Domestic Cat Predation in Florida

Domestic cats are efficient predators that have a serious impact on Florida's native wildlife. Photo: Dr. Gil Ewing

Background

Florida's native wildlife species are threatened by the growing number of free-roaming owned, stray, and feral domestic cats. The adverse impacts of cats in Florida is best documented for threatened and endangered species, especially beach and cotton mice, the Lower Keys marsh rabbit, and the Florida Scrub-Jay. Cats also kill birds with populations in decline, such as Black Skimmer, Least Tern, and the endangered Piping Plover. Disease spread by feral cats may threaten the endangered Florida panther and other wild animals.

Florida Cat Populations

Nationwide, cat owners keep an average of two cats per household. However, in the south, there is an average of 3.2 cats per household. Mild weather permits cats to spend more time outdoors and stray and feral cats may live longer. In some areas, large numbers of un-owned cats congregate in "colonies" at garbage dumps or feeding stations where food is left out for them. Cat colonies vary from simple groups of cats, to colonies where volunteers attempt to manage the colony (see "Managed" Cat Colonies in Florida).

Cat Predation on Florida's Wildlife

No one knows how many cats roam outdoors in Florida. However, given the mild climate and high human population, it is reasonable to assume that there are millions of outdoor cats and they are killing millions of animals each year. The following is a review of cat predation on some of Florida's threatened and endangered wildlife species.

Florida's beach mice populations are threatened by domestic cat predation. Photo: U.S. Fish and Wildlife Service

Beach Mice: Populations of beach mice are already at risk due to habitat loss, disease, and loss of genetic diversity. Domestic cat predation applies additional pressure to these fragile populations. Found only in the southeastern U. S., beach mice are important for maintaining native grasses which help stabilize the dunes. Six of the eight beach mice subspecies are federal and state listed as endangered or threatened, and one is extinct. Scientists consider predation and hurricanes to be the most important factors now affecting beach mouse survival.

The pallid beach mouse is extinct, and extensive sampling in 1989 at the typical habitat for the subspecies revealed high densities of feral cats.

Domestic cats have colonized the dune habitat preferred by the Anastasia Island beach mouse and pose a serious threat to remaining populations. Domestic cats use habitats well removed from development, and threaten this beach mouse throughout its range. When cats were removed, there was an abrupt increase in beach mice populations which were previously at very low numbers. This pattern suggests an inverse relationship between cat abundance and beach mouse population levels.

A cat colony has had a negative effect on a population of Choctawhatchee beach mouse near Grayton Beach State Park. During a radio telemetry study, eight of the 14 radio-collared mice were lost in the first two days. One radio was tracked and located in the digestive tract of a cat. Another radio was found in cat feces near the campground. At the time, there were at least two feeding stations where large amounts of cat food were dropped regularly.

Perdido Key beach mice were re-introduced to Perdido Key State Park in February 2000. Biologists believe that the mouse was extirpated from this park due in part to large numbers of free-roaming cats. Prior to reintroduction, non-native predators were humanely removed.

Although the Santa Rosa Island beach mouse is not listed as a threatened or endangered species, cats also impact its populations. Researchers have found an inverse relationship between the number of cat tracks and beach mouse tracks on the island. Areas near human housing have more cat tracks and fewer beach mouse tracks. The reverse is true in remote areas.

The Chadwick Beach cotton mouse, formerly found in Englewood Beach, Sarasota County, is extinct. Predation by the large numbers of cats associated with dense residential areas may have been an important factor in its disappearance.

The last remaining populations of the federal and state listed endangered Key Largo woodrat and Key Largo cotton mouse occur on approximately 3,000 acres of upland tropical hammock on the northern part of Key Largo, Monroe County. The north edge of their habitat is bordered by the Ocean Reef Club which maintains a cat colony of at least 500 stray cats. An annual budget of approximately $100,000 and a veterinarian are devoted to this colony. The south end of the species' ranges are bordered by another colony of approximately 30 cats. Cats are regularly observed throughout the uplands of Dagny Johnson Key Largo Hammocks Botanical State Park and Crocodile Lake National Wildlife Refuge. They most certainly prey on the two species, but the extent of predation is unknown.

The Lower Keys marsh rabbit is threatened by introduced predators, habitat destruction, disease, and climate change. The main source of juvenile to adult mortality in this rabbit is the domestic cat. If the current mortality rates continue, the Lower Keys marsh rabbit will likely go extinct within the next 20 - 30 years.

Birds: Although more mammals are killed by cats than birds in the continental U.S., the impact of cat predation on birds is significant. Many bird species in Florida are native resident and migratory songbirds with populations already in decline from habitat destruction, degradation, fragmentation, and pesticide pollution. Ground-nesting and feeding birds face the greatest risk of predation by cats.

Neotropical migrants that rely on small, forest remnants for migration stop-over sites may be especially vulnerable to the high densities of cats in some south Florida parks, such as Greynolds Park in Miami-Dade County. A survey conducted by the Everglades Research Group, Inc. concluded that the decline of upland bird populations during the period 1988 - 1998 was due to a managed cat colony in the park. It was not uncommon to observe 30-50 cats there. However, in 2001, the park commissioners strengthened the laws making it illegal to abandon animals and feed them in county parks. The cats have been trapped and removed from Greynolds

The Florida Scrub Jay is a federally listed species that is particularly vulnerable to domestic cat predation. Photo: Florida Fish and Wildlife Conservation Commission

Cats are known to prey on young and adult Florida Scrub-Jay, a federal and state listed threatened species. Jay survival after leaving the nest is much lower in residential areas than in undeveloped habitat at Archbold Biological Station, due in part to predation by .

Federal and state agencies are also working to control predators, including cats, in areas that contain federal and state listed species such as Loggerhead sea turtle, Green turtle, Least Tern, Black Skimmer, Snowy Plover and Piping Plover. These species are known to be killed by domestic cats.

Cats and Disease

Several deadly diseases affecting domestic cats have been documented in the highly endangered Florida panther, including feline panleukopenia (FPV) and feline leukemia virus (FeLV). FPV has the potential of being introduced to bobcats as well. Feline immunodeficiency virus (FIV) may have infected Florida panthers through their consumption of infected domestic cats. Feline leukemia virus (FeLV) is the leading cause of death due to infectious disease in cats and has recently been found in Florida panthers.

Domestic Cat Predation in Florida

Background

Florida Cat Populations

Cat Predation on Florida's Wildlife

Cats and Disease

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