2019 Island Fox Status Update

In 2018 most island fox populations were stable, but not without risk factors. 

As expected, high temperatures and below average rainfall in 2018 contributed to lower pup numbers and reduced adult survivorship across all islands. As first documented on Catalina Island, island fox reproduction is linked to annual rainfall. Fortunately, normal rainfall levels in 2019 should benefit all island fox populations.

In 2019 Channel Island foxes face four major threats:

• climate change: increasing regional temperatures and decreasing annual rainfall, which reduce food resources, increase wildfire threat, and promote parasite numbers
• biosecurity: the introduction of non-native plants, animals, and diseases
• parasites: rising tick numbers and tick-borne diseases; increased intestinal parasites on some islands
• reduction of management funding

The following update is drawn from FIF notes taken at the 2019 Island Fox Conservation Working Group meeting. Population numbers reported here are the official estimates from each island manager, as calculated from the fall 2018 count and reported May 21, 2019. Download the detailed 2019 Island Fox Status Update

Greatest Concern 
San Miguel Island foxes robustly recovered from 15 individuals in 2000 to over 500 by 2010 (lime-green line on graph below). As a smaller island, it will always have a smaller fox population. In 2015, however, following several years of drought, the population began declining. As of fall 2018, the population has dropped to an estimated 171 individuals (a decline of over 70%). This decline may involve several interconnected threats: climate change, biosecurity and parasites. Details regarding San Miguel will be posted in coming days.

Improved
San Nicolas Island foxes declined by 59% to 260 individuals during consecutive years of drought from 2012–2015 (pink line on graph above). The US Navy initiated native plant restoration projects in conjunction with Channel Islands Restoration. As these plants, like prickly pear cactus, mature they are providing food and habitat for island foxes and prey species. The fox population has increased to a more stable number–estimated 400 individuals. 

Stable
Santa Rosa Island foxes may have reached capacity for the island (pink line on "larger islands" graph above). Native vegetation is recovering and increasing resource options for foxes during periods of drought. No island foxes have been lost to golden eagles on this island or San Miguel since 2010. Parasites, including tick-borne disease, are a growing concern on Santa Rosa. FIF has refurbished 7 radio collars, and funded dietary research and health testing measures in 2019.

Santa Cruz Island foxes have reached capacity for their habitat. As a result the population decreased naturally during 2018 (green line on "larger islands" graph above). Parasites, especially tick-borne Lyme disease, are an increasing concern. Because the Cruz population has been stable since 2014, there is pressure to reduce funds for monitoring. This poses a potential threat because this population receives elevated contact from the outside world via island visitors. FIF has refurbished 20 radio collars for monitoring in 2019.

Santa Catalina Island foxes have also reached capacity for their habitat. In reaction to decreased rainfall, this population also declined naturally in 2018 (red line on "larger islands" graph above). Parasites, especially tick-borne Lyme disease, and biosecurity are an increasing concern for this population. Lyme disease and canine herpes virus were both introduced via human visitors and their pets. Monitoring of disease exposure is vital to this populations continued health. FIF has funded 5 new radio collars and health testing measures in 2019.

San Clemente Island foxes live on the most southern Channel Island (blue line on "smaller islands" graph above). In 2018, they were the first population to see deaths directly attributed to high temperatures. Reduced rainfall stressed the population and eight individual island foxes are known to have perished in the heatwave between June and July of 2018. Climate change is impacting this island fox most directly. 

Download the detailed 2019 Island Fox Status Update

More Radio Collars for Island Foxes !

This island fox is smiling because it is wearing a newly refurbished radio collar. More about M152

Two things happened this week:

• 7 newly refurbished radio collars arrived at Channel Islands National Park to be deployed on San Miguel and Santa Rosa Island foxes
• FIF funded our 27th radio collar this year!

Twenty refurbished radio collars went to Santa Cruz Island in May to be fitted on island foxes this summer. 

You helped fund these radio collars to monitor island fox health and welfare. 

But we aren't done yet. 

Health checks and annual counting are starting across the islands. This is when old damaged radio collars are removed and replaced with new or refurbished radio collars. 

 

FIF is hoping to fund:

• 5 more $350 new collar
• 13 more $220 refurbished collars 

We know we can do this with YOUR HELP!

The time to radio collar island foxes is right NOW! 

Please DONATE TODAY 

FIF Funds Important Health Investigations for Island Foxes

Why are these biologists smiling? Because you are helping island foxes.

Mike Watling (FIF) presents funds to Lara Brenner (CIC) and Laura Shaskey (CINP)

At the annual meeting of the Island Fox Conservation Working Group, Mike Watling, a member of the Friends of the Island Fox Advisory Committee, presented FIF donations to support important investigations into the health of island foxes.

$3,000 to the Fox Program at Catalina Island Conservancy

tick attached to fox lower eyelid

This funding will test a second year of tick samples to determine the threat to island foxes from Lyme disease introduced to several islands in 2018. More on tick-borne disease testing. 

It also represents support from a Fresno Chaffee Zoo Wildlife Conservation grant that will analyze blood samples from island foxes on Catalina for signs of introduced disease. Once again a stow-away raccoon was recently stopped before hopping from a private boat to Catalina Island. Introduction of new diseases via pets and transported wildlife continue to be a problem for all islands, but especially Catalina. In 2018, blood samples revealed for the first time that a small number of Catalina Island foxes were exposed to a form of canine herpes virus. This important testing also detected exposure to a common dog illness, Coronavirus. 30% of the tested island foxes had been exposed to Coronavirus. Fortunately, no island foxes are known to have died from this disease.

$2,000 to the Fox Program at Channel Islands National Park
Intestinal parasites are causing early deaths among island foxes on San Miguel Island. This funding is part of a multi-pronged investigation to understand why and how new parasites are plaguing foxes on this island and why well-known parasites are causing greater impacts on San Miguel Island foxes. (see other ways FIF is helping this investigation)  

When you donate to FIF 

your donations go right to work helping island foxes.