Western North
America. Originally, the sage grouse occurred in 16 western states
in the U.S.A. and three provinces in southwestern Canada, largely
sympatric with the distribution of sagebrush (Artemisia spp.).
Populations have been reduced throughout range and eliminated in
Arizona, British Columbia, New Mexico, Nebraska and Oklahoma.
Currently, sage grouse are found in two provinces in southwestern
Canada and in 11 western states of the USA. The Gunnison Sage
Grouse is spread in disjunct populations in southwestern Colorado
and southeastern Utah.
Population size and
trend
Related to extensive
conversion and degradation of habitat throughout range, sage
grouse numbers have been declining throughout during much of the
20th century. Although declines of sage grouse populations have
been particularly notable an the periphery of their distribution,
declines have also been significant within core populations.
Between the 1985 and 1994, most populations had declined by 20-50%
(average 33%). This most recent decline is at least partially
attributed to habitat loss and degradation by management actions
for livestock and big game as well as unusually dry weather
conditions in western North America. The sage grouse is believed
to be secure only in the central part of its range; populations of
California, Colorado, North Dakota, South Dakota, Utah, and
Washington are considered to be at risk. During the late 1970's,
annual harvest totaled about 280,000 birds. By 1998, the rangewide
breeding population was estimated to be about 140,000 birds. (See
Connelly and Braun 1997).
Habitat and
ecology
Sage grouse inhabit a
diversity of sagebrush (Artemisia spp.) ecosystems in western
North America, including tall sagebrush, short sagebrush,
forb-rich mosaics of low and tall sagebrush, riparian meadows,
sagebrush savannahs, and small quantities of cropland and planted
grasses. Sagebrush constitutes the almost exclusive winter diet
and at least two thirds of the adult´s summer diet. Adults
also consume insects and forbs; young chicks largely rely on
insects. The presence of sagebrush dominated habitats with a
healthy understorey of grasses and forbs is particularly important
for successful nesting and brood-rearing. Sage grouse lek on
traditional display grounds in relatively open areas, adjacent to
sagebrush habitats. Sage grouse show a high fidelity to seasonal
habitats. Seasonal variation in habitat quality and availability
is one explanation for migratory movements of up to >100km
(Connelly et al. 1988). Populations are usually characterised by
relatively high annual survival and low productivity compared to
other grouse species.
Hunting and cultural
importance
Sage grouse were an
important game species for Native Americans and European settlers.
Market hunting and poaching may have had dramatic impacts on some
populations during the late 1800's and early 1900's. During the
late 1970s, annual hunting bags totalled approx. 280,000 birds.
The species is no longer hunted in Canada and in parts of the US.
In the US the cultural importance of sage grouse hunting for sport
and food is still high. The influence of harvesting on population
dynamics is generally considered to be minimal or moderate;
however, the situation varies locally. As other prairie grouse,
sage grouse currently are receiving increasing attention from
naturalists and bird watchers who appreciate the spectacular
display of the birds on their strutting grounds.
Principal
threats
Small population
size. Due to habitat loss and fragmentation, some sage grouse
populations probably have declined below Minimum Viable Population
size. Such small and isolated populations are at a high risk to go
extinct due to demographic chance. They are also particularly
susceptible to random environmental events such as drought, that
may lead to reduced brood habitat quality and breeding success.
Small isolated populations may be vulnerable to declines in
genetic heterogeneity and fertility, and subsequently, to
extinction (Westemeier et al. 1998).
Lack of genetic
diversity. Lekking species in general may show a reduction of
genetic diversity. Investigations of sage grouse populations
suggest that there is a lack of genetic diversity overall and that
some regions have extremely low genetic diversity (Kahn et al.
1999). A lack of genetic diversity may lead to a reduction in
productivity and survival as well as an inability to adapt to
environmental changes such as disease and rapid habitat changes
(Westemeier et al. 1998).
Habitat degradation.
Degradation due to overgrazing by livestock, wildfires, removal of
sagebrush, and encroachment by noxious weeds and trees has reduced
the quality of most remaining sage grouse habitats. Reduction in
habitat quality may reduce survival and nesting and brood-rearing
success. Livestock grazing is common on sagebrush rangelands, and
grazing patterns and use of habitats vary depending on weather
conditions. Excessive grazing and land treatments (mechanical,
chemical, and fire) have negative impacts on sage grouse winter,
breeding, nesting and brood rearing habitat; grass height and
cover influence nest site selection and success. The area and
frequency of wild fire and prescribed burning apparently have
increased in at least parts of the sage grouse range. Fire may
negatively impact sage grouse populations by eliminating or
fragmenting relatively large blocks of wintering and nesting
habitat. The overall effects of fire and of grazing on sage grouse
habitat quality and population trends is still under
debate.
Habitat loss.
Large-scale conversion of prairie to cropland and development has
resulted in the loss of sage grouse in large portions of their
original range, particularly on the periphery. Other impacts
include increasing development, roads, powerlines, large-scale
mining projects, and increased recreational use in the sagebrush
ecosystem.
Pesticides and
herbicides. Pesticides may directly poison birds or indirectly
affect birds by reducing the abundance of invertebrates. Herbicide
treatment of rangeland may result in the loss of cover for
nesting, brood-rearing, and loafing.
Research needs
Ongoing research in sage
grouse include genetic investigations, understanding the role of
female social behaviour, playback experiments to attract males and
females to leks, and habitat studies (J. Young, pers. comm.).
Currently in Idaho, survival and recruitment of juveniles (young
>8 weeks of age) is being investigated and a study on chick
(young <8 weeks) survival is being initiated. Work is also
being conducted in several western states to better understand the
quantity and quality of remaining sage grouse habitats as well as
the effects of habitat fragmentation on this species (J. Connelly,
pers. comm.).
Monitoring and
assessment. Information on sex ratio, lek attendance by males
and females, and lek stability is needed so that lek surveys can
be used to adequately monitor populations of sage grouse
throughout their range.
Population dynamics.
The influence of habitat and predation on adult survival, nest
success, and survival of juveniles to the age of recruitment
remains a poorly understood aspect of sage grouse life history.
Further research is needed on predator prey populations dynamics
and the effects of hunting.
Habitat management and
restoration. Methodologies for restoration of nesting and
brood rearing habitats need to be developed. The information
necessary to adequately restore degraded habitats is
insufficiently unavailable. In this context, further research on
habitat recovery following disturbance and the influence of
domestic and wild herbivore use on nesting, brood rearing, and
winter habitat is needed. Applied experiments are needed to
evaluate the effects of habitat management and restoration on
populations of sage grouse.
Genetics and population
connectivity. Further research is needed on genetic
differences among populations and on juvenile recruitment and
dispersal patterns in both fragmented and contiguous landscapes to
ascertain information about population connectivity, gene flow,
genetic diversity, and genetic compatibility for population
augmentations and re-introductions.
Population
management. Methodologies for successful re-introductions and
population augmentation need to be identified.
Gunnison sage
grouse. With regard to the Gunnison sage grouse, better
understanding is needed of their winter ecology and juvenile
dispersal. Winters in the Gunnison Basin are severe and lack of
suitable winter habitat may be a major variable causing the
decline of the sage grouse. Historical data suggests that much of
the Gunnison sage grouse's winter habitat has been removed from
key wintering areas. Understanding the current patterns of winter
habitat use will assist local land managers in identifying,
protecting, and possibly enhancing critical habitat. Most
population models predicting minimum viable population sizes and
sustainability require data for juvenile dispersal. Currently no
such data exists for the Gunnison sage grouse.
Current conservation
measures
Legal protection.
Sage grouse are legally protected throughout their range;
regulated harvest is permitted in nine states. C. minimus is
likely to be considered for federal (U.S.A.) listing as a
'threatened' or 'endangered' species as soon as it is officially
designated as a distinct species.
Conservation plans.
Recently, local communities throughout key areas of the Gunnison
sage grouse's range have written conservation plans to help
recover the species.
Monitoring. Survey
and monitoring data are available from most range states and
provinces. Data on breeding populations are generally obtained by
monitoring lek attendance using standardised methods established
by the Western States Sage and Columbian Sharp-tailed Grouse
Technical Committee. Data on population structure and dynamics are
primarily obtained from lek counts and from wings of harvested
birds collected from hunters.
Habitat preservation and
restoration. Most sage grouse habitat in the US is federally
owned and appropriate management practices are being developed in
many areas. The Conservation Reserve Program may also increase
sage grouse habitat on private lands in some parts of the species'
range. The Conservation Reserve Program (CRP), the US federal
agricultural set-aside programme (Joyce et al. 1991, Dunn et al.
1993, Douglas and Schwartz 1993), has resulted in conversion of
millions of hectares of cropland to potential habitat for sage
grouse, with mixed success in some areas. Manipulation of grazing
by livestock, modification of fire regimes, and planting of
sagebrush are primary tools used to improve the quality of
habitat. Because nesting and brood-rearing habitat is usually
considered to be a limiting factor, most efforts are directed
toward increasing the protective cover of shrubs and
grasses.
Translocation.
Re-introductions, transplants, and augmentations of populations
have been tried many times during the 1900's, with mixed success.
Success of translocations appears to be related to the quantity of
adequate habitat at the release site.
Predator control.
Predator control may increase nesting success of sage grouse.
However the long-term affects of predator control on population
viability is not known. Because the political ramifications of
predator control are likely to be negative, it is possible that
predator control efforts should be directed toward manipulations
of habitat.
Water provision.
Water provision has not been shown to influence populations on a
large scale.
Priority conservation
measures
The endangered Gunnison
sage grouse has high priority for sage grouse conservation.
Specific recommendations concerning the Gunnison sage grouse are
described in Chapter 4. Below, general conservation needs for the
sage grouse are listed.
Conservation plans.
Conservation plans for each population of sage grouse should
be designed with the aid of public and private landowners and
interested citizens. The conservation plans should include
appropriate recommendations for habitat management, restoration,
configuration, and acquisition in order to maintain long-term
population viability. Efforts should be made to apply management
recommendations in conservation plans with reasonable
speed.
Habitat preservation and
restoration. Protect critical breeding, brood-rearing, and
winter habitat through land exchange programmes, conservation
easements, and purchase of private lands and management of public
lands to promote sage grouse. Restore habitats in disturbed and
especially in burned areas.
Habitat assessment.
Document the quantity and quality of remaining habitats throughout
the species range as a basis for species conservation and recovery
programmes.
Monitoring. Continue
both traditional methods of monitoring and implement long term
radio-tracking monitoring programmes to assess population trends,
with priority in fragmented areas, small populations, and for the
Gunnison Sage Grouse.
Education. Educate
both the public and management agencies about human impacts due to
development, grazing, recreation and management land
treatments.
Correspondents
Jack Connelly, Mike
Schroeder, Jessica Young
Key
publications
Braun, C.E. and Young, J.R.
1995. A new species of sage grouse in Colorado. Wilson
Onithological Society, Williamsburg, Virginia.
Connelly, J. and Braun, C.
E. 1997. Long-term changes in sage grouse populations in western
North America. Wildlife Biology 3:229-234.
Hupp, J.W. and C.E. Braun
1991. Geographical variation among sage grouse populations in
Colorado. Wilson Bulletin 103:255-261.
Kahn, N.W., Braun, C.,
Young, J., Wood, S. Mata, D. and Quinn,T.W. 1999. Rapid
morphological evolution in a new species of sage grouse in
Colorado inferred from phylogeographic analysis of mitochondrial
control region sequences. The Auk (in press).
Oyler-McCance, S. J. (1999)
Genetic and habitat factors underlying conservation strategies for
Gunnison Sage Grouse. Ph.D. dissertation. Colorado State
University, Colorado, USA
Young, J.R. 1994. The
influence of sexual selection on phenotypic and genetic divergence
of sage grouse. Ph.D. dissertation. Purdue University, IN,
USA.
Young, J.R., Hupp, J.W.,
Bradbury, J.W., and Braun, C.E. 1994. Pheontypic divergence of
secondary sexual traits among sage grouse populations. Animal
Behaviour 47:1353-1362.
