Gunnison Grouse, Centrocercus minimus
The Gunnison Grouse (Centrocercus minimus) is a species of grouse endemic to the United States, where it is known as the Gunnison Sage-Grouse. It’s similar to the closely related Greater Sage-Grouse in its appearance but about a third smaller in size, with much thicker plumes behind its head; it also has a less complex courtship dance. It’s restricted in range to southwestern Colorado and extreme southeastern Utah, with the largest population residing in the Gunnison Basin region in Colorado. Despite being native to a country where the avifuana is usually well known, it was overlooked until the 1990s because of the similarities with the Sage Grouse, and only described as a new species in 2000-making it the first new avian species to be described from the USA since the 19th century. The description of C. minimus as a separate species is supported by a molecular study of genetic variation, showing that gene flow between the large-bodied and the small bodied birds is not present.
Gunnison Grouse are prominent for their elaborate courtship rituals. Each spring, the males gather on leks and perform a “strutting display”. Groups of females observe these displays and choose the most attractive males to mate with. Only a few males do the majority of the breeding. The males perform on leks for several hours in the early morning and evening during spring months. Leks are usually open areas bordering dense sagebrush stands, and the same lek may be used by grouse for decades.
The numbers of this species are decreasing because of loss of habitat; their range has shrunk in historical times. Following petitions, the species has been proposed for listing under the Endangered Species Act, by the United States Fish and Wildlife Service.
The Gunnison Grouse occurs in 7 different counties in southwestern Colorado and 1 county in southeastern Utah.
The males gather on the lek or strutting grounds, which are small open areas where breeding takes place, in late February to April, as soon as the lek is somewhat snow-free. Only a few dominant males, normally 2, breed. After mating, the hen leaves the lek for the nesting grounds. The clutch size ranges from six to eight eggs; incubation lasts about 25 to 27 days. Sage Grouse apparently have high rates of nest desertion and predation on nests.
Sage Grouse are completely dependent on habitats that are dominated by sagebrush. Sagebrush is a critical component of their diet all year, and sage grouse select sagebrush almost entirely for their cover.
Image Caption: Gunnison Grouse, Centrocercus minimus. Credit: US Department of Interior/Wikipedia