
2008
2009
2010
2012
2011
Section
Size
(km2)
Density*
Pop.
Est.
Density
Pop.
Est.
Density
Pop.
Est.
Density
Pop.
Est.
Density
Pop.
Est.
7.79
Density
0.45
Pop.
Est.
14.43
Central
32.36
0.55
17.78
0.34
11.12
0.41
13.34
0.31
10.01
0.24
East
87.09
2.7
235.04
2.6
226.51
2.58
225.1
2.53
220.75
1.48
128.65
1.07
92.92
West
ACEC
Total
75.19
0.58
43.88
0.71
53.06
0.28
20.9
0.3
22.28
0.15
11.21
0.21
15.99
194.64
1.52
295.85
1.53
297.79
1.57
305.58
1.42
275.95
0.83
161.25
0.67
132.09
* Density = Adult curlews per square kilometer
17
CURLEW PRODUCTIVITY ON THE ACEC
In 2012, we focused over 700 hours on trying to locate curlew nests and we were able to locate and monitor a total of ten occupied
nests (Tables 3, 4; Figure 4). Though we spent time searching on all routes and saw pair activity on most, we only located nests on the
Emmett A, Emmett B, and Letha routes (Table 3). We located chicks (post-fledging) on Emmett A, Emmett B and Sandhollow routes
(Table 4). Only two nests hatched nestlings (but we believe that recently hatched chicks from these nests were likely preyed upon) and
eight nests failed (Table 3). In addition to monitored nests, we observed three additional chick groups (Table 4; Figure 4).
Table 3. Productivity and fate of long-billed curlew nests on the ACEC, 2012.
Estimated
# of eggs
Initiation
when found
date
# of eggs
produced
Nest fate
Cause of Failure (Best
Estimate)
# of
offspring
produced
Transect
Nest
Date
found
Letha
A
5/1/2012
4/28/12
2
Unknown
Failed
Unknown, but
presumably preyed
upon
0
Emmett A
B
5/2/2012
4/30/12
2
2
Failed
Avian Depredation
(shells located)
0
Emmett A
C
5/2/2012
4/30/2012
1 or 2 (found
1 or 2
Failed
0
already
depredated)
(found
already
depredated)
Mammalian
Depredation (shells
located)
Emmett B
D
5/6/2012
5/6/2012
1
Unknown
Failed
Abandoned single egg
(egg was soft
shelled…undeveloped?)
0
Emmett A
E
5/9/2012
5/8/2012
1
Unknown
Failed
Unknown, but
presumably preyed
upon
0
18
Transect
Nest
Date
found
Emmett A
F
5/9/2012
Estimated
# of eggs
Initiation
when found
date
5/6/2012
2
# of eggs
produced
Presumed
complete
(3 or 4)
Nest fate
Cause of Failure (Best
Estimate)
# of
offspring
produced
Failed
Mammalian
Depredation (shells
located)
0
(female
incubating for
hours)
Emmett A
G
5/11/2012
5/10/2012
1
Unknown
Failed
Unknown, but
presumably preyed
upon
0
Emmett A
H
5/14/2012
5/13/2012
1
1
Failed
Abandoned single egg
0
Emmett A
I
5/21/2012
4/20/2012
2 chicks
newly
hatched in
nest bowl
Unknown
Hatched but
young
nestlings
preyed upon
-
2 (not
fledged)
Emmett A
J
6/11/2012
5/10/2012
4 (3 eggs
and 1 chick
in nest
bowl)
4
Hatched but
young
nestlings
preyed upon
-
4 (not
fledged)
19
Table 4. GPS coordinates (NAD 83, UTM) for all long-billed curlew nests, probable nest/chick locations*, and fledged chicks on the
ACEC, 2012. * Where suggestive pair activity occurred (i.e., aggressive mobbing of ravens, raptors, and even other curlews) and/or
nest construction was observed but follow-up visits revealed no further nesting activity.
Removed due to sensitive location information.
20
Figure 4. Locations of confirmed long-billed curlew nests, probable nest/chick locations, and fledged chicks on the ACEC in 2012.
Labels correspond to those in Table 4.
Removed due to sensitive location information.
21
TERRITORY MAPPING
We focused our nest-searching and territory mapping in two key areas: the south-central portion
of Emmett A and Emmett B/Sandhollow (Figures 5-6). For comparison, we also show results
from 1979 territory mapping in the Emmett B/Sandhollow area (Figure 7; reproduced from
Redmond et al. 1981). The territories depicted in Figures 5-6 represent the territories that we
were most confident in our ability to delineate boundaries with any level of confidence; it should
be noted that there were many additional male curlews (who were likely unpaired) present in
each of these focal areas, but due to individuals not being marked, we were not comfortable
defining these territories. A visual comparison of figures 6 and 7 clearly shows a substantial
reduction in the number of occupied territories between 1979 and 2012 accompanied by an
apparent increase in territory size in 2012 relative to 1979 (however, no birds were color banded
so territories size and numbers are approximate). This apparent difference is also consistent with
survey data differences between time periods that show at least an 85% decrease in population
size from the late 1970’s to the current time.
22
Figure 5. Map showing approximate territories of male curlews observed in the south-central portion of the Emmett A survey route
during 2012.
23
Figure 6. Map showing approximate territories of male curlews observed in the vicinity of the
Sandhollow and Emmett B survey routes during 2012 (same study area used by Redmond et al.
1981 and shown in Figure 7).
24
Figure 7. Map showing approximate territories of male curlews (mostly paired) observed in the
vicinity of the Sandhollow and Emmett B survey routes during 1979 (from Redmond et al.
1981).
25
VEGETATION ALONG SURVEY ROUTES AND AT LONG-BILLED CURLEW NESTS.
Survey route vegetation: Vegetation along the survey routes was generally dominated by short
(<12 cm) and medium (<25 cm) grasses and (Table 5). In comparing 2012 to 2011 values, we
saw a decrease in the proportion of areas dominated by short grass on all routes except for Letha.
This was accompanied by moderate increases in the tall category for Emmett A and B and
Sandhollow; moderate decreases in % tall for Letha and New Plymouth and moderate decreases
in the medium category for Parma and Sandhollow (Table 6). We also compared 2011 values to
2009 (Table 6). Shrub-steppe vegetation was rare and limited in distribution to only a few sites.
Vegetation at Long-billed Curlew Nests: We measured a suite of vegetation coverage and height
variables at long-billed curlew nests and at nearby paired, unused sites (chosen randomly) for 4
nests (Tables 7-10). Annual grasses, bare ground, debris, and forbs comprised the bulk of ground
cover at nest sites and at paired, unused sites (Tables 7, 8). The bulk of vegetation consisted of
grasses and forbs of <25 cm and there was very little vegetation > 25 cm (Tables 9, 10).
Due to the density of territories, specifically in Emmett A, we could not select truly unused
paired sites for the other 6 nests. We only had a paired, unused site for nests A, C, D, and H
(tables 8 and 10). Due to low sample size of paired, unused sites, we did not test for vegetation
differences between used and unused sites. Moreover, cattle grazing was abundant at Emmett A
and B and it should be noted that most of the nest sites were grazed between the time of nest site
selection and our vegetation measurements. Therefore, our vegetation results may not be fair
indicators of nest site selection preferences.
OBSERVATIONS OF SENSITIVE SPECIES AND POTENTIAL CURLEW PREDATORS ON THE ACEC
We observed a number of species listed by BLM and/or IDFG (2005) as well as potentially
important predators during 2012 (Appendix B). In particular, many birds of prey were seen in the
area, likely due to the high concentration of ground squirrels. Potential curlew predators,
including ravens, coyotes, badgers, and weasels, were observed throughout the study area.
Though we don’t have data from the 1970s on the common raven population, Dr. Roland
Redmond (pers. comm., performed the curlew research from 1977-79) reported that raven
sightings were infrequent then and that, after an April 2011 visit to the study area, believes that
ravens are far more numerous now than when he worked in the area.
26
Table 5. Broad-scale vegetation characteristics along each survey route in the Long-billed Curlew ACEC, 2012. Percent tall,
medium, and short encompass the coverage of grasses and forbs combined; in the entire study area, this category was largely
composed of a mix of non-native, invasive grasses and forbs as well as some native species (mean  SE).
Route
Emmett A (34)
Emmett B (8)
Letha (29)
New Plymouth (23)
Parma (24)
Sandhollow (13)
% tall
% medium
% short
% sage-steppe
% crop
% other
24.3  1.5
46.8  1.4
26.3  1.2
0.0  0.0
0.0  0.0
0.7  0.6
28.1  3.6
38.8  2.8
21.9  2.0
11.3  3.3
0.0  0.0
0.0  0.0
19.2  1.3
37.7  1.8
28.6  1.6
10.0  2.0
0.2  0.1
1.4  0.9
17.7 1.4
29.5  1.7
51.8  2.2
1.1  0.4
0.0  0.0
0.0  0.0
15.5  1.2
37.3  2.5
43.8  2.6
0.0  0.0
0.0  0.0
0.0  0.0
12.8  2.0
67.0  2.6
20.2  1.9
0.0  0.0
0.0  0.0
0.0  0.0
Table 6. Differences between “2012 and 2011” and “2011 and 2009” (not surveyed in 2010) in broad-scale vegetation characteristics
along each survey route in the Long-billed Curlew ACEC. Values shown are 2012 minus 2011 and 2011 minus 2009: blue font
indicates an increase between years and red font indicates a decrease.
Route
Emmett A (34)
Emmett B (8)
Letha (29)
New Plymouth (23)
Parma (24)
Sandhollow (13)
% tall
2012:2011 2011:2009
24.3
-11.6
28.1
-10.9
-25.2
20.8
-12.5
15.8
4.0
-6.5
12.8
-3.4
% medium
2012:2011 2011:2009
3.8
18.6
-8.9
26.1
0.3
-6.4
3.2
-10.3
-19.5
-0.7
-31.9
22.2
% short
2012:2011 2011:2009
-27.2
-6.8
-21.9
-7.8
0.3
-12.6
-0.5
-10.9
-2.1
8.6
-2.6
-22.1
27
Table 7. Vegetation coverage characteristics around 2012 long-billed curlew nests (post-hatching or nest failure or post grazing).
Variables include percent cover of annual grasses, perennial grasses, bare ground, forbs, shrubs, and debris as well as the number of
shrubs intersected by the line-intercept method. (mean  SE).
Nest
% Annuals
% Perennials
% Bare
Ground
% Debris
% Forb
% Lichen
% Shrubs
Shrubintercept
A
25.3  1.5
0.7  0.4
8.5  1.0
60.2  1.3
3.2  0.4
2.0  0.5
0.0  0.0
0
B
14.7  1.2
0.1  0.1
18.5  2.0
56.25  2.0
10.3  0.7
0.1  0.1
0.0  0.0
0
C
12.3  1.6
5.3  1.9
10.6  2.3
62.6  2.6
5.1  0.9
3.8  0.8
0.0  0.0
0
D
14.0  1.1
1.5  0.4
5.1  0.7
70.1  1.3
9.2  0.7
0.0  0.0
0.0  0.0
0
E
13.3  1.3
1.3  0.5
9.7  1.5
63.7  1.4
4.2  0.3
7.5  1.2
0.0  0.0
0
F
18.6  2.0
0.0  0.0
5.5  1.1
65.8  1.6
5.1  0.3
4.8  0.7
0.0  0.0
0
G
16.0  1.7
5.5  1.2
8.7  2.6
65.1  2.8
3.6  0.6
1.1  0.3
0.0  0.0
0
H
13.1  1.1
1.7  1.0
13.3  1.6
59.5  1.6
4.5  0.3
7.7  0.9
0.0  0.0
0
I
14.8  1.3
2.5  0.5
7.1  2.6
63.6  2.4
11.8  0.8
0.0  0.0
0.0  0.0
0
J
10.1  1.2
0.8  0.3
8.0  1.4
71.6  1.2
5.75  0.2
3.6  0.8
0.0  0.0
0
28
Table 8. Vegetation coverage characteristics at random, unoccupied sites (located 250m in a random direction from each used nest)
that served as paired sites for 2012 long-billed curlew nests. Variables include percent cover of annual grasses, perennial grasses, bare
ground, forbs, shrubs, and debris as well as the number of shrubs intersected by the line-intercept method. Due to the high territory
densities around the other six nests, we could not locate unused paired sites for them. (mean  SE).
Paired Site for
Each Nest
A
C
D
H
%
Annuals
8.9 ± 0.9
12.0 ± 1.7
21.5 ± 1.5
18.0 ± 3.0
%
Perennials
0.1 ± 0.1
3.0 ± 1.0
0.1 ± 0.1
1.8 ± 0.5
%
Bare Ground
8.0 ± 2.0
8.3 ± 2.7
12.4 ± 2.3
9.3 ± 1.4
%
Debris
74.4 ± 2.2
65.9 ± 2.3
60.4 ± 2.2
64.6 ± 2.5
%
Forbs
6.8 ± 0.7
4.3 ± 0.3
4.4 ± 0.4
3.4 ± 0.4
%
Lichen
1.9 ± 0.6
6.6 ± 1.1
1.4 ± 0.4
3.0 ± 0.6
%
Shrubs
0.0 ± 0.0
0.0 ± 0.0
0.0 ± 0.0
0.0 ± 0.0
Shrubintercept
0
0
0
0
Table 9. Vegetation height characteristics around 2012 long-billed curlew nests. Variables include number of ‘touches’ along a
vertical rod of grasses, forbs, and shrubs within bands of 0-25cm, 26-50cm, and more than 50cm above ground level. (mean  SE).
≤25cm
≥50 cm
25-50cm
Nest
Grass
Forbs
Shrubs
Grass
Forbs
Shrubs
Grass
Forbs
Shrubs
A
B
C
D
E
F
G
H
I
J
3.3 ± 0.4 (131)
0.2 ± 0.1 (9)
0.0 ± 0.0 (0)
0.1 ± 0.1 (3)
0.02 ± 0.02 (1)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
3.4 ± 0.4 (136)
0.1 ± 0.1 (5)
0.0 ± 0.0 (0)
0.2 ± 0.1 (9)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.20 ± 0.1 (8)
0.0 ± 0.0 (0)
2.1 ± 0.4 (85)
4.9 ± 0.4 (195)
2.9 ± 0.3 (117)
2.5 ± 0.3 (98)
2.1 ± 0.3 (85)
2.6 ± 0.3 (103)
0.08 ± 0.04 (3)
0.2 ± 0.1 (7)
0.3 ± 0.1 (10)
0.6 ± 0.1 (25)
0.7 ± 0.1 (28)
0.1 ± 0.1 (5)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.03 ± 0.03 (1)
0.1 ± 0.1 (3)
0.2 ± 0.1 (6)
0.2 ± 0.1 (8)
0.03 ± 0.03 (1)
0.05 ± 0.03 (2)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.2 ± 0.1 (7)
0.05 ± 0.05 (2)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
2.0 ± 0.3 (79)
1.9 ± 0.3 (76)
0.2 ± 0.1 (7)
0.2 ± 0.1 (6)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.05 ± 0.03 (2)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
29
Table 10. Vegetation height characteristics at random, unoccupied sites (located 250m in a random direction from each used nest) that
served as paired sites for 2012 long-billed curlew nests. Variables include number of ‘touches’ along a vertical rod of grasses, forbs,
and shrubs within bands of 0-25cm, 26-50cm, and over 50cm above ground level. Due to the high territory densities around the other
six nests, we could not locate unused paired sites for them. (mean  SE).
Paired site
for each nest
A
C
D
H
Grass
≤25cm
Forbs
Shrubs
Grass
25-50cm
Forbs
Shrubs
Grass
≥50 cm
Forbs
Shrubs
1.4 ± 0.2 (56)
0.3 ± 0.1 (10)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.05 ± 0.05 (2)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
2.8 ± 0.4 (110)
0.1 ± 0.05 (4)
0.0 ± 0.0 (0)
0.08 ± 0.04 (3)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
3.6 ± 0.4 (145)
2.6 ± 0.3 (102)
0.2 ± 0.1 (7)
0.1 ± 0.1 (4)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.3 ± 0.2 (10)
0.0 ± 0.0 (0)
0.03 ± 0.03 (1)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
0.0 ± 0.0 (0)
30
DISCUSSION AND RECOMMENDATIONS
Varying, or inconsistent, survey techniques within the ACEC since the 1970s make it difficult to
assess trends. Data collected from 2007 through 2012 will provide a baseline for future
comparisons, but do not enable us to make comparisons with data collected since the ACEC was
established. However, if we assume that the population estimates derived by Jenni et al. (1982)
in the late 1970s are accurate and can be compared with current methods of estimating
population sizes, we should be able to evaluate if the curlew population in the ACEC has
changed over the past 30 years. Based on 2007-2012 survey data, we have derived a current
population estimate ranging from 132-306 adult curlews in the ACEC. This is significantly
lower than the 1970s estimates of 2,000 birds (~1,000 pairs; Jenni et al. 1982). Although some of
the difference may be attributed to estimation methods, it is unlikely to explain such a stark
contrast. Territory mapping data from 2012 compared to 1979 data provide further evidence that
curlew populations on the ACEC have declined substantially since the 1970s. In particular, the
surprisingly low population size and apparent low productivity in 2009-2012 is reason for
concern, as is a decrease in habitat quality and the abundance of human disturbance (off-road
vehicles and recreational shooting). The most pronounced decrease from 2011 to 2012 is in the
Sandhollow route, with a 2011 estimate of 1.53 birds/sq km that decreased by ~50% to 0.77
birds/sq km in 2012.
Productivity: Similar effort in 2012 was invested in nest searching than in previous years, but we
found 7 more nests than in 2011. 2012 survey data showed a slight drop in the curlew population
from 2011 to 2012.
Nest failure was extremely high in 2012. Given that the common raven is a skilled nest predator
whose populations have increased dramatically in recent decades (Sauer et al. 2008) and is a
species that has benefitted from anthropogenic changes in the West, including transmission lines
and roads (Leu et al. 2008), the suspected increase in ravens on the ACEC could be having a
serious impact on curlew nesting attempts. We observed direct evidence of avian nest predation.
In 2012 we only approached each nest once to assess status and then again near the expected
hatching date but otherwise were careful to view nests from afar. Though certainly possible, it is
difficult to ascertain if mammalian predators (chiefly coyote and badger) used our human scent
trails to the long-billed curlew nests we found.
Anthropogenic Impacts: In several areas within the ACEC there are prominent trash dumping
sites that are also used for shooting. Shooting of ground squirrels is prevalent throughout the
study area, with some areas receiving much higher shooting activity than others. Two of the
three areas with the highest densities of territorial birds regularly were used by people shooting
The combination of human traffic, dumping of materials that are potentially toxic, and the
prevalence of shooting in these areas all present significant hazards to nesting curlews. Two
male curlews were found shot and killed in 2010 and, though we could not be absolutely
certain of cause of death, we found three dead curlews along dirt roads in 2011 – their locations
potentially suggested foul play. In 2012 we found a male curlew right beside a road where we
have observed many shooters, and this bird appeared to be shot. It was not damaged from
predation or scavenged. In this instance, we presume that this bird was associated with the nest
31
that was found nearby (one of only two that succeeded in hatching); a brood which disappeared
within three days of hatching. Though hard to prove, it is possible that this individual was shot
as a result of conspicuously defending his brood, and that the brood was likely lost after the
male’s death. We also located two other dead curlews in an area not frequented by the public,
but these birds appeared to be naturally preyed upon. Thus, in addition to general shooting
disturbance within the study area (that could cause disturbance to reproductive efforts), we
know that at least some curlews are subject to direct mortality in the ACEC on an annual basis.
Range condition: Although much of the ACEC currently provides the correct habitat features
for long-billed curlews, the deleterious impact that cheatgrass (Bromus tectorum) can have on
soil conditions and soil productivity (Norton et al. 2004) might be reason for concern over the
long-term. Also, Kathi Kershaw (BLM ecologist, pers. comm.) pointed out that although the
Long-billed Curlew ACEC is dominated by cheatgrass, the occurrence of Sandberg bluegrass
(Poa secunda) in many areas plays a significant role, especially in years when little to no
cheatgrass germinates. Additionally, Sandberg bluegrass is probably the most capable native
bunchgrass to compete with cheatgrass for nutrients because it initiates annual growth during
the same time period as cheatgrass (K. Kershaw, pers. comm.). Thus, something worth
examining is whether or not curlews are selecting for or against Sandberg bluegrass.
Importantly, the 2010 and 2012 crews noticed the use of tall, dense vegetation, including
patches of tumble mustard (Sisymbrium altissimum), by adult curlews to hide their broods. In
fact, several times adult curlews were observed preventing their broods from leaving dense, tall
vegetation. Thus, while areas of shorter grass are likely important for nest placement and
vigilance during nesting, nearby areas of taller vegetation might also be important for broodrearing (Dugger and Dugger 2002).
Cattle grazing and off-road recreation: We observed cattle present as well as being herded
through high density nesting/territory areas during peak incubation/nestling times. Although we
cannot say absolutely, we suspect that moving large herds of cattle through a small, narrow
valley (as in Emmett A, Points 1-4) likely resulted in crushing of eggs or nestlings. Technicians
observed multiple curlews flushing off the ground and making defensive calls in response to
cattle being moved through both the Emmett A (Points 1-4) and the Emmett B/Sand Hollow
valleys in May. Off-road vehicles including ATVs and dirt bikes are common and their tire
tracks are abundant.
Future management, research, and monitoring: The substantial decline in curlews on the ACEC
since the 1970s, documented by abundance surveys, territory mapping, and nest
searching/monitoring, suggests that there is a need to begin active management to maintain
suitable habitat for long-billed curlews on the ACEC. Possible tools could include grazing
(although timing of herding needs to be addressed) and other forms of vegetation control as well
as recreation management (both off-roading and shooting). In April of 2011, Roland Redmond
(who conducted the study in the 1970s), Alan Sands (IDFG; was manager of the ACEC during
Redmond study and leading to creation of ACEC), Lara Rozell (Idaho Conservation League),
Rick Ward (IDFG), and Jay Carlisle spent time in the field with many BLM employees to
examine and discuss the current status of curlews. Among many issues discussed, there was
general agreement that shooting and vehicular recreation should be strictly limited during the
32
nesting season (March 15 through at least July 15). Options could include overall bans or
designation of a few ‘sacrifice zones’ (areas that currently have very little to no curlew use where
access for target shooting and/or vehicular recreation could pose little conflict).
We also discussed the fact that grazing on the ACEC is currently comprised of a higher
proportion of cattle (and lower proportion of sheep) than during the 1970s and 1980s. The area
now has more widespread areas of dead and standing weeds and, if sheep could do a better job of
knocking this back, incorporating more sheep might help improve curlew habitat. Other options
discussed included the potential for mechanical control of dead and standing weeds as well as the
potential for prescribed burning.
There is currently no funding for continued monitoring in 2013 and this will be a deficit in
assessing the population trend and assessing the effectiveness of management tools. Although
there may be enough potential threats on the ACEC to explain the decline in curlews over three
decades, there may exist other threats to this population during migration and/or on the wintering
grounds. Thus, we are currently seeking funding to employ satellite telemetry on at least three
adult curlews to learn more about their migration routes and winter destinations.
33
LITERATURE CITED
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plan, 2nd ed. Manomet Center for Conservation Sciences, Manomet, MA. 60 pp.
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Birds of North America, No. 628 (A. Poole and F. Gill, eds.). The Birds of North America,
Inc., Philadelphia, PA. 28 pp.
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119:414–425.
Fellows, S. 2004. Instructions to observers for conducting long-billed curlew surveys.
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Idaho Department of Fish and Game. 2005. State Wildlife Action Plan. Idaho Conservation
Data Center, Idaho Department of Fish and Game, Boise, ID.
http://fishandgame.idaho.gov/cms/tech/CDC/cwcs.cfm
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of long-billed curlew in western Idaho. Research Report. U.S. Bur. Land Manage. 234 pp.
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(Numenius americanus) rangewide survey and monitoring guidelines. U.S. Fish and Wildlife
Service, Denver, CO.
Leu, M., S. E. Hanser, and S. T. Knick. 2008. The human footprint in the West: a large-scale
analysis of anthropogenic impacts. Ecological Applications 18:1119-1139.
Nichols, J. D., J. E. Hines, J. R. Sauer, F. W. Fallon, J. E. Fallon, and P. J. Heglund. 2000. A
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Appendix A. Average number and range of long-billed curlews detected per survey at each
survey point within the ACEC 2007 – 2012. Coordinates are provided in datum NAD 27, UTM
Zone 11.
Removed due to sensitive location information.
36
Appendix B. Observations of other ‘sensitive’ species, including avian Species of Greatest Conservation Need as well golden eagle,
on the ACEC in spring/summer 2012. Note that sandhill cranes have been noted as common stopover migrants in/near agricultural
fields adjacent to the ACEC; thus, this list of sightings likely under-represents their abundance during April and early May. (UTM,
NAD 27).
Removed due to sensitive location information.
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