San Clemente Island FOX

(Urocyon littoralis clementae)

Fox densities on San Clemente Island have likely been relatively high since the 1970s when surveys were initiated. The Institute has been involved in monitoring fox population trends on three established trapping grids since 1988, and on a fourth grid since 2000, and two additional grids since 2001. Running 5-year averages on the three long-term grids suggest that the fox population may have declined approximately 25% between the first and second 5-year periods of this investigation. The San Clemente subspecies does not appear to have been affected by predation (San Miguel, Santa Rosa, and Santa Cruz islands) or disease (Santa Catalina Island) as with the subspecies on the three northern channel islands 

The island fox on San Clemente Island has been identified as a predator of the severely endangered race of the loggerhead shrike (Lanius ludovicianus mearnsi). On two occasions foxes have been recorded entering a shrike nest and preying upon nestlings. In order to help protect the shrike, and still have minimal impact on the fox population, the Institute helped devise a predator deterrent system. Foxes residing in the areas of shrike nests are equipped with a shock collar that is activated if they get within 10 meters of a shrike nest. The activation is keyed by a wire that is placed on the ground around the nest tree or shrub, which is attached to a transmitter. This system helps protect the nestling shrikes without having to resort to lethal control of the foxes.

To protect young shrikes from predation by foxes after they fledge from the nest and are outside the safety zone offered by the shock collar system, foxes are trapped and temporarily brought into captivity. After the fledgling shrikes are flying well enough to escape predation by terrestrial predators, shock collars are removed and the foxes are released back into the same area.