The island fox (Urocyon littoralis) is the smallest fox species in the United States and is the only medium-sized mammal unique to California. Despite weighing only 1.4 to 2.7 kg, it is still the largest native land mammal on the Channel Islands. It occurs on six of the eight Channel Islands, with each island supporting a genetically unique subspecies.

During the late Pleistocene, the three northern Channel Islands (San Miguel, Santa Cruz, and Santa Rosa) formed a single island. About 16,500 years ago gray foxes rafting on floating debris founded the island fox population on the northern Channel Islands. Approximately 11,500 years ago, rising sea levels split off first Santa Cruz Island, and later Santa Rosa and San Miguel  (ca. 9,500 years ago)  from the original landmass. Due to this fragmentation, the original fox population became isolated into three distinct populations, each evolving independently of one another. However, of all six subspecies, the northern Channel island foxes are most genetically similar to the mainland grey fox. According to the  fossil record, foxes first arrived San Clemente Island approximately 3,400 years ago. Most likely, Native Peoples carried them as revered pets aboard their boats. Foxes appeared on San Nicolas Island 2,200 years ago, and on Santa Catalina Island over 800 years ago.

Island foxes are primarily monogamous. Pairs produce 1-2 pups on average each year. Pups are born in a den located in natural cavities, rock piles, log piles, or in dense vegetation. Born in April or May, the pups emerge from the den in May or June and are dependent on their parents for another 2-3 months. Island foxes are omnivorous, feeding on a variety of insects as well as mice, birds, eggs, and fruit.