The Nature Conservancy. Protecting nature. Preserving life.™

Santa Cruz island fox © Ian Shive

At just four pounds and the size of a small house cat, the Santa Cruz Island fox has historically been the island’s top predator for thousands of years. However, history changed as introduced species and human disturbances took their toll on the island, driving the native fox population to near extinction.

The Nature Conservancy—together with the National Park Service, U.S. Fish and Wildlife Service and the California Department of Fish and Game—engaged in an intensive, science-based recovery project to save the island fox. In less than a decade, the fox population has made an unprecedented recovery—heralding it as one of the fastest and most successful endangered species recovery programs in U.S. history.

A Vanishing Species

For thousands of years the Santa Cruz Island fox roamed the island free from predators—until golden eagles from the mainland began nesting on the island in the 1990s. Attracted by the abundance of feral pigs on the island, the golden eagles also preyed on the island fox. Naïve to aerial predators, the foxes made easy targets, resulting in a rapid decline in population.

• The island fox population fell from 1,500 to fewer than 100 animals in less than a decade—a 95 percent reduction of the fox population.
• In March 2004, the U.S. Fish and Wildlife Service listed the Santa Cruz Island fox as an endangered species.

Island Fox Recovery

In 2002, the Conservancy and partners initiated an Island Fox Recovery Program—including captive breeding, monitoring foxes closely in the wild and vaccinating against canid diseases—to safeguard the limited remaining population against extinction.

• Biologists identified mating pairs, then carefully captured and housed them in a captive breeding facility, designed to mimic their natural environment.
• In six seasons, 85 pups were produced by the program and released to the wild.
• Due to the successful recovery of fox populations in the wild, the captive breeding program was phased out in 2007.
• The wild island fox population now stands at more than 1,300.

In addition, other key components of Santa Cruz Island’s complex restoration program were implemented to help restore the native community:

• Relocating golden eagles to the mainland
• Re-establishing native bald eagles to the island
• Removing non-native feral sheep and pigs

Restoration and Research Continues

Today, the island fox survival rate has increased to an astonishing 96 percent, and biologists continue to track and monitor foxes in the wild.

• Roughly 10 percent of the fox population is radio-collared, enabling researchers to study their movements and keep close tabs on the population.
• Fox health is monitored and vaccines administered annually for rabies and canine distemper—diseases easily contracted from domestic dogs illegally brought ashore by boaters. 

Fox Facts:

• Descendants of the larger mainland gray fox
• Grayish-white-and-black backs; dull-white underbellies; cinnamon-rust at the base of ears, sides of neck and limbs
• Diet includes summer holly, cholla cactus, rose, sumac, nightshade, native deer mice, ground-nesting birds and occasionally grasshoppers and crickets
• Habitat: valley and foothill grasslands, coastal dunes, coastal bluffs, coastal sage scrub, oak woodland and coastal marsh
• Foxes pair-bond for life—remaining monogamous until one of the partners dies
• Mating takes place in January and February, with one to five pups produced during late March through early May

Did you know…?

• The first foxes are believed to have found their island home more than 18,000 years ago by floating from the mainland on storm-generated debris.
• As sea levels rose, Santarosae—the offshore island land mass—separated to become the northern Channel Islands.
• Genetically distinct subspecies of foxes evolved on six of the Channel Islands—San Miguel, Santa Rosa, Santa Cruz, San Nicholas, San Clemente and Catalina.