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Tuesday, December 16, 2014

Give the Gift of Saving Island Foxes


Since 2005, you have helped Friends of the Island Fox fund more than $60,000 in conservation efforts to save the endangered island fox.

In 2014 donors funded our  

In addition, in 2014 FIF:
 

In the year 2000, four subspecies of island fox were facing imminent extinction. San Miguel and Santa Rosa Islands each only had 15 surviving individual island foxes. On all six islands combined there was a total of approximately 1,400 island foxes. 


In just fourteen years, island fox populations have returned to historic levels. The official population numbers from 2013 estimate over 5,700 island foxes across all of the islands.

Maintaining this successful recovery of the island fox means continued monitoring. Disease and introduced threats can quickly impact these rare island populations.

This holiday season give the gift of directly saving an endangered species.
Donate through the "Island Fox Donation" box on the upper right hand side of the screen (the box with the smiling island fox).

Wednesday, December 10, 2014

Island Foxes Take a Holiday

It's that time of year when island foxes take a holiday, a holiday from family life.

courtesy of National Park Service
Channel Island foxes typically form monogamous pairs. A male and a female with adjoining or overlapping territories, mate for life. Their committed relationship helps them to successfully defend territory with important food resources and enables them to successfully raise offspring.

Pups are born helpless and require dutiful parental care to survive. While the female may not allow the male into the den to see the pups for a period of time, the male plays an important role in supplying the female and the pups with food.

After the pups have been raised to an age where they can fend for themselves, 6-8 months, they set out to find their own territories. Female pups tend to establish territories close to their parents, while male pups disperse to the opposite side of the island. Male dispersal may be a natural selection adaptation to avoid breeding with close relatives.

When the pups head out, the parents tend to take a holiday from each other as well. From November to early January, island foxes live a more solitary life. Perhaps this separation enables island foxes to find adequate food during the late fall and early winter. Perhaps it creates a greater opportunity for those who have lost a mate, to find a new one. Or perhaps, after a spring and summer filled with parenting, island foxes just need a break and a little solitude.

When the male and female reunite in late December - early January, they will be ready to start a new family in the spring.

As well as monitoring for unexpected fatalities, radio tracking collars help biologists to understand island fox movement and territory size.

Wednesday, November 12, 2014

New Findings on Island Fox Diet

Providing the best opportunity for island foxes to survive in the wild means understanding how they use resources and interact with other species.

Researchers, headed by Brian Cypher, examined the diet of island foxes across all six Channel Islands. Their findings have just been published in Global Ecology and Conservation, 2(2014) 255–66. Their article: “Multi-population comparison of resource exploitation by island foxes: Implications for conservation,” looks at the dietary differences between the six island subspecies, compares seasonal dietary shifts and dependence on introduced species, and recommends considerations for future conservation efforts. (Original paper)

The scientists gathered island fox scat across the six islands during four seasons in 2009. The scat samples were analyzed at California State University-Stanislaus’ Endangered Species Recovery Program office in Bakersfield, CA.


San Miguel Island deer mouse, courtesy of C. Schwemm
The researchers discovered that sixteen species were most frequently found in island fox scat or droppings:
  • Animal Prey - island deer mice, birds, lizards, beetles and beetle larvae, Jerusalem crickets, silk-spinning sand crickets, and grasshoppers
  • Plant Fruits - from toyon, manzanita, prickly pear cactus, and summer holly
  • Introduced Species - earwigs, European snails, fruits of ice plant and Australian saltbush

toyon fruit, courtesy of K. Dearborn animalbytes.net
Like many members of the canine family, island foxes are generalists when it comes to searching for food. They hunt small prey, search out seasonal fruit, but will also eat carrion. To survive on the Channel Islands, island foxes have evolved to exploit all available food resources. The graph below is a simplified comparison of the frequency with which different items appeared in the diet of the six island fox subspecies over a year. (for complete tables and percentages see the original paper, below)


Arthropods in the Diet
An interesting finding is the importance of numerous insect species. Insect parts constituted a “significant proportion of each scat.” The dark purple band in the graphic above depicts the frequency of insects found in scat on each island. On all six islands, beetles were a primary food item year-round (most identifiable were darkling beetles and ten-lined June beetles). Insect prey offers calorie-rich food for little energy expenditure, making them an efficient food source. In addition there was evidence island foxes occasionally ate cockroaches, dragonflies, butterfly caterpillars, and wasps.

European earwigs are now found across North America, including the Channel Islands. This introduced species has become an important food resource for island foxes. Earwigs were a primary food source on San Nicolas, San Miguel, Santa Rosa, and Santa Cruz, and were an important food source on San Clemente in the spring and on Santa Catalina during the fall and winter.

Crustaceans–beach hoppers and various crabs–were occasionally found in scat, demonstrating that some island foxes search for food along shorelines. Introduced European garden snails are now found on several of the Channel Islands and island foxes have included them in their foraging. On the two islands, San Clemente and San Nicolas, garden snails (red band on graphic) have become a primary food resource for island foxes.

Vertebrate Prey 

island fox with 3 deer mice in jaws, courtesy NPS
Many people think of foxes as primarily mammal and bird predators. While the island fox does hunt, these larger prey items appeared less frequently in the diet than you might think. The blue band represents the frequency of deer mouse remains and the green band represents the frequency of lizards (on San Clemente and San Miguel) or birds (on Santa Rosa). At a glance you can see that lizards and birds are not primary food sources on three islands and, on all islands, deer mice are less frequently found in the diet than insects.

Some additional prey animals were found occasionally in fox scat: Catalina California ground squirrels (only found on Catalina), scavenged seal or sea lion, spotted skunk (competitors on Santa Rosa and Santa Cruz), a few black rats, a house mouse, and a bat. While island foxes have been seen catching snakes, no evidence of snake remains was found in 2009.

Native Fruiting Plants

Santa Cruz Island fox in tree searching for fruit
The larger the Channel Island, the greater its plant diversity. The two largest islands, Santa Cruz and Santa Catalina, offer island foxes abundant plant resources. On these two islands, native fruit is a major part of the diet. The orange band on the graphic above shows that, on Santa Cruz, the primary island-fox diet consists of insects and fruit. 

On Santa Rosa, where large introduced browsing animals (deer and elk) continued to degrade native plants until 2011, deer mice were more frequently found in the diet than fruit. As the plant resources on Santa Rosa Island recover, researchers will be watching to see if fruit becomes a greater part of the island fox diet.

While fruit is an important part of the diet for most island foxes, there can be a great deal of difference in the species consumed between islands. The chart below shows the plant species found in the scat with a more than 10% frequency. 



On Santa Catalina and Santa Cruz the number of native plant species is high and no introduced non-native plant species are used frequently by island foxes. The islands that have suffered the greatest alteration of their native plants, San Clemente, San Nicolas, and San Miguel, are currently sustaining island foxes with introduced plant species. Notice on San Miguel, no native plant fruit was found to be consumed by island foxes.

Conservation Implications 

Removing introduced animal species from the islands has eliminated some carrion opportunities for island foxes. However, carrion of large introduced animals is not believed to have ever been a primary food source for these omnivorous canines.

Removing introduced non-native plant species is a major goal across the Channel Islands, but this study reveals an important caution. Island foxes are consuming introduced ice plant and the garden snails it harbors. Before invasive ice plant and Australian saltbush can be removed, native fruiting plants will need to be reestablished so that island foxes have enough resources to survive.

Future Study
This study provides the first comprehensive look at island fox diet across the Channel Islands and through the seasons. However, it represents one year: 2009. Native plant resources fluctuate with annual weather. Climate change and drought are impacting native plants and fruit production. Have impacts to plant resources in 2013 and 2014 challenged survival for island foxes and their smaller prey, which are also dependent on plant foods? Have island foxes altered their diet in the face of drought? (Parasite threat from food source on San Miguel) Can conservation measures to restore the natural ecosystem be managed so that resources are not compromised for island foxes? And will island foxes expand their diet as their ecosystem is restored? Continued study of island fox diet is vital to informed conservation decision making.

Download the original Research Paper “Multi-population comparison of resource exploitation by island foxes: Implications for conservation”

Friday, October 10, 2014

How Small Is An Island Fox?

Santa Cruz Island fox, courtesy of Anita Machlis
Frequently the size of an island fox is compared to a house cat. However, that can be a bit misleading. 

While house cats average from 8-10 pounds in weight, some breeds can easily weigh up to 18 pounds. Cats typically stand 8-10 inches at the shoulder.

Island foxes on the other hand are considerably smaller. While size varies between the islands and the subspecies, adults range from a weight of 2.35 to 6 pounds. Their fur may give the appearance of bulk, but most island foxes are quite slight in their physic. Finding enough food is always a challenge for these island dwellers. 

The length of the legs varies between islands, but the tallest of the island foxes only stand 8 inches at the shoulder. The Santa Cruz Island fox, the smallest, typically stands 6.5 - 7 inches at the shoulder. 

In actuality, island foxes actually weigh 40% less and are 22% shorter than the average house cat.

While felines are designed for leaping and vertical climbing, island foxes have somewhat weak legs. They can run and climb horizontally, but they are not leapers.

Can you guess what this is?


This is the view from inside a recycling trash can. Island foxes have narrow bodies. The largest males have heads that are only 2.5 inches wide. If an island fox can get its head into an opening, it can usually get the rest of its body through as well. Most island foxes can easily fit through the opening for a can or bottle. 

Human trash can be attractive to an animal that has a hard time finding enough food. Once an island fox gets into a recycle bin or a slightly open trash can, it has a very hard time getting out. 


 How do island foxes measure up to other small fox species?
  • kit fox (Vulpes macrotis), North America: 4 - 4.85 pounds; stand 12 inches to the shoulder
  • fennec fox (Vulpes zerda), Africa: 3 -3.5 pounds; stand 8 inches to the shoulder
fennec fox (Vulpes zerda), courtesy of Pat Meyer
The kit fox and the fennec fox are more closely related to each other than either is to the island fox. Because of the range in size among island fox subspecies, some island foxes are smaller than fennec foxes. Some weigh more than kit foxes, but all are shorter than kit foxes. 

Monday, September 22, 2014

Island Fox Presentations for Audubon Chapters

How can you learn more about the current status of the Channel Island fox?

Friends of the Island Fox educators will be giving presentations at three different Audubon chapter meetings in Southern California over the next few months.

We'll be talking about the how the island fox became endangered, the efforts to save them, as well as the different island fox populations and their current status–successes and challenges.  

Come out and join us at one of the following locations:

Thursday, Sept. 25, 2014 - 7:00 PM

The San Fernando Valley Audubon
Encino Community Center 
4935 Balboa Blvd., Encino, CA


island scrub-jay

Tuesday, Nov. 18, 2014 - 7:00 PM

Palos Verde / South Bay Audubon
Madrona Nature Center 
3201 Plaza del Amo, Torrance, CA


bald eagle
 

Thursday, March 18, 2015 - 7:30 PM

El Dorado Audubon
El Dorado Nature Center in Long Beach
7550 E Spring St, Long Beach, CA

Island foxes have a very interconnected relationship with the birds in their ecosystem.

Or for information about Island Fox Programs for your organization or club contact pat@islandfox.org  

Wednesday, September 10, 2014

Fresno Chaffee Zoo Selects FIF for Five Year Grant

Fresno Chaffee Zoo representatives visiting Santa Cruz Island
The Animal Care Staff from the Fresno Chaffee Zoo has long supported island fox conservation. They first raised funds for radio-tracking collars in 2006.

The Fresno Chaffee Zoo awards conservation grants to a variety of worldwide conservation efforts each year. Over the past eight years, Friends of the Island Fox has received support from the Fresno Chaffee Zoo to fund:
This summer, we received notification that a five-year grant has been awarded to Friends of the Island Fox for island fox conservation. Of 66 applications only 8 were extend 5-year support. Among the grant recipients, FIF is the only organization working with a North American species in the United States!

We are thrilled by the support from our friends at the Fresno Chaffee Zoo. While Fresno may be over the hills from the Pacific Ocean and the Channel Islands, FIF has participated in Fresno's Earth Day celebration and found their visitors very interested in the island fox and its survival.


The success of island fox conservation is based on local support and dedicated partnerships. The first year of the Fresno Chaffee Zoo grant supported important serology or blood testing looking for the presence of canine diseases among island foxes and the replacement of equipment important to annual counting and health checks.

Their second year of support will continue supporting fieldwork by replacing 43 of the field capture cages that safely enable island foxes to be captured for annual counting and health checks.

During the annual evaluation of the six populations, approximately 100 specially adapted capture cages are employed on each island. To ensure disease is not transferred between islands, each Channel Island has its own set of field equipment. With the financial support from our island fox friends at the Fresno Chaffee Zoo, Channel Island fox conservation enters its 17th year with much needed new equipment.

Tuesday, August 12, 2014

Bald Eagle Recovery Spreads Across Channel Islands

Channel Islands National Park reported in July that 60 bald eagles are currently living across California's Channel Islands. In spring 2014 there were sixteen known breeding pairs and fourteen chicks successfully fledged or flew from the nest.

As bald eagles reestablish their population, they help protect island foxes by reducing the probability that golden eagles will colonize the islands. Bald eagles primarily prey on fish and seabirds, while the golden eagles prey specifically on mammals. In the late 1990s, golden eagles nearly caused the extinction of the island fox on three islands: San Miguel, Santa Rosa and Santa Cruz.

Milestone bald eagle birth in 2013.

A landmark this year was the return of bald eagles to San Clemente Island. It is believed this is the first time bald eagles have attempted to nest on this southern island in approximately 50 years. The U.S. Navy manages San Clemente Island and they have been successful in protecting island foxes and other island endemic species. The bald eagles are evidence of recovering habitat on the windswept island. 

The newly established pair was unsuccessful in nesting in 2014, but hopes are high that the pair will find success in the future.

According to the National Park Service the pair of bald eagles combine the successes found on the other Channel Islands. The female was hatched near Juneau, Alaska, in 2004. She was relocated as a juvenile to Santa Cruz Island as part of the efforts to reestablish bald eagles on the National Park islands.

The male eagle is a young adult, hatched in 2007. He began life in an incubator on Santa Catalina Island and was placed in a bald eagle nest on the island, where he was raised by foster eagle parents. 

With a number of active bald eagle nests on Santa Cruz and Santa Catalina Islands, the young pair looked south for territory of their own. Biologists hope that eventually all of the Channel Islands will have resident bald eagles. The recovery of the bald eagle and the island fox is dramatically interconnected. Success for the bald eagles supports island fox recovery and stability.


See Current Island Fox Recovery, island by island.

Tuesday, July 29, 2014

Considering Epidemic Disease Threats to Island Foxes

courtesy of Paul Bronstein
What saved the Catalina Island fox from rapid extinction when canine distemper virus was introduced between 1998-1999? 

An isthmus and human action

Epidemic disease poses a major threat to naive island species like the Channel Island fox. When distemper was introduced via a raccoon transported unknowingly to the island, the disease spread rapidly throughout the island fox population. Nearly all of the 103 surviving Catalina Island foxes lived north of the isthmus, a narrow neck of land connecting the western and eastern parts of the island.


photo from NOAA of Santa Catalina Island
Fox traffic across this exposed area is minimal.

At the recent Island Fox Conservation Working Group Meeting, Brian Hudgens from the Institute for Wildlife Studies (IWS) reported on his findings “Mapping Epidemic Risk in Island Foxes.”

Working with Julie King from the Catalina Island Conservancy, they considered the map of Catalina Island and the areas where epidemic disease is most likely to be introduced via human visitors–the towns of Avalon and Two Harbors, beaches and harbors, and youth camps. They combined this with fox related factors:

  1. island fox population density on Catalina
  2. typical home range size of individual island foxes
  3. range overlap with neighboring island foxes
  4. number of interactions with neighboring foxes
It quickly became apparent that island fox density on Catalina Island is highest in the areas near human habitation; the areas which also pose the greatest risk for disease introduction.

Next, Hudgens created a computer model calculating how introduced canine distemper virus would travel across the island and through the island fox population. What they didn’t expect was that in most cases it didn’t matter where the disease was introduced, in 3 - 4 months an epidemic would cause 100% mortality island-wide. The only deviation was a reduction to 90-100% mortality, if the disease was introduced at the far western end of the island, with the isthmus to hinder the infection spread.


Adding vaccination into the modeling dramatically changed the modeling outcome and the most significant protection was provided by island-wide vaccination of individual island foxes. When a significant number of island foxes across the island were vaccinated in the model, animals that were not vaccinated had a four-times better chance of surviving as well.

Friends of the Island Fox funded 400 island fox distemper vaccinations in 2012.

Each vaccination for rabies or distemper costs $10.
 

Vaccination provides vital protection for these rare island foxes. Successful recovery can only be maintained through vigilant proactive protection.  

Tuesday, July 01, 2014

Channel Island Fox Status Update June 2014

photo courtesy of Dave Graber
photo courtesy of Kevin Schafer
The annual meeting of the Island Fox Conservation Working Group reported that the general status of the six subspecies of Channel Island foxes is GOOD.

All subspecies are maintaining stable populations of over 300 individuals. There are no known specific issues that put any of the Channel Island fox subspecies in eminent threat of extinction. Each island, however, faces its own concerns and challenges. 

  
Island Fox Update 2014 pdf, a specific island-by-island summary
  • San Miguel Island - 577 (low of 15 in the year 2000). Population recovered with over 500 individuals since 2010. Concern: New threat from parasites.
  • Santa Rosa Island - 894 (low of 15 in the year 2000). Population steadily increasing.
  • Santa Cruz Island - 1,085 (low of 62 in the year 2002). Population recovered and stable with over 1,000 individuals since 2009.
  • Santa Catalina Island - 1,852 (low of 103 in the year 2000). Population recovered and stable with over 1,000 individuals since 2010. Concern: Climate change impacts and high risk for introduced disease.
  • San Clemente Island - 1,002 (not Endangered). Population stable. Concern: New disease threat connected to mineral particulates in the air.
  • San Nicolas Island - 350 (not Endangered). Population high, but declining. Concern: Cause of decline currently unknown, see below.

Concerns:

As populations reach the carrying capacity on some islands, there are new challenges to island fox survival. Continued drought appears to be impacting prey and plant species on some islands, which in turn impacts the island fox. Not only are resources reduced, there may be new threats posed by parasites. (Spiny-headed worm on San Miguel Island).

raccoon stowaway on Catalina Express, Dec. 2013
photo courtesy of Ciara Virdan
Introduced disease remains a threat to all island foxes, especially on islands visited by people. Dogs, cats, and introduced species, like raccoons, are all avenues for disease to be transported to isolated and disease-naive island foxes.

 Canine distemper virus (CDV) caused the population collapse of island foxes on Santa Catalina in 1998-2000. Vaccination against CDV is part of protecting island foxes on all six islands. Island foxes, and many other wild species, are unable to withstand the standard CDV vaccine given to dogs and depend on a vaccine produced by Merial, the corporation that makes Frontline and other veterinary products. Unfortunately, there has been no production of the vaccine this year. If the vaccine is not available by fall counting and health checks, island foxes may go unprotected for the 2014-2015 year.


On San Nicholas Island where the fox population has been high and stable for years, annual monitoring has revealed a trend toward decline that is currently unexplained. A group of island foxes on San Nicolas Island will be radio collared in the fall during annual counting to help biologists determine the cause for the decline. (For more specifics see Island Fox Update 2014 pdf above)

Positive Notes:

While there are concerns regarding San Miguel and San Nicolas, island foxes are doing well. Working with U.C. Davis and veterinary pathologists, National Park biologists hope to determine the specific reasons behind the appearance of new parasites on San Miguel Island and the long-term threat they pose to the island fox population.

Monitoring with radio collars on San Nicolas Island will enable biologists to locate individual island foxes that die in a timely manner. Necropsies performed on these animals will help provide information regarding cause of death.

The most positive note of all is that the Island Fox Conservation Recovery Group continues to meet. Nothing is more important for the continued recovery of the island fox than bringing this group of people together who can share their expertise, their experience, and their creative solutions. Friends of the Island Fox thanks all of our donors who made this annual meeting possible!

Wednesday, June 18, 2014

Endangered Island Foxes Stabilizing But Need to Monitor Continues

courtesy of Kevin Schafer
The annual meeting of the Island Fox Conservation Working Group took place yesterday, hosted by Friends of the Island Fox

The good news is that the four endangered populations of island foxes on San Miguel, Santa Rosa, Santa Cruz, and Santa Catalina Islands continue to recover and stabilize. 

Island foxes on the two Navy islands, San Clemente and San Nicolas, are not considered endangered by the U.S. Fish & Wildlife Service (USFWS) and their populations remain stable and at high densities (number of individual animals per square kilometer).

The graph below shows population numbers for San Miguel Island through fall 2013. The population was initially estimated in 1994. Actual individuals were counted when island foxes were in captive breeding pens on the island. Through 2007, the island foxes on San Miguel were gradually returned to the wild. Wild population figures are estimated through an annual catching of individuals and computer extrapolation of that data. More on Counting Island Foxes.


The graph shows how San Miguel's population dropped dramatically due to golden eagle predation at the turn of the century. Fifteen surviving individuals became the founders of the current San Miguel Island fox subspecies; captive breeding by the National Park Service saved this subspecies from extinction.

The population has made an amazing and rapid recovery to a level greater than historically estimated before the crisis. Statistical analysis through fall 2013 calculated that for the fifth year in a row,  individual island foxes on San Miguel have a 90% chance of surviving through the next year and the potential for species extinction is very low.  

Currently the density of island foxes on San Miguel is very high, 10-20 individuals per kilometer in some habitat areas. National Park biologist Tim Coonan believes the data shows the San Miguel Island fox population has fully recovered and has reached the "carrying capacity" for this small island. This means the food and territory resources available on San Miguel can not support continued population increase. The minor population ups and downs since 2010 follow the pattern of a population responding to resource availability. 

Conservation efforts on behalf of the San Miguel Island fox have been very successful. Across Santa Rosa, Santa Cruz and Santa Catalina the stories of population recovery from the brink of extinction are all inspiring.


However, there is an additional cautionary chapter in the San Miguel story. As the island foxes in the National Park have recovered, funding has decreased for their management. The staff that works with the foxes on San Miguel and Santa Rosa has gone from six to three technicians. 

Since the end of 2013 thru May of 2014, seventeen radio-collared island foxes on San Miguel have died from peritonitis caused by a parasitic spiny-headed worm (the exact species is still being determined). This parasite has not been a problem on the Channel Islands before and typically does not cause mortality in canines. The spiny-headed worm is transmitted to the fox through another animal-species host that the fox has eaten.

Today as the biologists, veterinarians, land managers and government officials meet for a second day, they are sharing expertise and ideas about how to respond to this potential threat to the San Miguel Island fox. Over the next few months they will be looking for answers to new questions:
  • What prey species is carrying the parasite?
  • Have island foxes on San Miguel changed to a prey species that is a vector for this parasite?
  • Across San Miguel Island a higher number of island foxes are appearing underweight. Are these foxes infected with the parasite as well?
  • Is drought a factor in this problem?
  • Is high population density a factor?  
  • Why is the number of these parasites so high in individual foxes?
  • During the fall count, there appeared to be a very low number of pups on San Miguel. Is this a natural response to high population density and reduced resources? Is the parasite impacting female health and therefore reproduction?
  • Is the parasite a possible threat to other Channel Island fox subspecies?
Channel Island foxes are rare creatures. Prior to the near extinctions of 2000, little was known about this endemic California species. If there is one thing that has become obvious over the years, it is that change to the island habitat, either directly by people or indirectly through environmental toxins, climate change, or introduced invasive species, island fox survival requires vigilance. 

The continuity of public support and scientific experts engaged in island fox conservation is vital to maintaining this unique species into the future. Funding the Island Fox Conservation Working Group meeting is an important part of island fox conservation.

Stay tuned for more information from the Working Group meeting.