Inbreeding in Northern Spotted Owls - Insights From Over 30 Years of Monitoring Data

They used over 30 years of monitoring data from 14187 Northern Spotted Owls to estimate inbreeding rates and identify common forms of inbreeding. Inbreeding was highest in the Washington Cascades (15 percent), lowest in western Oregon (3.5 percent) and northern California (2.7 percent), and intermediate for the Olympic Peninsula of Washington (6.1 percent). There is strong selection against inbred birds; only 6.8 percent of inbred birds were later identified as parents. Habitat loss and competition with Barred Owls remain primary threats to Northern Spotted Owls. However, given the negative consequences of inbreeding, if habitat loss is controlled and Barred Owl populations can be managed, Spotted Owl populations in Washington may benefit from translocations of individuals from Oregon or California to introduce new genetic variation and reduce future inbreeding events.

Miller, M.P., Haig, S.M., Forsman, E.D., Anthony, R.G., Diller, L., Dugger, K.M., Franklin, A.B., Gremel, S.A., Lesmeister, D.B., Higley, M., Herter, D.R., Sovern, S.G., 2018, Variation in inbreeding rates across the range of Northern Spotted Owls (Strix occidentalis caurina)- insights from over 30 years of monitoring data: The Auk: Ornithological Advances, v. 135, no. 4, p. 821-833, https://doi.org/10.1642/AUK-18-1.1.