Dietary Shifts Related to Water Availability and the Demographic Response to Changing Prey Abundance of Carnivores in the West Desert, Utah

The decrease in number and range of North American large carnivores, has often all owed smaller carnivores ( \u3c 15 kg) to fill the role of the top predator. This has favored some carnivores such as coyotes (Canis latrans), who have expanded their distribution. Other small carnivores such as kit foxes (Vulpes macrotis) have experienced a range shrinkage and their population status throughout the United States is a concern. Historically, western U.S. natural resource management agencies installed artificial water sources to assist desert wildlife, but some researchers believe the access to water allowed more coyotes to live in Utah’s West Desert. In the late-1980s, research proposed that without free drinking water, coyotes would have to triple their food consumption to survive. More recent coyote research has found no evidence to support these claims. We used data collected between 2010 and 2013 on the U.S. Army Dugway Proving Ground (DPG) in Utah’s West Desert to examine if the coyotes’ changed their diet when drinking water was removed and to determine how kit foxes respond to changing prey abundance. We examined coyote scats to see if they shifted towards eating more large-bodied prey (i.e., leporids such as jackrabbits and cottontails) in the areas void of drinking water. We found no evidence of a dietary shift towards larger prey to meet energy requirements in the areas where there was no available free water. Our results, in addition to previous DPG research, provide strong evidence that coyotes in the West Desert are desert-adapted carnivores and are not influenced by artificial water sources. The 4-year DPG dataset also allowed us to investigate if kit fox litter sizes and pup survival changed when prey abundance changed. We found no connection between kit fox litter size and rodent or leporid abundance. However, we found a 3-fold increase in kit fox pup survival in 2012 when rodent abundance nearly doubled. Diet analysis of kit fox scats showed four prey categories (rodent, insect, kangaroo rat, leporid) represented 78.5% occurrence of all prey items. We found that kit foxes changed their diet when kangaroo rat abundance changed. As prey resources have changed over the last 60 years, the DPG kit foxes have shown to be flexible in their diet by shifting away from their historical leporid use to now heavily relying on rodents. In addition to more research on kit foxes, we recommend that future studies also focus on their prey populations to help ensure the future of the West Desert kit fox