Impacts of Ravens on Sage-grouse Nests in Southern Wyoming

Project Information

Utah Hill University, Berryman Institute
Project Status: Active
Tags: habitat conservation project, sage grouse, avian species, wildlife, Habitat

Project Synopsis: Raven control (removal) efforts of varying intensity have been carried out around lambing grounds in Lincoln, Sweetwater, Uinta, and Carbon counties in Wyoming by United States Department of Agriculture/Wildlife Services (WS). This has provided a unique opportunity to study the potential effects of raven removal on sage-grouse nest success.

Increased anthropogenic development (energy development and urbanization) may have a negative impact on sage-grouse nesting success and productivity as a result of increased raven populations and raven depredation of sage-grouse nests. Structures associated with anthropogenic development may provide perches that ravens need to forage or ravens may be drawn to food provided around areas of human activity. We hypothesize that the reduction in sage-grouse nesting success and productivity near areas of anthropogenic development can be mitigated by controlling (removing) ravens. To test this hypothesis, we will examine the impact of raven removal on sage-grouse by monitoring: sage-grouse nesting success, raven densities, WS raven removal effort, DRC-1339 (chemical used to remove ravens) distribution at study sites, and WS mammalian predator removal.

Starting in 2009, WS implemented raven removal at half of our study sites. We will compare sage-grouse nesting success and productivity between removal and non-removal study sites (started in 2008). Continuing this project for 5 years (including2011 AND 2012) will increase the likelihood of detecting the impact of raven removal on sage-grouse nesting success and productivity. Through our research, we hope to identify a method to mitigate some of the adverse impacts of anthropogenic development on sage-grouse.

We will also address several other questions related to sage-grouse nesting and raven removal. These additional questions include: do sage-grouse avoid nesting in areas with high densities of avian predators, is sage-grouse nesting success correlated to distance from human development areas that have food available, and is survival of sage-grouse hens correlated to avian predator density? This will be accomplished by comparing avian predator densities among study sites and among years to sage-grouse nest success rates, random and actual nest sites, hen monthly survival rates, and comparing avian predator densities.

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