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 ...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).展开更多
文摘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).
