Unique As An Island Fox

We talk about the island fox being a unique and rare species, but what do we mean?

Unlike most North American fox species, the island fox (Urocyon littoralis) lives in very small, isolated habitats. Because each subspecies of island fox is limited to its specific island, all are restricted by geography to small populations. The smaller islands–San Miguel and San Nicolas–can only support a maximum of 400–500 individual island foxes. The largest two islands–Santa Cruz and Santa Catalina–appear able to sustain 2,000–2,500 individuals. Even at their maximum, these are small vulnerable populations. Current status

Island foxes are descended from one of the most, if not the most, ancient of living fox species, the gray fox (Urocyon cinereoargenteus). (island fox beside gray fox). As such, island foxes maintain some ancient traits that are shared with felines and other carnivore species, but not with other more modern canines–like wolves and red foxes.

Island foxes can rotate their front paws to climb. It is not unusual to see them up in small trees or large shrubs.

During captive breeding efforts to save island foxes from extinction, it was discovered that females do not go into a seasonal breeding heat. Female island foxes only have a hormonal surge and ovulate after contact with a male. This is called induced ovulation. Island foxes are the only known canine species to exhibit this reproductive trait, which is typical of cat and bear species. It is a primitive trait of Order Carnivora. This trait is most likely true for gray foxes, but because they are numerous in the wild, their reproduction has not been closely studied.

While the island fox evolved from an ancient canine lineage, it is a recently evolved species. Mitochondrial DNA places the island fox splitting away from the gray fox ancestor approximately 9,000 years ago.

Island foxes are the smallest fox species in North America. (island fox vs. fennec) Their small size is the result of island dwarfism. They also are impacted by island syndrome: changes in behavior and characteristics that have evolved over time due to the conditions in their island environment.

Island foxes are more active during the day than most gray foxes, because they lack a natural predator on the islands.

Resources on the Channel Islands are limited. Therefore, island foxes are highly omnivorous and eat a range of native fruits.

Living in a limited area, they sometimes experience higher density than most other fox species (more individuals living per square kilometer). Island foxes can be more accepting of other foxes in their territory during some parts of the year, but display higher levels of aggression and territoriality toward other foxes during breeding season. Observing island fox behavior

Island foxes have shortened tails. The number of vertebra in the tail ranges from 15–22 (depending on the subspecies). The cause or benefit for this adaptation remains unknown.

Perhaps the most unique trait of island foxes is their long and close relationship with humans. Living on the Channel Islands for thousands of years with indigenous peoples and then generations of ranchers, island foxes are habituated to people. They are wild creatures that are comfortable in the company of people. It is an amazing experience to share trails on the island with these bold little foxes. Step aside and they walk right past you.

 

In the following weeks we'll compare California's other fox species with the island fox.  

Series installments:

Red Fox: Life on the Edge

Gemini Foxes: Kit Fox and Swift Fox

Arctic Fox: Fox of the Tundra

The Island Fox's Origin - The Gray Fox

References

Coonan, Timothy J., Catherin A. Schwemm, and David K. Garcelon. 2010. Decline and Recovery of the Island Fox. Cambridge, UK: Cambridge University Press

Wang, Xiaoming and Richard H. Tedford. 2008. Dogs: Their Fossil Relatives & Evolutionary History. New York: Columbia University Press

 

 

Fox Foto Friday - Island Foxes in the Wild

an island fox during March on Santa Cruz

It's hard for people to believe that you can easily see an island fox in the wild on Santa Cruz Island. This island fox was walking across the dirt road near the visitor center. It was happy to give us time to take its photo.

The unique relationship between island foxes and people began around 9,000 years ago. The Chumash and other native peoples living on the islands regarded the island fox as an important neighbor. They did not hunt the island fox or confine it as a pet.

People are surprised when they view wild island foxes going about their daily lives with little regard for the human visitors. Maintaining this relationship means respecting the island fox and its right to live safe from threat or interference on its island home.

When Visiting Island Foxes
More on Santa Cruz Island 

Island Fox Summer Puzzle

The story of the island fox is all around you on the Channel Islands. Below is a collection of items found along the beach and trails of Santa Cruz Island during a Friends of the Island Fox's trip to see the island fox. Can you identify these items?

photo courtesy of Judy Millner

Island foxes do not swim in the ocean, but they will scavenge dead animals that wash ashore. Can you find the kelp crab carapace, mussel and two different clam shells, and remnants of a harbor seal (vertebra and half of a pelvis bone)?

DDT impacted bald eagles living on the Channel Islands. Their extinction led to a change in the natural balance which ultimately threatened island foxes. The brown pelican was also impacted by DDT in the marine environment. Fortunately, the brown pelican population has recovered because of conservation measures.  Find two hollow pelican bones. Native peoples used these bones to make flute-like instruments.

Native people have intermittently lived on the Channel Islands for over 12,000 years. The Chumash people have had a long and valued relationship with the island fox. Another island resource they valued was soapstone. Find this soft, colorful stone that was carved into a variety of items. 

Island foxes do not typically eat sea urchins, moon snails or wavy turban snails. However, these kelp forest creatures depend on a healthy island ecosystem to minimize erosion that would dump silt into the clear water surrounding the islands. This tidal area is a vital habitat for sunlight-dependent kelp forests. The island fox helps reduce island erosion by being the largest seed disperser for the island's fruiting plants. Find these sea creatures that need the island fox: three sea urchins, one moon snail and two wavy turban snails.

While the hard shell-like tunnels of the calcerous tube worm might smell interesting to an island fox, these worms live in the ocean filtering small particles of food from the water. They build their tunnels on tidal rocks and frequently on man-made docks. Find the two structures made by calcerous tube worms.

Since the mid-1800s, people have had a big impact on the Santa Cruz Island ecosystem. Find all of the items related to modern people: eucalyptus (introduced plant), concrete (from buildings), lower limb bone (canon bone) of an ungulate (sheep, goat or pig, all introduced animals), jaw bone of a pig, and a piece of molded fiberglass. 

Answers below:

• kelp crab (1), mussel and two different clam shells (10), and remnants of a harbor seal (5)
• two hollow pelican bones (8)
• colorful soapstone (9) 
• three sea urchins (2), one moon snail (13) and two wavy turban snails (12) 
• calcerous tube worms (14) 
•  eucalyptus (3), concrete tumbled in the ocean (11), lower limb bone of a sheep, goat or pig (6), jaw bone of a pig (7), a piece of molded fiberglass (4)

Hats Off to Foxes!

Endangered Channel Island foxes have friends across the United States. 

For the second year in a row the Fort Collins Colorado Foxes are bringing awareness about the endangered island fox to fans in Colorado. The Foxes are part of a summer Mountain Collegiate Baseball League. Last year the team helped FIF reach our goal to inoculate 400 island foxes against the distemper virus.

 This year, when: 

the Fort Collins Foxes meet the Boulder Collegians

on June 15th in Fort Collins, CO

the team will raffle off a replica Major League jersey to raise funds to help support microchipping 250 young island foxes.  (More on June 15 events and the drawing)

If you can't attend the game you can still support foxes by wearing one of the many styles of Foxes' baseball caps. When you purchase a Foxes baseball cap on-line, the team will make a 15% donation to Friends of the Island Fox. 

So raise your hats to the Fort Collins Foxes!

The Channel Island Fox and People

Island foxes have a long history with people.  We don't know for sure how island foxes first arrived on the Channel Islands. There are two basic theories:

1. Gray foxes were stranded on the northern islands during the ice age when water levels were lower and the distance from the mainland to the islands was approximately four miles. The water level was low enough that San Miguel, Santa Rosa, Santa Cruz and Anacapa were one big island. Other animals like mammoths swam over to the island and lived there as well. Over thousands of years both the island fox and the mammoth adapted to smaller territory and less resources on the islands and became dwarf in size.
2. Native Americans transported mainland gray foxes out to the islands and over a few thousand years the species evolved to be the island fox.

There is very little fossil evidence of foxes on the islands. Scientists are currently evaluating 6,000-year-old-fossil fox bones found on the northern islands to determine if they are island fox bones or bones of the ancestral gray fox. If the DNA shows the remains belonged to an island fox then it is more likely that this island species was on the Channel Islands before humans arrived in North America.

For at least several thousand years, island foxes interacted with the island communities of Chumash people. On Santa Cruz Island, Chumash villages existed in the areas of both Scorpion Anchorage and Prisoner’s Harbor. Over time, these native people transported island foxes to the southern islands of Santa Catalina, San Clemente and San Nicolas.

The island fox was not a pet, it was a wild animal that lived side-by-side with the native people. Images of island foxes appear in rock art on Santa Catalina Island and archeologists have found ancient ceremonial burials of island foxes in several locations.

Island foxes lived on San Nicolas Island with the Lone Woman whose story was told in the novel “Island of the Blue Dolphins” by Scott O’Dell. The facts of this classic story of survival are gradually coming to light. Archeologists have recently found the cave on this treeless, windswept island where the woman found shelter. L.A. Times article

treeless San Nicolas Island, one of the California Channel Islands

As more artifacts are uncovered, we may finally know who this woman was and what interactions she had with animals, like the island fox, that shared the island with her.

Today, campers and day visitors are interacting with the island fox. When you stop and watch an island fox, you are a time traveler seeing what native people saw thousands of years ago.