Facts on Cats and Wildlife: A Conservation Dilemma

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Hummingbird Habitats
A Fact Sheet Series on Managing Lands for Wildlife

University of Maine Cooperative Extension
Bulletin #7148

Facts on Cats and Wildlife¹: A Conservation Dilemma

Domestic cats first arrived in North America with European colonists several hundred years ago. Since that time, cats have multiplied and thrived as cherished pets, unwanted strays and semi-wild predators. Although often overlooked as a problem, free-ranging cats affect other animals, often far from the homes and farms they share with people. Because we brought the domestic cat to North America, we have a responsibility to both the cats and to the wild animals they may affect. This fact sheet includes some interesting and perhaps surprising facts on the challenges posed by free-ranging domestic cats in the United States.

How Cats Became Domesticated

Domestic cats originated from an ancestral wild species, Felis silvestris, the European and African Wild Cat. The domestic cat is now considered a separate species, Felis catus. In appearance, domestic cats are similar to their wild relatives, and many of their behaviors, such as hunting and other activity patterns, remain essentially unchanged from their ancestral form.

Tips for Happy Indoor Cats

Kittens who are kept indoors usually show no desire to venture outside as cats. With knowledge, patience and time, we can change most cats who roam outdoors into happy indoor pets. These tips will help.

Provide a safe outside enclosure, such as a screened porch.
Provide window shelves so cats can monitor the outdoors from the safety of the indoors.
Play with your cat each day. Paper bags and cardboard boxes are sources of unending delight when you are away.
Plant kitty grass (available from pet supply stores) in indoor pots so your cat can graze.
Clean litter boxes regularly.

Source: “Keeping Cats Indoors Isn’t Just for the Birds,” a publication produced by the American Humane Society, American Bird Conservancy and the Humane Society of the United States.

Cats were first domesticated in Egypt around 2000 B.C. Domestic cats spread slowly to other parts of the globe, possibly because Egyptians prevented the export of the animal they worshipped as a goddess. However, by 500 B.C., the Greeks had acquired domestic cats, and they spread cats throughout their sphere of influence. The Romans introduced the domestic cat to Britain by A.D. 300. Domestic cats have now been introduced around the world, mostly by colonists from Europe.

How Many Cats are There in the United States?

The number of pet cats in the United States has grown from 30 million in 1970 to 60 million in 1990. (These estimates are based on U.S. Census data and only include those cats that people claim to “own” as pets, not cats that are semi-wild or free-ranging.) Nationwide, approximately 30 percent of households have cats. In rural areas where free-ranging cats are usually not regarded as pets, approximately 60 percent of households have cats. The combined total of pets and free-ranging cats in the United States is probably more than 100 million. Because of their close association with humans, most of these cats are concentrated in areas where people live rather than in remote, undeveloped areas.

The Legal Status of Domestic Cats

The laws that relate to domestic cats vary by local government. In most areas, the person who provides care for a cat is legally responsible for its welfare and control. As with other domestic animals, if ownership can be established by collars or other means of identification, a cat is considered personal property. It is usually the responsibility of the owner to control the cat’s movements. In most areas, cats can be live-trapped and either returned to the owner or turned over to authorities if they wander onto other peoples’ property. Many municipalities have leash laws and require vaccination and neutering of pet cats.

What Effects Do Domestic Cats Have on Wildlife?

Although rural, free-ranging cats have greater access to wild animals and undoubtedly take the greatest toll, even urban house pets take live prey when allowed outside. Extensive studies of the feeding habits of free-ranging domestic cats over 50 years and four continents indicate that small mammals make up approximately 70 percent of these cats’ prey. Birds make up about 20 percent. The remaining 10 percent is a variety of other animals. The diets of free-ranging cat populations, however, reflect the food locally available.

Truths about Cats and Birds

We all know that cats don’t have nine lives. There are three other myths about cat predation we’d like to dispel.

1. “Belled” cats do kill wildlife. Cats with bells on their collars can learn to stalk their prey silently. Even if they don’t, wild animals do not necessarily associate the ringing of a bell with danger.
2. Even well-fed cats kill wildlife. The urge to hunt and the urge to eat are controlled by different portions of the cat’s brain.
3. Once caught by a cat, few birds survive, even if they appear to have escaped. Infection from the cat’s teeth or claws or the stress of capture usually results in death.

Source: “Keeping Cats Indoors Isn’t Just for the Birds,” a publication produced by the American Humane Society, American Bird Conservancy and the Humane Society of the United States.

Observation of free-ranging domestic cats shows that some individuals can kill over 1,000 wild animals per year, although smaller numbers are more typical. Some data suggest that free-ranging cats living in small towns kill an average of 14 wild animals each per year. Rural cats kill many more wild animals than urban or suburban cats do. Several studies found that up to 90 percent of free-ranging domestic cats’ diet was wild animals, and less than 10 percent of rural cats killed no wild animals.

Nationwide, cats kill over a billion small mammals and millions of birds each year. Some of these kills are house mice, rats and other species considered pests, but many are native songbirds and mammals whose populations are already stressed by other factors, such as habitat destruction and pesticide pollution.

Despite the difficulties in showing the effect most predators have on their prey, cats are known to have serious impacts on small mammals and birds. Worldwide, cats may have been involved in the extinction of more bird species than any other cause, except habitat destruction. Cats are contributing to the endangerment of populations of certain birds, such as least terns, piping plovers and loggerhead shrikes. In Florida, marsh rabbits in Key West have been threatened by predation from domestic cats. Cats introduced by people living on the barrier islands of Florida’s coast have depleted several unique species of mice and woodrats to near extinction.

Not only do cats prey on many small mammals and birds, but they can outnumber and compete with native predators. Domestic cats eat many of the same animals that native predators do. When present in large numbers, cats can reduce the availability of prey for native predators, such as hawks and weasels.

Free-ranging domestic cats can also transmit new diseases to wild animals. Domestic cats have spread feline leukemia virus to mountain lions and may have recently infected the endangered Florida panther with feline panleukopenia (feline distemper) and an immune deficiency disease. These diseases may pose a serious threat to this rare species. Some free-ranging domestic cats also carry several diseases that are easily transmitted to humans, including rabies and toxoplasmosis.

Domestic Cats vs. Native Predators

Although cats make affectionate pets, many domestic cats hunt as effectively as wild predators. However, they differ from wild predators in three important ways. First, people protect cats from disease, predation and competition, factors that can control numbers of wild predators, such as bobcats, foxes or coyotes. Second, they often have a dependable food supply and are, therefore, not influenced by changes in prey populations. Populations of native predators will decline when prey becomes scarce. Cats receiving food from people remain abundant and continue to hunt even rare species. Third, unlike many native predators, cat densities are either poorly limited or not limited by territoriality.

These three factors allow domestic cats to exist at much higher densities than native predators. With abundant food, densities can reach over nine per acre. In addition, cats often form large feeding and breeding “colonies” (81 cats were recorded in one colony, and colonies of over 20 are not uncommon). Unlike some predators, a cat’s desire to hunt is not suppressed by its food supply. Even when fed regularly by people, a cat’s urge to hunt remains strong.

In Summary

Free-ranging cats are abundant and widespread predators. They often exist at much higher densities than native predators. They prey on large numbers of wild animals, some of which are rare or endangered. They compete with native predators, and they harbor a variety of diseases. Yet, cats are popular pets. If we want to care for our pets—and still protect our native wildlife—we need to be aware of their adverse effects on wildlife.

Risks for Outdoor Cats

The average life expectancy of an outdoor cat is just two to five years, while an indoor cat may survive for 17 or more years. Cats who roam are constantly in danger. Here is a list of risks that outdoor cats face.

Cars. Millions of cats are run over by cars each year. Seeking warmth, outdoor cats crawl into car engines and are killed or maimed when the car is restarted. Motorists risk accidents in attempting to avoid hitting free-roaming cats.
Animal Attacks. Torn ears, scratched eyes, abscesses, internal injuries, diseases and sometimes death result from encounters with dogs, other cats and wild animals, like raccoons, coyotes and foxes.
Human Cruelty. Each year, animal shelters and veterinarians treat cats who have been shot, stabbed or set on fire. Unsupervised cats may also be captured and sold to research laboratories or used as “bait” to train fighting dogs.
Overpopulation. Unaltered free-roaming cats are the single most important reason for cat over-population. As a result, millions of homeless cats must be euthanized each year.
Disease. Cats allowed outdoors risk exposure to fatal diseases, including rabies, feline leukemia, distemper and feline immunodeficiency virus (FIV). Vaccines are not 100 percent effective; there is no vaccine at this time for FIV.
Parasites. Cats allowed outdoors are more likely to contract debilitating parasites, such as worms, ticks, mites and fleas.
Poisons and Traps. Exposure to pesticides, rodenticides and antifreeze kills thousands of outdoor cats each year. Cats are maimed and killed in traps set for furbearing animals.

Source: “Keeping Cats Indoors Isn’t Just for the Birds,” a publication produced by the American Humane Society, American Bird Conservancy and the Humane Society of the United States.

What You Can Do

Keep only as many pet cats as you can feed and care for. Control reproduction and humanely euthanize any unwanted cats. On farms, keep the smallest number of free-ranging cats needed to control rodents. Well-fed, neutered females will stay close to farm buildings and do most of their killing where rodent control is needed most. Traps and rodenticides, as well as rodent-proof storage and construction, can be even more effective than cats.
If at all possible, for the sake of your cat and local wildlife, keep your cat indoors. Confinement will prevent unwanted reproduction, predation on wild animals and the spread of disease. Bells don’t work very well because, even if the bell rings, it’s usually too late for the prey being stalked. Declawing many reduce hunting success, but many declawed cats are still good predators. Keeping your cats indoors helps protect the wildlife around your yard and prevents your cat from picking up diseases from strays or getting injured. If you decide to let your cats outdoors, consider using a fence enclosure or runway.
Neuter your cats or prevent them from breeding and encourage others to do so. Support or initiate efforts for licensing and neutering pets. In areas where such laws already exist, insist that they be enforced. For information on local licensing and neutering laws, contact your local health department or Humane Society.
Locate bird feeders in sites that do not provide cover for preying cats. Cats are a big source of mortality among birds that come to feeders. To prevent cats from climbing to bird nests, put animal guards around any trees in your yard that may have nesting birds.
Don’t dispose of unwanted cats by releasing them in rural areas. This practice enlarges rural cat populations and is an inhumane way of dealing with unwanted cats. Cats suffer in an unfamiliar setting, even if they are good predators. Contact your local animal welfare organization for help.
Eliminate sources of food, such as garbage or outdoor pet food dishes, that attract stray cats.
Don’t feed stray cats. Feeding strays maintains high densities of cats that kill and compete with native wildlife populations. Cat colonies will form around sources of food and grow to the limits of the food supply. Colonies can grow to include dozens of animals. The cats suffer because of disease and physical injury. Native wildlife suffers from predation and competition, and colonies can be a source of disease for animals and humans. Those concerned with the welfare of animals can improve the lives of the many native species by protecting and improving native habitats.

Contacts

Humane Society of the United States, 2100 L St., NW, Washington, D.C. 20037. Website: http://www.hsus.org

American Bird Conservancy, 1250 24th St. NW, Suite 220, Washington, D.C. 20037. Phone: (202) 467-8348.

Native Species Network, P.O. Box 405, Bodega Bay, CA 94923. E-mail: nsn@wco.com.

¹Authors of this publication are John S. Coleman, Stanley A. Temple and Scott R. Craven. This publication was originally produced by the University of Wisconsin Extension, with funding provided by the U.S. Fish and Wildlife Service, National Conservation Center, Division of Education. Reprinted with permission of University of Wisconsin Extension.

For more information, contact your University of Maine Cooperative Extension county office.

See the University of Maine Cooperative Extension Online Publications Catalog for the complete Habitats fact sheet series.

Published and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914, by the University of Maine Cooperative Extension, the Land Grant University of the state of Maine and the U.S. Department of Agriculture cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide equal opportunities in programs and employment.

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