Gunnison sage grouse were not considered their own species until the 1990s because of close behavioral similarities to the greater sage grouse (Centrocercus urophasianus). However there are morphological, genetic, and mating pattern differences that distinguish the two species.
Species can communicate with callings, courtship vocalizations, and feather signaling. Callings can be used to defend territory or to alert others about a threat. Courtship vocalizations help females distinguish the fitness between males during mating season. On the lek, older males will establish and defend their territory by sometimes chasing or fighting other males. Males will often position themselves laterally to females to project the loudest sound. Feather signals are made by the spreading of the tail feathers or the flapping of the wings.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Habitat fragmentation, invasive plant species, and low vegetative diversity are the main issues endangering Gunnison sage grouse populations. The Colorado Parks and Wildlife is working with the Colorado Cattlemen's Association, Gunnison County, and the Bureau of Land Management to better understand factors impacting Gunnison sage grouse populations. The Bureau of Land Management (BLM) has been working with the Candidate Conservation Agreement (CCA) to try and conserve public lands that have sage grouse populations. Locals have also shown an interest in protecting the remaining populations. In 2010, the US Fish and Wildlife Service (FWS) listed the sage grouse as "warranted but precluded" under the Endangered Species Act to indicate that, although the species is not of top priority, they play an important ecological role. By listing the sage grouse, it has helped raise awareness and protect sagebrush habitats from further fragmentation.
US Migratory Bird Act: protected
US Federal List: endangered
CITES: no special status
State of Michigan List: endangered
Gunnison sage grouse and ranchers depend on the same habitats, which may lead to competition of resources between livestock and sage grouse. However, this is a minor problem, as both ranchers and sage grouse seem to have a mutually beneficial relationship.
Sage grouse and ranchers both depend on the same habitats. If ranching profits decrease, the pressure to sell land increases, which often results in habitat fragmentation. If sustainable yields can be attained from these lands, it can help protect the remaining sage grouse populations. Gunnison sage grouse have diverse seasonal habitat requirements which make them a potential keystone species for other grassland species.
Positive Impacts: ecotourism ; research and education
Light to moderate grazing in the early season can promote forb and arthropod abundance in both upland and riparian habitats, whereas intense foraging can cause detrimental decreases in sagebrush distribution and promote introduction of invasive grasses. Gunnison sage grouse are infected with some kinds of blood parasites (Haemoproteus).
Ecosystem Impact: keystone species
Mutualist Species:
Commensal/Parasitic Species:
Gunnison sage grouse have varying food preferences, depending on the life stage and season. In the early summer, insects and forbs are an essential component of the chicks' diet. Insects provide a source of protein for growth and development. In late summer, chicks begin to forage on forbs, and sagebrush is later added to the diet. As sagebrush habitats dry out in colder months, adults and chicks forage on forbs and sagebrush in riparian habitats. In the fall and winter, most sage grouse consume mainly sagebrush leaves. Certain types of sagebrush can be preferred based on protein levels and leaf textures. Gunnison sage grouse do not have muscular gizzards, so it is difficult for them to grind and digest seeds.
Animal Foods: insects
Plant Foods: leaves; seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: omnivore
Gunnison sage grouse are native to North America, and are found in southwestern Colorado and southeastern Utah. However, population distributions have been declining rapidly due to habitat destruction. Only five distinct populations remain, and the Gunnison Basin has the highest population diversity. Efforts to introduce sage grouse to New Mexico, Oregon, Montana, Wyoming, Utah, Colorado, and Idaho have been unsuccessful.
Gunnison sage grouse have a potential distribution of 46,521 sq km, but a current range of 4,787 sq km. There is a large difference between the potential and actual distribution of populations, which may be due to habitat alteration and degradation.
Biogeographic Regions: nearctic (Native )
Gunnison sage grouse are a sagebrush (Artemisia) obligate species and also depend on a variety of other grasses and habitats for mating, nesting, and brood-rearing. There are three categories of sage grouse populations: non-migratory, one stage migratory, and two stage migratory. Populations that are non-migratory display limited movement regardless of season. One stage migratory populations prefer different habitat conditions in summer and winter. Three stage migratory populations prefer different habitats for winter, summer, and mating seasons. Mating habitats are often low vegetative density areas with high visibility called leks. Regardless of migratory preferences, all sage grouse populations rely on sagebrush and riparian habitats for feeding and cover. They are found at elevations of 2,200 to 4,300 m.
Range elevation: 2200 to 4300 m.
Range depth: 8.5 (high) m.
Average depth: 4.8 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland
Other Habitat Features: agricultural ; riparian
In the wild, Gunnison sage grouse have an expected lifespan of 3 to 6 years but can live up to 9 years. Survival rates are low in captivity, and their expected lifespan in captivity is 1 years. This makes rescue efforts difficult for this endangered species. The Colorado Division of Wildlife (CDOW) tried captive rearing and only 11 of 40 chick eggs survived their first year. Despite low survival rate in captivity, CDOW believe that better techniques for raising Gunnison sage grouse have been attained from the process. Sage grouse mortality is higher for males than for females in the wild due to their larger size and flashy appearance. Females and chicks have lower mortality rates because they have a speckled brown and white coloration that functions as camouflage.
Range lifespan
Status: wild: 9 (high) years.
Typical lifespan
Status: wild: 3 to 6 years.
Typical lifespan
Status: captivity: 1 (high) years.
Gunnison sage grouse display sexual dimorphism. Males have white breasts with two round yellow air sacs (cervical apteria) on their chest. These air sacs have scale-like feathers that males inflate (making a popping noise) during the spring to attract mates. Males have a black belly with a white V-shaped area separating their throat from their chest. They also have spiky brown and white tail feathers that can be fanned out for sexual signaling. Females are smaller and lighter than males and have a gray-brown coloration. Female have shorter tail feathers with less plumage and also lack the prominent air sacs present on males. Chicks resemble females and have a brown and white speckled appearance for camouflage. Adult sage grouse from southwestern Colorado have shorter and narrower beaks than adult sage grouse from northern Colorado. There are also morphological variations between Gunnison sage grouse and their close relative, greater sage grouse Centrocercus urophasianus. Gunnison sage grouse are smaller with longer black filoplumes on their heads. They are typically 32 to 51 cm long with a wingspan of 6 to 76 cm and a mass of 990 to 2435 g.
Range mass: 990 to 2435 g.
Range length: 32 to 51 cm.
Range wingspan: 66 to 76 cm.
Sexual Dimorphism: male larger; male more colorful; sexes shaped differently; ornamentation
Other Physical Features: endothermic ; bilateral symmetry
Sage grouse are easy targets due to their large size and inability to run fast. Males are also ostentatious and can be spotted by predators relatively easily. Females and chicks have a lower mortality rate due to smaller mass and the ability to camouflage with their surroundings. There has been research showing that a decrease in black tailed jackrabbit (Lepus californicus) populations has led to an increase in predation of sage grouse. In other regions, decreases in preferred prey populations have resulted in a shift of preferred prey to sage grouse. Dense, tall vegetation can help provide cover to protect nests from predators. Coyotes (Canis latrans), ground squirrels (Sciuridae), and American badgers (Taxidea taxus) are common nest predators. Sage grouse are also a popular game bird. Colorado and Utah have prohibited hunting for sage grouse in certain areas to protect dwindling population numbers.
Known Predators:
Anti-predator Adaptations: cryptic
Gunnison sage grouse display "clumped polygyny," where multiple males compete to mate with females on an arena called a lek. Beginning mid-March through late May, many males begin to migrate to lek sites and often return to the same one each season. Males are very territorial and may defend their lek from intruders. Only one or two males (10-15%) is rewarded with the chance to reproduce with the surveying females. Adult and yearling females often get the opportunity to breed, whereas only select adult males and rarely any yearling males are able to mate.
Leks are often in places with low vegetation and sagebrush cover to maximize visibility. Males compete for females by popping their air sacs and strutting back and forth around the lek for hours. A male can also fan out his tail to try and impress females. Male Gunnison sage grouse have slower courtship displays than their close relatives, greater sage grouse (Centrocercus urophasianus). There are structural differences in mating calls between the two species as well. Females in the Gunnison Basin and northern Colorado can distinguish between male courtship vocalizations. Due to regional differences, females often prefer courtship vocalizations from regions nearby. This preferential breeding behavior creates a reproductive barrier between populations of Gunnison sage grouse that are geographically separated and may be an underlying factor causing species isolation and endangerment. Research has also shown that mating outside of the lek occurs occasionally.
Mating System: polygynous
Males do not participate in either nesting or brood rearing processes. The pre-laying period is from late March to April, when hens search for the ideal nesting sites. Better nesting sites have a greater diversity of forbs and sagebrush for both nutrition and cover. Forbs are a good source of calcium, phosphorous, and proteins that hens feed on during the gestation period to lay healthy eggs. Nesting occurs from mid-April to June and hens may then migrate to locations far from the lek to find optimal nesting conditions. Hens select nest sites that have adequate sagebrush and grass to provide cover from predators while the hen is incubating the eggs. Hens are loyal to successful nesting areas and will return season after season.
Hens have one brood per season and lay 6 to 8 eggs that hatch in 25 to 27 days. Small clutch sizes and annual mating opportunities have resulted in decreasing population numbers. Despite the small clutch size, most eggs hatch in June. Chicks are precocial and weigh 30 g at birth on average. Soon after hatching, they leave the nesting area for a riparian habitat to feed on insects. Chicks are able to make short flights and feed on their own by 2 to 3 weeks of age. They may follow their mothers until the fall. Chicks are able to sustain flight by 5 to 6 weeks of age and are considered independent at 10 to 12 weeks of age. In the winter, chicks and mothers separate into sexually segregated flocks and may be reunited in the spring when flocks migrate to lek sites to compete for mates.
Breeding interval: Gunnison sage grouse breed annually in the spring.
Breeding season: Gunnison sage grouse breed from April to June.
Range eggs per season: 6 to 9.
Average eggs per season: 7.
Range time to hatching: 25 to 27 days.
Range fledging age: 2 to 3 weeks.
Range time to independence: 10 to 12 weeks.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Besides reproduction, males take no part in nest building or brood rearing. Females look for nesting sites that have adequate coverage and resources to raise chicks. Herbaceous dicots are an important dietary requirement for egg laying and provide a rich source of protein and phosphorous. Females often return to the same nesting sites annually if nest success rates are high. Chicks follow the mothers shortly after hatching. Hens offer a limited amount of parental care and chicks are mostly on their own for food procurement.
Parental Investment: precocial ; female parental care ; pre-hatching/birth (Provisioning: Female); pre-weaning/fledging (Provisioning: Female); pre-independence (Provisioning: Female)
The Gunnison grouse, Gunnison sage-grouse or lesser sage-grouse (Centrocercus minimus) is a species of grouse endemic to the United States. It is similar to the closely related greater sage-grouse (Centrocercus urophasianus) in appearance, but about a third smaller in size, with much thicker plumes behind the head; it also has a less elaborate courtship dance. It is 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 avifauna is relatively well known, it was overlooked until the 1990s due to 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.[7] 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 absent.[8]
Gunnison sage-grouse are notable for their elaborate courtship rituals. Each spring, males congregate on leks and perform a "strutting display". Groups of females observe these displays and select the most attractive males with which to mate. Only a few males do most of the breeding. Males perform on leks for several hours in the early morning and evening during the spring. Leks are generally open areas adjacent to dense sagebrush stands, and the same lek may be used by grouse for decades.
This species is in decline because of loss of habitat; their range has shrunk. Following petitions, the species was proposed for listing under the Endangered Species Act by the United States Fish and Wildlife Service, and was eventually protected as a threatened species starting on December 22, 2014.[2][3][9] The known population size of this species remains quite small, and it was estimated that fewer than 4,000 individuals existed in when the species was successfully protected under the Act. A 2019 survey found the population in Colorado to be reduced to an estimated 1,800 birds with only around 429 reproductive males, a record low for the species since surveys began.[10]
Gunnison sage-grouse occur in seven counties in southwestern Colorado and one county in southeastern Utah. It was once found in Arizona, New Mexico, and Oklahoma, but is now extirpated in those states.
Males gather on the lek or strutting grounds, which are small, open areas where breeding occurs, in late February to April, as soon as the lek is relatively free of snow. Only a few dominant males, usually two, breed. After mating, the hen leaves the lek for the nesting grounds. Clutch size ranges from six to eight eggs; incubation time is 25 to 27 days. Sage-grouse apparently have high rates of nest desertion and nest predation.[11]
Gunnison sage-grouse are totally dependent on sagebrush-dominated habitats. Sagebrush is a crucial component of the adult's diet year-round, and they select sagebrush almost exclusively for cover. However, in order to rear a brood of chicks, the young require high protein broadleaved plants and wildflowers that bring insects, also for protein. However, cattle and sheep also relish these plants, and the removal of these critical chick-food plants is a major reason for this bird's decline.
This article incorporates public domain material from Centrocercus minimus. United States Department of Agriculture.
The Gunnison grouse, Gunnison sage-grouse or lesser sage-grouse (Centrocercus minimus) is a species of grouse endemic to the United States. It is similar to the closely related greater sage-grouse (Centrocercus urophasianus) in appearance, but about a third smaller in size, with much thicker plumes behind the head; it also has a less elaborate courtship dance. It is 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 avifauna is relatively well known, it was overlooked until the 1990s due to 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 absent.
