Owned cats have huge advantages over native predators. They may be afforded some protection from disease, predation, competition, and starvation, factors which control native predators such as owls, bobcats, and foxes. Cats with dependable food supplies are not as vulnerable to changes in prey populations. Unlike many native predators, cats are not strictly territorial, keeping members of their own species out of a given area. As a result, cats can exist at much higher densities and may out-compete native predators for food. In addition, unaltered cats are prolific breeders. A female cat can have up to three litters per year, with four to six kittens per litter.

Owned cats have huge advantages over native predators. They may be afforded some protection from disease, predation, competition, and starvation, factors which control native predators such as owls, bobcats, and foxes. Cats with dependable food supplies are not as vulnerable to changes in prey populations. Unlike many native predators, cats are not strictly territorial, keeping members of their own species out of a given area. As a result, cats can exist at much higher densities and may out-compete native predators for food. In addition, unaltered cats are prolific breeders. A female cat can have up to three litters per year, with four to six kittens per litter.

Unvaccinated cats can transmit rabies and cats are the domestic animal most frequently reported rabid to the Centers for Disease Control and Prevention. Cats are also suspected of spreading feline leukemia virus to a mountain lion in California and may have infected the endangered Florida panther with feline distemper. Feline infectious peritonitis has been diagnosed in mountain lion and lynx, and feline immunodeficiency virus has been found in Florida panther and bobcat.
 

Studies of Cat Predation

Extensive studies of the feeding habits of domestic, free-roaming cats have been conducted over the last 50 years in Europe, North America, Australia, Africa, and on at least 22 islands. These studies show that approximately 60 to 70 percent of the wildlife cats kill are small mammals, 20 to 30 percent are birds, and up to 10 percent are amphibians, reptiles, and insects.

Scientists have found that the number and types of animals killed by cats vary greatly, depending on the individual cat, time of year, and availability of prey. Some free-roaming domestic cats kill more than 100 animals each year. Some cats specialize in killing birds while others take mainly small mammals. One regularly fed cat that roamed a wildlife experiment station was recorded to have killed more than 1600 animals (mostly small mammals) over 18 months. Rural cats take more prey than suburban or urban cats. Birds that nest or feed on the ground are the most susceptible to cat predation, as are nestlings and fledglings of many other bird species. Following are summaries of specific studies:

Wisconsin Study: Researchers at the University of Wisconsin coupled their four-year cat predation study with data from other studies, and predicted a range of values for the number of birds killed each year in the state. By estimating the number of free-ranging cats in rural areas, the number of kills per cat, and the proportion of birds killed, the researchers calculated that rural free-roaming cats kill at least 7.8 million and perhaps as many as 217 million birds a year in Wisconsin. They estimated that in some parts of the state, free-roaming cat densities reach 114 cats per square mile, outnumbering all similar-sized native predators. (Coleman, J.S. and S.A. Temple. 1995. How many birds do cats kill? Wildlife Control Technology:44.)Wisconsin Study: Researchers at the University of Wisconsin coupled their four-year cat predation study with data from other studies, and predicted a range of values for the number of birds killed each year in the state. By estimating the number of free-ranging cats in rural areas, the number of kills per cat, and the proportion of birds killed, the researchers calculated that rural free-roaming cats kill at least 7.8 million and perhaps as many as 217 million birds a year in Wisconsin. They estimated that in some parts of the state, free-roaming cat densities reach 114 cats per square mile, outnumbering all similar-sized native predators. (Coleman, J.S. and S.A. Temple. 1995. How many birds do cats kill? Wildlife Control Technology:44.)

Virginia Study: Virginia researchers compared free-roaming domestic pet cats in a rural setting and a more urban one. A total of 27 native species (eight bird, two amphibian, nine reptile, and eight mammal, including the star-nosed mole, a species of special state concern) were captured by a single rural cat. Four urban cats captured 21 native species (six bird, seven reptile, eight mammal). Between January and November 1990 each cat caught, on average, 26 native individuals in the urban area, and 83 in the rural area. The study did not count prey killed and completely consumed, prey killed and left elsewhere, or non-native prey. (Mitchell, J. and R.A.Beck. 1992. Free-ranging domestic cat predation on native vertebrates in rural and urban Virginia. Virginia Journal of Science 43:197-206.)Virginia Study: Virginia researchers compared free-roaming domestic pet cats in a rural setting and a more urban one. A total of 27 native species (eight bird, two amphibian, nine reptile, and eight mammal, including the star-nosed mole, a species of special state concern) were captured by a single rural cat. Four urban cats captured 21 native species (six bird, seven reptile, eight mammal). Between January and November 1990 each cat caught, on average, 26 native individuals in the urban area, and 83 in the rural area. The study did not count prey killed and completely consumed, prey killed and left elsewhere, or non-native prey. (Mitchell, J. and R.A.Beck. 1992. Free-ranging domestic cat predation on native vertebrates in rural and urban Virginia. Virginia Journal of Science 43:197-206.)

Cats at Bird Feeders Study: A continent-wide survey of 5,500 homes with bird feeders during the winter of 1989-90 showed that the domestic cat was a significant predator of birds at feeders. Species killed by cats at bird feeders included Dark-eyed Junco, Pine Siskin, Northern Cardinal, and American Goldfinch. (Dunn, E.H. and D.L. Tessaglia. 1994. Predation of birds at feeders in winter. J. Field Ornithology 65(1):8-16.) Cats at Bird Feeders Study: A continent-wide survey of 5,500 homes with bird feeders during the winter of 1989-90 showed that the domestic cat was a significant predator of birds at feeders. Species killed by cats at bird feeders included Dark-eyed Junco, Pine Siskin, Northern Cardinal, and American Goldfinch. (Dunn, E.H. and D.L. Tessaglia. 1994. Predation of birds at feeders in winter. J. Field Ornithology 65(1):8-16.)

Because some island bird populations evolved in the absence of mammalian predators, they have no defense mechanisms against them. When an efficient predator such as the domestic cat is introduced or abandoned on an island, elimination of entire bird populations can result. Domestic cats are considered primarily responsible for the extinction of eight island bird species and the eradication of over 40 bird species from New Zealand islands alone. Island bird species that are now extinct primarily due to cat predation include the following: Stephen’s Island Wren, South Island Thrush, Chatham Island Rail, Stewart Island Snipe, and the Auckland Island Merganser. On Marion Island in the Sub-Antarctic Indian Ocean, cats were estimated to kill about 450,000 seabirds annually prior to cat eradication efforts.

Cats can have highly significant impacts on local wildlife populations, especially in habitat "islands" such as suburban and urban parks, wildlife refuges, and other habitats that are surrounded by human development. For birds, the loss of species from habitat islands is well documented, and nest predation is an important cause of the decline of neotropical migrants. The Point Arena mountain beaver, Stephen’s kangaroo rat, and Pacific pocket mouse, protected under the Federal Endangered Species Act, now live on habitat islands created by destruction and fragmentation of their habitat in California. Domestic cat predation by pet and feral cats on these species is a serious threat to their future existence on the habitat that is left.

The Migratory Bird Treaty Act (MBTA) prohibits the hunting, taking, capturing, or killing of any migratory bird. However, owners of free-roaming domestic cats permit their pets to kill birds protected by the MBTA in seeming violation of this landmark law. Domestic cats are also killing birds and other wildlife protected under the Endangered Species Act.

Through the Endangered Species Act, the federal government protects and restores wildlife at risk of extinction. Habitat loss is the most significant cause of species declines, and predation, including killing by cats, ranks second. Although cats may not be responsible for the perilous status of endangered wildlife, the loss of even a single animal can be a setback to the survival of the species. It is not possible to document fully the predation of protected species by cats, but the following is a list of protected species for which there is at least one documented case of cat predation in the U.S.

Light-footed Clapper Rail, Rallus longirostris levipes

California Clapper Rail, Rallus longirostris obsoletus

California Least Tern, Sterna antillarum browni