Landscape features and weather influence nest survival of a ground-nesting bird of conservation concern,the greater sage-grouse,in humanaltered environments

Introduction:Ground-nesting birds experience high levels of nest predation.However,birds can make selection decisions related to nest site location and characteristics that may result in physical,visual,and olfactory impediments to predators.Methods:We studied daily survival rate[DSR]of greater sage-grouse(Centrocercus urophasianus)from 2008 to 2010 in an area in Wyoming experiencing large-scale alterations to the landscape.We used generalized linear mixed models to model fixed and random effects,and a correlation within nesting attempts,individual birds,and years.Results:Predation of the nest was the most common source of nest failure(84.7%)followed by direct predation of the female(13.6%).Generally,landscape variables at the nest site(≤30 m)were more influential on DSR of nests than features at larger spatial scales.Percentage of shrub canopy cover at the nest site(15-m scale)and distances to natural gas wells and mesic areas had a positive relationship with DSR of nests,whereas distance to roads had a negative relationship with DSR of nests.When added to the vegetation model,maximum wind speed on the day of nest failure and a 1-day lag in precipitation(i.e.,precipitation the day before failure)improved model fit whereby both variables negatively influenced DSR of nests.Conclusions:Nest site characteristics that reduce visibility(i.e.,shrub canopy cover)have the potential to reduce depredation,whereas anthropogenic(i.e.,distance to wells)and mesic landscape features appear to facilitate depredation.Last,predators may be more efficient at locating nests under certain weather conditions(i.e.,high winds and moisture).

Incorporating within- and between-patch resource selection in identification of critical habitat for brood-rearing greater sage-grouse

Introduction:Incorporating information on animal behavior in resource-based predictive modeling(e.g.,occurrence mapping)can elucidate the relationship between process and spatial pattern and depict habitat in terms of its structure as well as its function.In this paper,we assigned location data on brood-rearing greater sage-grouse(Centrocercus urophasianus)to either within-patch(encamped)or between-patch(traveling)behavioral modes by estimating a movement-based relative displacement index.Objectives were to estimate and validate spatially explicit models of within-versus between-patch resource selection for application in habitat management and compare these models to a non-behaviorally adjusted model.Results:A single model,the vegetation and water resources model,was most plausible for both the encamped and traveling modes,including the non-behaviorally adjusted model.When encamped,sage-grouse selected for taller shrubs,avoided bare ground,and were closer to mesic areas.Traveling sage-grouse selected for greater litter cover and herbaceous vegetation.Preference for proximity to mesic areas was common to both encamped and traveling modes and to the non-behaviorally adjusted model.The non-behaviorally adjusted map was similar to the encamped model and validated well.However,we observed different selection patterns during traveling that could have been masked had behavioral state not been accounted for.Conclusions:Characterizing habitat that structured between-patch movement broadens our understanding of the habitat needs of brood-rearing sage-grouse,and the combined raster surface offers a reliable habitat management tool that is readily amenable to application by GIS users in efforts to focus sustainable landscape management.