US-IALE 2018

AUTHORS: Michael Egan*, Purdue University; Casey Day, Purdue University; Todd Katzner, U.S. Geological Survey; Patrick Zollner, Purdue University

ABSTRACT: Gray fox populations have experienced declines in parts of the eastern United States that differ from the typical pattern of mesopredator release. One hypothesis to explain these population trends is that they have had a negative response to urbanization relative to other mesocarnivores. Alternatively, gray fox declines may be the result of interspecific interactions, particularly competition with abundant coyotes throughout their range. Evidence for both these alternatives have been documented at some spatial scales, however landscape scale studies have only occasionally been used to study how these two factors affect gray fox distributions. To test these hypotheses throughout the gray fox’s range, we used single and two species occupancy models across multiple landscapes to evaluate the effects of habitat covariates and interspecific interactions on gray fox occupancy. Model results indicate that both coyote and gray fox occupancy was positively related to the amount of forest present but these same models provided no evidence that gray foxes were impacted by urban cover. Additionally, model results indicate that, while coyote presence did not impact gray fox occupancy, gray fox occupancy was negatively related to coyote abundance. Based on these results, we concluded that coyote abundance is a stronger driver of low gray fox occupancy in the eastern U.S. than urbanization.