The greater sage-grouse (Centrocercus urophasianus), also known as the sagehen, is the largest grouse in North America. Its range is sagebrush country in the western United States and southern Alberta and Saskatchewan, Canada. It was known as simply the sage grouse until the Gunnison sage-grouse was recognized as a separate species in 2000. The Mono Basin population of sage grouse may also be distinct.
The greater sage-grouse is a permanent resident in its breeding grounds but may move short distances to lower elevations during winter. It makes use of a complex lek system in mating and nests on the ground under sagebrush or grass patches. It forages on the ground, mainly eating sagebrush but also other plants and insects. Greater sage-grouse do not have a muscular crop and are not able to digest hard seeds like other grouse.
The species is in decline across its range due to habitat loss, and has been recognized as threatened or near threatened by several national and international organizations.
Description
Adult greater sage-grouse have a long, pointed tail and legs with feathers to the toes. The adult male has a yellow patch over each eye, is grayish on top with a white breast, and has a dark brown throat and a black belly; two yellowish sacs on the neck are inflated during courtship display. The adult female is mottled gray-brown with a light brown throat and dark belly. Adult males range in length from 26 to 30 inches and weigh between 4 and 7 pounds. Adult females are smaller, ranging in length from 19 to 23 inches and weighing between 2 and 4 pounds.
Distribution and habitat
Greater sage-grouse are obligate residents of the sagebrush (Artemisia spp.) ecosystem, usually inhabiting sagebrush-grassland or juniper (Juniperus spp.) sagebrush-grassland communities. Meadows surrounded by sagebrush may be used as feeding grounds. Use of meadows with a crown cover of silver sagebrush (A. cana) is especially important in Nevada during the summer.
Greater sage-grouse occur throughout the range of big sagebrush (A. tridentata), except on the periphery of big sagebrush distribution. Greater Sage-Grouse prefer mountain big sagebrush (A. t. ssp. vaseyana) and Wyoming big sagebrush (A. t. ssp. wyomingensis) communities to basin big sagebrush (A. t. ssp. tridentata) communities.
Sagebrush cover types other than big sagebrush can fulfill greater sage-grouse habitat requirements; in fact, the grouse may prefer other sagebrush cover types to big sagebrush. Greater sage-grouse in Antelope Valley, California, for example, use black sagebrush (A. nova) cover types more often than the more common big sagebrush cover types. Hens with broods on the National Antelope Refuge in Oregon were most frequently found (54–67% of observations) in low sagebrush (A. arbuscula) cover. Desert shrub habitat may also be used by greater sage-grouse.
Sagebrush communities supporting greater sage-grouse include silver sagebrush and fringed sagebrush (A. frigida).
Their historic range spanned 16 American states and Alberta, British Columbia, and Saskatchewan in Canada. Between 1988 and 2012, the Canadian population declined by 98%. By 2012, they were extirpated from British Columbia and left with only remnant populations in Alberta with 40 to 60 adult birds, and in Saskatchewan with only 55 to 80 adult birds. By 2013, sage grouse were also extirpated from five U.S. states. In 2013, the Canadian Governor in Council on behalf of the Minister of the Environment, under the Species at Risk Act, annexed an emergency order for the protection of the greater sage-grouse.
Ecology
Lek mating system
Greater sage-grouse are notable for their elaborate courtship rituals. Each spring, males congregate in leks and perform a "strutting display". Groups of females observe these displays and select the most attractive males with which to mate. The dominant male located in the center of the lek typically copulates with around 80% of the females on the lek. Males perform in leks for several hours in the early morning and evening during the spring. Video Males gather in leks to court, usually in late February to April. Only a few dominant males, usually two, breed. Sage grouse mating behaviors are complex. After mating, the hen leaves the lek for the nesting grounds.