Common ravens (corvus corax) are significant nest predators of gallinaceous species including grouse

The Bureau of Land Management (BLM) awarded a $300,000 Cooperative Agreement under the Threatened and Endangered Species Program (CFDA 15.246) to Texas A&M AgriLife Research to determine the presence, habitat selection, and density of common ravens in relation to anthropogenic structures and subsidies within the range of the endangered Gunnison's sage-grouse population in Colorado. The project aims to provide comprehensive information about the impacts of raven predation on the Gunnison's sage-grouse population, which has experienced significant range and population declines due to habitat loss, disruption, and predation. The 5-year project will establish 150-180 point-count locations across selected Gunnison's sage-grouse population areas to collect data and collaborate with the Colorado Bureau of Land Management on survey methods and frequency.

The endangered gunnisons sage-grouse (centrocercus minimus) is native to the american west but has experienced significant range and population declines due to habitat loss, habitat disruption, and predation. Ravens have been increasing in abundance in the western united states since the 1950S, including within the range of the gunnisons sage grouse. Indeed, research estimated a 293% increase in 2018 in raven abundance within compared to outside of gunnisons sage-grouse range. In general, high population densities of common ravens are supported by anthropogenic resources such as agricultural, landfills, and road kill, with concomitant impacts on predation, range use, and behavior. Anecdotal evidence indicates that common ravens are supported at artificially high population numbers in the gusg range due to anthropogenic activities (e.g., waste dump, chicken farm). These activities likely result in nest predation rates that are unsustainable by the gusg population. Colorado bureau of land management (BLM) natural resource managers need comprehensive information about the impacts of predators in general, but ravens in particular on gusg populations. Our goal is to determine raven presence, habitat selection, and density in relation to anthropogenic structures and subsidies in and around gunnisons sage-grouse nesting locations. We propose establishing 150-180 point-count locations through selected gusg population areas beginning with the crawford population. We will determine how many gusg population areas to include in consultation with BLM personnel. Point count locations will be randomly placed along pre-determined grid locations. Preferably, we will include existing point-count survey locations and methods already used by BLM to allow data synthesis and comparison. Survey frequency and timing will be determined in consultation with BLM personnel.