With four million to six million unwanted animals-mostly cats-put to sleep
each year in the United States, some people might consider it more humane
to free the felines into the wild. But as these cats forage for food and
establish their territories, they kill more than a billion small mammals
and birds each year, many of which are threatened or endangered, a
University of Florida study shows.
Feral, or free-roaming, untamed cats pose a serious threat to endangered
species nationwide as colonies of the wild cats have grown, largely because
local groups provide funding and resources to sustain them, according to
the University of Florida study commissioned by the U.S. Fish and Wildlife
In addition, although the study found those who release cats into the wild
or support feral cat colonies are violating numerous federal and state
wildlife protection laws, enforcement of the law in these cases has largely
been ignored, according to the study that was published in the spring 2004
volume of the "Journal of Land Use & Environmental Law."
"The domestic cat species is not indigenous to Florida or anywhere else in
North America," said Pamela Hatley, a law student at University of
Florida's Levin College of Law who conducted the study. "They impact native
wildlife in three primary ways: predation, competition, and disease."
Feral cats spread diseases-rabies in particular-that can also kill
wildlife, according to John Cely, wildlife biologist with the S.C.
Department of Natural Resources (DNR) Wildlife Section. The Centers for
Disease Control and Prevention report that rabies is more than twice as
common in cats as it is in dogs or cattle, and cats have the highest
incidence of rabies among domestic species.
The number of feral cats in the United States is estimated to be 40 million
to 60 million, according to the study, which was commissioned by the U.S.
Fish and Wildlife Service to determine the applicability of federal, state
and local wildlife laws to the practice of releasing cats into the wild and
maintaining feral cat colonies. Compounding the problem is that another 40
million domestic cats nationwide also roam outside, hunting and killing
For example, the Lower Florida Keys marsh rabbit is a federal endangered
species with a remaining population of about 100 to 300. A 1999 study found
free-roaming cats were responsible for 53 percent of the deaths of these
rabbits in one year, and a 2002 study indicated the species could be
extinct within two or three decades.
Cats also have been recognized as instinctive predators and a serious
threat to the Key Largo cotton mouse, Key Largo woodrat, Choctawhatchee
beach mouse, Perdido Key beach mouse, green sea turtle, roseate tern, least
tern and Florida scrub jay.
Cat predation also is a serious problem in California and Hawaii, where,
like Florida, the climate is ideal for cats to survive outside and breed
year-round. As a result, endangered animals, such as the Hawaiian goose,
California brown pelican and blunt nosed leopard lizard also face
There are some 15 million cats in Florida that spend all or part of their
time outside preying on wildlife. It is estimated that cats kill as many as
271 million small mammals and 68 million birds each year in Florida, many
of these members of threatened and endangered species.
As an alternative to euthanasia, many cat advocates believe in
trap-neuter-release, or TNR, programs, in which feral cats are spayed or
neutered and returned to colonies where caretakers look after them. While
the programs aim to reduce wild cat populations, however, irresponsible pet
owners continue to release unwanted cats that often join feral cat
In Florida, such colonies are known to exist in 17 counties. The largest,
in Key Largo, may include as many as 1,000 cats and operates on an annual
budget of $100,000. TNR programs and managing large numbers of cats in
colonies do not effectively control cat overpopulation or the predation of
endangered animals, the study found.
And although the study determined that releasing cats into the wild and
supporting feral cat colonies is a violation of federal laws, such as the
Migratory Bird Treaty Act and the Endangered Species Act, enforcement of
these and other state and local regulations with the same goals is rare
against those who release cats or support feral colonies.
The Florida Fish & Wildlife Conservation Commission, for example, has left
enforcement of state laws up to local governments, whose ordinances vary
greatly as to what they prohibit and the fines involved. "It is essential
that our state and local governments take steps to educate the public about
the destructive impact of free-roaming cats on native wildlife, and
strictly enforce against the release of cats into the wild," Hatley said.
Michael Wooten, an associate professor of biology at Auburn University, has
done extensive research on endangered beach mice nationwide. His studies
have found limited direct evidence that feral cats hunt the endangered
mice, but he said he has observed immense indirect evidence, including cat
paw prints in the dunes where mice live and mouse-tracking devices in the
bellies of cats.
"Predators in general have taken quite a toll on the beach mouse
population," Wooten said. "Where you have cat colonies, there is a decrease
on the mouse population."
Feral cat colonies are a well-intentioned but misguided idea, according to
Wooten "If people really loved animals, they wouldn't release large groups
of predators into the wild," he said.