Kr. Crooks et D. Vanvuren, RESOURCE UTILIZATION BY 2 INSULAR ENDEMIC MAMMALIAN CARNIVORES, THE ISLAND FOX AND ISLAND SPOTTED SKUNK, Oecologia, 104(3), 1995, pp. 301-307
We compared resource utilization of two insular endemic mammalian carn
ivores, the island spotted skunk and island fox, along niche dimension
s of space, food, and time on Santa Cruz Island. We predicted that res
ource use by foxes and skunks would differ along one or more niche dim
ensions, and that both species would have broader niches or higher den
sities compared with mainland relatives. Island foxes and island spott
ed skunks differed to some extent in habitat use, diets, and circadian
activity, which may account for their long-term coexistence. Nonethel
ess, substantial overlap between skunks and foxes in spatial, dietary,
and temporal dimensions suggests that competition between the two spe
cies does occur. Moreover, competition may be asymmetric, affecting sk
unks more than foxes. Compared with mainland foxes, island foxes have
smaller body size, smaller home range, increased population density, i
ncreased diurnal activity, and behavior that is more highly inquisitiv
e and less flight-prone - all common features of insular faunas. Islan
d skunks, however, apparently have not developed these changes, perhap
s due to asymmetric competition with foxes in conjunction with severe
ecosystem disturbances caused by feral sheep.