November 30, 2004 - Foxy Ed

Edhat’s Endangered Species of the Month is the Island Grey Fox (Urocyon littoralis). Or as it is most commonly known, the Channel Island Fox.

Wild and crazy guys like American foxes, but the island fox is one of the rarest and most unique of all carnivore species. It is the only carnivore unique to the state of California.  Island foxes are distributed as six different subspecies, one for each of the six Channel Islands on which they occur (San Miguel, Santa Rosa, Santa Cruz, Santa Catalina, San Nicolas, and San Clemente). Foxes from separate islands are capable of interbreeding, but are physically and genetically distinct. For example, the number of vertebrae in the tail differs significantly from island to island. Subspecies are named for their island of origin (Santa Cruz Island Fox, San Nicolas Island Fox, etc.).

The Island fox has pepper-and-salt fur on the top with a buff colored under fur and a black stripe ending at the black tip of the tail.

Island foxes are omnivorous. Their diet consists primarily of fruits, insects, and deer mice. Occasionally, foxes forage along the shoreline for crabs and other marine invertebrates.

Island foxes mate for life, and breed only once a year. Kits are born in the spring. Litter sizes range from one to five kits, averaging just over two. Born in the protection of a den, pups are cute, blind, and helpless with short dark brown hair. They emerge from the den at about one month, but stay under their parent’s care for an extended period of time.  As with most wild canids, mom and dad both play an important role bringing up baby.

In 1993, the National Park Service began monitoring island fox populations.  In 1994, there were estimated to be over 400 foxes on San Miguel. But by 1995, an alarming decline had begun. Interestingly, the first documented decline on San Miguel in 1995 coincided with the first golden eagle sighting.  The decline continued, and by 1998, the San Miguel population was down to only a few dozen. Similar declines occurred on neighboring islands.

In 1998, taxpayer dollars funded two separate studies to determine the cause of island fox mortality.  The National Park Service studied the foxes on San Miguel Island.  The California Department of Fish and Game studied the foxes on Santa Cruz Island.  Both studies reached similar conclusions.

The main cause of the decline was determined to be predation by the golden eagles that had recently moved to the islands, thus replacing the island fox’s spot at the top of the food chain. Initially, the birds had taken up residence to hunt the island’s non-native pigs and sheep.  The golden eagles were able to survive in their new home because DDT and hunting had wiped out the native bald eagles.  Unfortunately for the foxes, not all eagles are alike. You see, while bald eagles eat mostly fish, while golden eagles prefer mammals.

The fox population also declined because of diseases and parasites.  Because of their insular existence, island foxes have little immunity to parasites and diseases.  They are especially vulnerable to those a domestic dog might be carrying. One year, on Santa Catalina Island, about 90% of the fox population was lost due to canine distemper virus.

A newcomer to the Endangered Species list, the island fox was federally listed on March 5, 2004. The National Park Service is attempting to slow the decline of the fox population on the Channel Islands. Among other action items, is the attempted reintroduction of bald eagles on the islands.  Hmm.  Remember the sheep and the pigs and the sea otters? As a prophetically wise margarine commercial once warned, “It’s not nice to fool with Mother Nature”.

The picture we showed in yesterday’s contest did not outfox many Edhat subscribers.  Fifty-three of them correctly identified the picture as either an Island or Grey Fox.  We sorted the winners by their handle and then pulled out a string of old Christmas lights from a box in our office. We knew that one bulb was out, and when we plugged it in, we found that it was the 36th bulb. The 36th name on our list was PoopiePants, who wins a 2005 Axxess Card and an Edhat t-shirt.

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