Ecology of the desert kit fox (Vulpes macrotis arsipus) in Chuckwalla Valley, California

Abstract

The desert kit fox (Vulpes macrotis arsipus) is an uncommon to rare inhabitant of the Mojave and Colorado deserts in California. This previously low-key subspecies is now being threatened by a suite of direct and indirect impacts due to the rapid increase in large-scale industrial renewable energy development in important habitat areas. This study attempts to assess habitat selection by desert kit foxes in Chuckwalla Valley, CA, in the context of the increasing presence of solar energy project sites in the area. An Unmanned Aerial System (UAS) was used to assess desert kit fox burrow and vegetation density from aerial imagery, and line-transect surveys were conducted to assess desert kit fox scat, prey, and predator densities. The presence of localized land development and an existing Habitat Suitability Index were assessed using GIS. The relationship between these variables and the desert kit foxes was assessed by fitting Generalized Linear Models. I found that ecological predictors of desert kit fox habitat occupancy gauged by burrow density can contradict those of habitat use gauged by scat density. Thus, habitat suitability and habitat connectivity may be impacted differently by land development. Proximity to development directly influenced habitat occupancy and use models as well. The Habitat Suitability Index based on widely accepted desert kit fox ecology was strongly contradicted by regression results and individual observations. In addition, coyote presence was found to negatively impact habitat occupancy and use, which suggests that water availability associated with land development may indirectly impact desert kit foxes. I conclude that current knowledge and the assumptions of cumulative impacts of land development are inadequate for the assessment of the impacts of large-scale renewable energy development in desert kit fox habitat.