What You Should Know About The Precarious Existence Of The Channel Island Foxes

Roughly the size of a house cat, the Channel Island foxes are barely back from the brink of extinction. A recent study by researchers from USC reveal the recovering populations lack genetic diversity, leaving them more vulnerable to environmental changes.

Meet the little local foxes  

The Channel Islands off the coast of Southern California are home to six unique species of petite fox. On each island, they've evolved differently in size, color and biology. On average, they’re about 4 to 5 pounds with a brown and gray coloration.

They're also incredibly cute.

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A Channel Island fox poses in front of brush.

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U.S. Navy

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U.S. Navy

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“Its a dwarf species small fox that descends from gray foxes on the mainland,” said Suzanne Edmands, who is a professor of biological sciences at USC and senior researcher on the study.

“We used to think they got there on their own by swimming or rafting 16,000 years ago," she said, "but DNA and isotope data suggest might have been more recent and they may have been brought there by native peoples maybe 7,000 years ago.”

They live on six of the eight Channel Islands; Catalina, San Nicholas, San Clemente, Santa Rosa, and San Miguel.

Edge of extinction to impressive recovery 

By the late 1990s, the populations on four islands were near extinction — for different reasons. Some Channel Island fox populations fell to as few as 15 foxes, according to Edmands.

On Catalina, foxes were dying from canine distemper suspected to have spread from raccoons, while the foxes on the three northern islands were being eaten by golden eagles.

“And the golden eagles came in because of introduced sheep and pigs and goats, which the golden eagles eat in addition to foxes,” said Edmands.

Another factor: Bald eagles usually compete with golden eagles, but they were dying from DDT poisoning, so golden eagles were unfettered.

In 2004, the Channel Island foxes received federal protection under the Endangered Species Act. After 12 years of conservation efforts, which included captive breeding and programs to reduce predators, the Channel Islands foxes populations recovered enough to move into threatened rather than endangered status.

Federal officials say Channel Island foxes made the fastest recovery for any mammal listed on the endangered species list.

Future challenges

A Channel Island fox stands in profile with the ocean behind it.

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National Park Service

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National Park Service

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Edmands and Nicole Adams, who was a doctoral student at the time, looked at the foxes’ genomes to determine if genetic diversity had recovered along with the population.

The short answer: It did not. And that’s a problem for the animals’ survival if changes are introduced into their environments such as drought, wildfire, climate change, and new pathogens.

“There's also already evidence that fox populations have higher risk of cancer,” Edmands said. “There's been an increase in ear tumors on Catalina Foxes since the population crash ... possibly related to changes in genetics that happen just by chance when the population numbers declined.”

Edmands added there may be a connection between ear mites and the cancer.

How to help the foxes survive

It could take millions of years for genetic diversity to naturally return to where it was before the fox populations declined. Edmands said one possibility is genetic rescue, where foxes are swapped from different islands.

“It's been successful in some cases but the concern is that these fox subspecies, they're different,” she said. “And so moving them, mixing them like that could disrupt local adaptation on the different islands.”

Other strategies include vigilant population monitoring and administering medical treatment such as vaccines and medicines for potentially cancer-causing ear mites.

Also, controlling competitor populations such as stray cats, and keeping down predator populations like golden eagles by reducing the livestock that attracts them to the fox’s habitat.

What you can do

And lastly, follow the rules when visiting the Channel Islands to help protect these adorable little foxes. On the islands that make up the Channel Islands National Park , those include:

• Do not feed, collect, disturb, or harm park wildlife, plant life, or other natural and cultural features.
• Hike only on designated trails.
• Remove your garbage and secure your food.
• No fishing within marine reserves.
• No pets: Domestic house pets can carry diseases that could harm the rare island fox or other animals that are unique to the islands.

Read on for all the park rules.