Friday, February 26, 2021

Gemini Foxes: The Kit Fox and Swift Fox

Santa Cruz Island fox

In the first installment of Foxes of North America we introduced you to the beautiful and intelligent red fox, a fox that prefers to live on the edge and is very different from the island fox.

Here we'll take a quick look at the kit and swift foxes. Don't be fooled by their general appearance–they are not island foxes.

According to J. David Henry in his book Foxes: Living on the Edge, "The kit fox and the swift fox are the Gemini foxes of North America," because they share many physiological and morphological similarities. Kit and swift foxes inhabit the arid regions of North America and are adapted to habitats with relatively open vegetation.


Kit Fox, photo courtesy of CA Fish & Wildlife

Kit Fox

Kit foxes are native to the desert and semi-arid shrublands and grasslands of the southwestern US, including parts of Oregon, Colorado, and northwestern Mexico. They are a small fox species with a slender appearance, 5 pounds on average. Their coat is grizzled to tawny gray with buffy highlights on the neck, sides and legs. Their face has a typical "foxy" appearance, except for their ears, which are much longer than those of any other North American canid. This adaptation may help them dissipate body heat in the desert and could help them hunt insects and mice. To protect their feet from the hot sands, kit foxes have considerable hair between the pads, forming a kind of "sand shoe." Kit foxes are often confused with gray foxes because their ranges overlap, but kit foxes can be distinguished by the lack of a black ridge running the length of the tail as well as by their large ears.

The scientific name is Vulpes macrotis, which translates to "big eared fox."

San Joaquin Kit Fox, photo courtesy Tory Westall, ESRP - CSU Stanislaus

Kit foxes are opportunistic foragers that rely heavily on rodents and insects for sustenance. Kangaroo rats, pocket mice, and ground squirrels are common rodent prey. Like island foxes, kit foxes also consume beetles and grasshoppers. Kit foxes are also known to consume rabbits, birds, reptiles, and a variety of non-insect invertebrates

A unique feature of both the kit fox and the swift fox is the continuous use of underground dens throughout the year. Other canid species, including the island fox, use underground dens only during pup season. The Gemini Foxes clump their dens in suitable habitat and use them to provide critical protection from predators and shelter from extreme temperatures in desert summers and northern winters.

The San Joaquin subspecies of kit fox (V. macrotis mutica), which is restricted to the San Joaquin Valley and adjacent valleys in California, is currently listed as endangered under the Endangered Species Act. The kit fox is also listed as endangered by the State of Colorado and as threatened by the State of Oregon. The most serious threats include habitat loss and declining habitat suitability due to invasion of non-native grasses.

Swift Fox, photo courtesy K. Schafer

Swift Fox

Swift foxes primarily occur in the short and mixed-grass prairies from New Mexico and Texas north to southern Canada. Similar in size and appearance to the kit fox, the swift fox is pale yellowish-red and grey, with a thick grey stripe down its back that extends to its black-tipped tail. Its underside is lighter in color, and it has black patches on either side of its muzzle. You can distinguish swift foxes from kit foxes by the swift fox's smaller and rounder ears. Also, the swift fox's tail is shorter in relation to its body size than that of the kit fox.

Their scientific name is Vulpes velox, which simply translates to "swift fox."


Swift Fox, photo courtesy Gordon Court

Swift foxes are resourceful foragers, with a varied diet that includes small mammals, such as prairie dogs, birds, insects, plants and carrion. To reduce risk of predation by coyotes, swift foxes avoid areas with high prey density, such as areas of high plant diversity. They prefer open habitat where visibility is greatest.

Once abundant throughout their range, swift fox populations began to decline in the late 1800s due to rodent and predator control programs and the plowing of prairie into cultivated crop fields. As a result, the species is currently recognized as a species of conservation concern over much of its range. In Canada, the swift fox was gone or extripated by the 1930s. However, in 1983, a privately run program began breeding swift foxes in captivity in the US so that they could eventually be reintroduced back into the wild in Canada. Experts from this captive breeding effort provided advice for the captive breeding of island foxes in the early 2000s. While swift foxes are still classified as endangered, the swift fox's return is one of the most successful species reintroduction stories in Canada, just as the island fox's recovery is hailed as a success in the US.

Coming up next is the Fox of the Tundra: Arctic Fox

For additional information on the San Joaquin Kit fox visit:


Butler, Andrew R., Kristy L.S. Bly, Heather Harris, Robert M. Inman, Axel Moehrenschlager, Donelle Schwaim, and David S. Jachowski. May 22, 2020. "Home range size and resource us by swift foxes in northeastern Montana." Journal of Mammalogy, vol. 101, (3), pg 684–696. Accessed at:

Cyper, B.L. 2003. "Foxes (Vulpes species, Urocyon species and Alopex lagopus)." In Wild Mammals of North America: Biology, Management, and Conservation, 2nd edition by G. Feldhamer, B. Thompson, and J. Chapman (eds), pg 511–546. Baltimore: Johns Hopkins University Press.

Elbroch, M. and K. Rinehart. 2001. Behavior of North American Mammals. pg 94–100. Peterson Reference Guides.

Harris, Heather (ed). July 2020. Swift Fox Conservation Team Report for 2017–2018. Montana: Montana Fish, Wildlife & Parks Glasgow.

Henry, J. D. 1996. Living on the Edge, Foxes. Minocqua, WI: Northword Press. 

Kelly, Erica C., Brian L. Cypher, and David J. Gemano. 2019. "Temporal variation in foraging patterns of Desert Kit Foxes (Vulpes macrotis arsipus) in the Mojave Desert, California, USA." Journal of Arid Environments, vol 167, pg 1–7. ISSN 0140-1963.

Meaney, C.A., M. Reed-Eckert, and G.P. Beauvais. August 21, 2006. Kit Fox (Vulpes macrotis): a technical conservation assessment. USDA Forest Service, Rocky Mountain Region. Accessed at: 



Friday, February 19, 2021

Not All Foxes Are The Same - Red Fox vs. Island Fox

Santa Cruz Island fox
Foxes are small- to medium-sized members of the dog family that are found throughout the world. In North America there are six species of fox: Red Fox, Gray Fox, Kit Fox, Swift Fox, Arctic Fox, and of course, the Island Fox. Foxes are the smallest of the North American wild canids, the others being wolves and coyotes. Foxes are very intelligent and adaptable. They occupy varying landscapes across the continent from the vast Arctic tundra to the desert scrub land of the American southwest. From the wind-swept prairies to the boreal forests, the foxes of North America have carved out a niche as specially adapted predators of small prey. 

In the first of a multi-part post on different foxes, we'll introduce you to the Red Fox.


European red fox

Life on the Edge: Red Fox

The red fox is the most widely distributed land carnivore on the planet, with a range covering more than 28 million square miles. By contrast, the San Miguel Island fox has a very small range: only 24 square miles. Red foxes occupy five of the seven continents, including Australia, where they were introduced by English settlers in the 1800's. Only South America and Antarctica are free from these adaptable animals.

The scientific name for the red fox is Vulpes vulpes, the "fox's fox," which is fitting since most people conjure up an image of the red fox when asked about foxes. (Island fox's scientific name.) The presence of red foxes all over the world has led to their appearance in pop culture and folklore as people are readily drawn to this beautiful and cunning creature. More than any other canid, the red fox has received positive representation in literature and film. Aesop's Fables contain numerous tales of foxes. Disney's The Fox and the Hound tells the story of two unlikely friends, a red fox named Tod and a dog named Copper. To indigenous tribes of North America, the fox is a spiritual animal with different meanings across cultures–from a clever trickster to being associated with intelligence and wisdom.

Tod fox from Disney's The Fox and the Hound

Red foxes are the largest of the North American fox species, with a long, bushy tail, a narrow pointed muzzle, and thick soft fur. Their legs are slender with black fur covering the feet, nose, and the back of their erect, pointed ears. The coat of the upper body, head, and tail are bright red to yellowish-red. The tip of the tail is white. Adults are approximately 36–42 inches in total length and their tail accounts for slightly more than one-third of their length. Most adults weigh 10–11 pounds, as much as three times the size of an island fox.

Sacramento Valley red fox; photo courtesy Ben Sacks/UC Davis

Red foxes prefer habitat along edge environments where two habitat types meet, such as the intersection of open meadows and woodlands. In the west, red foxes are primarily found in higher, sub-alpine elevations. In California there are two native sub-species, the Sierra Nevada red fox and the newly described Sacramento Valley red fox. These two native red fox populations are small and geographically isolated (like being on an island). The study of island fox populations has played an important role in helping biologists evaluate the vulnerability of these red foxes to survive into the future.

Red foxes thrive near human settlements, most likely due to the protections humans provide against the foxes main predators: coyotes, bears, and mountain lions.

Red foxes are primarily active at twilight and night, although they may be seen during the day when foraging to feed their young. While omnivorous, their diet consists primarily of rodents, including voles, pocket gophers, and deer mice, as well as cottontail rabbits, jackrabbits, and snowshoe hairs. Like island foxes, red foxes readily eat fruits when they are in season. In some areas, fruits make up 100% of their diet! They commonly consume blueberries, blackberries, and raspberries, as well as apples, grapes, and even acorns.

Like many canids, North American foxes are basically monogamous, and the red fox is no different. Mating occurs between December and April. Pups are born between April and May. (Similar to island foxes.) The typical litter size is 3–6 pups. The male initially participates in feeding and rearing the kits, but moves on as the kits mature.

Red foxes are an adaptable and successful species. They have been extensively studied and their populations are stable apart from the two California sub-species. These beautiful animals extrude the cuddle factor more than any other fox species. (Well, except maybe island foxes.)

San Clemente Island fox
How is the Island Fox Unique?

Coming up next: Gemini Foxes: Kit Fox and Swift Fox;


Cyper, B.L. 2003. "Foxes (Vulpes species, Urocyon species and Alopex lagopus)." In Wild Mammals of North America: Biology, Management, and Conservation, 2nd edition by G. Feldhamer, B. Thompson, and J. Chapman (eds), pg 511–546. Baltimore: Johns Hopkins University Press.

Elbroch, M. and K. Rinehart. 2001. Behavior of North American Mammals. pg 105–111. Peterson Reference Guides.

Henry, J. D. 1996. Living on the Edge, Foxes. Minocqua, WI: Northword Press.

Saunders, D. A. 1988. "Red Fox: (Vulpes vulpes desmarest)." In Adirondack Mammals, pg 216. New York: State University of New York, College of Environmental Science and Forestry.


Friday, February 12, 2021

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. See Red Fox; See Kit Fox and Swift Fox 


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



Friday, January 29, 2021

Fox Foto Friday - Island Foxes Healthy Inside and Out


While we're all stuck at home, the word from the islands is that island foxes are thriving. Across the Channel Islands biologists are reporting healthy looking individuals and a fair number of pups.

2020 was a normal rain year with a hot summer. Populations may have adjusted down from the record highs of 2019, but that is to be expected. The rains across the islands this week, will help increase resources for island foxes throughout 2021. What do island foxes eat?

During 2020 health checks, island foxes on Santa Cruz, Santa Rosa, San Miguel, San Clemente, and San Nicolas joined their cousins on Santa Catalina by being swabbed for their microbiome. Samples have arrived at the lab for DNA analysis. Find out more about Dr. DeCandia's island fox microbiome research.

To survive into the future, island foxes need to be healthy inside and out. That's why FIF is helping investigate the biodiversity in the microbes and bacteria on their skin and throughout their bodies.

Friday, November 20, 2020

Fox Foto Friday - A Slice of Fox Science

What is it?


This is a microscope slide with thin slices from the canine tooth of a deceased island fox. 

Researchers Stacy Baker and Juliann Schamel are looking at these thin slices through a canine tooth to see if they can discern annual growth layers. If so, this could provide an accurate way to age island foxes at death. Why is that important?

The sample slides from individual island foxes have come back from the lab in Montana. See more on the process and the annual layers.

Baker and Schamel will be analyzing the specimen slides from individuals with known ages. If the layers align with known ages, they will look at the specimens from individuals like M152 to try and determine how old these individual foxes were at death.

This important work is funded by Friends of the Island Fox through a grant from Safari West.

More about island fox research funded by Friends of the Island Fox and donors like you.

2020 FIF Research Grant recipient 

What We Do - FIF Research projects

Tuesday, October 20, 2020

FIF Research Grant to Investigate Diversity of Island Fox Microbiome

Friends of the Island Fox is happy to announce Alexandra DeCandia, Ph.D. is the recipient of FIF's 2020 Research Grant.

You may remember DeCandia's article from April 2020 regarding her doctoral work at Princeton University: Mites, Microbes, and Cancer in Santa Catalina Island Foxes. Microbes can be found on the skin, in the digestive system, and in connection with the body's openings.

A healthy animal has a diversity of microbes. In this way, a single island fox is like an island. If something should happen to the biodiversity of microbes on an individual, the ecosystem on that individual might become out of balance. Some microbes might thrive, while others perish. An imbalance of microbes can impact an animal's overall health.

When island foxes on a specific island go through a near-extinction population bottleneck, there is a potential for a loss of microbe diversity that can be passed on to surviving island foxes. 

DeCandia investigated if there was a connection between the diversity of microbes on Catalina Island foxes and an unusual prevalence of cancer in this subspecies.

Looking into island fox ear canal

What she found was "evidence of disrupted microbial communities in mite-infected ear canals that may contribute to sustained inflammation." Inflammation can play a role in cancer and this microbial imbalance may be connected to why Santa Catalina Island foxes are the only island foxes known to develop cancerous tumors in their ear canals.

DeCandia's work was published in Molecular Ecology and when she presented her findings at the Annual Island Fox Conservation Working Group Meeting in May of this year, everyone was intrigued. A healthy microbial biome is vital to healthy digestion, immune response to disease, behavior, and even development. Because island foxes on five islands have been through population bottlenecks, where the number of surviving individuals was very low, there is a potential that island foxes on other islands may have disrupted microbial communities as well.

As island foxes are counted and given health checks across the islands this year, they are also getting swabbed for microbes in their ear canals and at their anuses. DeCandia describes the process as "similar to cleaning your ears with a cotton swab, except you don't throw away the swab afterwards." The swab samples will be sent to DeCandia at the Smithsonian Conservation Biology Institute in Washington D.C.



DeCandia in the lab

FIF Research Grant funding will be used to extract DNA samples and process DNA sequencing to identify the various microbes in island fox ear canals and digestive systems. 

This investigation provides a unique opportunity to do comparative analyses between subspecies of island foxes on different islands. DeCandia hopes to:

  1. survey variation of microbes within island foxes on each island
  2. characterize the differences between islands
  3. identify the drivers of ear canal tumors on Santa Catalina Island

This work is at the cutting edge of science and may have important consequences for the long term survival of the island fox.

If you are an FIF donor, 

you are making this important work possible.


If you haven't donated yet, Please Donate 

This is Science, For Fox Sake!


Sunday, October 11, 2020

Remember This Fox Face? - Fox Foto Day

 Do you remember this island fox face? 


This is F257–a female island fox on Santa Rosa Island. She first started wearing a radio-tracking collar (funded by FIF) last December when she was captured as a youngster.

In 2020, F257 is 18 months old and a mature female. It surprised everyone when she was caught in the exact same place she was found last year. This means she didn't disperse, or travel away, from her parents' territory.

It is typically expected that island fox pups will move away to find their own territory as they mature. Female offspring sometimes stay close to their parent's territory and that seems to be what F257 is doing.

She is looking healthy and happy in her territory adjacent to the coastline.

Friends of the Island Fox sends a "Hello" and "Thank You" to the biologists working across the Channel Islands. They are finishing up health checks and annual island fox counting. FIF is hearing good news from the field. Individual island foxes look healthy and populations appear stable.

Radio collars, like the one F257 is wearing, provide an important conservation monitoring system that provides an early alert system regarding threats to island foxes.

Your donations help to fund radio-tracking collars for island foxes.

Saturday, September 26, 2020

Friends of the Island Fox Welcomes New Board Member: Lara Brenner

Friends of the Island Fox is thrilled to welcome Lara Brenner to its Board of Directors.

Lara is a wildlife biologist and scientific writer who has been working with island foxes on Santa Catalina and Santa Cruz Island since 2017. She has a degree in Environmental Studies from Carleton College and a Master of Science in Wildlife Biology from the University of Montana.

FIF worked with Lara on the testing of ticks on Catalina Island and efforts to slow down traffic to save island foxes from being hit by vehicles.

She brings the unique experience of working with island foxes in the field.

Lara says: Compared to most mesocarnivores, island foxes are a joy to work with. Their relative docility takes a lot of the uncertainty out of catching and handling them, while their curiosity and fearlessness inspire some truly cheeky behaviors (like trying to steal a bag of bait right out of your hand!).

First-time observers are often amazed to see an island fox sitting calmly on a biologist's lap with few restraints, and I've often heard the comment that they must know we're trying to help them. 

I think it's more an artifact of evolution - after around 10,000 years as the apex land predator, they have no concept that they could be in any danger from a larger mammal! Of course, island foxes are still wild animals and it doesn't pay to let your guard down. I wouldn't want to reach into a cage without my trusty leather gloves - a bite from an island fox is no joke!

FIF Welcomes Lara Brenner.

[What's a mesocarnivore? A medium-sized carnivore. (Think raccoon, bobcat, gray fox or feral cat.) Most medium-sized predators have to be feisty in order to catch their prey and also defend themselves from larger predators.]

Friday, August 28, 2020

Fox Foto Friday - It's Research

 It's Research For Fox Sake!


This is an up close image of tiny bits of island fox whisker in a mini aluminum specimen holder. The micro-sample of whisker is on it's way to a mass spectrometer for analysis. Find out more about Juliann Schamel's research project with FIF.

The deadline to apply for FIF's 2020 Research Grant is August 31, 2020. 

Grant Application information

We're looking for research to support!

Tuesday, August 11, 2020

Celebrating the Successful Recovery of the Island Fox

Once on the brink of extinction, the island fox now roams freely across the Channel Islands. It's a conservation success story. On the four-year anniversary of the official U.S. Fish & Wildlife Service announcement removing the island fox (Urocyon littoralis) from the Endangered Species List (ESL), foxes are stable in number and overall health.

Official numbers reported at May 2020 IFC  Working Group

In spite of the fact that this remarkable recovery is still celebrated today, conservation work is never completely done. Island foxes remain a conservation-reliant species. Threats still exist to the foxes from parasites, viruses, and human impacts as the islands are visited more and more each year. Keeping island foxes safe and healthy requires understanding of their diet, reproduction, lifespan, behavior, and disease threats.

On-going research doesn't just benefit the island fox. The lessons learned help other rare species as well. The Sierra Nevada red fox is benefiting from viable population modes that were developed for island foxes on Catalina. While not a one-to-one relationship, it is a reference that provides related information for another fox's demographic needs. It's science for Fox sake!


The power of partnership and focus can realize dramatic results and we have to look no farther than the group of islands off the Southern California coast. Today each spring fox kits are born as helpless little beings that would not survive without their parent's constant attention. In the course of six short months these tiny helpless creatures grow into self-sufficient cinnamon, gray, and black-colored predators that leave their birth den and seek out their own piece of the island. Those long summer days spent with their parents learning fox philosophy ensure the cycle, inherent in the fox's life, completes itself for the continued survival of the island fox. - Mike Watling

Friends of the Island Fox celebrates the recovery and continued success of the island fox with all of our donors, Island Fox Ambassadors, volunteers, and partners, especially:

Friends of the Island Fox is accepting applications for our 2020 FIF Research Grant through August 31, 2020. More info and application