Park efforts aid recovery of island foxes

CHANNEL ISLANDS, Calif. — One of the swiftest biological recoveries that man has been apart of is happening in the Channel Islands not too far from the California mainland. The island foxes that roam the islands were on the brink of extinction but have made an extreme turn around due to a dedicated National Park Service crew and years of captive breeding.

“It’s not the most recent, but the most compelling restoration story on the island. We saved them,” Park Ranger Bill Faulkner said.

The island fox is the largest mammal native to the Channel Islands. They are descendants of the gray fox found on the mainland. However, due to limited nutrition on the isolated island they are just one-third the size.

Usually weighing around four to five pounds, the island fox is similar in size to a house cat and just as social. Unlike mainland foxes, island foxes are not nocturnal and are seen throughout the day and are friendlier towards humans.

The foxes were brought to the island by the Chumash Native American tribe that was native to the Channel Islands and traded among the islands. The Chumash revered the foxes and considered them to be sacred.

After a land survey, the park service concluded that from 1995 to 2000 the three subspecies of island foxes populations on the islands had declined by as much as 95 percent due to disease, but mostly predation from golden eagles. Action needed to be taken and that’s exactly what the park service did.

The island foxes, which are endemic or native to San Miguel, Santa Rosa, Santa Cruz Island that are a part of the Channel Islands, were listed as a federal endangered species in 2004.

The park service’s first plan of action was to remove the golden eagles, which were responsible for the majority of the decline in foxes on the islands. The golden eagles were captured and relocated to a more suitable environment on the mainland so that they could not prey on the foxes.

The removal of the feral pigs that populated the island was essential as well because it was the pigs that initially attracted the golden eagles.

At right and below, restoration efforts have increased the numbers of the small fox found in the Channel Islands National Park (Photo courtesy of Channel Islands National Park).

To the advantage of the islands ecosystem, in 2002 the Institute for Wildlife Studies re-introduced bald eagles to the area. In 2006, Santa Cruz hosted the first two successful nests of bald eagles in over 50 years. Bald eagle breeding on the islands was eliminated in the mid-1950s due to the effects of spraying organochlorine chemicals or DDT.

With bald eagles back on the islands, their highly territorial behavior prevents golden eagles from colonizing the islands.

To protect remaining foxes from mortality and increase the low population, a captive breeding program was started on the three islands.

Captive breeding is the process of breeding animals in human controlled environments with restricted settings, and eventually a release of the animals into the wild when the threat to the species is lessened.

The foxes were kept in pens on each of the three islands upon which they were captured.

“We decided not to bring them off the islands in case of diseases,” stated Tim Coonan, who is the wildlife biologist for the Channel Islands National Park and in charge of the island fox recovery.

In 1999, the 15 foxes left from San Miguel and the 14 from Santa Rosa went into captivity. A year later, less than 70 were captured on Santa Cruz.

With more than 10 years of captive breeding and the removal and re-introduction of species to the islands to recover the natural habitats, the island fox population grew.

The foxes were released back into the wild beginning in 2003 and the last were released in 2008 with the San Miguel and Santa Rosa populations quadrupling due to the captive breeding.

Tim Coonan boasts that the captive breeding was very effective.

“They’re doing very well so far since their release into the wild.” Coonan stated.

As of the summer of 2010 the Channel Islands have collectively more than 1,700 wild island foxes.

The island that has witnessed the biggest recovery is Santa Cruz Island with an increase from less than 70 foxes in 2000 to more than 1,000 today. The survival rate for foxes on the island is an amazing 96 percent.

San Miguel has a population today of around 320 with survivorship of 94 percent. Santa Rosa however is experiencing slower population growth. It is the only island of the three still exposed to golden eagle predation.

According to the National Park Service, it may take San Miguel and Santa Rosa more than a decade to recover on the same level of Santa Cruz.

There have been few known mortalities due to the golden eagles, but the survival rate for foxes on the island has declined from 91 percent to a 61 percent today with a population of 390.

“On some islands there are only a few hundred but, in just six years, 15 to more than 300, less than 70 to 100? It’s pretty amazing,” Park Ranger Tara Brown boasts to a tour group on Santa Cruz Island. Brown has been a volunteer at the Channel Islands since 2005.

The increase in population among the islands has helped bring back the natural ecosystem of the area.

Visitors also get to see more of the foxes in their natural habitat.

“We’ve restored the balance in that area. The foxes were saved. You’ll see them running around.” Faulkner enthusiastically stated.

The island foxes road to recovery is still a work in progress.

Although populations have increased the foxes, especially on San Miguel and Santa Rosa islands are still under the threat of extinction.

Nonetheless, the recovery story of how man managed to save a declining species within a decade is celebrated throughout the Channel Islands National Park.

“They’re pretty much back in full force!” exclaimed Ranger Brown.

If You Go

Island foxes show peaks in activity at dusk and dawn. They are sometimes seen forage along the shoreline for crabs and marine invertebrates. They communicate by barking. They mark their territory with urine and scat and have been known to do so on well-traveled paths on the islands. They take shelter in dens in the ground for the protection of small pups.