2021 Island Fox Status Update

All island fox populations are healthy and stable, but biosecurity and the potential of deepening drought raises concerns.

 

 

 

That is the update from the Island Fox Conservation Working Group meeting held May 18, 2021, which reports on the status of island foxes across the islands. The following information is taken from FIF notes taken at the meeting. Population numbers reported here are official estimates from each land manager as calculated from the 2020 counting period. (How are island foxes counted)

Overview: COVID-19 restrictions impacted human travel to the islands, but all islands were able to implement protocols to keep biologists and island foxes safe. Annual counting was delayed on some islands and research was halted temporarily, but all efforts were able to resume.

Following a year of normal rainfall in 2019, 2020's lower rainfall levels resulted in island fox populations on San Miguel, Santa Cruz, and Santa Catalina Islands adjusting downward within expected normal levels. Reduced resources, resulted in fewer pups being born, but adult survivorship remained high and the estimated number of foxes per square kilometer, or fox density, remained high (Miguel 7.4 foxes per km squared, Cruz 9.4, and Catalina 9.3). 

The major threats to island foxes in 2021 are:

• biosecurity: the threat of introduced viruses, disease, or nonnative animal species
• climate change impacts: increasing regional temperatures, decreasing rainfall, and prolonged drought, which reduces food resources, increases wildfire threats, and promotes parasites
• parasites: ticks, fleas, tick-borne diseases and intestinal parasites on some islands
  

How is Friends of the Island Fox helping Island Foxes? -video update

Greatest Concern

Santa Catalina Island foxes continue to maintain a stable population and fox density is high. However, an outbreak of canine distemper virus is currently impacting wild raccoons on the adjacent mainland. In 2020, a raccoon roamed Catalina's interior for several weeks until it was caught. The Catalina Island Conservancy reminded everyone that if distemper arrives on the island again, the high fox density could facilitate the rapid transmission of this fatal virus. FIF is currently raising funding to support the vaccination of 300–350 island foxes on Catalina Island. This is vital to protecting a core population and reducing opportunities for the virus to spread.

 FIF help support testing for disease antibodies in island foxes in 2020. This effort revealed an increasing prevalence of Adenovirus and Coronavirus on Catalina, fortunately neither virus appears to be causing mortalities. The increase, however, reminded everyone of how canine distemper virus would also spread if foxes were not vaccinated.

Tick below island fox eye

Though no tick-borne disease has yet been found among Catalina Island foxes, 48% have evidence of ticks and fleas. Studying tick-borne illness continues to be important for foxes and people. 

Interactions with people are greatest on Catalina and 75% of island fox deaths on this island were related to people–car strikes, attacks by pet dogs, etc. If drought conditions persist, parasites are expected to increase and foxes may be more attracted to human-inhabited areas.

 

San Miguel Island foxes have returned to stability, but they are a naturally small population. Renewed drought could cause declines as it did from 2015–2018. Research continues to search for the vector species that is being consumed by island foxes and leads to fatalities from an intestinal parasite. Channel Islands National Park continues to watch this population closely. (In the graph below the Green line shows even years, the population estimate in 2019 was 453.)

Stable

The two other smaller islands San Nicolas and San Clemente remain stable. In fact, San Clemente experienced a localized rain event that occurred at the perfect time in spring 2020. Plant life and deermice thrived and the island fox population boomed (see Blue line in graph below). Human impacts–car strike, entrapment in man-made structures, toxic waste, and improperly deployed rodenticide remain the greatest threat to these island foxes.

Santa Cruz Island foxes remain close to carrying capacity for their habitat and naturally adjusted downward in a lower rain year. Adult foxes had a 93.1% probablity of surviving in 2020. Study of tick-borne disease continues. Biosecurity is a concern for this second most visited island. The Nature Conservancy is analyzing boater activity around the island and determining the most critical areas to deploy biosecurity cameras to watch for nonnative species making their way onto the island. This may be important technology looking forward.

 

Santa Rosa Island foxes are believed to have increased in 2020 and have yet to reach a carrying capacity plateau. (Pink line in graph above.) The estimated population now exceeds all other islands and the density is estimated at 11.3 foxes per km squared. The high number of foxes on this island may increase survival challenges for island foxes as drought impacts heighten. Another thought is that prior range-size data may no longer accurately represent this island. The last time data on range size was studied on Santa Rosa was 2009–10, when fox density was much lower. Friends of the Island Fox would like to support a GPS/telemetry collar investigation of island fox range size on Santa Rosa Island to update the understanding of range size in a dense population. This data is vital to accurate population estimates and understanding of how disease might move through this population.

*Note graphs show population estimates from even years. Population graphs with data from all years show greater fluctuation. 2019 was a record high population year for Santa Cruz and Santa Catalina Islands, these two populations adjusted downward in 2020. 

Researchers also gave updates on island fox diet and microbiome investigations. FIF will report on this in the coming weeks.

 

2021 Update For FIF Donors

Tuesday May 18, 2021 Friends of the Island Fox Board members participated in the annual Island Fox Conservation Working Group meeting (via a virtual space hosted by the Santa Barbara Zoo).

We thought we'd try something new and share the FIF Update with you so you could see exactly where your donations have gone this past fiscal year and where we are focusing our efforts right now.

 

We can't say it enough "Radio collars, radio collars, radio collars!" This season's radio collars and vaccinations will be shipping out in the next few weeks, along with the bill. 

Your donations help fund these vital efforts to protect island foxes.

Biologists, researchers and pathologists from across the Channel Islands also reported on island fox status and health. 

The news is good and FIF will post a summary of the Working Group Meeting next week.

Fox Foto Friday - 250 Radio Collars To Date

Mike Watling, Chair of FIF's Board of Directors, recently took this photo of an island fox wearing a radio-tracking collar just at dusk on Santa Rosa Island. 

Did you help fund this radio collar?

Since 2005, Friends of the Island Fox has been committed to funding radio-tracking collars for island foxes. In 2006, FIF donors funded 10 radio collars for island foxes being released from captive breeding back into the wild. See video of captive-born island foxes being released in 2006.

In 2021, donors like you funded our 250th radio collar. This landmark collar will go on an island fox on Catalina Island this summer. 

Today island foxes live their lives running free in the wild. Individuals with radio collars help alert biologists to threats for the entire island population. Radio collars also monitor specific foxes recovering from health challenges or injury.

Meet two island foxes with radio collars: F257 and Vixen

FIF is committed to raising funds for an additional:

• 15 new radio collars at $350 each
• 19 refurbished radio collars at $220 each

These radio collars and vaccinations are needed for summer 2021. With your help island foxes will continue to thrive in the wild long into the future.

 

Distemper Outbreak in Long Beach Raises Threat to Island Foxes

courtesy of M. Baffa

April 15, 2021 the City of Long Beach issued a press release "Animal Care Services Reports Distemper Outbreak." The city reported that "38 raccoons and at least one skunk" had been found with the highly transmissible disease: canine distemper virus (CDV). 

This is the kind of situation that led to the serious decline of the Santa Catalina Island fox between 1998–2000. A wild raccoon infected with canine distemper virus was unknowingly transported to the island. Canine distemper virus killed 90% of the Catalina Island foxes within months and necessitated a multi-year effort to recover their population.

CDV can easily be passed from wildlife to pet dogs through direct contact or the sharing of food or water bowls. You can help protect the island fox and your pets. Vaccinate your pet dog against canine distemper virus. A vaccinated pet is protected and stops transmission from continuing. When there are high levels of CDV on the mainland, the threat to island foxes magnifies.

There are currently over 2,000 individual island foxes on Catalina Island. CDV is especially deadly to puppies and island fox pups. Island fox pups were born across the islands in April; they will be especially vulnerable for the next few months.

Friends of the Island Fox is raising funds to assist the Catalina Island Conservancy in vaccinating 300–350 island foxes on Catalina Island this summer. That is still only around 15% of the population. Vaccinating island foxes is the best chance for protection.

There are several months between now and when island foxes will be vaccinated. You can help protect island foxes from this heightened disease threat:

• Vaccinate your dog against canine distemper
• Do not feed wildlife, especially in harbor or port areas
• Dispose of trash in secured bins so wildlife can not access it
  
• If you have a boat, or know someone who does, always be aware of wildlife that may be hiding on board. If you detect a raccoon or other animal, return to port, DO NOT continue on to Catalina. Be wary of transporting any wildlife or feral animals to Catalina or any of the Channel Islands.
  
• Consider donating to FIF - a $20 donation will vaccinate an island fox against canine distemper virus and rabies.

Island foxes need all of us to be vigilant and stop the spread of this current CDV outbreak.

Your donation will help vaccinate island foxes against deadly canine distemper virus. 

Investigating the Relationship Between Island Foxes and Island Spotted Skunks

Islands typically support few terrestrial, or ground-living, carnivores due to the challenges of traveling over water to arrive on islands. On Santa Cruz and Santa Rosa Islands we have the rare occurrence of  two insular carnivores: the island fox and the island spotted skunk (Spilogale gracilis amphialus).

How the skunk got to the islands remains unclear, yet evidence has shown they have existed with the foxes for at least 7,000 years. (Fox arrival on the islands)

The spotted skunk and island fox are rivals, competing for the same resources in the form of aggression and predation. Averaging 3–4 lbs on the northern islands, the island fox is the larger and more dominate species. Island spotted skunks are about half the size. However, there is little understanding of when and where these two species interact.

In 2020, Friends of the Island Fox provided some funding to aid in a better understanding of the activity pattern of skunks and foxes on Santa Cruz Island. (More on FIF Research Grants)

Modern Global Positioning Satellite (GPS) collar technology can now capture additional information from wildlife that was not previously accessible–including accelerometers, which measure the forces of active movement. In this study, several foxes and skunks were fitted with GPS and accelerometer enabled collars to map the movement of each species with the aim of revealing the environmental factors that are most important in driving the fox's activity, such as changes in temperature, reproduction, and/or competition.

Researcher Calypso Gagorik with island spotted skunk

Calypso Gagorik, the project's principle investigator, says: "Given that the spotted skunks are strictly nocturnal, the chance of fox-skunk encounters may be entirely driven by changes in daily fox activity patterns."

skunk radio collar

The map below shows the GPS data points of one spotted skunk and one island fox that have overlapping home ranges. (Red dots represent island fox locations and Blue indicators are island spotted skunk locations. Skunk locations are taken less frequently because the batteries on their collars are considerably smaller. Each GPS location mark requires battery use.) What still needs to be analyzed is whether the fox and skunk were active at the same time of the day.

 

The importance of this research according to Gagorik, is "if foxes and skunks utilize similar area, but are active at totally different times, then the chance of interspecific interactions may actually be quite low." In other words, an island fox might visit a water source during the day, while the island spotted skunk might drink from the same location at night.

Researcher Victor Zhang with spotted skunk

Previous accelerometer data that was collected in 2019 have informed Gagorik and, fellow researcher, Victor Zhang "that the timing of daily fox activity varies greatly across the year, and the current analyses (completion summer 2021) will aim to reveal the environmental factors that are most important in driving changes in fox activity timing." Island foxes may be hunting prey at night during the winter and feeding on fruit during the day in summer. Gagorik adds, "Knowledge of these relationships will allow us to better predict the behavioral responses of both species to environmental change, as well as generate new knowledge on fox and skunk ecology." (Calypso Gagorik, email communication).

Previous data has shown that foxes occupy a flexible niche within the island community. They possess the ability to take advantage of the various habitat types, which make up the Channel Islands. On the other hand, the island spotted skunk may have a more specialized niche driven by fox activity.

Friends of the Island Fox is committed to research that will expand understanding of island fox biology and behavior. The more we know about island foxes the better we will ensure a future for both species.

 

"Examining temporal niche and movement patterns of the island fox (Urocyon littoralis) and the island spotted skunk (Spilogale gracilis amphiala) on Santa Cruz Island, CA" was investigated by Calypso Gagorik and Victor Zhang in conjunction with Northern Arizona University and under the supervision of The Nature Conservancy.

FIF is accepting applications for our 2021 Research Grant thru August 31, 2021

Friends of the Island Fox 2021 Research Grant

Applications for Friends of the Island Fox's 2021 Research Grant are now available.

Slide of tooth sample from deceased island fox

Structures in island fox teeth may help clarify island fox lifespan.

Whisker samples can provide data on island fox diet.

Part of FIF's mission is to support research that will help build scientific understanding of island fox biology, health, behavior, ecology, and any aspect that influences the species' long-term survival. 

FIF welcomes applications for the $5,000 available in research funding.

 

Download FIF 2021 Research Grant Application

Applications will be accepted through August 31, 2021

2020 Grant Recipient:  

Alexandra DeCandia - Island Fox Microbiome

Previous Research Grant Recipients and other island fox research

Your donations to Friends of the Island Fox

help make this research grant possible

 

 

Island Foxes On Facebook

Friends of the Island Fox is migrating!

OK, we're moving to a new Facebook home.

FIF has been on Facebook since April 2011. We've changed, Facebook has changed, and island foxes on Santa Rosa Island have gone from a population of 449 to an estimated 2,427.

We want to keep telling you about island fox conservation successes!

If you follow us on Facebook, we hope you'll migrate to: 

FIF's New Facebook page

 @FriendsoftheIslandFox

The old page will no longer be updated. 

We're expanding our horizons, just like this island fox spotted last week on a mountain top on Santa Rosa Island.

Spread the news to your friends.

You can also follow us on Twitter @ifoxtweet or sign-up for our bimonthly e-newsletter.

Fox Foto Friday - Island Foxes in Washington D.C.?

What smells like an island fox? Came from an island fox? But is contained on the tip of a cotton swab? A sample of island fox microbiome.

Island fox being swab with cotton swab

Friends of the Island Fox recently heard from FIF 2020 Research Grant recipient, Alexandria DeCandia, Ph.D.

DeCandia wrote "I wanted to let you know that microbiome samples from all six islands have arrived on the east coast :)" Swabs taken from island foxes during health checks have been transferred to a lab in Washington D.C. She added, "I'm very much looking forward to the next steps of this research!"

FIF's Research Grant is funding the DNA analysis of the swabs to get a picture of the biodiversity of microbes living on and in island foxes.

What Is She Looking For?

DeCandia's research is cutting edge science. Her early analysis of Catalina Island foxes led to some important findings on the possible relationships between bacteria in island fox ear canals and a tendency toward extreme immune system response to ear mites. This next stage of research builds on that work.

Maintaining healthy island foxes across the islands requires greater in depth understanding of their health, diet, position in the ecosystem, and interactions with other species, including humans. 

Friends of the Island Fox invests in research to invest in the island fox's future. Applications for the FIF 2021 Research Grant will be available April 15, 2021.

Is That An Island Fox? Identifying North American Foxes

Fox species overlap in many parts of North America, which can make it difficult to distinguish one species from the next. In California alone, there are four fox species:

• island fox - seen in the wild only on the Channel Islands
  
• gray fox
• red fox
• kit fox

The last three occur only on the mainland. If you are fortunate to see a small to medium canid in the field, you should ask yourself a few questions to aid in identification:

fox silhouette

 

coyote silhouette

1. Is it a coyote or a fox? 

Coyotes now inhabit most of North America, but they are typically larger than foxes and appear more dog-like with a larger face. The coyote tail is also shorter for their body than a fox's. While most foxes have distinct color markings to aid in identification, coyotes do not.

If it is a fox: 

2. Start with the tip of the tail:

White tail tip: Probably a red fox. Even if the fur coloring is not red or cinnamon, a fox with a white-tipped tail is a red fox.  The image to the right shows a "silver fox," an almost black-colored fox with white-tipped guard hairs beside a red fox. Both show a white tail tip. 

The silver fox is a color phase of the red fox (Vulpes vulpes). Most foxes used in the fur trade are red foxes. They are bred for various colorations. (FIF's red fox pelts are used in education. The silver fox pelt was rescued from a 1940s coat and the wild red fox was a car strike victim in 2005.)

 

gray fox; ancestor of the island fox

Black tail tip:

With a black stripe all the way down the back - you are looking at a gray fox. (If you are on the Channel Islands, it's an island fox.)

island fox on Catalina Island

 

kit fox; courtesy of K. Schafer

 

Just a black tail tip: Consider your location.

The Gemini foxes, the kit fox and the swift fox, seldom overlap in range. If you are located in parts of New Mexico and adjacent parts of Texas, big ears will separate the kit fox from the swift fox. In general, understanding the habitat where you see the fox will provide a clue as to the species you're observing.

No, definitive tail tip coloration: Arctic fox

Arctic foxes are easy to identify by their white coat in winter or their compact body size with small rounded ears and no contrasting marks on the tail.

Use this downloadable Identifying the Foxes of North America chart to help you know your local foxes. 

In this series of posts, we only touched the basics for each of the species covered. A list of research used in writing this project can be found at the end of each post. These resources are a great starting point for more information about the foxes that may live in your area. In addition, reading the abstracts of research articles provides wonderful insights into the latest information regarding a particular species. While the thought of wading through heavy scientist language may make your head spin, the abstract's concise language will slow that spin, allowing you the opportunity to glean useful information to assist in the better understanding of the fox you're interested in. It will also help sort fox fact from fiction.

Thank you to FIF Board Members - Mike Watling and Lara Brenner for this series on North American Foxes.

Series installments:

How is the Island Fox Unique?

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

 

The Island Fox's Origin - The Gray Fox

Gray fox (left) with two island foxes at CALM Zoo, Bakersfield CA

In previous posts we've introduced the red fox, the most widely distributed land carnivore on the planet, kit and swift foxes (the Gemini foxes), who inhabit the arid regions of North America, and the arctic fox, a true species of the north. In this installment of Foxes of North America, we conclude with the progenitor to the island fox: the gray fox.

island fox

 

As we've previously discussed on the Friends of the Island Fox website, the island fox descended from the gray fox (the island fox's "progenitor" or ancestor) between 7,000–9,000 years ago. In evolutionary time, that's relatively recent. When you examine the canid family tree, you'll find that the gray fox and its predecessors have been continuously inhabiting southern North America and Central America since the middle Miocene (10 million years ago). The genus Urocyon is the most primitive living canine lineage, closest to the origin of all canid species.

 

 

gray fox, Southern CA

Gray Fox: The Fox of the Forest

Gray foxes are commonly associated with deciduous or mixed coniferous forests. In contrast to the red fox, which prefers forest openings–meadows and farmlands–the gray fox prefers the cover of woodlands. Forested habitats allow this inconspicuous fox to elude predators in a most unusual way for a canid: it climbs trees! 

One set of traits retained from the gray fox's early divergence from other carnivores, (and one that other canids have lost) are its highly re-curved, semi-retractable claws and rotating forearms. These feline-like qualities allow a gray fox to hug trees much the same way a cat does. The gray fox's relatively short leg to body ratio lowers its center of gravity, aiding in balance and making it easier to use trees as a means of escape and to forage for bird eggs and fruits. (Island foxes have inherited this climbing ability.)

Found from southern Canada to northern Columbia and Venezuela, the gray fox is the only fox species to range across both North and South America. Gray foxes are absent from the northern plains and Rockies, as their short legs make it difficult to navigate areas with deep snow. In Southern Canada, gray foxes live in coniferous forests, where dense foliage may help mitigate the effects of heavy snowfall.

gray fox, photo courtesy of Jim Carretta

 

The scientific name for gray foxes, Urocyon cinereoargentus, breaks down as follows: Urocyon is Greek for "tailed dog" and cinereoargentus translates to "silvery gray," which accurately describes this handsomely dappled fox. (Island fox's scientific name.) Its underside is a cinnamon-rufous color and there is white fur on the face, throat, belly and hind legs. The tail has a black tip, which helps distinguish it from the red fox, whose tail is white tipped. There are distinct black spots on either side of the muzzle. The long bushy tail makes the gray fox appear larger than it really is. In general, they stand about 14 inches at the shoulder; weigh from 7–13 pounds and are 31–44 inches long from head to tail. (Compare to the island fox)

The gray fox is the most omnivorous of the wild canids. Just like the island fox, their varied diet consists of small mammals, birds, fruits, nuts and invertebrates such as Jerusalem crickets and grasshoppers. Their diet varies throughout the year based on prey availability, which allows them to adapt to changing environments.

island fox family allogrooming

While mostly solitary, gray foxes do spend time in pairs or in small family groups through out the year. More than any other fox species, gray foxes can be seen allogrooming, which is when individuals socially groom each other and their pups to remove ticks and pests. If you visit a Channel Island, you can see that this trait has been carried over to island foxes, as they are often observed grooming each other.

The gray fox's tendency to prefer areas with thick tree coverage makes this elusive species the least studied of the North American foxes. Overall, the gray fox population is healthy, and habitat loss doesn't appear to be impacting the species for now. Farmers who raise poultry feel that gray foxes are pests, but biologists claim this threat is overstated. On the contrary, gray foxes provide a benefit to humans by keeping rodent populations in check.

Indigenous peoples realized the value of their neighbor the gray fox and thus began a relationship that would lead to the evolution of the island fox.

Previous installments:

How is the Island Fox Unique?

Red Fox: Life on the Edge

Gemini Foxes: Kit Fox and Swift Fox

Arctic Fox: Fox of the Tundra

References

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.