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Daily nest survival rates of Gunnison Sage-Grouse ( Centrocercus minimus ): assessing local- and landscape-scale drivers

Thomas R. Stanley·Cameron L. Aldridge·Joanne Saher·Theresa Childers
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Abstract

The Gunnison Sage-Grouse ( Centrocercus minimus ) is a species of conservation concern and is a candidate for listing under the U.S. Endangered Species Act because of substantial declines in populations from historic levels. It is thought that loss, fragmentation, and deterioration of sagebrush ( Artemisia spp.) habitat have contributed to the decline and isolation of this species into seven geographically distinct subpopulations. Nest survival is known to be a primary driver of demography of Greater Sage-Grouse ( C. urophasianus ), but no unbiased estimates of daily nest survival rates (hereafter nest survival) exist for Gunnison Sage-Grouse or published studies identifying factors that influence nest survival. We estimated nest survival of Gunnison Sage-Grouse for the western portion of Colorado's Gunnison Basin subpopulation, and assessed the effects and relative importance of local- and landscape-scale habitat characteristics on nest survival. Our top performing model was one that allowed variation in nest survival among areas, suggesting a larger landscape-area effect. Overall nest success during a 38-day nesting period (egg-laying plus incubation) was 50% (daily survival rate; SE = 0.982 [0.003]), which is higher than previous estimates for Gunnison Sage-Grouse and generally higher than published for the closely related Greater Sage-Grouse. We did not find strong evidence that local-scale habitat variables were better predictors of nest survival than landscape-scale predictors, nor did we find strong evidence that any of the habitat variables we measured were good predictors of nest survival. Nest success of Gunnison Sage-Grouse in the western portion of the Gunnison Basin was higher than previously believed.

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Thomas R. Stanley, Cameron L. Aldridge, Joanne Saher, Theresa Childers. 2015. Daily nest survival rates of Gunnison Sage-Grouse ( Centrocercus minimus ): assessing local- and landscape-scale drivers. https://doi.org/10.1676/14-003.1

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