Morris Animal Foundation | Foundation funding played significant role in conservation of endangered island foxes

Foundation funding played significant role in conservation of endangered island foxes

Lead researcher instrumental in saving species from extinction

The Catalina Island fox has been living on Catalina Island for at least 4,000 years. Weighing only 4 to 6 pounds, this tiny fox is the largest predator on the island. This subspecies, a descendent of the gray fox, is found only on Catalina Island, one of the Channel Islands off the southern coast of California, and no one is completely certain how these foxes came to live there. One thing is certain: without a decade-long conservation program, this species would likely have become extinct.

A catastrophic population decline of about 95 percent in the late 1990s left an estimated 100 island foxes surviving on Catalina Island. As a result, the U.S. Fish and Wildlife Service placed these foxes, along with three other island fox subspecies that were declining, on the endangered species list in 2004. Researchers began looking at health issues of these foxes, and some of the studies funded by Morris Animal Foundation have helped to bring the foxes back from the verge of extinction.

The late Dr. Linda Munson was instrumental in leading efforts in the late 1990s to develop strategies for stopping and reversing the declines, and she was the lead researcher or collaborator on several Morris Animal Foundation–funded studies. Through pathological and disease research conducted by Dr. Munson and other Foundation-funded researchers, captive breeding, vaccination, and other management tactics that were developed and implemented as part of the species recovery plan, the Catalina Island foxes and the other three endangered subspecies have begun to recover.

In the course of that effort, Dr. Munson and other scientists identified that cancerous ear canal tumors were a potentially serious emerging health issue in the Catalina Island foxes. Dr. Munson was instrumental in defining the extent of that problem in the population and the risk factors that related to tumor development.

The research showed that Catalina Island foxes have an unusually high prevalence of ear canal cancer, which doesn’t affect foxes on the other Channel Islands. This cancer causes considerable illness and has the potential to negatively affect population recovery. With funding from Morris Animal Foundation, Dr. Munson and her team of researchers from the University of California–Davis, the Catalina Island Conservancy and the Institute for Wildlife Studies determined that ear mites cause inflammation, which may play a role in the development of ear canal cancer. She then played a key role in planning and executing a Morris Animal Foundation–funded study that looked at the effects of treating the Catalina foxes for ear mites.

In that recently completed study, foxes were examined in the summer months for the presence of ear mites, and samples were taken to assess the severity of inflammation in their ears. The infected animals were then randomly assigned to receive treatment for ear mites or to not receive treatment. At the final recapture examination, 90 percent of the treated foxes were free of ear mites and had less apparent inflammation. In addition, some foxes remained free of mites for up to six months after only one treatment, which suggests that significant reductions in mite burdens could be accomplished with occasional re-trapping and treatment. In contrast, 84 percent of the untreated foxes were still infested with mites. The foxes in the no-treatment group later received treatment to alleviate inflammation.

The study findings prompted the Catalina Island Conservancy to initiate ear-mite treatment of any foxes handled as part of routine population monitoring. As a result, the prevalence of ear-mite infestation in the Santa Catalina Island fox population, as a whole, has significantly decreased, and the risk for ear canal cancer may be reduced.

Sadly, Dr. Munson died last year after a long battle with cancer. Her colleague Dr. T. Winston Vickers states: “Linda’s leadership, wise counsel and collegial approach to that extensive multidisciplinary and multiagency effort that extended for more than 10 years were a critical factor in its success.”

We at the Foundation would also like to pay tribute to Dr. Munson’s contribution to bringing the island fox populations back from near extinction. Her efforts truly exemplify how one person can make a difference in so many ways.

Please click here to read a tribute written by Dr. Vickers.

Biologist Julie King removes the fox from the trap                       Biologist Calvin Duncan with a fox pup


Biologists King & Puzzo examine the fox teeth                                     Dr. Vickers & Biologist Puzzo examine the fox