A SYNTHESIS OF COMMON RAVEN ECOLOGY AND PREDATION IMPACTS ON SENSITIVE AVIAN SPECIES
|Seth J Dettenmaier; U.S. Geological Survey; email@example.com; Peter S. Coates, William C. Webb, Seth M. Harju, Shawn T. O'Neil, John C. Tull, Pat J. Jackson, David J. Delehanty|
Decades of scientific evidence reveal common raven (Corvus corax; raven) populations are increasing and expanding across their geographic range. Concomitant elevated predation rates in threatened and endangered avian species during nesting periods may hamper species recovery. We conducted an extensive literature review to identify knowledge gaps and synthesize environmental features which support raven population growth. Raven occurrence, demographic results, and resource use appeared 31, 21, and 17 times, respectively. We identified 13 explanatory covariates regularly used to explain variation in raven ecological processes, including vegetation, human settlement, recreation, and linear rights-of-way. We explored impacts of raven predation on nests and young of sensitive avian species using the “Raven Impact Index” (RII), a species-specific index that incorporates species demographic rates, abundance of ravens within each sensitive species’ breeding range, and the degree of overlap between raven and prey distributions. We found evidence of nest predation on 8 sensitive avian species, and suspected nest predation on 1 additional species. The RII varied among species, with greater sage-grouse (Centrocercus urophasianus) having the highest relative impact values, followed by snowy plover (Charadrius nivosus nivosus). Our species RII can help inform management decisions to mitigate the negative effects of raven predation of sensitive avian species.