[8]Because the island fox is geographically isolated, it has not acquired immunity to parasites and diseases brought in from the mainland and is especially vulnerable to those that the domestic dog (Canis familiaris) may carry.

In addition, predation by the golden eagle (Aquila chrysaetos) and human activities devastated fox numbers on several of the Channel Islands in the 1990s.

Pups are born in the spring and emerge from the den in early summer; the mother lactates for 7–9 weeks.

[13] Apparently, the explanation for the absence of inbreeding depression is that, over the long-term, the small population size of island foxes facilitated a reduced burden of strongly deleterious recessive mutations through genetic purging by natural selection.

[13] Purging of deleterious recessive mutations occurs when their detrimental effect is expressed in homozygous individuals.

Its preferred habitat is complex layer vegetation with a high density of woody, perennially fruiting shrubs.

The island fox eats fruits, insects, birds, eggs, land snails,[14] crabs, lizards, amphibians,[14] and small mammals, including deer mice (Peromyscus sp.

[16] Archaeological investigations have found island foxes (often juveniles) deliberately buried, sometimes in association with human remains.

[17] As of 2013, the IUCN lists the entire species as near threatened, an improvement from its previous status of "critically endangered".

[19] Golden eagle predation, discovered when foxes were radio-collared and monitored, proved to be the cause of the high mortality rates.

[20] The feral pigs on Santa Rosa, which themselves preyed on the foxes, were exterminated by the National Park Service in the early 1990s, which removed one of the golden eagle's food sources.

It has also been proposed that the complete removal of golden eagles may be the only action that could save three subspecies of the island fox from extinction.

[23] However, the pigs on Santa Cruz Island were killed by the Nature Conservancy on the idea that they drew the eagles to the foxes.

Because the island fox is isolated, it has not acquired immunity to parasites and diseases brought in from the mainland and is especially vulnerable to those the domestic dog may carry.

A canine distemper outbreak in 1998 killed approximately 90% of Santa Catalina Island's foxes, reducing the population from 1,300 to 103 in 2000.

[26] Scientists believe the distemper virus was introduced by a pet dog or a raccoon from the mainland that hitched a ride on a boat or a barge.

Diminished food supply and general degradation of the habitat due to introduced mammal species, including feral cats (Felis catus), pigs, sheep (Ovis aries), goats (Capra hircus), and American bison (Bison bison), the last having been introduced to Catalina Island in the 1920s by a Hollywood film crew shooting a Western,[28] also has had a negative effect on fox populations.

[29] With the gradual recovery of the shrike population on San Clemente Island, the Navy no longer controls the foxes.

[26] [34] Because the Channel Islands are almost entirely owned and controlled by either the Catalina Island Conservancy, The Nature Conservancy, or the federal government, the fox has a chance to receive the protection it needs, including constant supervision by interested officials without the ongoing threat of human encroachment on its habitat.