Who Is On San Miguel Island?

It's spring on San Miguel Island and wildlife technicians are counting one of the species important to island foxes. Can you guess which one?

Follow along with the Channel Island National Park team as they document 1 second a day on San Miguel Island.



Find out more about the island fox and this other island animal

Discover new observations of this animal interacting with bald eagles 

A huge thank you to the wildlife technicians at Channel Islands National Park for sending FIF this glimpse into their days on San Miguel. 

Insight on Channel Island Fox Territory Size & Habitat Use

A newly published study on Home-Range Size and Habitat Selection by Male Island Foxes (Urocyon littoralis) in a Low-Density Population by Elizabeth M. Drake, et al. reveals the largest documented territory ranges for male island foxes and new information regarding use of habitat at specific times of day. 

Prior to the catastrophic decline of island foxes on Santa Rosa (1996-2000), the population numbered over 1,700 individuals with a density of ~4 adult foxes per square km. Recovery on Santa Rosa was a slower process than on the other islands and this provided an opportunity to study territory size as the population recovered. The new study was carried out on Santa Rosa Island from 2009-2010, when the population was under 400 individuals and the density of adult foxes was less than 1 per square km. 

Santa Rosa Island

Drake found that in this period of low-density, male Santa Rosa Island foxes averaged territories of 3.39 square km in size. This is considerably larger than the less than .5 square km territories documented both on San Clemente (Sanchez, 2012) and on Santa Cruz prior to the population decline (Roemer et al., 2001). It is also much larger than the ~1 square km territories found on Santa Catalina when the population was well into recovery (King et al., 2014). 

While it is not surprising that island foxes expand territory size when there is less population density, the need for resources does not appear to be the driving force. During this period of fewer foxes, resources were plentiful. Therefore less territory was actually needed to provide adequate food for an individual island fox.

Drake found little overlap of territory between the individual males. In most cases, only minor overlap occurred at territorial borders, suggesting vigorous protection of territory.

Since Drake's data collection the population on Santa Rosa has more than doubled. As the density increases will the lack of territory overlap remain constant and will territory size decrease? Additional study is needed to answer these and other questions.

The study also looked at use of specific habitat. Surprisingly, there did not seem to be habitat types that were more desirable. But they did find significant data on use of habitat type at different times. 

The researchers found island foxes avoided bare landscape and grasslands during the day, but spent a significant amount of time in these areas at night. This use of specific terrain at night may suggest nocturnal hunting for deer mice and insects. Daylight hours were more typically spent in scrub and woodland areas. 

Link to Full Paper
http://www.bioone.org/doi/abs/10.1894/SWNAT-D-14-00021.1

Referenced papers above:
King, J. L., C. L. Duncan, and D. K. Garcelon. 2014. Status of the Santa Catalina Island fox 13 years after its decline. Western North American Naturalist. 7:382–396.

Roemer, G. W., D. A. Smith, D. K. Garcelon, R. K. Wayne. 2001. The behavioural ecology of the island fox (Urocyon littoralis). Journal of Zoology London 255:1–14.

Sanchez, J. N. 2012. Spatial ecology of disease spread in the island fox. M.S. thesis, Humboldt State University, Arcata, California.  

Island Fox Pups Grow Up

courtesy of NPS volunteer Inge Rose

During the warm days of summer, island fox pups grow up fast. Through rough and tumble play with their siblings, they learn to stalk and pounce. Small paws pin a sister or brother to the ground. They practice grabbing hold with their sharp little teeth and shaking. All of these behaviors are important skills for hunting.

Stalking and pouncing are the actions used by island foxes to catch island deer mice, birds, lizards and snakes, and even some insects, like grasshoppers. Island fox catches a snake.


Digging with agile, clawed paws enables island foxes to catch Jerusalem crickets and beetles. Insects are probably the first prey that most island fox pups hunt on their own. (See the Twitter adventures of Tani, a young island fox grows up, in the right side panel.)


Both parents help to teach the island fox pups where and how to find the variety of food they will need to survive on the rugged Channel Islands. As summer continues, fruit will ripen on a variety of native plants, bringing new food opportunities to the growing island foxes.

Link to a video of island fox pups on Catalina Island sent to FIF by an island fox friend. Watch for the three pups, just like in Tani's family.

Island Fox and the Jerusalem Cricket

Island fox pups on the Channel Islands are now about 6 weeks old and about to emerge from the family den. Friends of the Island Fox's Twitter fox, Tani, is learning what to eat. Both the mother and father island fox bring food to their pups. Follow Tani's tweets in the black Twitter box on the right.


Island foxes are omnivorous, they eat both plant food and other animals. Insects are fairly easy to find and they are an important part of an island fox's diet. Jerusalem crickets are a favorite food for island foxes. This large insect can be found in the soil under native plants and it provides a protein-rich meal. Jerusalem crickets are also known as earth babies, ninõs de la tierra or potato bugs (but they don't eat potatoes).

Jerusalem cricket

The island fox, the Catalina cherry and the Jerusalem cricket all depend on each other. The island fox eats the Jerusalem cricket, but it also eats the fruit of the Catalina cherry. The seeds of this plant are too big for the finches and small birds to swallow. But the island fox does swallow some of the seeds and helps to disperse the cherry seeds across the island so new plants can grow. Fox Scat The Jerusalem cricket lives under the Catalina cherry plant and eats some of its roots and dead leaves on the ground. It is a decomposer helping create healthy soil where new plants can grow. The island fox, the Catalina cherry and the Jerusalem cricket are just a small part of the interconnected web of plants and animals on the Channel Islands.


The island fox has evolved to have very pointed teeth so it can pick up small insects. The teeth act like tweezers carefully picking up grasshoppers and crickets, while leaving twigs and leaves behind.


Island foxes also eat the native island deer mice, some small birds and their eggs. As summer comes to the island, fruit will start to play an important role in the what the foxes eat.


Follow along with Tani on Twitter or on Facebook as an island fox grows up.