ESTIMATING THE EFFECTS OF OFF-HIGHWAY VEHICLES ON OAK-CHAPARRAL BIRDS USING COMMUNITY MODELING.
Jerry S. Cole; The Institute for Bird Populations; P. O. Box 1346, Point Reyes Station, CA, 94956; (415) 663-1436; jcole@birdpop.org; Nicole L. Michel, Rodney B. Siegel, Nicolas Somilleda Jr.
Increased participation in outdoor vehicular recreation has led to an expansion of natural areas accessed by the public. Yet the effects of recreation on birds and other wildlife on those lands remains unclear. We assessed the effect of off-highway vehicles (OHVs) on the abundance and diversity of bird species occurring on a state-managed OHV recreation area near Hollister, California. We used a hierarchical community distance sampling model to compare bird community and species-level abundance and Shannon's Diversity Indices in park regions open and closed to OHV users during 2012-2014. We also tested whether the extent of surrounding land area covered by OHV trails affected avian abundance and diversity. We found no significant effects of OHV use, nor of area of OHV trails, on the bird community as a whole, although we found significant responses in several individual species. We found diversity was significantly lower in OHV use areas during the spring, but not during the winter. Within OHV use areas, we found no effect of the cover of OHV trails on diversity during either season. Our results suggest that under careful management, OHV recreation may have only minor effects on the avian community in parks managed specifically for vehicular recreation.
Poster Session