Spatial Ecology of the Gray Fox (Urocyon cinereoargenteus) in Southeastern Arizona

Abstract

Where animals occur over space and time can inform effective conservation and management efforts for vector species of zoonotic diseases. Gray foxes (Urocyon cinereoargenteus) are a common and widespread species across their geographic range that can exist close to human disturbance. However, little is known about their space use in the southwestern United States, where they are a significant reservoir for a unique strain of the rabies virus. Gray foxes overlap with bobcats (Lynx rufus), coyotes (Canis latrans), and striped skunks (Mephitis mephitis) across the southwestern United States. Space use by gray foxes has been impacted by presence of other mesocarnivores. How vector species interact with the landscape has a direct impact on the spread of diseases like rabies. Mesocarnivores were the source of over 90% of all reported rabies cases in 2016. We used remotely triggered cameras to detect gray foxes, bobcats, coyotes, and skunks and understand their habitat use in isolated vs. well-connected landscapes. We deployed 80 cameras, divided between two study sites in eastern Arizona, the Pinaleño and White Mountains, and stratified each in a random design by vegetation type. We collected data from June 2016 to August 2017, encompassing 19,700 camera trapping days. Gray foxes occupied an estimated 95.6% of sites. We ran a multi-species multi-season model to examine how occupancy of gray foxes changed. Our results showed that occupancy by coyotes, bobcats, and skunks had a negative influence on gray fox occupancy. We detected gray foxes across all sampled elevations and vegetation communities. Additionally, we used data acquired from VHF and GPS satellite collars on gray foxes in the White Mountains and Pinaleño Mountains of Arizona to compare habitat use, movement patterns, and home range requirements between a well-connected landscape and an isolated sky island. We sought to compare space use estimates between continuous and isolated forests using GPS and VHF technology. Average home range size was 3.78 ± 2.74 km2 (SD) and gray foxes select for upper evergreen forests in the Pinaleño Mountains and pine-juniper woodlands in the White Mountains. We were able to define specific vegetation communities used by adult gray foxes where oral vaccination efforts can be focused by rabies disease managers. Disease management for rabies epizootic events in the southwestern U.S. will benefit from our study of gray fox space use. Our results contribute greater insight into gray fox habitat use in isolated vs. well-connected landscapes. Understanding habitat use by gray foxes in Arizona can be used to inform rabies management across the broader southwestern United States.