| Sage-grouse nesting and brood habitat use in southern Canada. (vol 66, pg 433, 2002) | Aldrige, CL | 2003 |
Sage-grouse nesting and brood habitat use in southern Canada. (vol 66, pg 433, 2002)KeywordsAlberta, Artemisia, broods, Centrocercus urophasianus, greater sage-grouse, nesting, sagebrush AbstractGreater
sage-grouse
(Centrocercus
urophasianus)
populations
have
declined
from
66
to
92%
during
the
last
30
years
in
Canada,
where
they
are
listed
as
endangered.
We
used
radiotelemetry
to
examine
greater
sage-grouse
nest
and
brood
habitat
use
in
Alberta
and
assess
the
relationship
between
habitat
and
the
population
decline.
We
also
identified
the
patch
size
at
which
sage-grouse
were
selecting
nest
and
brood-rearing
sites.
Nest
areas
were
in
silver
sagebrush
(Artemisia
cana)
stands
that
had
greater
amounts
of
tall
cover
(P
<
0.001)
at
a
patch
size
of
7.5
to
15
m
in
radius.
Within
those
sagebrush
stands,
nests
were
located
beneath
the
densest
sagebrush
present.
Areas
used
for
brood
rearing
had
greater
amounts
of
taller
sagebrush
cover
in
an
area
215
m
in
radius
than
at
random
locations.
Brood
locations
were
not
selected
based
on
forb
content;
mesic
areas
containing
forbs
(20-40%
cover)
as
a
food
resource
for
chicks
were
limiting
(only
12%
cover
available).
Overall
cover
of
sagebrush
is
considerably
lower
in
Canada
(5-11%)
compared
with
sagebrush
(Artemisia
spp.)
cover
in
other
areas
throughout
the
range
of
greater
sage-grouse
(15-25%).
If
management
goals
are
to
provide
suitable
nesting
and
brood-rearing
habitat,
efforts
should
be
directed
toward
protecting
and
enhancing
sagebrush
stands
230
m2
and
increasing
overall
sage-
brush
cover.
Management
strategies
also
should
focus
on
increasing
the
availability
of
mesic
sites
and
increasing
the
abundance
of
sites
with
>10%
forb
cover,
to
enhance
brood
rearing
habita AuthorsAldrige, CL; Brigham, RM Year Published2003 PublicationJournal of Wildlife Management Locations |
| Northern Harrier, Circus cyaneus, attacks on Greater Sage-Grouse, Centerocercus urophasianus, in southern Alberta | Fletcher, QE | 2003 |
Northern Harrier, Circus cyaneus, attacks on Greater Sage-Grouse, Centerocercus urophasianus, in southern AlbertaKeywordsGreater Sage-Grouse, Centrocercus urophasianus, Northern Harrier, Circus cyaneus, endangered species, lek,
predation, Alberta AbstractThe Greater Sage-Grouse (Centrocercus urophasianus) is an endangered species in Canada, making it critical to understand all known causes of mortality. We report the first recorded observations of female Northern Harrier (Circus cyaneus) attacks on male Greater Sage-Grouse. Although no attacks were successful, our observations suggest that Northern Harriers are predators of Greater Sage-Grouse. AuthorsFletcher, QE; Dockrill, CW; Saher, DJ; Aldridge, CL Year Published2003 PublicationCanadian Field-Naturalist Locations |
| Potential gas development impacts on sage grouse nest initiation and movement | Lyon, AG | 2003 |
Potential gas development impacts on sage grouse nest initiation and movementKeywordsCentrocercus urophasianus, natural gas, development, nest initiation, sage grouse, wyoming AbstractThe decline of greater sage grouse (Centrocercus urophasianus) over the last 50 years has raised concern over how natural gas development might affect sage grouse populations. We examined the effects of vehicular activity due to gas-well development near Pinedale, Wyoming, on productivity and movements of sage grouse. In 1998-1999, we captured and radiomarked 48 female sage grouse on 6 leks classified as disturbed or undisturbed, based on the presence or absence of natural gas development within 3 km. The mean distance from disturbed leks to selected nest sites was greater (P=0.019 with outliers removed, P= 0.004 with outliers included) than distance moved from undisturbed leks. Nest-initiation rate for hens from disturbed leks was 65%, while hens from undisturbed leks initiated nests 89% (P=0.07) of the time. Nest success at both disturbed and undisturbed leks was 50%. Our results suggest that light traffic disturbance (1-12 vehicles/day) during the breeding season might reduce nest-initiation rates and increase distances moved from leks during nest-site selection. We recommend further investigation concentrating on hen behavior (i.e., distance moved from lek to nest site, breeding behavior, lek attendance), reproductive effort, and nest success in relation to natural gas development as development intensifies. AuthorsLyon, AG; Anderson, SH Year Published2003 PublicationWildlife Society Bulletin Locations |
| Changes in the distribution and status of sage-grouse in Utah | Beck, JL | 2003 |
Changes in the distribution and status of sage-grouse in UtahKeywordssage-grouse, sagebrush habitats, habitat loss, Utah, Centrocercus urophasianus, Centrocercus minimus, greater sage-grouse, Gunnison sage-grouse, Artemisia tridentata AbstractSage-grouse (Centrocercus spp.) were abundant in all of Utah's 29 counties at the time of European settlement wherever sagebrush (Artemisia spp.) occurred. Greater Sage-Grouse (C. urophasianus) inhabited areas north and west of the Colorado River, and Gunnison Sage-Grouse (C. minimus) occupied suitable habitat south and east of the Colorado River. The largest Greater Sage-Grouse populations in Utah are currently restricted to suitable habitats in Box Elder, Garfield, Rich, Uintah, and Wayne Counties. A remnant breeding population of Gunnison Sage-Grouse occurs in eastern San Juan County. We stratified Greater Sage-Grouse populations (1971-2000) by counties where the 1996 to 2000 moving average for estimated spring breeding populations was >500 (GT500) or <500 (LT500). Males per lek declined in all populations from 1971 to 2000; however, there were consistently more males observed on GT500 than on LT500 leks. Juveniles per adult lien (including yearling hens) Greater Sage-Grouse in the 1973-2000 fall harvest in Box Elder, Rich, and Wayne Counties did not differ from 2.25, a ratio suggesting sustainable or increasing sage-grouse populations. Declines are attributed to loss, fragmentation, and degradation of sagebrush habitat. Sage-grouse conservation ultimately depends on management and enhancement of remaining sagebrush rangelnads in Utah. AuthorsBeck, JL; Mitchell, DL; Maxfield, BD Year Published2003 PublicationWestern North American Naturalist Locations |
| Direct identification of northern Sage-grouse, Centrocercus urophasianus, nest predators using remote sensing cameras | Holloran, MJ | 2003 |
Direct identification of northern Sage-grouse, Centrocercus urophasianus, nest predators using remote sensing camerasKeywordsCentrocercus urophasianus, Sage-grouse, Cervus canadensis, American Elk, ground squirrel, predator. AbstractThe status and apparent decline of Sage-grouse (Centrocercus spp.) has been of increasing concern and lower nesting success could be contributing to population declines. Our objective was to directly identify Sage-grouse nest predators. Following visual confirmation of radio-marked Sage-grouse nest establishment in 1997-1999, we installed automatic 35 mm cameras controlled by an active infrared monitor. Of 26 nests monitored by cameras, 22 successfully hatched and four were unsuccessful. American Elk (Cervus canadensis), Badger (Taxidea taxus), and Black-billed Magpie (Pica hudsonia) destroyed three of the four unsuccessful nests, and domestic cattle caused abandonment of the fourth. Richardson's (Spermophilus richardsonii) and Thirteen-lined Ground Squirrels (S. tridecemlineatus) were recorded at nests, but were not detected in predation. AuthorsHolloran, MJ; Anderson, SH Year Published2003 PublicationCanadian Field-Naturalist Locations |
| Distribution, abundance, and status of the Greater Sage-Grouse, Centrocercus urophasianus, in Canada | Aldridge, CL | 2003 |
Distribution, abundance, and status of the Greater Sage-Grouse, Centrocercus urophasianus, in CanadaKeywordsgreater sage-grouse, Centrocercus urophasianus, distribution, endangered status, Saskatchewan, Alberta, Canada AbstractWe reviewed the historic and present distribution of Greater Sage-Grouse (Centrocercus urophasianus) in Canada and found that the species has been eliminated from approximately 90% of its estimated historic distribution. Sage-grouse have been extirpated from British Columbia and reduced to remnant populations in Alberta and Saskatchewan. Estimates of the size of the population decline in Canada range from 66 to 92% over the last 30 years based on currently occupied habitat. As a result. sage grouse have been listed as Endangered in both Alberta and Saskatchewan by provincial governments an federally in Canada by COSEWIC. Intensive surveys from 1994 to 1999 in both provinces suggest that the 1999 spring breeding population had declined to between 813 and 1204 individuals. The number of active lek sites has continued to decline. suggesting that some habitats have become unsuitable to support viable sage-grouse populations. Number of yearling males recruiting to leks each spring has been low, suggesting that production and overwinter survival of young are the major problems related to the decline. Low chick survival rate, with only 18% surviving to 50 days of age, is the most likely parameter contributing to the population decline. These declines could be related to one or any combination of habitat changes. livestock grazing pressure, oil and gas developments, or climate change, all of which could lead to increased predation rates and decreased survival. It is questionable if the present population of sage-grouse in Canada is large enough to remain viable. AuthorsAldridge, CL; Brigham, RM Year Published2003 PublicationCanadian Field-Naturalist Locations |
| Blood parasites in sage-grouse from Nevada and Oregon | Dunbar, MR | 2003 |
Blood parasites in sage-grouse from Nevada and OregonKeywordsblood parasites, Centrocercus urophasianus, Leucocytozoon lovatt, Nevada, Oregon, Plasmodium, sage-grouse AbstractPeripheral blood smears from 196 adult and yearling female greater sage-grouse (Centrocercus urophasianus) were examined for blood parasites (167 from the breeding and 29 from the brood-rearing season) to determine prevalence of blood parasites, to attempt to correlate infection with chick survival, and to establish base-line values of prevalence in sage-grouse from Nevada and Oregon (USA). Birds were captured and released on two study areas during 19992001; Sheldon National Wildlife Refuge (SNWR) in northwestern Nevada, and Hart Mountain National Antelope Refuge (HMNAR) in southeastern Oregon. Birds from a third study area, Beaty's Butte grazing allotment (BB) in southeastern Oregon, were sampled in 2000 and 2001. Overall, 19 birds (10%) were positive for Leucocytozoon lovati (=L. bonasae), 1 (0.5%) for Plasmodium pedioecetii, and 2 (1%) for microfilariae. Although prevalence of L. lovati on HMNAR was 39% during the breeding season in 1999 and 100% during the brood-rearing season in 2000, statistically, prevalence of L. lovati among study areas and years was not different. However, there were statistical differences between capture periods. Overall, 31% of the hens were positive for L. lovati during the brood-rearing season compared to 6% during the breeding season. There was no difference in packed cell volume between infected and non-infected birds and no difference between age-classes. However, mean sage-grouse productivity on HMNAR was higher (1.6 chicks/hen) for non-infected (n=10) compared to infected hens (0.7 chicks/hen; n=7), during 1999. Based on these limited observations on HMNAR in 1999, the possible effects that L. lovati may have on young sage-grouse could be detrimental to sage-grouse populations in Nevada and Oregon. AuthorsDunbar, MR; Tornquist, S; Giordano, MR Year Published2003 PublicationJournal of Wildlife Diseases Locations |
| Long-range visibility of greater sage grouse leks: a GIS-based analysis | Aspbury, A | 2004 |
KeywordsNo keywords available AbstractWe investigated whether male greater sage grouse, Centrocercus urophasianus, select lek locations on the basis of topographic features that affect their visibility to both conspecific females and a major avian predator, the golden eagle, Aquila chrysaetos. We mapped locations of displaying males at all leks in a local population and used a Geographic Information System (GIS) and digital elevation model (DEM) to generate 'viewsheds' around male locations within a boundary set by the estimated maximal visual acuity of the viewer. Areas visible around leks were compared to those visible around random sites with the same conformation of displaying males. Male sage grouse displayed at sites where surrounding topography both diminished long-range visibility (>1000 m) and enhanced short-range visibility (<500 m) to ground observers. These characteristics could (1) force eagles to monitor lek activity from the air, where they may be more visible to their prey, (2) make displaying males more visible to females and (3) allow males to monitor predators approaching the lek more easily. These results suggest that, in open habitats, visually signalling animals may exploit local topography to control both their visibility to receivers and the visibility of their immediate surroundings. (C) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved. AuthorsAspbury, A; Gibson, RM Year Published2004 PublicationAnimal Behaviour LocationsDOI10.1016/j.anbehav.2003.06.021 |
| How predation risk affects the temporal dynamics of avian leks: Greater sage grouse versus golden eagles | Boyko, AR | 2004 |
Keywordslek mating system, dynamic game theory, greater sage grouse, mating skew, density dependence, predation AbstractLeks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner and leave later than subordinates, especially if mating skew is high, predation risk is low, or the relationship between lek size and female arrival rate is weak. Both high mean levels of predation risk and small lek size should reduce lek attendance, but the relative tendency of predators to attack large versus small leks has little influence on predicted lekking behavior. Field observations confirmed the predicted effects of female arrival rate, lek size, male dominance, and weather-dependent predator arrival rates on lek departure times. Predicted effects of female arrival rates and male dominance on seasonal lek attendance were also supported. Our model provides an empirically supported adaptive explanation for short-term lek dynamics. It also suggests alternative interpretations for phenomena previously invoked to support the hotshot and skew models of lek formation. AuthorsBoyko, AR; Gibson, RM; Lucas, JR Year Published2004 PublicationAmerican Naturalist LocationsDOI10.1086/380419 |
| West Nile virus: pending crisis for greater sage-grouse | Naugle, DE | 2004 |
KeywordsCentrocercus urophasianus, emerging infectious disease, endangered species; greater sage-grouse; mosquito; population decline; survival; vector surveillance; West Nile virus AbstractScientists have feared that emerging infectious diseases could complicate efforts to conserve rare and endangered species, but quantifying impacts has proven difficult until now. We report unexpected impacts of West Nile virus (WNv) on radio-marked greater sage-grouse (Centrocercus urophasianus), a species that has declined 45-80% and is endangered in Canada and under current consideration for federal listing in the US. We show that WNv reduced late-summer survival an average of 25% in four radio-marked populations in the western US and Canada. Serum from 112 sage-grouse collected after the outbreak show that none had antibodies, suggesting that they lack resistance. The spread of WNv represents a significant new stressor on sage-grouse and probably other at-risk species. While managing habitat might lessen its impact on sage-grouse populations, WNv has left wildlife and public health officials scrambling to address surface water and vector control issues in western North America. AuthorsNaugle, DE; Aldridge, CL; Walker, BL; Cornish, TE; Moynahan, BJ; Holloran, MJ; Brown, K; Johnson, GD; Schmidtmann, ET; Mayer, RT; Kato, CY; Matchett, MR; Christiansen, TJ; Cook, WE; Creekmore, T; Falise, RD; Rinkes, ET; Boyce, MS Year Published2004 PublicationEcology Letters LocationsDOI10.1111/j.1461-0248.2004.00631.x |
