U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version

October 2007


Published in Western North American Naturalist 67(3),2007, pp. 389-401.


Variation in kit fox (Vulpes macroiis) population parameters can be influenced by vegetative cover and the distribution and abundance of other predator and prey species. Dramatic changes to Great Basin Desert habitats, which can potentially impact mammalian species, have occurred in some areas in Utah. We examined kit Fox demographics and prey populations from 1999 to 2001 on Dugway Proving Ground (DPG), a U.S. Army facility in Utah, and compared some parameters to historical levels (1956-1958, 1966-1969). Adult survival rates were fairly consistent between 1999 and 2000 and between 1999 and 2001; however, survival was greater in 2001 than in 2000. Reproductive rates ranged from 1.0 to 3.8 pups per female in 1999-2000 and were similar to historical numbers (1.0-4.2 pups per female). We found a decrease in pre-whelping kit fox density from tile 1960s (0.12 foxes • km-2) to 1999-2001 (0.04 foxes • km-2); however, densities were similar between the current study and the 1950s (0.08 foxes • km-2). Using 9 years of data, we found density dependence between reproductive rates of the current year and annual fox density from the previous year. Using 7 years of data, we found a slight correlation between kit fox annual density and a 1-year lag in leporid abundance, even though leporid abundance was lower during the present study than it was historically Compared to historical levels, current small mammal abundance and species composition has changed in several habitats. Kit fox breeding density and annual density were inversely correlated with coyote (Canis latrans) density. Changes to the landscape at DPG, especially due to invasion of cheatgrass (Bromus tectorum) and addition of artificial water sources, have caused a change in available lit fox habitat and prey species, and have increased the abundance of coyotes, the kit fox's major competitor.