Quick Answer
No, dusky and blue grouse are considered separate species. The dusky grouse (Dendragapus obscurus) is found in western North America while the blue grouse (Dendragapus parvus) is found in northern North America. They were previously considered subspecies of the same species but have since been recognized as distinct based on differences in appearance, behavior, habitat, and genetics.
Differences Between Dusky and Blue Grouse
Dusky and blue grouse differ in the following ways:
Appearance
– Dusky grouse are grayish overall with reddish brown on the belly and tail. Males have yellow skin over the eye.
– Blue grouse are more blue-gray in color with a barred pattern on the belly and tail. Males lack yellow eye combs.
Behavior
– Dusky grouse stay in fir and pine forests year-round while blue grouse move to higher elevation spruce-fir forests in summer.
– Dusky grouse males produce hooting sounds when displaying while blue grouse produce popping sounds.
Range
– The dusky grouse range includes coastal and inland forests of western North America from southeast Alaska to California.
– The blue grouse range stretches across the boreal forests of northern North America from Alaska to Labrador and south into the western mountains.
Taxonomy and Classification
Both dusky and blue grouse belong to the order Galliformes and the family Phasianidae along with other grouse species. They were originally classified as a single species (Tetrao obscurus) with five subspecies:
Dusky grouse (T. o. obscurus) | Found from northern California to southeast Alaska |
Sooty grouse (T. o. fuliginosus) | Found in coastal regions of Pacific Northwest |
Richardson’s grouse (T. o. richardsonii) | Found from southern Yukon to northern Alberta and Manitoba |
Oregon grouse (T. o. oreophilus) | Found in mountain ranges of Washington, Oregon, Idaho and western Montana |
Sierra grouse (T. o. sierrae) | Found in Sierra Nevada range in California |
In the 1990s, phylogenetic studies of mitochondrial DNA found enough genetic divergence between the dusky, sooty, and sierra subspecies and the Richardson’s and Oregon subspecies to recognize them as separate species. The dusky grouse was split off as Dendragapus obscurus while the blue grouse was split off as Dendragapus parvus.
Field Identification
Despite their evolutionary divergence, dusky and blue grouse can be challenging to distinguish visually in the field. Focusing on differences in color pattern, tail shape, and range can help identify them:
Color Pattern
– Dusky grouse have more uniform grayish body plumage with warm reddish brown on the belly and undertail.
– Blue grouse tend to be more sharply patterned with gray and black barring on a pale belly and grayish banding on undertail coverts.
Tail Shape
– Male dusky grouse have broader, more squared-off tails compared to blue grouse.
– Blue grouse often appear longer-tailed in the field.
Range
– If a medium-sized, grayish grouse is spotted in the boreal forest, it’s likely a blue grouse.
– In the coastal Northwest, dusky grouse are more expected. Use range as an initial clue but confirm with plumage details.
Observing vocalizations can also help distinguish between the hooting display of dusky grouse versus the popping display of blue grouse.
Habitat and Ecology
Beyond appearance and range, dusky and blue grouse differ subtly in aspects of their breeding habitats and ecology:
Breeding Habitat
– Dusky grouse breed mainly in fir forests interspersed with pine and other conifers.
– Blue grouse utilize higher elevation spruce-fir forests for breeding.
Winter Habitat
– Dusky grouse spend winters in the same conifer forests used for breeding.
– Blue grouse migrate downslope to pine and aspen forests for winter.
Diet
– Both species eat buds, leaves, berries and seeds but dusky grouse make greater use of pine needles.
– The blue grouse diet contains more deciduous shrubs and berries.
Clutch Size
– Dusky grouse average 5-6 eggs per clutch.
– Blue grouse lay slightly smaller clutches of 4-5 eggs.
These habitat differences reflect adaptations of each species to the forest ecosystems within their respective ranges.
Conservation Status
Neither dusky or blue grouse are considered threatened species currently. Their conservation status is as follows:
Dusky Grouse
– Listed as a species of Least Concern by the IUCN Red List.
– Stable and widespread populations but some local declines.
Blue Grouse
– Also of Least Concern according to the IUCN Red List.
– Occupies a vast range and population trends are generally stable.
Forest habitat loss is a concern for both species in parts of their range, especially due to logging and wildfires. Both species are still hunted recreationally in most areas. Careful habitat conservation efforts focused on maintaining healthy, mature conifer forests will benefit dusky and blue grouse into the future.
Conclusion
In summary, dusky and blue grouse exhibit enough differences in appearance, genetics, habitat, and behavior to be considered separate species. Understanding the distinctions between these cryptic grouse comes down to remembering key identification points including color patterns, tail shape, vocalizations, and geographic range. With close observation and attention to these clues, birdwatchers can confidently identify dusky grouse in western forests and blue grouse in northern boreal habitats. Though they occupy distinct ranges, conservation of conifer forests is important for maintaining populations of both species.