Greater Sage-Grouse Life History

Habitat

Habitat GrasslandsGreater Sage-Grouse live only on the sagebrush steppe of western North America, and they use several types of sagebrush habitat in different parts of the year. They usually nest in areas with relatively dense cover from big sagebrush (Artemisia tridentata), although they also use areas with rabbitbrush, greasewood, and grassy areas. Leks are located in clear areas such as broad ridgetops, grassy swales, dry lakebeds, and sometimes recently burned areas. Adult hens lead their growing chicks to areas with good forage, including irrigated pastures, wet meadows, and alfalfa fields, in addition to sagebrush.Back to top

Food

Food PlantsSage-grouse eat leaves, buds, flowers, forbs, and insects. Leaves (primarily of sagebrush) dominate the diet throughout most of the year. However, in the first three weeks after hatching, chicks cannot digest sagebrush, and forbs and various insects (beetles, grasshoppers, and ants, especially) make up the bulk of the juvenile diet. Dandelions and other forbs are important for females as they prepare for laying. Back to top

Nesting

Nest Placement

Nest GroundFemales do all the nest-building, incubation, and raising of the chicks without any help from males. They place their nests on the ground, usually under a sagebrush shrub and sometimes under tufts of grass within dense patches of shrubs. Nests tend to have at least two directions that are not heavily vegetated, which presumably function as possible escape routes for incubating females.

Nest Description

Females make bowl-shaped nests scraped into the soft soil and lined with leaves, grasses and forbs, small twigs, and feathers that the female plucks from her breast. The cup interior is about 8 inches across and 2–4 inches deep.

Nesting Facts
Clutch Size:4-11 eggs
Egg Length:2.2-2.3 in (5.5-5.8 cm)
Egg Width:1.5-1.5 in (3.8-3.9 cm)
Incubation Period:25-29 days
Egg Description:Variable shades of olive-buff or pale greenish, with fine, darker markings.
Condition at Hatching:The downy, well-camouflaged chicks are precocial, able to feed themselves within minutes of hatching. Typically able to fly weakly after 10 days, and strongly after about 5 weeks.
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Behavior

Behavior Ground Forager

Greater Sage-Grouse offer one of the best examples of the breeding system known as lekking—where males gather in a confined area to perform courtship displays for females. Males are intensely territorial on leks, defending areas just a few yards across. Females visit these leks to size up the displays and choose their mates. Despite all the male brawn on display, it’s the females that are in charge. When a female chooses a male she crouches, spreading and drooping her wings slightly in an invitation to the male. Many females end up mating with the same male; most of the other males on the lek wind up with no mating opportunities at all. After mating, males have no further contact with the female or the young.

From roughly March through May, males gather on leks at dawn. There they perform a complex, highly choreographed display that is among the most extraordinary wildlife sights in North America. With tail fanned and erect, a male repeatedly gulps air while stepping forward; then forcefully releases it. Standing tall, with inflated chest held high, the male sweeps his wings across his white breast, creating a swishing noise. He tilts his head back, rapidly inflating, bouncing, and deflating the yellow, balloon-like pouches on his chest. The outward popping of these bare pouches creates a series of echoing pops. These displays are performed almost continuously, and up to 10 times per minute, for several hours in the early morning.

Rival males often find themselves locked in a standoff, facing head to tail a foot or two apart. During these threat displays, males crouch low and bob quickly, giving a low, repeated clucking. These standoffs may boil over into battering attacks with the wings; they may drive away or exhaust they opponent, but rarely cause serious injury.

Greater Sage-Grouse are strong, fast fliers (up to 50 mph in level flight), but endurance is not a strong suit. Sustained flights rarely exceed a few miles. Most of their movement is on foot, typically averaging less than a mile per day.

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Conservation

Conservation Declining

Greater Sage-Grouse have declined greatly from presettlement estimates as high as 16 million to as few as 200,000 today—reflecting the widespread loss, alteration, or fragmentation of the vast sagebrush steppe that they depend on. Between 1966 and 2015 populations declined by almost 3.5% per year, resulting in a cumulative decline of 83%, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 150,000, with 94% living in the U.S. and 6% in Canada. Greater Sage-Grouse is a U.S.-Canada Stewardship species, and a Tri-National Concern species. It rates a 15 out of 20 on the Continental Concern Score and is on the 2016 State of North America's Birds' Watch List, which includes bird species that are most at risk of extinction without significant conservation actions to reverse declines and reduce threats.

Considering the species’ dependence on different areas in different seasons, the need for corridors of suitable habitat to move between those areas, and the fact that sage-grouse reproduction requires social interactions within sizeable groups, their sensitivity to habitat fragmentation is extreme. Research suggests that a population of sage-grouse tied to a single lek might depend on more than 75,000 acres of unbroken sage, while a dispersed population with multiple nearby leks may use 250,000 acres.

Even small amounts of disturbance (such as patches of cultivated land, telephone poles and utility lines, or minor roads) reduce sage-grouse populations. The disturbance associated with infrastructure, construction, and operation of drill pads and wells also has measurable, negative impacts on lek attendance and population size. Fragmentation of sagebrush habitat has reached a point where less than 5 percent of sagebrush habitat lies more than 1.5 miles from a paved road, and this is a major obstacle in striking a balance between the realities of development and the needs of sage-grouse.

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Credits

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Schroeder, Michael A., Jessica R. Young and Clait E. Braun. 1999. Greater Sage-Grouse (Centrocercus urophasianus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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