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. 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. Open areas such as swales, irrigated fields, meadows, burns, roadsides, and areas with low, sparse sagebrush cover are used as leks. Of 45 leks, 11 were on windswept ridges or exposed knolls, 10 were in flat sagebrush, seven were in bare openings, and the remaining 17 were on various other site types. Leks are usually surrounded by areas with 20 to 50% sagebrush cover, with sagebrush no more than tall.