Little is known about historic fox numbers on Santa Rosa Island. In 1972, trapping efforts resulted in a 36% capture rate. In 1998 the trap success had dropped to only 7.6%. A ranch manager, who has lived on the island for over 50 years, observed in 1998 that foxes were scarcer than during any time in his memory. Biologists believe that golden eagles have also affected the fox population on Santa Rosa Island. Golden eagles are now regularly observed on the island, and there is the possibility of a nesting pair. Capture and monitoring efforts will continue through 2000. Long-term recovery of the fox population on the island will likely depend on the success of the captive breeding efforts and other management techniques used by biologists.
Captive Breeding Program
In February 2000, the Channel Islands National Park constructed a fox captive breeding facility after the fox population on this island had also declined precipitously. The facility is similar to that on San Miguel Island, with a total of 12 breeding pens and two quarantine pens. A total of 14 foxes (5 males: 9 females) were captured and brought into the facility between March and November 2000. Three of the females were pregnant when brought into the facility, and they gave birth to 9 pups, 8 of which survived. Including the captive-reared pups, the total number of animals in captivity on Santa Rosa Island is 22. In 2001, additional breeding pens were constructed on both islands to allow expansion of the facilities for housing offspring produced during the 2001 breeding season. This expansion allows the number of captive breeding pairs to be increased in order to produce more foxes for eventual release into the wild. The Institute is cooperating with the National Park Service's island fox conservation efforts by contributing to the development of veterinary protocols, providing emergency veterinary assistance, and assisting in a genetic analysis of captive animals to determine the best pairing of individuals for breeding (in cooperation with California State University, Los Angeles).