It is an island fox (Urocyon littoralis). It is the only other species in the genus Urocyon besides the gray fox. It looks very similar to that species, but it is quite a bit smaller. The normal gray fox of the mainland weighs 8 to 15 pounds, while the island foxes weigh only 3 to 6 pounds. The island foxes have significantly shorter tails in proportion to their bodies than the mainland gray foxes do, which is one reason why they are sometimes called “short-tailed foxes.”
It is often claimed that the island fox is the second smallest of all wild dogs. Only the fennec fox is more diminutive. However, I have a little trouble verifying this claim, but I will say that the island fox is very likely the smallest canid in the New World.
The animals are found exclusively on the Channel Islands of California. Six of the eight islands have foxes, and each island has its own unique subspecies. Each is a little bit different from the other, but one of the main differences between the different subspecies is the number of vertebrae in the tail. They also differ in their markings.
The foxes are believed to have colonized the Northern Channel Islands 10,000 to 16,000 years ago. Lower ocean levels during the last ice age allowed the foxes a better opportunity to visit the islands in search of food. In fact, they weren’t really visiting the islands. The were visiting a single large island that now makes up the four northernmost islands.
As the sea level rose, the foxes from those three larger islands in the northern part of the archipelago became isolated from each other. The single large island had become four. Anacapa Island had no fresh water on it, so it could not support a population of island foxes.
Okay. That explains how the foxes got to the northern islands.
But what about the southern islands? After all, those islands aren’t very close to those northern islands that the foxes first colonized.
Well, there is a thing about animals that evolve on islands. If there are few major predators, the animals become very docile and curious. There simply is no reason to be scared of anything. It is a dangerous development, of course, because one can easily make a list that have either gone extinct or are endangered simply because they evolved into fearless and docile creatures.
Island foxes are a good example of what wild dogs are like when they evolve without persecution from man. Unlike wild gray foxes on the mainland, these foxes are not extremely afraid of people. Most wild dogs, if not victims of generations of persecution, are actually quite curious about our species. For some reason, we catch their fancy, even if it is just an excuse to beg food.
These foxes had a relationship with the Native Americans who lived on the islands. They were most likely kept as pets, and the foxes were then carried from island to island. It is believed that these foxes colonized the southern islands through human introduction.
The San Clemete fox began to separate into its own subspecies in the past 3,000 to 4,000 years. The San Nicolas subspecies is believed to be only about 2,000 years old, and the Santa Catalina subspecies is the most recent. It may have evolved as recently as 800 years ago.
The foxes are critically endangered. Introduced species have had a negative effect on the island fox population. Cats compete for the foxes for food. Grazing animals have diminished some of the foxes’ habitat. The grasslands and the chaparral are not exactly as they once were. The land is now much more eroded, and the foxes are more exposed than they once were.
Among these grazing animals are a herd of bison that a Hollywood film crew introduced as living props in a Western that was filmed there. The status of these animals is quite controversial. Virtually all orthodox conservationists want them removed. However, the tourists love them, and because tourists love bison and tourists bring money, the bison remain.
The real problem these foxes face comes from predation from golden eagles. On the northern islands, the number one reason for fox mortality is the golden eagle.
Yes, and we know that golden eagles are a protected species. And they are native to California.
The foxes have thrived on their islands when there were tons of golden eagles in the vicinity.
Why would the foxes now suffer from golden eagle predation?
Well, the answer has to do with several actors on the island ecosystem.
Originally, golden eagles almost never came to the Channel Islands. Those islands don’t have enough prey to tempt them from the mainland. Furthermore, the islands were home to bald eagles, which do not tolerate golden eagles near their nests. Bald eagles eat mostly fish and were no major threat to the foxes.
When the bald eagle population crashed last century, the golden eagles didn’t have to worry about intruding on their territories anymore.
However, they still did not start colonizing the islands until the golden eagles discovered that there were large numbers of feral pigs on the island. Feral piglets are a good food source for a bird of prey, and they soon colonized the island, living almost exclusively on piglets. However, they occasionally caught foxes, and because the foxes had evolved without much selective pressure from predation, even just a little predation has proven disastrous.
Conservationist have tried to mitigate these problems by killing off of feral pigs, but the eagles still persist. It is now believed that the only way to take care of this problem is to remove the golden eagles from the islands.
And then there is the problem with the San Clemente loggerhead shrike. This is an endemic subspecies of the very common “butcher bird” of the mainland. However, it has suffered greatly from introduced species. Rats and feral cats have taken their toll on shrike numbers.
Island foxes also raid their nests, so it is been decided that something must be done to prevent the foxes from preying upon shrike nests.
Because the foxes are critically endangered, it was decided to use non-lethal methods. The most successful of these involved the use of e-collars. The foxes were all captured and fitted with the collars. Whenever, a fox approached a shrike nest, it would be shocked. Very quickly, the foxes learned to avoid the areas where shrikes were nesting.
Everything about these foxes has proven to be unusual and complex. Not only do they own their current distribution to the actions of man, they currently owe their survival to our understanding a complex island ecosystem. We are only just now figuring out how to do it, and even then, it is a daunting challenge.
But we will get there.
Let’s hope so.
Any time we are dealing with the genus Urocyon we must remember that we are looking at a living fossil. Both species in the genus represent what is generally believed to the be one of the oldest– if not the oldest– extant form of wild dog. They have many primitive traits, not the least of which is their ability to climb trees almost as well as any cat.
I should also note here that the island fox is thought of as a separate species from the more common gray fox for some rather interesting reasons. It has not been reproductively isolated from the mainland very long. Indeed, they can still crossbreed, and it was recently found that the island fox has nearly identical mtDNA sequences with the gray foxes of Southern California.
Its status as a full species bothers me a bit.
This is particularly true, when you understand that I am adamant that dogs and wolves represent a single species. The differences between an island fox and a gray fox are nothing compared to the differences between a chihuahua and an arctic wolf.
Dogs and wolves separated a long time ago– much longer than the paltry 10,000 years that exists between mainland gray and island foxes. The original mtDNA studies found that they separated over 100,000 years ago. Current consensus now says that this happened anywhere from 15,000 to 40,000 years ago. That’s still alonger than island foxes have been separated from their mainland cousins.
This gets even more interesting. If one takes into account how widely distributed the mainland gray fox and how variable it is in appearance, then one could see that there might be room to count the island gray fox as a subspecies.
Keep in mind that the gray fox is very widely distributed. Its range includes areas in Canada very close to the US border, and from there, its range extends south through Mexico and Central America to Colombia and Venezuela. Most people are unaware of the gray fox’s wide distribution.
And throughout its range it varies in appearance. The smallest individuals are half the size the largest ones.
So one could theoretically put the island fox within the same species as the gray fox. It would fit nicely with the diversity that exists within that much more common species.
However, it is also useful to understand the island fox as a species. It has a very different lifestyle than virtually all of its mainland cousins. It lives on an island where it is the largest mammalian predator. It has evolved without significant predation as a selective pressure on its behavior.
Behaviorally and ecologically, it is quite unique.
And thus, I am still conflicted about how I would classify this animal.