San Clemente Island Fox (Urocyon littoralis clementae)

Young foxes playing and licking

The Institute has been involved in monitoring fox population trends on San Clemente Island most years since 1988. This has been the first long-term island fox monitoring project on any of the Channel Islands.  Starting with three mark-recapture trapping grids and incrementally expanding to six allowed for monitoring population trends across the island in a variety of habitat types. The monitoring was initially funded through grants obtained by IWS. Starting in 1999, the U.S. Navy began funding the monitoring effort. 

Additional research conducted on San Clemente Island foxes included detailed study of home range size and overlap, examination of fox diet, and an investigation into disease exposure and general pathology of the fox population. Starting in 2007, Colorado State University began studies to look at mortality factors of island foxes and the impacts of roads on fox home range and survival. From 2007 through 2010, Ganda and Associates, Inc. implemented a newly designed monitoring program that incorporated 12 fox trapping grids spread across the island.  This approach was designed to give greater information on habitat-specific population estimates. In 2011, IWS took over running these 12 grids during the last year of the 5-year monitoring effort. 

Fox shock collarThe island fox on San Clemente Island has been identified as a predator of the severely endangered race of the loggerhead shrike (Lanius ludovicianus mearnsi). This presents a novel challenge for wildlife conservationists as both the fox and shrike are unique species on the island. As an alternative to lethal control, the Institute helped devise a shock collar for foxes residing in the areas of shrike nests that was activated if they got within 10 meters of a nest. The system was used until shrike populations had sufficiently increased to a point where concern over nest predation by foxes was minimal. Sonic deterrents are also being tested.

In 2010, IWS finalized an Epidemic Response Plan for San Clemente Island foxes. The plan, completed in collaboration with several wildlife veterinarians and pathologists, provides the Navy with a series of trigger points based on the number of telemetry-collared foxes that might die during a specific period of time. The program has a tiered approach to responses that should be taken at different mortality rates.  The plan also provides the Navy with action plans for epidemics caused by different disease organisms and suggestions for how to help avoid epidemics of common canine diseases.