| The effect of vegetation structure on predation of artificial Greater Sage-Grouse nests | Watters, ME | 2002 |
The effect of vegetation structure on predation of artificial Greater Sage-Grouse nestsKeywordsNo keywords available AbstractIn Canada, Greater Sage-Grouse (Centrocercus urophasianus) are considered an endangered species by the Committee On the Status of Endangered Wildlife In Canada (COSEWIC), due to declining population numbers and distribution. Encroachment of agriculture and subsequent destruction of suitable sagebrush (Artemisia spp.) habitat is thought to be responsible for historical population declines However, subtle changes in habitat quality may also result in reduced escape and nesting cover, which may lead to increased levels of predation. We examined the influence of vegetation cover and height on the fate of artificial Greater Sage-Grouse nests Because most natural sage-grouse nests are associated with sagebrush, we predicted that sagebrush height and cover would be crucial to the success of nests. Lateral cover is important in protecting nests from detection by predators, and thus we predicted that nests surrounded by shorter grass would suffer greater predation rates than nests with taller grass. To experimentally test this hypothesis, we trimmed grass surrounding some artificial nests Richardson's ground squirrels (Spermophilus richardsonii) were the primary predators of artificial nests, with some predation by corvids and badgers (Taxidea taxus). Successful nests tended to be surrounded by shorter sagebrush, taller grasses, and taller, denser forbs than predated nests. Trimming grass around nests did not affect nest fate However, ground squirrels typically attacked nests with less forb cover and fewer sagebrush, and avian predators tended to destroy nests at inactive leks with greater lateral cover. Thus, lateral cover provided by forbs and sagebrush appeared to be important for protecting nests from mammalian predators. These results suggest implementing management strategies that improve sagebrush habitat by providing tall, dense forbs and sagebrush, which could increase Greater Sage-Grouse nest success and recruitment. AuthorsWatters, ME; McLash, TL; Aldridge, CL; Brigham, RM Year Published2002 PublicationEcoscience Locations |
| Effect of method, site, and taxon on line-intercept estimates of sagebrush cover | Wambolt, CL | 2006 |
KeywordsArtemisia nova; A. tridentata vaseyana; A. t. wyomingensis; black sagebrush; Centrocercus spp.; cover; line intercept; mountain big sagebrush; sage-grouse; vegetation; Wyoming big sagebrush AbstractSage-grouse (Centrocercus spp.) are arguably the best known of the many wildlife species that inhabit sagebrush (Artemisia spp.) ecosystems. Lack of standardization in the procedures used to assess sagebrush cover may contribute to inconsistencies in reported habitat requirements for sage-grouse and other wildlife. We compared 3 applications of the line-intercept method for 3 sagebrush taxa. We sampled 2 mountain big sagebrush (A. tridentata vaseyana) sites, 2 Wyoming big sagebrush (A. t. wyomingensis) sites, and 1 black sagebrush (A. nova) site to determine whether the results generated by the 3 methods differed. Percent cover as determined by agency methods was up to 2.6 times greater than that from research applications. Cover differences among techniques were influenced by taxa and site (P <= 0.001) because both affected shrub morphology. We believe it will be difficult to identify and achieve wildlife habitat guidelines for minimal sagebrush cover requirements if methodologies are not standardized. AuthorsWambolt, CL; Frisina, MR; Knapp, SJ; Frisina, RM Year Published2006 PublicationWildlife Society Bulletin LocationsDOI10.2193/0091-7648(2006)34[440:EOMSAT]2.0.CO;2 |
| Evaluation of the lek-count index for greater sage-grouse | Walsh, DP | 2004 |
Keywordsbounded count, Centrocercus urophasianus, detection probability, greater sage-grouse, index, lek-attendance rates, lek counts, mark–resight, prairie grouse AbstractCounts of birds attending leks traditionally have been used as an index to the population size of greater sage-grouse (Centrocercus urophasianus) and, more recently, as a means to estimate population size. The relationship between this index and the actual population has not been studied. We used intensive counts of individually marked and unmarked greater sage-grouse on leks to evaluate how sex and age of birds, time of day, and time of season impact lek-attendance patterns and lek counts. These within-season sources of variation need to be considered when estimating detection probability of birds on leks and ultimately adjusting the lek-count index to estimate true population parameters. On average, 42% of marked adult males, 4% of marked hens, and 19% of yearling males were observed on leks per sighting occasion with all 15 known leks being intensively counted. We discovered that lek counts as currently conducted may be useful as an index to greater sage-grouse populations, but standardization of protocols is needed to allow for better spatial and temporal comparisons of lek-count data. Also the probability of detecting birds on leks must be estimated in order to relate lek counts to population parameters. Lastly, we evaluated use of the bounded-count methodology for correcting lek-count data. We showed large biases associated with this technique and below-nominal coverage of confidence intervals even at large numbers of counts, demonstrating the unreliability of the bounded-count method to correct lek-count data. AuthorsWalsh, DP; White, GC; Remington, TE; Bowden, DC Year Published2004 PublicationWildlife Society Bulletin LocationsDOI10.2193/0091-7648(2004)32[56:EOTLIF]2.0.CO;2 |
| Population Estimation Techniques for Lekking Species | Walsh, Daniel P. | 2010 |
KeywordsBowden's estimator, grouse, lekking species, mark–resight, mixed logit-normal mark–resight model, population estimation AbstractWith the decline of many lekking species, the need to develop a rigorous population estimation technique is critical for successful conservation and management. We employed mark-resight methods to estimate population size for 2 lekking species: greater sage-grouse (Centrocercus urophasianus) and Gunnison sage-grouse (Centrocercus minimus). We evaluated 2 different estimators: Bowden's estimator and the mixed logit-normal mark-resight model. We captured and marked 75 greater sage-grouse. We counted marked and unmarked birds as they attended 15 known leks. We used 36 and 37 marked Gunnison sage-grouse to estimate population size in 2003 and 2004, respectively. We observed marked and unmarked Gunnison sage-grouse daily as they attended 6 leks in 2003 and 3 leks in 2004. Based on our examination of the assumptions of each mark-resight estimator, relative to behavior and biology of these species, we concluded the mixed logit-normal mark-resight model is preferred. We recommend wildlife managers employ mark-resight approaches when statistically rigorous population estimates are required for management and conservation of lekking species. AuthorsWalsh, Daniel P.; Stiver, Julie R.; White, Gary C.; Remington, Thomas E.; Apa, Anthony D. Year Published2010 PublicationJournal of Wildlife Management LocationsDOI10.2193/2009-353 |
| Breeding Season Movements and Habitat Selection of Male Sage Grouse | WALLESTAD, R | 1974 |
KeywordsNo keywords available AbstractMovements
and
habitat
requirements
of
sage
grouse
(Centrocercus
urophasianus)
cocks
were
studied
in
central
Montana
during
the
breeding
seasons
of
1968
and
1972.
Fifteen
sage
grouse
cocks
were
captured
and
radio-equipped.
Movements
of
up
to
0.8
mile
(1.3
km)
from
the
strutting
grounds
were
common,
with
82
percent
of
the
locations
falling
beyond
0.2
mile
(0.3
km).
Sagebrush
(Artemisia
tridentata)
with
a
canopy
coverage
of
20-50
percent
occurred
at
80
percent
of
the
110
locations
mea-
sured.
Average
sagebrush
canopy
coverage
at
these
sites
was
32
percent.
Strutting
grounds
are
key
ac-
tivity
areas
within
wintering-nesting
complexes
which
can
be
readily
identified
and
delimited,
and
should
be
given
complete
protection
from
sagebrush
removal
projects.
Results
of
this
and
previous
studies
in
this
area
indicate
that
this
protection
should
extend
to
a
radius
of
no
less
than
1.5
miles
(2.4
km)
from
strutting
grounds AuthorsWALLESTAD, R; SCHLADWEILER, P Year Published1974 PublicationThe Journal of Wildlife Management LocationsDOI10.2307/3800030 |
| Male Sage Grouse Responses to Sagebrush Treatment | WALLESTAD, R | 1975 |
KeywordsNo keywords available AbstractMale
sage
grouse
(Centrocercus
urophasianus)
populations
on
six
central
Montana
strutting
grounds
were
studied
in
relation
to
sagebrush
(Artemisia
tridentata)
treatment.
Populations
on
3
strutting
grounds
within
0.5
km
of
treated
areas
increased
28
percent,
whereas
2
grounds
farther
than
4
km
from
treated
areas
increased
323
percent.
Over
a
2-year
period,
a
31
percent
loss
of
suitable
habi-
tat
within
0.5
km
of
another
strutting
ground
resulted
in
a
63
percent
decrease
in
numbers
of
strutting
males AuthorsWALLESTAD, R Year Published1975 PublicationThe Journal of Wildlife Management LocationsDOI10.2307/3800387 |
| Foods of Adult Sage Grouse in Central Montana | WALLESTAD, R | 1975 |
KeywordsNo keywords available AbstractNo abstract available AuthorsWALLESTAD, R; PETERSON, JG; ENG, RL Year Published1975 PublicationThe Journal of Wildlife Management LocationsDOI10.2307/3800409 |
| MOVEMENT AND NESTING OF SAGE GROUSE HENS IN CENTRAL MONTANA | WALLESTAD, R | 1974 |
KeywordsNo keywords available AbstractMovements and nesting cover
of
sage
grouse
(Centrocercus
urophasianus)
hens
were
studied
in
central
Montana
during
the
springs
of
1969,
1970,
1971,
and
1972.
Thirty-one
sage
grouse
hens
were
radio-equipped
resulting
in
22
nests
being
located.
Nineteen
additional
nests
were
located
dur-
ing
nest
searches
and
work
incidental
to
telemetry.
Adults
laid
larger
clutches
than
yearling
hens
and
also
were
more
successful
in
bringing
off
a
brood.
Sixty-eight
percent
of
the
22
nests
of
radio-equipped
hens
occurred
within
1.5
miles
(2.5
km)
of
the
strutting
ground
where
the
hens
were
captured.
Sagebrush
(Artemisia
tridentata)
formed
the
nesting
cover
over
all
of
the
nests
located.
Successful
nests
were
located
in
sagebrush
stands
with
a
higher
average
canopy
coverage
than
those
of
unsuccessful
nests,
and
had
significantly
greater
sagebrush
cover
within
24
inches
(60
cm)
of
nest
and
within
a
100-square
foot
(9-m2)
plot
around
nest.
Consideration
of
the
ecological
requirements
of
animals
affected
by
pub-
licly
funded
programs
is
important.
This
is
especially
true
of
sage
grouse
since
extensive
areas
of
sage-
brush
have
already
been
eliminated
or
modified
by
such
programs
with
little
apparent
regard
for
the
welfare
of
this
unique
game
bird AuthorsWALLESTAD, R; PYRAH, D Year Published1974 PublicationJournal of Wildlife Management LocationsDOI10.2307/3800029 |
| SUMMER MOVEMENTS AND HABITAT USE BY SAGE GROUSE BROODS IN CENTRAL MONTANA | WALLESTA.RO | 1971 |
KeywordsNo keywords available AbstractThe
habitat
use
and
movements
of
sage
grouse
(Centrocercus
urophasianus)
broods
were
studied
with
the
aid
of
radiotelemetry
in
central
Montana
during
the
summers
of
1968
and
19619.
Five
hundred
and
eleven
locations
were
obtained
on
13
radio-marked
sage
grouse
broods.
In
both
sum-
mers
big
sagebrush
(Artemsa
trixlentrata)
in
scattered
(1-10
percent)
and
common
(10-25
percent)
densities
received
the
greatest
utilization
by
broods.
Sagebrush
heights
at
brood
sites
ranged
mainly
between
6
and
18
inches.
For
the
2
years
combined,
sagebrush
canopy
coverage
averaged
14
percent
for
June,
12
percent
for
July,
10
percent
for
August,
and
21
percent
for
September.
Broods
utilized
sagebrush-grassland
benches
early
in
the
summer
(June
and
July)
and
shifted
to
greasewood
(Sarcobatus
vermicalatus)
bottoms
and/or
alfalfa
(Medicago
sativa)
fields
as
the
forbs
on
the
higher
elevations
became
desiccated.
Broods
remained
in
these
bottom
types
until
late
August
and
early
September
and
then
shifted
back
into
sagebrush.
Sizes
of
areas
used
by
broods
averaged
213
acres
in
sagebrush
in
early
summer
(June
and
July),
144
acres
in
alfalfa
fields
(July
and
August),
91
acres
in
greasewood
bottoms
(July
and
August),
and
128
acres
in
sagebrush
in
late
summer
(August
and
September).
Availability
of
food
appeared
to
be
the
factor
that
determined
the
vegetational
types
utilized
by
broods
during
different
periods
of
the
summer AuthorsWALLESTA.RO Year Published1971 PublicationJournal of Wildlife Management LocationsDOI10.2307/3799881 |
| West Nile Virus and Greater Sage-Grouse: Estimating Infection Rate in a Wild Bird Population | Walker, Brett L. | 2007 |
KeywordsCentrocercus urophasianus, coal-bed natural gas, energy development, flavivirus, greater sage-grouse, infection rate, sagebrush-steppe, West Nile virus AbstractUnderstanding impacts of disease on wild bird populations requires knowing not only mortality rate following infection, but also the proportion of the population that is infected. Greater sage-grouse (Centrocercus urophasianus) in western North America are known to have a high mortality rate following infection with West Nile virus (WNv), but actual infection rates in wild populations remain unknown. We used rates of WNv-related mortality and seroprevalence from radiomarked females to estimate infection rates in a wild greater sage-grouse population in the Powder River basin (PRB) of Montana and Wyoming from 2003 to 2005. Minimum WNv-related mortality rates ranged from 2.4% to 13.3% among years and maximum possible rates ranged from 8.2% to 28.9%. All live-captured birds in 2003 and 2004 tested seronegative. In spring 2005 and spring 2006, 10.3% and 1.8% respectively, of newly captured females tested seropositive for neutralizing antibodies to WNv. These are the first documented cases of sage-grouse surviving infection with WNv. Low to moderate WNv-related mortality in summer followed by low seroprevalence the following spring in all years indicates that annual infection rates were between 4% and 29%. This suggests that most sage-grouse in the PRB have not yet been exposed and remain susceptible. Impacts of WNv in the PRB in the near future will likely depend more on annual variation in temperature and changes in vector distribution than on the spread of resistance. Until the epizootiology of WNv in sagebrush-steppe ecosystems is better understood, we suggest that management to reduce impacts of WNv focus on eliminating man-made water sources that support breeding mosquitoes known to vector the virus. Our findings also underscore problems with using seroprevalence as a surrogate for infection rate and for identifying competent hosts in highly susceptible species. AuthorsWalker, Brett L.; Naugle, David E.; Doherty, Kevin E.; Cornish, Todd E. Year Published2007 PublicationAvian Diseases LocationsDOI10.1637/0005-2086(2007)51[691:WNVAGS]2.0.CO;2 |
