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Dusky Grouse - Dendragapus obscurus
Other Names:
Blue Grouse
Native Species Global Rank :
G5
State Rank :
S4
(see State Rank Reason below)
Agency Status USFWS :
USFS :
BLM :
PIF :
3
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Copyright by: The Macaulay Library at the Cornell Lab of Ornithology, Ithaca, NY, all rights reserved.
State Rank Reason (see State Rank above)
Species is apparently secure and not at risk of extirpation or facing significant threats in all or most of its range.
Details on Status Ranking and Review
Dusky Grouse (Dendragapus obscurus ) Conservation Status Review
Population Size
Score U - Unknown
Comment Unknown.
Range Extent
Score G - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment 218268 square kilometers based on Natural Heritage Program range maps
Area of Occupancy
Score H - >20,000 km squared (greater than 5,000,000 acres)
Comment 35732 square kilometers based on GAP predicted model.
Long-term Trend
Score E - Relatively Stable (±25% change)
Comment Historic covertypes largely still in place.
Short-term Trend
Score U - Unknown. Short-term trend in population, range, area occupied, and number and condition of occurrences unknown.
Comment No clear data.
Threats
Score G - Slightly threatened. Threats, while recognizable, are of low severity, or affecting only a small portion of the population or area.
Comment Fire, Canopy removal, harvest
Severity Low - Low but nontrivial reduction of species population or reversible degradation or reduction of habitat in area affected, with recovery expected in 10-50 years.
Comment Populations likely to quickly recover
Scope Low - 5-20% of total population or area affected
Comment Fire increasingly a threat, but only likely to impact smaller regions of occupied habitat at any one time.
Immediacy Moderate - Threat is likely to be operational within 2-5 years.
Comment Ongoing, but climate change could increase fire and canopy removal.
Intrinsic Vulnerability
Score B - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
Environmental Specificity
Score C - Moderate. Generalist. Broad-scale or diverse (general) habitat(s) or other abiotic and/or biotic factors are used or required by the species but some key requirements are scarce in the generalized range of the species within the area of interest.
Comment Drier conifer forests.
General Description
The Dusky Grouse (until recently known as the Blue Grouse) is the largest of Montana's three species of mountain grouse. Both sexes have long, square tails which are unbarred. Males have slate-colored upper parts, white-based neck feathers around the air sacs, and yellow-orange eye combs. Females tend to be browner than males and have barring on the head, neck, and back. Both sexes have uniform blue-gray breasts and bellies, and feathered legs. Adult males range from 18.5 to 22.5 inches in length and 2.5 to 3 pounds in weight; adult females range from 17 to 19 inches in length and average about 2 pounds in weight.
For a comprehensive review of the conservation status, habitat use, and ecology of this and other Montana bird species, please see
Marks et al. 2016, Birds of Montana. Diagnostic Characteristics
Dusky Grouse are most likely to be confused with Spruce (Franklin) Grouse in Montana. Male Spruce Grouse, however, are considerably smaller than male Dusky Grouse and have a black breast patch. Female Spruce Grouse have white under parts with conspicuous black barring, while female Dusky Grouse are bluish-gray beneath.
Species Range
Observations in Montana Natural Heritage Program Database
Number of Observations: 2958
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
Relative Density
Recency
SUMMER (Feb 16 - Dec 14)
Direct Evidence of Breeding
Indirect Evidence of Breeding
No Evidence of Breeding
WINTER (Dec 15 - Feb 15)
Regularly Observed
Not Regularly Observed
(Observations spanning multiple months or years are excluded from time charts)
Habitat
Dusky Grouse winter at high elevations in conifer stands. In early spring, they descend to lower altitudes, where they prefer forest edges and openings. Broods may be found quite far from timber during summer and early fall. In the Bridger Mountains in early summer, broods were often observed in grass-forb areas (with arrow-leaf balsamroot being dominant); increased use of deciduous thickets was observed in late July to August (Mussehl 1958). See also Martinka 1970 for habitat comments from the Sapphire Mountains.
Ecological Systems Associated with this Species
Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system,
even if point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at:
mtnhp.org/requests ) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
Literature Cited
Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
Commonly Associated with these Ecological SystemsAlpine Systems
Forest and Woodland Systems
Grassland Systems
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
Occasionally Associated with these Ecological SystemsForest and Woodland Systems
Human Land Use
Food Habits
In winter they eat mainly conifer needles. In summer they eat a mixed diet of insects, green plants and berries. The young eat mainly insects (Mussehl 1971).
Ecology
Brood movement in summer is generally less than 0.5 mile. Brood break-up appeared concurrent with fall dispersal, in late August to early September and had lateral and altitudinal components. Brood range densities were 27 (1957) and 34 (1958) in a 1 square mile area (Mussehl 1958).
Reproductive Characteristics
Hatching dates in the Bridger Mountains ranged from May 25 to July 11, with the peak the 3rd week of June (Mussehl 1958). Near Fortine, hatching dates were June 10 to August 15; broods ranged from 1 to 10 young.
References
Literature Cited AboveLegend:
Additional ReferencesLegend: Do you know of a citation we're missing? Effects of recreation on Rocky Mountain wildlife: a review for Montana . [Montana]: Montana Chapter of the Wildlife Society.
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