Meeting Abstract

31.2  Jan. 5  PHYSIOLOGICAL MEASURES OF DISTURBANCE RELATED TO VEHICLE EXPOSURE IN THE NORTHERN SPOTTED OWL HAYWARD, L.S.*; WASSER, S.K.; University of Washington lhayward@u.washington.edu

We used non-invasive measures of fecal corticosterone metabolites to investigate the effects of vehicle exposure on physiology of the Northern Spotted Owl (NSO), Strix occidentalis caurina, in two complementary studies. The first study draws on samples collected throughout the range of the NSO in Washington, Oregon and California by collaborators involved in long-term demographic studies. Using these samples, we investigated the effect of proximity to road on NSO corticosterone. After controlling for the effects of sex, season and year, we found that proximity to road had a highly significant positive effect on levels of corticosterone. We also found that NSO in National Forests had significantly higher levels of corticosterone than NSO in National Parks. In contrast, presence of barred owl had no effect on corticosterone in the NSO. The second study involves the experimental application of acute off-highway vehicle exposure to NSO. We conducted our experiments in the Mendocino and Shasta-Trinity National Forests of Northern California with help from our partners in US Forest Service, US Fish and Wildlife and Blue Ribbon Coalition. We found that acute exposure to experimentally applied OHV use significantly increased corticosterone in male, but not female, NSO. This sex difference is consistent with previous work demonstrating that proximity to logging roads and intensely harvested forest correlates with higher glucocorticoids in male, but not female, NSO. Sex differences in demands associated with reproduction may underlie the variation in vulnerability to disturbance in this species