The Gunnison Sage-Grouse (Centrocercus minimus) is described as a new species from southwestern Colorado and contrasted with the Sage-Grouse (Centrocercus urophasianus) from northern Colorado and western North America. Gunnison Sage-Grouse differ from all other described sage-grouse (C. u. urophasianus, C. u. phaios) in morphological measurements, plumage, courtship display, and genetics. The species currently is limited to 8 isolated populations in southwestern Colorado and adjacent San Juan County, Utah. Total estimated spring breeding population is fewer than 5000 individuals with the largest population (,3000) in the Gunnison Basin (Gunnison and Saguache counties), Colorado. A dark brown sage-grouse with black underparts and prominent black, long, thin, specialized, ornamental contour feathers arising from the dorsal base and sides of the neck on males (lost after breeding with few apparent until molting in mid- to late November), coarsely barred brown, long tail feathers with prominent white to yellow-white bars, brown rounded wings, and feathered gray-brown tarsi. Rounded air sacs (cervical apteria) greenish-yellow within a white upper breast, with scale-like feathers on males prominent in spring. Females smaller than males, similar in general plumage appearance but without specialized ornamental contour feathers arising from the dorsal base of the neck and without the prominent white upper breast and discernible air sacs of males. Tail length shorter than males but with same coarsely barred brown with prominent white to yellowwhite bars. Both sexes smaller in mass and feather lengths than adult/yearling C. urophasianus with no overlap. Strut rates are slower and audible sounds differ markedly from C. urophasianus during breeding displays. Distribution.?Gunnison Sage-Grouse currently exist in 6, possibly 7, counties in southwestern Colorado (Braun 1995, Commons 1997) and 1 county in southeastern Utah (Barber 1991). The known historic distribution (Fig. 1) of this species in Colorado was in sagebrush (Artemisia spp.) communities below 3000 m south of the Eagle and Colorado rivers from near Leadville (Lake County) south, and in sagebrush dominated shrubsteppe habitat into the San Luis Valley to the boundary with New Mexico and west to the Utah state line. It was known to occur in Grand and San Juan counties, Utah, south and east of the Colorado River. The distribution of the species was discontinuous within this area (Rogers 1964, Braun 1995) separated by river valleys and high forested mountains.
Young, J.R., C.E. Braun, S.J. Oyler-McCance, J.W. Hupp, & T.W. Quinn. 2000. A new species of sage-grouse (Phasianidae: Centrocercus) from southwestern Colorado. Wilson Bulletin 112: 445?453.