Dispersal of San Joaquin kit foxes, Vulpes macrotis mutica, on Naval Petroleum Reserve No. 1, Kern County, California

Between 1980-1986, the movements of 332 pups and 267 adult San Joaquin kit foxes (Vulpes macrotis mutica) were analyzed to determine which animals had dispersed. Of 129 foxes radiocollared as pups and whose parental den ranges were known, 48 (33 males, 15 females) dispersed; about 51% dispersed between July-September, and all but 11 dispersed as pups. There was no sex-specific difference in the average date that dispersal commenced. The number of days between dispersal and death was greater for pups that delayed dispersing until they became adults. Of the 90 radiocollared adults, 23 (14 males, 9 females) dispersed. Adults were found dispersing nearly equally in all months. Foxes less than 1 y old dispersed more frequently than older animals. When dispersal distances of radiocollared pups and adults were combined, no sex-specific differences were found in the average dispersal distance of 4.0 +- 0.5 miles. However, pups dispersed 5.0 +- 0.9 miles, while adults dispersed 3.0 +- 0.5 miles. An adult male traveled 29 miles. No evidence gathered demonstrated that petroleum development activities were responsible for a tendency for more foxes to disperse from developed habitat than from undeveloped habitat. Of the dispersing radiocollared foxes that were recovered dead, 47.9% were more » killed by predators, 15.1% were killed by vehicles, 1.4% died from other causes, and 35.6% died from unknown causes. These proportions were similar to those observed for nondispersers. 35 refs., 3 figs., 15 tabs. « less