Fox Foto Friday - Sylvie Update

"Sylvie" at the Living Desert 3/8/26

This photo of "Sylvie" the San Nicolas Island fox was taken this month at the Living Desert Zoo. When we remember back to her foot injury as a young fox in 2023, it's amazing to see her run, jump, and climb!

 

This x-ray shows the compound fracture that could have cost her life. 

But school children, seniors, and people like you all rallied together to fund orthopedic surgery so she could live a protected, but long life. Find out more about Sylvie's Journey, her surgery, recovery and see video of her and the team of people that rescued her.

You can see Sylvie, too, at the Living Desert Zoo and Gardens. 

Without a community of friends, this little island fox would not have survived. 

Together we can solve problems and save species. 

Fox Foto Friday - Island Fox Status

photo courtesy of Megan Sarrail

Island foxes are a model of conservation success! 

In August of 2016, island foxes were removed from federal Endangered Species status on four islands. Over the past ten years, their survival has been monitored using radio tracking collars and annual health checks.

California's February-2026 issued "State and Federally Listed Endangered and Threatened Animals of California" lists island foxes as a California State "Threatened" species on all islands.

Update 3/31/26: Island fox friend and retired member of the Island Fox Conservation Working Group, Dale Steele, clarifies "All subspecies of the Island Fox have been listed as "Threatened" [by California] since 1971. The recently published list of state and federal listed species is the most recent update including other recent petition decisions but did not change or add the Island Fox. 

Why are island foxes still considered "Threatened" when their numbers have recovered across the islands?  

While conservation efforts have been very successful, each island fox population is unique, small and limited to a single island. Looking forward all island foxes will continue to face a range of threats–from introduced disease to climate change and human impacts.

Immediate threats to island fox survival will change, but keeping an eye on this tiny canine's challenges and successes will help to keep them thriving into the future. Conservation is a process, not a checkbox. 

Vaccinating Island Foxes is an Annual Need

 

Companion dogs are vaccinated against canine distemper annually and so are island foxes.

This Since June biologists have been out in the field across the Channel Islands vaccinating island foxes against rabies and canine distemper virus. The vaccine being administered across 4 islands was provided by donors like you. Who's helping fund vaccinations?

Did you know?

• Canine distemper virus (CDV) is a dog version of the measles virus. It's highly contagious like measles, entering the body through the respiratory system. New research suggests that measles from humans was transferred to dogs 500 years ago during the Spanish colonization of South America. 

 

• Distemper spreads rapidly through wildlife populations. CDV infects dogs, foxes, wolves, and coyotes, but also raccoons, ferrets, and skunks. The virus is especially deadly to African and Asian species of big cats (lions, leopards, tigers, etc.)

 

• CDV is so lethal to island foxes, they can't withstand the vaccine created for domestic dogs. Island foxes are treated with a dead-virus vaccine that is made in small batches, by one company, and is used by a short list of endangered species: black-footed ferret, giant panda, Iberian lynx, African wild dog, African lion, all tiger species, and other large cats.

 

•  A new study from Penn State University has found evidence that canine distemper virus is influencing grey wolf evolution. A gene mutation, CPD103, creates a black coat in grey wolves. This mutation also makes the lungs less susceptible to the introduction of disease. Black-colored grey wolves are less likely to become infected with CDV. In areas where CDV occurs in high rates, entire wolf populations become darker in color, because the lighter colored individuals are lost to the disease. Read more about this study.

 

Health efforts for rare wildlife go hand-in-hand with research. FIF raises funds to vaccinate island foxes and to investigate important health research.

Celebrating 20 Years of Island Fox Conservation and Looking to the Future

Pat Meyer meets Jane Goodall in 2006

 

Friends of the Island Fox (FIF) was founded in 2005, when Channel Island foxes were critically endangered on four islands.

See a short history of the organization presented during our August "Date with a Fox" on-line program and hear from FIF Board member Justin Purnell about a fieldwork study program for high school students that provides a personal experience with the island ecosystem.

 

Friends of the Island Fox is partnering with the Field Studies Cooperative to provide more students with this life-changing opportunity. 

 

Island Fox Status Update 2025

In 2024, island foxes remained healthy. Normal rainfall levels led to population balancing; high density populations decreased in number and low density populations increased. San Clemente Island, however, realized a third consecutive year of population decline. Concern for these island foxes grows because a specific cause for the decline remains unknown.

island fox on San Clemente Island

The following is an update across the Channel Islands from notes compiled by Friends of the Island Fox at the Island Fox Conservation Working Group Meeting May 15, 2025 hosted at the Santa Barbara Zoo (hybrid meeting).

Reported population numbers are the official estimates submitted by the land managers and calculated by them from island foxes captured for health checks June 2024–January 2025. (How island foxes are captured and given health checks) 

Overview: While food and shelter resources for island foxes were good across the islands in 2024, dry conditions were more prevalent on San Clemente Island and a wildfire burned a third of the island. Monitoring systems documented island foxes surviving the fire, but it is possible the fire contributed to the low number of pups documented. Weather extremes are becoming more frequent across the islands. 

Fox Density: Because island size, weather, and habitat varies from island to island, comparing island fox density can be more informative than comparing population sizes. Fox density reflects the number of island foxes found within a square kilometer (per sq km). (More on density).

A density of 8–12 island foxes per sq km, is the fairly high density of individual animals typically found across the Channel Islands. When a density rises above this range, as San Miguel Island did in 2023 (see graphic above), it is not surprising when the population adjusts down the following year, especially if weather conditions are not optimum for growing native fruit and supplying large amounts of insect and rodent prey.

The two smallest islands with island foxes, San Miguel and San Nicolas, remain most stable when their population density is around 8 island foxes per sq km. Food resources on these smaller islands are never as plentiful as on the larger islands. While the population number decline on San Miguel may seem concerning, the downward adjustment in density creates a more sustainable population. 

The larger islands, Santa Rosa, Santa Catalina, and Santa Cruz provide greater biodiversity of resources and can maintain higher island fox population densities. Densities over 12 foxes per sq km, however, can mean that some island foxes are pushed to very small territories with lower quality resources. Drought, flooding, or the introduction of disease, often has a greater negative impact when foxes are living in high density.

The density graphic above also shows how thin the island fox density was on San Clemente Island in 2023 and 2024. Everyone is watching this island closely and investigating leads on the causes. 

Pup on Northern Islands in August 2024

 

In 2025, the leading threats to island foxes are:

• reduced funding for Federal lands: Monitoring island foxes requires staffing. Reductions in Federal funding for National Park staffing, especially biologists, and unknown budgetary cuts affecting U.S. Navy base environmental efforts threatens island fox health checks and monitoring in 2025. Across Federal lands health checks began early in hopes of completing them before funding cuts were enacted. The ability to continue monitoring on Santa Rosa, San Miguel, San Clemente, and San Nicolas Islands remains in jeopardy for 2026 and into the future. 
• biosecurity: Annual vaccination of island foxes for the deadly canine distemper virus remains a priority. If health checks are discontinued on Federal lands, there will be no annual opportunity for vaccination. Additionally, canine adenovirus (dog flu) has swept across several islands and may be impacting pup survival.
• climate change: Weather extremes not only influence island fox health and resources, they also impact island fox monitoring. The heavy rains of 2023 limited access to Santa Cruz Island and the data collected that year led to a false representation of an upward spike in population numbers. Quality monitoring requires consistency in data collection. Monitoring data in 2024 revealed a stable population on Santa Cruz–mitigating the spike. This highlights the importance of annually collected data to provide the most accurate depiction of island fox population trends across the islands.    

island fox having teeth examined during a health check

 

Greatest Concern: We know how quickly an entire population of island foxes can be impacted by disease, resource loss, or an introduced threat. Quality monitoring is the cornerstone of island fox recovery success. Millions of dollars invested in island fox recovery could be swept away to save a few $100,000 in annual monitoring costs. 

 

Smaller Islands

Because of the amount of years tracked, the graph above shows population estimates for even years only. While smaller populations can be more volatile, San Nicolas and San Miguel Islands remain stable. 

San Miguel Island (lime green line): The downward adjustment of the population from an estimated 525 individual island foxes to 322 reflects a rebalancing to a more sustainable population density. Trends suggest the resources on the island can support 300–450 foxes. Pup numbers were typical in 2024 and individual health appeared good.

San Nicolas Island (pink line): The population remained stable. General health remained good and pup numbers increased. Forty percent of the population shows antibodies for exposure to adenovirus. Ear mites are prevalent. In 2025 foxes receiving health checks will be treated with a topical intervention, following protocols developed on Catalina Island. The hope is to reduce ear mite infestation and increase overall health.

San Clemente Island (blue line): Adult survival dropped from an 89% chance of surviving the year to 69%, and only 7 pups were documented in 2024. Investigations continue into pup survival, the impacts of adenovirus (exposure now prevalent in 80% of the population), and the quality of food resources. The wildfire may have also contributed to population decline. Car strikes add an additional threat to survival. Providing necropsies of individuals killed by vehicles may be vital to identifying health concerns that have gone undetected. 

Larger Islands

Because of the amount of years tracked, the graph above shows population estimates for even years only. As all of these islands hover at carrying capacity, their populations remain stable.

Santa Catalina Island (red line): This population increased slightly in 2024. Treating island foxes for ear mites has reduced cancerous tumors and increased overall health. Introduced adenovirus, corona, herpes, and parvo viruses all continue to decline. Biosecurity threats are greatest to this island, but no raccoons or other invasive species were detected on the island in 2024. The greatest threats to island foxes on this island are people and their pets. Eighteen island foxes were killed by cars and two were attacked by dogs. Rodenticide and unintended poisoning is a growing threat on all human-inhabited islands.

Santa Rosa Island (pink line with black centers): This island currently has the greatest island fox density–13.2 island foxes per sq km. As the density has increased, adult annual survival has declined slightly to a 72% chance of surviving the year. How this high density impacts available resources and fox territory is under investigation this summer with a group of known individual foxes wearing GPS tracking collars and being monitored for diet and health.

Santa Cruz Island (black line): This island continues to have the largest island fox population. As expected, the estimate of over 4,000 individuals in 2023 was an anomaly created by not being able to count foxes at historic counting locations because of stormy weather and flooding. Returning to count in the historic spots in 2024 resulted in a scientifically supportable and healthy population estimate of 3,086. 

Your donations help fund vaccinations and radio collars for monitoring island foxes. 

As July and August unfold, biologists are in the field vaccinating island foxes and fitting them with radio-tracking collars funded by Friends of the Island Fox.

Healthy island foxes depend on people like you supporting conservation efforts. 

 

Fox Foto Friday - Creating a Living Library

 What's in these vials?

 

courtesy L. Brenner, TNC

Island fox blood samples going back decades. 

During annual health check-ups, samples are taken of island fox blood. Blood samples can be used to screen for increased antibodies to a specific virus, to check for toxins, or to provide genetic information.

 

 

These island fox blood samples from Santa Cruz Island are currently being archived and prepared for long-term cryogenic storage at the Museum of Southwestern Biology (MSB) at the University of New Mexico. 

For years, island fox samples have been housed in freezers spread across counties and agencies. While a collection of samples are stored at the School of Veterinary Medicine at UC Davis, samples from different islands have been stashed in a variety of locations with ever-changing safety measures or lack there of. The value of these specimens to science is degraded if they experience unreliable freezing, are not accessible, or are misplaced.

In 2023, FIF worked with the Dept. of Defense and the U.S. Navy to move some specimens from San Nicolas Island foxes to the Museum of Southwestern Biology (MSB), one of the largest and most advanced centers for archiving mammal specimens.

 

At the end of 2024, FIF assisted The Nature Conservancy with sending historic island fox blood samples from Santa Cruz Island to the MSB. The last group arrived in New Mexico March 26, 2025.

FIF's goal is to have scientific samples from all six islands archived, protected, and available to future researchers. 

 

Island foxes on San Miguel and Santa Rosa Islands have been through a historic genetic bottleneck; one that most geneticists considered impossible to recover from. Yet today, island foxes persevere. Island foxes can teach us about evolution, adaptation, and species sustainability. The information in this living library will provide future researchers with access to crucial data.

Donations to FIF help support important island fox research 

Apply for FIF's 2025 Research Grant 

Genetic research currently supported by Friends of the Island Fox:

• Transcriptomics in RNA and island fox health
• Comparing the genetics of the small founding populations on San Miguel and Santa Rosa Islands with today's island fox populations

Island Fox F257 is Back and Beautiful at Middle Age

 

F257 August 2024

Channel Island National Park biologists are on Santa Rosa Island this week capturing island foxes, counting them, checking their health, and updating radio-tracking collars. Biologist Juliann Schamel contacted FIF with great news: Female island fox 257 was captured for the 5th year in a row and she's looking great! Here's Juliann's update:

F257 was born in 2019, and has spent her entire life in her natal area, which overlooks the East Point estuary [as] Santa Cruz Island floats on the horizon.  Every year since 2019, she has gone into traps at our long-term monitoring site at Old Ranch.  She has spent a total of 18 nights in our "island hotel."  Every year, she moves between Trap 1, Trap 11, and Trap 12, which are in a triangle 200 meters apart from each other.

F257 is five years old now, and remains in great health.  She has been monitored with VHF collars throughout her life, and is currently wearing her third collar.  She has Age Class 2 tooth wear.  As an adult, she has fluctuated in weight between 1.8–2.2 kilograms (4–4.9 pounds). 

 

island fox whisker sample

This year, during her health check ... she also contributed samples to microbiome, leptospirosis, and stable isotope research (gut swab, urine, and whiskers).

 

In 2023, she had signs of nursing pups for the first time.  This year she does not show signs of having had pups.  (As pictured, her belly is white.) Data from our long-term monitoring sites has allowed us to document fox recovery to carrying capacity, which was reached in 2020. (What is carrying capacity?) 

 

Since then, the population has displayed density-dependent reproductive suppression (which I think is SO COOL!!!!) - very few pups were weaned in 2021, 2022, and 2023, adult survival remained high, and the total population has remained around 2,500.  Collecting long-term data during this time period has allowed us to document which adult females reproduce and which do not in this high-density landscape (how old are they? what habitat do they live in? how dense are the foxes in their local area?), which will provide further insight into what environmental factors influence fox biology, and how fox ecology in turn influences the landscape.  Old Ranch, where F257 lives, has a high density of adult foxes with high survival, and this area has not produced many pups in the past several years.  With the VHF collar, we will be able to monitor F257's health and status for years to come!

It's been so lovely to see F257 again! - Juliann Schamel

Schamel is not only a fox biologist out on the northern Channel Islands, she's also researching the complex interactions between island foxes and the landscape on Santa Rosa Island. 

 

"Date with a Fox" with Juliann Schamel

More on island fox density

Your Donations funded F257's radio collar and 

vaccinations for rabies and distemper!

Island Fox Status Update 2024

In 2023, island fox populations remained healthy and stable across all six islands. Weather extremes, however, effected islands in different ways.

Island fox on San Clemente Island courtesy of J. Sanchez

The following is an update across the Channel Islands from notes compiled by Friends of the Island Fox at the Island Fox Conservation Working Group Meeting May 8, 2024 hosted at the Santa Barbara Zoo (hybrid meeting).

Reported population numbers are the official estimates submitted by the land managers and calculated by them from island foxes captured for health checks July–December 2023. (How island foxes are captured and given health checks)

Overview: Rainfall was abundant in 2023, but the impact on plant and prey species varied by island. Island fox populations on smaller islands grew, while island fox numbers on larger islands adjusted downward slightly. The anomaly was Santa Cruz Island, which appears to have experienced a significant population increase, creating a historic record for a single island population.

Range Size and Diet Research: Ongoing research by FIF Research Grant recipient Katie Elder revealed that fox home ranges on Santa Rosa Island have declined in size by 83% since 2009. It's not surprising that home range territories have gotten smaller as the fox population has recovered from less than 400 individuals to over 2,500. The surprise is how strictly the 15 male foxes monitored for a year with GPS collars stayed confined within their small territories. This means that individuals in poor habitats have less access to varied resources; inland foxes aren't accessing beach foods and individuals with grassland home ranges may have less access to fruiting plants. How will individual survival be challenged if drought conditions return?

Density: On the northern islands, island fox density has become high: 11.35–14 island foxes per square kilometer. What is island fox density? While it's great to see increased populations of island foxes, high density means individual fox territories are close together. Disease can be transmitted more easily through a dense population. As the Range Size research reveals, high population density may also mean island foxes have less flexibility to survive fluctuations in their available resources.  

Climate Impacts: For the first time, islands documented increased rainfall that did not coincide with island fox population growth. The timing of storms or extreme high levels of rain may have negatively impacted deer mouse or insect populations resulting in fewer resources for island foxes.    

In 2024, the leading threats to island foxes are:

• biosecurity: the threat of introduced viruses, accidental transportation of a deadly parasitic worm from San Miguel Island to other islands, disease, and/or non-native animals
• reduced funding for monitoring
• climate change: extreme weather effects food resources, heightens parasites, challenges health, and can make it more difficult for biologists to access the islands
  

Greatest Concern: Biosecurity threats are heightened by the high density of island foxes on northern islands and rising tourism on Catalina Island. Canine distemper and other dog diseases remain threats. A new investigation has identified the parasitic spiny-headed worm on San Miguel Island that has caused fox fatalities in the past, especially in drought years. The investigation to find the prey species that acts as an intermediary host continues. New findings reveal that this lethal intestinal parasite was most likely transported to the island by humans. It is vitally important that this parasite not be moved to other islands.

Be a BioSecurity Guardian–Clean, Check, and Close everything you take to the islands. Watch Biosecurity Video.

Smaller Islands

San Miguel and San Nicolas Islands appear to have equally benefited from additional moisture and available resources. Their populations grew at the same rate in 2023. San Clemente Island remained stable at its lower population size.

San Miguel Island (lime green line): While adult annual survival declined, healthy pups stabilized and increased the population. This island currently has the greatest island fox density: 14 foxes per square kilometer.

San Nicolas Island (pink line): General health remains good, but lifespan appears to be 7–8 years, rather than the 10–12 years on larger islands. Density remains moderate at 8.4 foxes per sq km. Dog flu has declined, but remains prevalent. Car strike causes the greatest island fox mortality and more days of foggy weather increased fox fatalities.

San Clemente Island (blue line): Adult island foxes on this island had a high 89% chance of surviving the year, but pup survival continues to be investigated. This island currently has the lowest fox density: 4.06 foxes per sq km. Approximately 5% of the population is lost annually to car strike and inexperienced young island foxes are more likely to be hit.

 

Larger Islands

The larger islands were all thought to have reached carrying capacity. Santa Catalina and Santa Rosa Islands adjusted downward at nearly the same small rate in this extremely wet year. Because their populations are so large, this adjustment is not unexpected. Santa Cruz Island, however, increased at the same high rate as the small islands, creating a historic population estimate.

Santa Catalina Island (red line): The population remained stable with a density of 9.22 foxes per sq km. Analysis of tick samples collected from island foxes from 2019–2022 showed no tick-borne disease. This is important because 60% of Catalina Island foxes carry ticks. Both dog flu and corona virus declined in 2023, but biosecurity remains a huge concern on this island. From car strike and dog attack to foxes being drown in scuba wash tanks and entrapped in human structures, humans and pets currently pose the greatest threat to island foxes. In 2023, over 62% of known fox fatalities were human caused.

Santa Rosa Island (pink line with black centers): This population remains stable with a high density of 11.35 foxes per sq km and adults had an 89.5% chance of surviving the year. Research is showing that Rosa foxes are becoming dietary specialists. How will this impact individual foxes and the island ecosystem?

Santa Cruz Island (black line): With an adult annual survival rate of 94.7%, this island was estimated to have a historic population size of 4,057. The fox density is currently 12.9 foxes per sq km. Due to a record 35 inches of rain, foxes could not be counted in some of the traditional grid locations. There is a possibility that the high population calculation may be slightly inflated by data fluctuations.

Weather has a profound effect on island resources. Changing weather patterns–tropical summer storms, extreme winter rainfall, increased summer heat, denser fog–all impact island habitats and island foxes. 

Your donations help monitor island fox survival with radio collars and provide vaccinations to protect them from introduced disease. Research is investigating health, behavior, and how best to support stable island fox populations in a changing world.

Healthy island fox populations depend on people like you supporting conservation efforts. 

 

What is Island Fox Density?

 

Density is a term used in biology to express the number of individual living things in a given area. Biologists use a defined area size–ie. a square meter, square kilometer or square hectare–to quantify density. 

A square kilometer is equivalent to the footprint of Disneyland in southern California and a square hectare is equivalent to a professional baseball field.

Understanding how many island foxes are living in a square kilometer is part of the calculation for estimating the size of an island-wide population.

At the recent Island Fox Conservation Working Group Meeting, land managers reported on the island fox density for their islands. There was a noticeable difference between northern and southern islands.

Northern islands are reporting considerably higher island fox density. The causes for this are not completely clear. Northern islands may benefit from less extreme weather–higher average rainfall and more moderate summer temperatures–which support diverse prey and plant food for island foxes. Northern islands also have fewer impacts from humans; Catalina Island and the two Navy islands, San Clemente and San Miguel, have roads and cars that cause the highest percentage of fatalities for island foxes. 

High density, however, can have a downside. Catalina Island has been stable for the past 10 years with a density around 9 foxes per sq km. The island with the highest density in 2023–14 foxes per sq km–was also the smallest, San Miguel Island. When density increases, individual island fox territory decreases. A smaller territory means a smaller area to find food. High density can push some individuals into habitats with fewer quality resources. San Miguel's resources are less diverse than the larger islands and there are fewer options for foxes when drought or other weather extremes occur.

 

When island foxes are living closer to each other, the possibility of disease moving rapidly through a population also becomes heightened. Parasites can spread more easily.

Understanding population density is important for calculating risks to populations and making informed conservation decisions. 

Unexpected Creatures During Island Fox Counting - Part 4

Welcome guest blogger Jessica Sanchez, wildlife veterinarian and FIF Board Member. She's explained how island foxes are captured annually in Part 1, shown how a fox's body condition is evaluated in Part 2, and demonstrated health procedures preformed on island foxes during an annual health check in Part 3. As she explains, she might be out capturing island foxes, but they aren't the only animals she encounters.

We also catch island spotted skunks, although this has become rarer in recent years.

You know you have caught a skunk even before you get to the trap because...

1. of the smell
2. they ball up all the grass and vegetation in the trap to make a cozy little nest for themselves
   

If you're lucky, they will still be asleep in this nest when you approach the trap the next morning. All of this gives you time to pause and carefully plan your approach to getting them out of the humane box trap. 

Skunks also get a microchip for identification and we take a tiny 2–3mm biopsy of the ear, with a special cartilage snip device, for genetic testing. Then they receive a thorough exam. (similar to island foxes) We try to handle the little skunks carefully so they don't spray us–this is for our benefit and theirs as it can take up to a couple of weeks for skunks to regenerate their spray and they need it to defend themselves. 

Currently, island spotted skunks are not vaccinated, though researchers are investigating options to potentially do so in the future.

Island spotted skunks aren't the only surprise that might be found in a box trap set out for island foxes. See what else Sanchez has found:

 

An island scrub-jay!

The final steps of a long day catching island foxes are to wash off any skunk spray and/or fleas, check yourself for ticks, enjoy a beautiful sunset, and get a good night's sleep before doing it again the next day! - Jessica Sanchez

Part 1 - capturing island foxes

Part 2 - Health Check: body condition

Part 3 - Health Check: veterinary procedures

 

Island Fox Gets a Health Check - Part 3

Welcome guest blogger Jessica Sanchez, wildlife veterinarian and FIF Board Member. She's explained how island foxes are captured annually in Part 1 and shown how a fox's body condition is evaluated in Part 2. But an island fox health check includes additional health measures.

We check the foxes for ectoparasites such as ticks, fleas, mites, and lice. We comb their fur to find fleas, and pay special attention to their ears, armpits, and belly area–where lice and ticks are often found. 

Ticks are collected so we can identify the species and test them for viruses or bacteria they might be carrying. Since ticks can feed on multiple hosts in their lifetime, testing the ticks tells us about what diseases the island spotted skunks, deermice, and other island species might be exposed to as well. 

 

 

We take a look in the fox's ears using an otoscope, just like the doctor uses to examine your ear canal. On Santa Catalina Island, where ear mites introduced by feral cats have been associated with ear tumors, foxes are treated with a topical medication to kill ear mites and reduce inflammation in the ear canal.

We collect blood from the jugular vein. This is used to test for exposure to disease, genetic analyses, and to look at other health parameters like liver and kidney function.

One of the most important steps is to administer vaccinations. A subset of the population is vaccinated every year for rabies and canine distemper virus. Neither disease is currently found on the Channel Islands, but we vaccinate as a preventative measure after the Santa Catalina Island foxes almost went extinct due to the introduction of canine distemper in 1999–2000. Vaccinations ensure that if there is ever an outbreak of either disease, at least the vaccinated foxes will survive to repopulate the island. (FIF's efforts to provide vaccine for island foxes in 2023)

A subset of foxes also gets radio collared. 

 

These collars are small, less than 5% of their body weight, and do not interfere with the foxes going about their daily life. Collars serve multiple purposes, allowing us to track the size and location of home ranges, monitor survival, and find dead animals quickly so their carcasses can be sent for necropsy ASAP to identify the cause of death. 

Most of the radio collared foxes are unvaccinated "sentinels," meaning if a disease outbreak occurs, they are not protected and may get sick, but their deaths will be detected via the change in their collar signal so we can recover the bodies for necropsy. Without collared animals, we would not know foxes were dying and would not be able to find the carcasses to get more information about the cause. Monitoring mortalities also gives us information on trends in other causes of death, such as internal parasites or being hit by cars, so we can address those threats as well.

Foxes are released after their workups and immediately run off! - Jessica Sanchez

 

In Part 4, Jessica details what happens when an island spotted skunk is unexpectedly caught during island fox health checks.