California Department of Fish and Wildlife

Ferrets in the Wild

Introduction Table of Content Ferret Bibliography Population Estimates
Ferret Survey Biology and Uses Ferrets in the Wild World Distribution
California's Concerns Native Carnivores Other Mustelidae Tables

Escape of Ferrets to the Wild

"Ferrets may escape into the wild in any country where they are kept . . ." - King (1990)

Domestic ferrets frequently escape from cages and from households and fur farms.

Ferrets are accomplished escape artists.  They need only a 1-inch by 2-inch opening to get their head through, and the rest of the body will follow.

Not all releases into the wild are the result of accidental escapes. In 1998, animal-rights activists released 10 ferrets and 161 minks from a Wisconsin facility that provides vaccines for the fur industry. Also, pet ferrets are abandoned by some owners, just as some people abandon rabbits, cats, dogs, and other kinds of pets.

In California, many stray ferrets are found every year. From 1989 to 1998, 47 stray ferrets from communities in the general Sacramento region of the State were transported to the Department of Fish and Wildlife field station for temporary holding. This represents but a small fraction of what escapes in the State as a whole. Such rescued ferrets are held until transported by volunteers to states where ferrets are legal.

It is completely within the realm of possibility to find a stray ferret . . . a slow increase in human interaction may be necessary before a ferret will once more become outward and friendly”. - Jeans (1994).

Survival of Released or Escaped Domestic Ferrets

Pet ferret literature routinely describes the ferret as having been domesticated for so long that domestic ferrets are now dependent on people to survive, that they have no hunting skills left, and that they can not survive in the wild. A common claim is that an escaped ferret will die within three days.

Probably, most escaped or abandoned ferrets either are re-caught or will die from dehydration if there is not a water supply available, or starvation if they can't find food right away. "...the ferret, being by nature an obligate carnivore, has an extremely short digestive tract, and requires meals as often as every four to six hours." In ferrets, the food transit time is just a few hours. While searching for food and water in unfamiliar settings, ferrets also run the risk of becoming prey of other predators. Any animal that has been confined all of its life and then is abruptly thrust into unfamiliar outdoors surroundings would have little chance of surviving.

However, ferrets can and do survive in the wild in various places around the world and under a variety of conditions (World Distribution). The individuals that have a good chance of surviving are those that soon detect the odor of animals they had previously fed upon. These are the ferrets that are experienced in hunting rabbits and rodents, that had prior experience killing animals, such as field, house mice, and "feeder" mice in households , or that are soon able to scavenge or find cat food or other familiar-smelling pet food left outside. "Feeder mice" and feeder rats are rodents that are commercially sold as frozen or live animal food or that pet owners breed and raise themselves as live or freshly killed food for their pet snakes or other carnivores.  Some labs and pet ferret owners feed live mice to their ferrets as a nutritious supplement or alternative to commercial ferret food.

In 1995 in Oneida County, New York, an escaped pet ferret was gone approximately two weeks. After the owners got it back, it was found to have been exposed to rabies.

In southeast Alaska, domestic ferrets in good condition were trapped in the wild far from human habitation during winters in the years following legalization of ferrets as pets in that state.

"Released from captivity, the ferret (if it survives) quickly reverts, and in a generation or two, is absorbed into the wild population." - Wellstead (1981)

Many wild populations of domestic ferrets in the world resulted from the escape of ferrets. Escaped fur animals at times have contributed to local populations of ferrets in the wild, and have even threatened locally rare wildlife.

Some ferret literature states that an intact female will almost certainly die if not bred, but other sources indicate rates of mortality of 20-50%. Bissonnette, T. H. (1950), wrote, "The old superstition, that if a female ferret is not mated and allowed to become pregnant she will die as a result, is not true. Females may be kept over two years at least without mating and live a healthy life properly fed and kept free from dirt and infection.

"Given the many factors determining the chance of arrival and success or failure of an exotic species in a new environment, any attempt to predict future additions to the list must be highly speculative. Nonetheless, their popularity as pets, the known escapes or releases, and the evidence of persistence of some individuals in the wild suggest that the ferret (Mustela putorius) and ocelot (Felis pardalis) may eventually establish wild breeding populations in Florida. I am aware of accounts of ocelot sightings in the wild in the Miami area in 1958, Alachua County in 1962, and Highlands County during the 1970s—and there are undoubtedly more. Ferrets were captured in Highland Hammock State Park (Highlands County) in 1978 and Jonathan Dickinson State Park (Martin County) in 1979 (R. Roberts, pers. comm.). The latter animal may have been one that was lost by a park visitor eight months before. Other sightings of ferrets in the wild in Highlands and DeSoto counties occurred in 1973 and 1987."  [Layne, J.N., p.185 in Simberloff, D., D.C. Schmitz, and T.C. Brown. 1997. (eds.) Strangers in paradise; impact and management of nonindigenous species in Florida. Island Press, Washington, D.C. 435 pp.]

Difficulty Detecting Free-living Ferrets

"Ferrets are mainly nocturnal, so are not often directly observed in the wild . . ." - King (1990)

"Now you see it now you don’t" - might be the best description of all that most people see of a ferret, stoat or weasel. Mustelids are widely distributed in New Zealand, but because they are small, secretive and fast moving, they are difficult to observe in the wild." - N.Z. Department of Conservation

Except at breeding time or when the female is raising young, feral ferrets are solitary. Ferrets do not live in colonies, as do prairie dogs.

Ferrets would be as difficult to detect in the wild as mink were in Britain. "Mink had been escaping from fur farms for many years, but only recently have established breeding feral mink populations been discovered. Many of these carnivores are nocturnal terrestrial predators and detection of them by the novice can be difficult." - Linn (1958)

On San Juan Island, Washington (USA), a feral ferret population was discovered accidentally in 1974, when domestic ferrets were unexpectedly caught in rabbit traps during a study of the European rabbit population on the island by the National Park Service.  Since no research was conducted on ferrets, the impacts of ferrets on wildlife were not investigated, and the presumed disappearance of the population sometime in the 1980s was not documented (Stevens, 1975Stevens, 1982).

Although individual ferrets would not be readily detectable, survey methods such as baited track plates or cameras may be useful in detecting populations of ferrets.  

Difficulty Controlling Ferrets

Once they've become well established as a breeding population, most non-native species, especially smaller ones, are too difficult to eradicate, for technical, economic, and social reasons. "Predatory mammals are especially difficult, and sometimes impossible to eradicate, for example, feral cats, dogs, mink, and ferrets." - IUCN, The World Conservation Union, Position Statement on Translocation of Living Organisms, 1987

In wildlife areas, it is difficult for land and wildlife managers to take actions to control or eradicate predatory animals, whether introduced or native, that threaten other wildlife.  At many of California's coastal wetland wildlife areas, agency efforts to protect endangered birds and other native wildlife by trapping a recently arrived, non-native predator, the red fox, has often been met with strong opposition, including legal actions, by various citizen's groups concerned about the welfare of the foxes. The same public opposition to agency control of feral and free-roaming domestic cats in wildlife areas has been occurring in California's urban parklands, coastal wetlands, and other wildlife areas.