A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Wildlife Biology
Several studies on birds have shown that avoidance of predators and dangerous habitat can have dramatic effects on habitat use by prey species. Sage-grouse hens chose locations with lower raven and raptor densities, selected locations farther away from man-made structures and forested habitat, and used locations that were flatter. Depredation of sage-grouse nests can be an influential factor limiting their populations. I found that Wildlife Services decreased raven density, but I did not detect a direct improvement to sage-grouse nest success. However, sage-grouse nest success was 22% when ravens were seen near a sage-grouse nest and 41% when no raven was seen near a sage-grouse nest. Survival of adult female sage-grouse has been demonstrated to be the most important aspect of a sage-grouse’s life-cycle with respect to population growth. I found that sage-grouse hen survival was negatively related with golden eagle (Aquila chrysaetos) density when topography was flatter, proximity to man-made structures and forested habitat, and a hen’s nesting and brood-rearing status (i.e., whether the hen was incubating eggs for caring for chicks)."
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