Feral and free-ranging domestic cats are exotic species to North America. Exotic species are recognized as one of the most widespread and serious threats to the integrity of native wildlife populations and natural ecosystems. Exotic species present special challenges for wildlife managers because their negative impacts on native species are poorly understood by the public to the point that many exotic species are perceived as a natural component of the environment. Some exotic species have advocacy groups that promote their continued presence, and few policies and laws deal directly with their control. Perhaps no issue has captured more of the challenges for contemporary wildlife management than the impacts of feral or free-ranging domestic cats and their impacts on native wildlife.
Domestic cats originated from an ancestral wild species, the European and African wild cat (Felis silvestris). The domestic cat (Felis catus) is now considered a separate species, and is found on all 7 continents, with 600 million cats worldwide and 148-188 million within the U.S.. Domestic cats have great reproductive potential. Individuals become sexually mature as early as 6 months of age, and reproduction can occur throughout the year. A single female may produce as many as 3 litters each year with 2 to 4 kittens per litter, with the capacity to successfully raise as many as 12 offspring in any given year.
A growing body of literature strongly suggests that domestic cats are significant predators on small mammals, birds, reptiles, and amphibians. Feral and free-ranging cats also serve as reservoirs for several diseases, including rabies, toxoplasmosis, bartonellosis, typhus, and feline immunodeficiency virus, that can have significant effects on the health of humans, wildlife, and other domestic animals. Because humans often feed free-ranging cats, they can reach population levels that may result in abnormally high predation rates on wildlife and increase the spread of diseases. Domestic cats have tremendous impacts on wildlife and are responsible for the extinction of numerous mammals, reptiles, and at least 33 bird species globally. Effects of cat predation and disease spread are most pronounced in island settings (both actual islands and islands of habitat), where populations of wildlife are already low or stressed by other factors. Effects are also significant in natural areas where cat colonies become established. Competition with native predators, disease implications for native wildlife populations, and pet owners’ attitudes toward wildlife and wildlife management also are important issues.
Extensive popular debate over absolute numbers or types of prey taken by feral and free-ranging cats is not productive. The number of cats is undeniably large. Even if conservative estimates of prey taken are considered, the number of prey animals killed is immense. The supplemental feeding of cats does not deter them from killing wildlife; often they do not eat what they kill. Likewise, population-level impacts of diseases associated with cats have only been established in a few wildlife species, such as southern sea otters (Enhydra lutris nereis), but negative individual impacts clearly occur in an extremely wide range of species. Humans introduced cats to North America, and humans are ultimately responsible for the effects these animals have on native wildlife species.
The policy of The Wildlife Society regarding feral and free-ranging domestic cats is to:
- Support and encourage the humane elimination of feral cat populations, including feral cat colonies, through adoption into indoor-only homes of eligible cats and humane euthanasia of unadoptable cats.
- Support the passage and enforcement of local and state ordinances prohibiting the feeding of feral cats, especially on public lands, and the release of unwanted pet or feral cats into the wild.
- Oppose the passage of any local or state ordinances that legalize the maintenance of “managed” (trap/neuter/release) free-ranging cat colonies.
- Support educational programs and materials that provide scientific information on feral cats and the negative effects on cats from living outdoors, and call on pet owners to keep cats indoors, in outdoor enclosures, or on a leash.
- Support programs to educate and encourage pet owners to neuter or spay their cats, and encourage all pet adoption programs to require potential owners to spay or neuter their pet.
- Support the development and dissemination of information on what individual cat owners can do to minimize predation by free-ranging cats, and to minimize potential disease transmission to humans, wildlife, cats, and other domestic animals.
- Pledge to work with the conservation and animal welfare communities to educate the public about the effects of free-ranging and feral cats on native wildlife, including birds, small mammals, reptiles, amphibians, and endangered species.
- Support educational efforts to encourage the agricultural community to keep farm-cat numbers at low, manageable levels and use alternative, environmentally safe rodent control methods.
- Support efforts to reduce risks to the health of humans and other animals posed by diseases and parasites of feral cats, including but not limited to removal of free-ranging cats and elimination of feral cat colonies. Encourage researchers to develop, obtain, and disseminate information on the impacts of feral and free-ranging cats on native wildlife populations, relative to predation, competition, and diseases.
- Recognize that cats as pets have a long association with humans, and that responsible cat owners are to be encouraged to continue caring for the animals under their control.
The Wildlife Society’s Position Statement on Invasive and Feral Species states that the Society opposes “introduction or maintenance of invasive species and feral species that threaten the survival of indigenous species” (TWS 2016).