ASSESSING HOW FOREST STRUCTURE SHAPES PREDATOR-PREY INTERACTIONS BETWEEN SPOTTED OWLS AND WOODRATS IN SOUTHERN CALIFORNIA

Zachary Wilkinson; University of Wisconsin - Madison; zwilkinson2@wisc.edu; H. A. Kramer, G. Jones, C. Zulla, J. Barry, K. McGinn, S. Sawyer, R. Gutierrez, M. Z. Peery

The spotted owl is an old-forest nesting species that has shaped forest management for several decades in western North America. However, it remains unclear as to which habitat conditions are most influential on predator-prey interactions between spotted owls and their primary prey, woodrats. In southern California, spotted owl populations have declined substantially since the late 1980s for reasons that remain undetermined. Accordingly, we tagged ten nesting male owls in the San Bernardino Mountains, California with high resolution GPS transmitters while placing video cameras focused on their nests to: (i) characterize forest structure at successful prey capture sites; (ii) understand how habitat conditions influence prey delivery rates; and (iii) determine the extent to which habitat-mediated variation in prey delivery rates affects spotted owl reproduction. We identified 330 prey deliveries to nests including 91 (27.5%) dusky-footed woodrats, 73 (22.1%) white-footed mice, and 28 (8.5%) valley pocket gophers. Of these deliveries, we ascertained locations for 123 prey captures. Here, we present the results of resource selection function analyses relating habitat conditions to successful prey captures and how delivery rates affect spotted owl fecundity, plus discuss the implications of our findings for the management of rapidly changing forests in southern California.

Spotted Owl Ecological Associations   Student Paper Zoom Presentation