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Sage Grouse Population and Habitat In Montana

Sage Grouse Range Has Diminished

Once found in 13 western states and three Canadian provinces, sage grouse are found today in 11 states and two provinces. The bird's remaining strongholds are in Montana, Wyoming, Idaho, Nevada, and Oregon. Throughout the sage grouse's range, habitat has been lost to the changes associated with expanding human populations, conversion of sagebrush lands to agriculture, and energy development.

Montana Population Has Undergone Highs and Lows

In Montana, sage grouse populations dropped in the late 1800s, probably because of market hunting, which was halted in 1900. Through the 1920s, sage grouse were so abundant that the state fish and game authorities received a complaint in 1925 about the bird being a "pest."

With the Dustbowl of the 1930s and '40s, the sage grouse population again dropped. Recovery began in the 1950s, and the bird rebounded in the 1960s and '70s, a period of favorable precipitation. In the 1980s, populations began another decline, rebounded in the mid-1990s, and began another downward trend in the late 1990s, corresponding with moisture.

In addition to those population shifts, there appears to be a 10-year cycle in which sage grouse populations rise during the first half of the decade and decline in the second half of the decade.

For sage grouse populations to remain stable, there should be 240 juveniles produced per 100 adult hens. In the mid 1990s, productivity rose to 340 juveniles per 100 hens, but as of 2000-2002 declined to approximately 130 juveniles per 100 hens.

What Do Sage Grouse Need During The Year?

Over the course of a year, sage grouse diet is more than 60% sagebrush. Others foods are forbs (broad-leafed plants) and insects. The sage grouse's digestive system is not able to grind or digest seeds, so seeds are not part of the diet.

In winter, sage grouse require thick, dense sagebrush, on a flat or gently rolling landscape, and they are 100% dependent on sagebrush for food. When snow depths reach 12 inches, the grouse began to retreat to the tallest, most dense sagebrush, sometimes contracting their range to 10% of its original size.

In spring, the sage grouse begin to use leks, or strutting grounds, which are low, flat areas of sparse sagebrush and little or no grass. Around sunrise, males strut on the leks and use their chest air sacs to make their characteristic "ker-ploop" sound, to attract females to mate. Sage grouse usually use the same leks year after year and generation after generation. Lek attendance varies widely, from a few birds to more than 100. Biologists track lek attendance to help determine the status of sage grouse populations.

After breeding, hens seek out nesting sites that provide cover. Some avian nest predators can potentially impact nest success or juvenile survival in certain locations. The highest percent of successful nests are found under relatively tall, dense sagebrush with an understory of grass and forbs. The grouse broaden their diet to include forbs (they favor milky stemmed forbs such as dandelions). Incubation is 28 days.

After hatching, hens look for brood-rearing habitat: lighter density sagebrush in more open areas, with supplies of grass and forbs. In the first few weeks, chicks depend on a diet of insects for high protein to fuel their rapid growth. During this period, chicks are unable to regulate their body temperature, and a consistent cold rain will kill them. A chick's diet during its first summer will consist of 75% forbs and 25% insects. The more different kinds of plants available, the better, because variety in plants helps supply variety in insects.

In summer, as the landscape begin to dry, sage grouse move to moister areas so they can find plants and insects: seeps, riparian areas, greasewood bottoms, irrigated alfalfa fields, roadside borrow pits, streams from dams, or trickles of water from reservoirs.

When fall arrives, especially after the first killing frost diminishes insect populations and kills the forbs, the grouse shift back to their winter ranges and their 100% sagebrush diet.

Research On Predation Shows Mixed Results

In research on the effect of predator control on sage grouse populations, half of studies show an impact and half show no impact. In one experiment conducted by the Montana Department of Fish, Wildlife, and Parks and USDA Wildlife Services in 1998-2000, two areas with leks were identified, as many coyotes as possible were killed in one of the areas, and no coyotes were killed in the other. Lek activity in both areas remained the same.

One common thread emerges from the research: when habitat is degraded or broken up, the impact of predation is worse. In some cases where habitat has been altered, new predators have arrived -- for example, fox are more adept than coyote at catching sage grouse, so a decrease in coyote in favor of fox can affect grouse populations. Over the decades, numbers of golden eagles and other birds of prey have increased because of legal protections; their impact on sage grouse populations has not been documented.

Hunter Harvest

Sage grouse move back to their winter ranges in late August and early September. The Montana sage grouse hunting season occurs in September and October. Harvest has declined steadily since the late 1970s. There are indications that hunter preferences have shifted away from sage grouse toward other game birds, possibly due to the decline in sage grouse populations.

June 2004. Source: Charlie Eustace, game bird biologist, consultant to the Montana sage grouse local working groups. For more information about the Montana sage grouse local working groups, contact Anne Cossitt, Park City, 633-2213,