Habitat selection by sympatric, translocated Greater sage-grouse and Columbian sharp-tailed grouse in Eastern Washington

Kourtney Faith Stonehouse

Greater sage-grouse (Centrocercus urophasianus) and Columbian sharp-tailed grouse (Tympanuchus phasianellus columbianus) have declined substantially in Washington, primarily because of conversion of native shrub-steppe to agriculture. In response, state and federal agencies have acquired and restored remaining habitat and augmented and reintroduced grouse to suitable areas. We examined how sympatric, translocated sage-grouse and sharp-tailed grouse used space and selected habitats within their home ranges, at nest sites, and at leks in spring- summer within remnant shrub-steppe surrounded by a matrix of cropland in eastern Washington. Because of differences in their life history requirements, we expected extensive habitat partitioning between species. Using radiolocations of ≥ 43 birds of each species, we found that sage-grouse had larger home ranges than sharp-tailed grouse, and the composite of home ranges overlapped substantially between species. When we created Resource Utilization Function models relating utilization distributions of grouse locations to habitat features within their home ranges, we found that areas of highest probability of use for both species overlapped by 72%. Both species selected restored fields and areas further from trees and roads/distribution lines. Sage-grouse selected less rugged areas, but selected different densities of shrubs equally, vii whereas sharp-tailed grouse selected sparse shrub cover to a greater degree than higher densities of shrub cover. At nest sites within the landscape, both species selected restored fields and less rugged areas, but sage-grouse also selected areas with higher shrub cover and patch richness, and areas further from trees and distribution lines, resulting in only 20% overlap of areas with the highest predicted probability of use from Resource Selection Function models. At the nest microsite, sage-grouse selected for greater shrub and lower annual forb cover, and taller perennial grasses, whereas sharp-tailed grouse selected for lower annual grass and substrate cover, and taller perennial forbs. Sharp-tailed grouse also strongly selected for restored fields at lek sites. Because Washington is highly fragmented by cropland, understanding how populations of species with different life history characteristics, such as sage-grouse and sharp-tailed grouse, coexist within remaining tracts of sagebrush (Artemisia spp.) at different spatial scales is important for effectively conserving and managing shrub-steppe communities.

Habitat selection by sympatric, translocated Greater sage-grouse and Columbian sharp-tailed grouse in Eastern Washington

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