Recent Trends in Western Screech-Owl and Barred Owl Abundances on Bainbridge Island, Washington

Abstract

In an ongoing 15-y study concerning population dynamics of Barred Owls (Strix varia) on Bainbridge Island, Kitsap County, Washington, I documented a steep decline in the Western Screech-Owl (Megascops kennicottii) population and a steady increase in the Barred Owl population. From 1995 through 2010, I conducted 358 auditory playback surveys that showed both changes in abundance and spatial distribution of both species on the island. Statewide Christmas Bird Count data from the same time period also reflect an overall decline in the Western Screech-Owl population and an increase in the Barred Owl population. Further, at least 2 other studies have shown Western Screech-Owl to be prey for Barred Owl, also contributing to the body of evidence that leads to a possible correlation between the increasing number of Barred Owls and the decline of Western Screech-Owls.