DEMOGRAPHY AND STATUS OF THE ISLAND FOX AND THE ISLAND SPOTTED SKUNK ON SANTA-CRUZ ISLAND, CALIFORNIA

The island spotted skunk and island fox of Santa Cruz Island are insular endemics whose continued existences are uncertain and about which little is known. Through trapping, I evaluated relative abundance, sex ratio, age structure, and variation in weight according to age, sex, and season for both species. Foxes were abundant and easily captured (23% overall trap success), while skunks were rare and difficult to capture (0.57% overall trap success). Male: female ratios for both species did not differ significantly from 1:1. Age distribution of foxes revealed a large number of young individuals, possibly reflecting a rapidly growing population in response to cessation of a prolonged drought. Average weight for skunks was 620 g for males and 500 g for females. Average weight for foxes was 2.00 kg for adult males and 1.88 kg for adult females; males consistently weighed more than females across all age classes and seasons. Fox pups grew rapidly, reaching full weight as young adults in their first winter. The low rate of success in trapping skunks, in conjunction with data from visual sightings, suggests the relative rarity of the island spotted skunk on Santa Cruz Island and warrants further monitoring of the subspecies.