"Blue Grouse"
Male Dusky Grouse displaying, Yellowstone NP; note purple air sac and red eye wattle
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Galliformes Family: Tetraonidae Genus: Dendragapus Elliot, 1823
Species
Dusky Grouse Dendragapus obscurus Sooty Grouse Dendragapus fuliginosus Spruce Grouse Dendragapus canadensis Siberian Grouse Dendragapus falcipennis
Synonyms
Palaeotetrix

The genus Dendragapus, contains two closely related species of grouse that have often been treated as a single variable taxon; the Dusky Grouse Dendragapus obscurus and the Sooty Grouse Dendragapus fuliginosus.^[1]. In addition, the Spruce Grouse and Siberian Grouse have been moved to this genus.

Description

Male Sooty Grouse displaying; note yellow air sac and eye wattle

These are large grouse that inhabit highland regions of North America and Eurasia. The Sooty Grouse is found in the Pacific Coast Ranges and Sierra Nevada, and the Dusky Grouse in the Rocky Mountains.^[2][3] These two taxa were originally regarded as separate species, but were considered conspecific for much of the twentieth century. However, in 2006 the American Ornithologists' Union re-split them,^[1] following the DNA-based work of Barrowclough et al. (2004).^[4] whose results supported the earlier work of Brooks (1929) ^[5] who regarded the two taxa as separate species based on morphology, behavior and vocalizations. The precise ranges of the two species are well-defined in the south, separated by extensive areas of unsuitable forest-free habitat, but somewhat uncertain in the north of the range of the genus where there is no separation; Barrowclough et al.'s study did not include these northern populations.

Sooty Grouse female (female Dusky Grouse are very similar)

Adults have a long square tail, gray at the end (lighter in the Sooty Grouse). Adult males are mainly dark (especially Sooty Grouse) with a yellow (Sooty Grouse) or purplish (Dusky Grouse) throat air sac surrounded by white, and a yellow (Sooty Grouse) or yellow to red (Dusky Grouse) wattle over the eye during display. Adult females of both species are mottled brown with dark brown and white marks on the underparts.^[3]

Their breeding habitat is the edges of conifer and mixed forests in mountainous regions of North America and Eurasia. Their range is closely associated with that of various conifers. The nest is a scrape on the ground concealed under a shrub or log.

All species have healthy populations, except for some population decline and habitat loss of the Sooty Grouse at the southern end of its range in southern California.^[2], and the Siberian Grouse which is considered near-threatened.

Fossils

Late Pleistocene fossil species that have been described are Dendragapus gilli (western and west-central USA), initially placed in a distinct genus Palaeotetrix, and Dendragapus lucasi (known only from Fossil Lake, USA), although as the Falcipennis grouse were formerly included in Dendragapus, it is not completely certain that these fossils are correctly assigned here.

References

• Zwickel, Fred C. and Bendell, James F. Blue Grouse: Their Biology and Natural History. Ottawa: NRC Research Press. 2004. ISBN 978-0-660-19271-0