Evaluating Common Raven Take for Greater Sage-Grouse in Oregon’s Baker County Priority Conservation Area and Great Basin Region

Authors

• Frank F. Rivera-Milán, U.S. Fish and Wildlife ServiceFollow
• Peter S. Coates, USGS
• Jacqueline B. Cupples, U.S. Fish and Wildlife Service
• Michael Green, U.S. Fish and Wildlife Service
• Patrick K. Devers, U.S. Fish and Wildlife Service

Date of this Version

Winter 2021

Document Type

Article

Citation

Human–Wildlife Interactions (Winter 2021) 15(3): article 24 

doi: 10.26077/mft7-3s49 

Special topic: Raven management 

Comments

United States government work. Public domain

Abstract

The common raven (Corvus corax; raven) is a nest predator of species of conservation concern, such as the greater sage-grouse (Centrocercus urophasianus). Reducing raven abundance by take requires authorization under the Migratory Bird Treaty Act. To support U.S. Fish and Wildlife Service’s take decisions (e.g., those that authorize killing a specified proportion or number of individuals annually in a defined area), including the most recent one for Oregon’s Baker County Priority Area for Conservation (PAC), we modeled raven population dynamics under hypothetical scenarios with take rates ranging from below to above the maximum sustained yield (MSY; i.e., tr_msy= 0.01-0.60). We fit a Bayesian state-space logistic model to estimate abundance based on the Breeding Bird Survey route-level count data for the PAC during 1997-2019 and Great Basin Region (GBR) during 1968-2019. We predicted abundance for 2019-2030 and evaluated potential take levels (PTL) for the PAC and GBR. Abundance averaged 682 (SE = 93) for the PAC during 1997-2019 and 333,027 (SE = 20,504) for the GBR during 1968-2019. With take rates between 0.41 and 0.60, predicted abundance averaged 308 (SD = 405) for the PAC and 142,258 (SD = 53,474) for the GBR during 2019-2030. With management factor F = 0.75-2 for takes ranging from below to above the MSY, the PTL 50^th percentiles were 150-401 yr^-1 for the PAC and 60,457-161,219 yr^-1 for the GBR. Our modeling framework is flexible and can be part of a comprehensive management strategy for ravens in the western United States.