Managing Domestic Cats in the Wildlands

There is a lack of information on feral cats (Felis catus formerly F. domesticus) and their effects on wildlife populations. They arrived in the US several hundred years ago.

There are 4 types of cats (Vant Woudt 1990). The first type creates no known environmental problem. Cats, however, may be shifted among the four categories:

1. House cats (rarely if ever the house or apartment; cherished pets)
2. Roaming cats (that normally remain close to home and owner)
3. Stray cats (semi-wild predators; that have no home or owner but stay in the human environment for food and shelter)
4. Feral cats (that survive and may breed in the wild without human support. The feral cat is a domestic house cat that has been abandoned to live in the wild or one that has strayed into or been born in the wild. The definition also includes free-ranging or roaming and stray cats (even though humans care them for).

Feral cats are often much larger than domestic ones. Survivor cats, after abandonment, are curbed by (1) attachment to the owner, food, and shelter; (2) incapacity to compete with native predators, even becoming one of their prey (e.g., owls and coyotes); (3) malnutrition (succumbing to exposure, disease, and parasites); (4) low immunity or resistance to diseases and parasites (there are many); and (5) lack of parental examples and play conducive to preparing an animal for life in the wild (Van't Woudt 1990).

Cats respond to movement; sense of smell is poorly developed. While they climb trees, they do it poorly and rarely can get to tree bird nests. The bird species subject to feral cats are thus of a type (that needs analysis) and it is likely that a single animal can effect long-term, whole-population numbers. Cats (unlike many other mammals) are rarely involved in waterfowl predation. They are carnivores and lizards are a prey of considerable importance and thus of local concern where such species are threatened or increases are desired,

There are relatively few management techniques for reducing feral cat populations. Recent studies are reported, but it is important to emphasize that other studies are needed to gain a better understanding of feral cat population and how to control them.

Feral cats are extremely efficient at preying on small birds and mammals. The general public typically only sees cats as a way of removing pest species and as pets, but they are also direct competitors with declining raptor populations and destructive to native species. In a study by George (1974), he asked 49 wildlife protective agencies about the distribution and density of cats in the U.S. None had any data on cat numbers. In 1916 Forbush wrote extensively about the great harm done by farm cats and feral cats to bird populations. There is lack of knowledge of cats and an understanding about their effects as an introduced species. Laboratory studies have suggested that hunger and hunting in cats are controlled by separate parts of the brain. Even though humans may feed cats, cats still have an instinct to hunt. Bradt reported that a cat that consumed domestic food killed 1,600 mammals and 60 birds in an 18-month period. Maister Salmon who published "The Compleat English Physician" in 1693 described the cat as the mortal enemy of the rat, mouse "and every sort of bird which it seizes as its prey." Forbush (1916:43) summarized his questionnaire saying that cats kill 2.7 birds per cat per day. He reported a careful (but single) observation -- 58 birds in a year -- and suggested a mature cat in good hunting grounds will catch about 50 birds a year. At a conservative 10 birds per cat-year, farm cats in Massachusetts (1916) kill about 700,000 birds a year.

Phil Eggborn reported on studies in Richmond, Virginia. Five cats killed 187 animals during 11 months in 1990. Animals were mice, chipmunks, rabbits, flying squirrels, songbirds, lizards, snakes, and frogs. One cat brought home 83 carcasses (a number not including those left in the field). Researchers estimated that Virginia's one million cats kill between 3 million and 26 million birds a year (similar to the 20 million estimated killed in England each year).

In Connecticut alone, cats are the third largest carriers of rabies. Nation wide, they are the domestic animal most frequently reported to have rabies. They may transmit the human disease toxoplasmosis. Fleas and well as tapeworms may present problems. Cat-scratch fever is a danger. They have spread feline leukemia virus to mountain lions and feline panleucopaenia (feline distemper)(Van Rensburg et al. 1987) to the Florida panther (Coleman et al.1996).

Feral cats congregate in stairwells in cities and leave objectionable odor.

Cats are said to be endangering populations of least terns, piping plovers, and loggerhead shrikes and marsh rabbits (in Florida). They have eliminated certain bird species on islands.

The growth of cats in the U.S. is essentially unrestricted and according to the Pet Food Institute the number of cats in the U.S. numbered 42 million in 1981, a 65% increase from the previous decade (Warner, 1985). Coleman et al. (1996) estimated 60 million in 1990. Thirty percent of households have cats. Frank Chapman in BirdLore (1902) estimated that there were more than 25 million cats in the US. George (1974) made an admittedly conservative estimate that 10 million cats were present in the countryside and that they removed an estimated 5.5 billion rodents and 2.5 billion other invertebrates per year from 26,000 square miles of land. Forbush reported that the Animal Rescue League of Boston destroyed 30,688 feral cats in 1914 -- 210,090 from 1905 to 1914. In New York in 1911, the ASPCA destroyed 303,949 cats.

Coleman et al. (1996) reported cat densities of 114 per square mile in Wisconsin.

Cats may have 2 to 4 litters yearly with 5 to 9 kittens in each litter (mean of 1.4 litters per year; 4.4 kittens per litter). A mating pair and their offspring can produce 600 cats in two years. (1000 female adults can produce 6000 kittens a year). The coyote, fox, and eagle are the only predators. Raccoons, weasels, and owls may take kittens. Causes of rural cat mortality (Illinois, Warner 1985) were:

Vehicles	37%
Disease	24
Humans	11
Dogs	10
Winter Storms	6
Machinery	4
Farm Chemicals	4
Livestock	1
"Old Age"	1

There are some people who claim that cats are being made a scapegoat for wildlife population decline when habitat and other forces are in action. There is no evidence that natural predators have ever caused population extinction, even major loss in nature. The cat is often non-native, introduced, subsidized by human feeding, and the dense populations of mice around farm structures are hardly "natural."

There is some harm done to natural populations by cats, both in abundance and richness, thus in the usual expressions of biodiversity. Cats may reduce prey of other animals of managerial importance (e.g., the raptors). Cats can keep small populations (mice, ground-nesting birds, and lizards) small but cannot adequately control "outbreaks" or high-density populations. More studies may be needed, but the likely effects (uses) of knowledge from such studies need to be evaluated. Benefits may exceed the costs.

After this review of the problems associated with feral cats, the following seems possible.

Create a management system. The objectives, for example, might be:

1. Reduce the number of animals.
2. Eliminate the animals.
3. Reduce the effects (odor, noise, etc.).
4. Reduce the effects on wildlife (preying on birds, lizards, etc.).
5. Reduce disease potentials to other animals (distemper, etc.).
6. Reduce disease potentials to humans (rabies, toxoplasmosis, etc.).

Weights of relative importance for these 6 objectives and other aspects of objective-setting need to be used to make the list more complete and precise.

The inputs might be samples to estimate population levels; density estimates; ranges; food habits; timing of problems; presence of disease.

The processes may be as follows:

1. Education is the most important of the possible management techniques for feral cats. It is necessary to educate the public about the destructive nature of cats to wildlife populations. Television ads and brochures showing statistics on the damage caused and actual pictures of cat predation to make the public aware might achieve this. Special interest groups like humane societies and/or wildlife societies might fund this. The American Bird Conservancy 1250 24th St, NW, Suite 400, Washington, DC 20037 or email abc@abcbirds.org may be helpful in a program to reduce cat predation.
2. Increase sterilization of cats (spay females; neuter males) to reduce the possibility of unwanted cats and growth of feral populations. Funds from local and state governments could offset the high cost.
3. Declaw cats to reduce the success of predation. Due to the high cost, use of special funds will probably be necessary.
4. Encourage owners to keep cats indoors, at least at night.
5. Contact the American Bird Conservancy, Cats Indoors!, The Campaign for Safer Birds and Cats, 1250 24th Street, NW, Suite 400, Washington, DC 20037, phone 202-778-9666, Email abc@abcbirds.org. Also see more specifically the cat site related to birds and cats indoors.
6. Require cats to be registered/licensed like dogs to raise managerial revenues. Also require that they wear a collar with such license. (Those without such collars are likely to be feral.) Where collars are unacceptable, tattooing may be required.
7. A simple way to reduce predation success is to place bells on free-ranging cats. This is relatively inexpensive and may warn prey of the cat's presence. It has limited value.
8. Conduct research and use results on possible ways to lessen the hunting instinct.
9. Hunt and trap (snares and No.2 coil spring traps with padded and off-set jaws) or anesthetize (drug plus canned tuna) feral cats year-around to disrupt breeding and reduce the population. This may be difficult because of local feelings about cats.
10. Place cat guards on trees and below feeders and birdhouses. Remove hiding cover for cats near feeders.
11. Use fences (less than 3 inch openings; also electric fence strand on top of fence) to protect special areas for wildlife. A top covering may be needed.
12. Remove offending animals. See No. 8 above. Caution: Cats are "personal property" and subject to the laws related to destruction of such property. Laws vary throughout the US, even by county or parish. Check carefully on recent local changes. Taking the "wrong" cat may result in a suit.
13. Encourage tethering of cats (collar with leash on a running wire).
14. Encourage keeping only white cats (less effective as predators).
15. Use guard dogs to protect wildlife populations.
16. Eliminate foods such as garbage or outdoors pet food dishes.
17. Encourage effective professional vertebrate animal damage control.
18. Promote vaccination of all cats against rabies and require such condition be displayed on a collar.
19. Prevent legislation and ordinances that allow "cat colonies", commonly 20 per colony, places where feral cats congregate primarily because some people feed them at such places. A national feral cat protection group, the ACA (Alley Cat Allies), supports such colonies. It is active in Richmond and Washington, DC. The American Association of Wildlife Veterinarians has adopted a resolution opposing such colonies (1996), as did the Native Species Network (email: nsn@wco.com).
20. In extreme situations, introduce distemper into feral colonies. On Marion Island an 8% reduction per year over 5 years was achieved in a large population. Control was achieved and the disease was no longer spreading.
21. Promote fines for people who fail to vaccinate, license, and control feral cats.
22. Make everyone aware of places where unwanted cats may be taken. Prevent kittens from being released into the wild.
23. Use scaring devices (noise, lights, and movement) but these typically are only temporary and divert pressures elsewhere.
24. Establish fines and punishment for anyone interfering with efforts to reduce feral cats or their undesirable influences (neutering clinics, trapping, etc.)
25. Require vaccinations for everyone involved in studying or handing feral cats.
26. Use bounties, but only for very short periods, because fraud always occurs with them.

Feedback will include monitoring of the population and modifying the procedures, inputs, and objectives based on the findings. The system Context may need to be evaluated as well. The feral cat problem may affect the rural areas or the urban situation may be affected by the population in the rural areas. Problems may be temporary or have an unusual source for which an entire system need not be created. Feedback may include confirming or changing the objectives and making them more precise and adding constraints and policies (Type 4 as seen in the section on Objectives). For example, it may be impossible to eliminate the feral cat; thus a reasonable objective may be to reduce their effects to an acceptable level.

Feedforward within the system includes estimating future cat populations within society, changes in attitudes toward them, and developments in control procedures and techniques and then making changes today to get ready for the predicted future.

It is unreasonable to spend large amounts of money and other resources on wildlife management, songbirds, and backyard ecology while, at the same time, ignoring the widespread and harmful effects of domestic cats.

Literature Cited

Coleman, J.S., S.A. Temple, and S.R. Craven. 1997. Cats and wildlife: a conservation dilemma. Univ. Wisconsin-Extension, Madison WI (http://www.wisc.edu/wildlife/e-pubs.html)

Coman, B.J. and E.H. Jones. 1986. Ecology of feral cats in Victoria. Trees and Victoria's Resources, 23:20-21.

Fitzgerald, B.M. 1988. Diet of the domestic cat and their impact on prey populations, p. 123-141 in D.C. Turner and P. Bateson (eds.) The domestic cat. Cambridge Univ. Press, Cambridge England

Forbush, E.H. 1916. The domestic cat: bird killer, mouser, and destroyer of wildlife: means of utilizing and controlling it. Econ. Biol. Bul. No.2, Mass. State Board of Agriculture, Boston, MA 112pp.

Hubbs, E.L. 1951. Food habits of the feral house cats in the Sacramento Valley. Calif. Fish and Game 37:177-189.

Van Rensburg, P.J.J., J.D. Skinner, and R.J. Van Aarde. 1987. Effects of feline panleucopaenia on the population characteristics of feral cats on Marion Island. J. Appl. Ecol. 24:63-73

Van't Woudt, B. D. 1990. Roaming stray, and feral domestic cats and dogs as wildlife problems, p. 291-295 in L.R. Davis, R.E. Marsh, and D.E. Beadle (eds.) Proc. 14th Vertebrate Pest Conf. Univ. Calif, Davis, CA. 372pp.

Warner, R.E. 1985 Demography and movements of free-ranging domestic cats in rural Illinois. J.Wildl. Manage. 49:340-346

With contributions by: Jeremy A. Kessinger (1992), Jennifer Mercer, and Anthony L. John II (1995)
Department of Fisheries and Wildlife Sciences
Virginia Polytechnic Institute and State University
Blacksburg, VA 24061-0321 Revised 9-98 RHG

Robert H. Giles, Jr., Ph.D.

This Web site is maintained by R. H. Giles, Jr.
Last revision January 17, 2000.