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.

Testing for Disease Threats on Catalina Island

At the Island Fox Working Group Meeting in May, FIF provided $4,500 to support testing for disease antibodies on Catalina Island during 2022 island fox health checks.

This effort spots viruses introduced to the island. If a fox comes in contact with a virus, its immune system will develop antibodies to try and fight off the disease.

This is similar to how COVID-19 is tracked in humans.

 

We know this effort is important because FIF funding in 2021  helped biologists on Catalina Island discover that antibodies for Adenovirus (dog flu) were present in 80% of Catalina Island foxes. This is a steep increase from 2020. 

While no island foxes are believed to have died from Adenovirus, this rapid increase reminded everyone of how canine distemper virus would spread if it reoccurred on the island and foxes were not vaccinated.

A blood sample might not seem as exciting as a radio collar, but both are important to island fox survival. This effort was funded by donors like you and a one-time grant from the Fresno Chaffee Zoo Wildlife Conservation Fund.

Your donations help protect island foxes from disease.

Please donate today

Island Fox M152 Has a Health Check

When M152 was fitted with his refurbished radio collar, he also received a health check.

During the health check he wore a special hood. Having his eyes covered makes the health check less stressful and helps the island fox remain calm.

M152 was:
Weighed - to compare his weight with previous years and to provide an overall view of the population across the island. How much did M152 weigh?

Blood Sample - A sample of his blood was taken to look for evidence of exposure to disease. In 2016-2017 blood samples documented adenovirus, commonly called "kennel cough," as it moved across Catalina Island infecting 85% of the island fox population. (See 2018 Update) Fortunately, no island fox deaths were attributed to the virus, but it demonstrated how fast an infectious disease can spread through island foxes. Testing blood samples provides an early warning of dangerous diseases like canine distemper, parvo, and more. It can also indicate whether disease might be influencing low pup survival. Some of M152's blood was also set aside to test for specific white blood cells. A high number of these cells may be evidence of a parasite infection. Some of the blood sample will also be used for DNA studies to determine the familial relationships between individual foxes. How are the pups in M152's territory related to him? All of this is above and beyond simple monitoring. 

Your donations help make this health research possible.

Disease - M152 showed no signs of disease. He appeared healthy.

M152 courtesy of Channel Islands National Park

Whisker Sample - A whisker sample was taken for an important research study on diet funded by Friends of the Island Fox.

Tick Testing - M152 was examined for fleas and ticks. Luckily he was tick free! But not all island foxes are so lucky. 

small red dot is a tick on the fox's ear

Tick-borne disease is a new threat to island foxes. Two infectious diseases carried by ticks have recently been discovered on the Channel Islands: Lyme disease and relapsing fever. Ticks found on island foxes, like the one on the back of an island fox's ear, pictured at right, are being removed and tested for disease. This is important research for island foxes and people. 

How many ticks are carrying disease? How many island foxes are infected? Lyme disease seriously impacts dogs; is it impacting island foxes? The tick is removed and tested to see if it is a disease carrier.

Tick after removal and prepared for testing.

Tick-borne disease is a new threat.

We need your help to fund testing of ticks.  

Removing the tick is also beneficial to the island fox.

Island fox ear after tick is removed.

Island foxes need your help. 

Friends of the Island Fox funds radio collars, 

proactive health testing, and vital research. 

With your continued support, we can hold onto success and keep island foxes like M152 healthy into the future. 

Please donate today.