Diet of the San Joaquin kit fox, Vulpes macrotis mutica, on Naval Petroleum Reserve No. 1, Kern County, California, 1980-1984

A total of 1430 scats of the San Joaquin kit fox, Vulpes macrotis mutica, were collected between 1980 and 1984 on Naval Petroleum Reserve No. 1, Kern County, California, and analyzed to determine frequency of occurrence of prey items. Lagomorphs (black-tailed jackrabbits and desert cotton-tails) were the primary prey species (frequency of occurrence = 73%); while kangaroo rats (Dipodomys spp.) were the next most common (13%). The proportions of lagomorphs and kangaroo rats in the diet did not differ between sexes of foxes, periods of the year, or topography. Intensity of petroleum developments had no observable influence on food habits. There were annual differences in diet: proportions of lagomorphs declined, and proportions of kangaroo rats increased between 1980-1984. Changes in the frequency of occurrence of lagomorphs were significantly correlated with changes in their relative abundance in undeveloped-flat habitat. The frequency of occurrence of kangaroo rats was not significantly correlated with their relative abundance. San Joaquin kit fox on NPR-1 fed primarily on lagomorphs, and had the ability to sustain themselves on kangaroo rats and other secondary prey when their primary prey declined.