This article was first published in The Viking News, November ?, 2004 (Volume 76, No. ?), a bi-weekly publication of the State University of New York, Westchester Community College.
By Taffy Lee Williams
Maybe you knew that habitat loss is the leading cause of extinctions of native wildlife. But did you know that the second greatest threat to native species survival is the common "exotic" outdoor cat?
Cats are by far Americans' favorite pet: 30% of our households have at least one cat. In all there are roughly 66 million pet cats. However, studies have shown that only 35% of these are kept indoors; this means that 40 million domestic cats are free to roam outside at will. Besides that, up to 60 million additional strays and their feral offspring have descended upon America's native wildlife pushing many beleaguered endangered species into extinction.
That cats kill wildlife is so well accepted and even ignored that most people find it hard to believe that they could cause such serious harm. Yet each year in the US, free roaming and domestic cats kill literally hundreds of millions of birds and well over a billion small mammals. Reptiles and amphibians provide additional prey for cats as well.
Cats were bred to size and "domesticated" by the Egyptians around 7000 years ago from the African wildcat. Although "tamed" to human interaction their instinct for hunting has never waned. Now the super-abundance of cats in the wild has created a catastrophic problem around the world, in fact, anywhere humans keep them as pets. Because of their huge popularity and because people refuse to keep their cats indoors, the problem has taken on a serious global dimension.
Several studies over the past 50 years have brought important information to light on the true extent of the problem. A University of Wisconsin team, using a radio-collared tracking system, determined that in one year in Wisconsin alone, 20 to 150 million songbirds are killed by rural cats. The study found up to 114 cats per square mile, or 6 cats per square acre, in some areas, which far outnumbers by many times the combined populations of native predators of comparable size, including fox, coyote, ferret, opossum and raccoon.
Another Arizona suburban neighborhood study found that each cat studied committed over 80 kills per year; of these 62% were small mammals, 26% birds, and 11% reptiles. This coincides closely with extensive cat kill studies in Europe, North America, Australia, Africa and at least 22 islands: In general, 60% to 70% of all prey items are small mammals, 20-30% are birds, and approximately 10% reptiles and insects.
One single Australian cat was documented with over 1000 kills in an 18-month period. During the same time period, one well-fed US cat near an experimental station was found responsible for 1600 kills. In the United Kingdom, 964 cats brought in 14,000 prey items (an average of 40 victims each) over a 5-month period. In New Zealand, the extinction of over 40 species of birds as well as the extermination of 8 island bird species, including the South Island thrush and the Auckland merganser, was caused by domestic cat predation.
Amazingly, in a well-documented case, an entire species, the Stevens Island wren, was exterminated by a single cat. In the southern sub-Antarctic Indian Ocean, an estimated 450,000 seabirds were destroyed by cat predation annually before an eradication program was implemented.
Cat owners claim that feeding their cats well inhibits their hunting instinct. However, in the studies mentioned, well-fed cats actually achieved higher kill numbers, being healthier and stronger than their more feral comrades. In addition, bell-wearers attained greater kill rates than non-bell wearers. The bell forces the cat to become more stealthy, and better hunters. Even de-clawed cats are still often very successful hunters.
A look at some of the many species taken at random by cats we find the English sparrow and various finches, nuthatches, swifts, swallows, woodpeckers, jays, doves and even bats. Numerous ground nesting songbirds, including bobolinks, dickcissels, meadowlarks, and game birds such as quail and pheasant, have seriously dwindled or disappeared in much of their range where cats have been introduced. Shore birds that nest (and sleep) on the sand, such as terns, sandpipers and killdeer, offer easy pickings to roaming cats. Small mammal prey items include rabbits, squirrels, chipmunks, voles and shrews. While cats easily kill fledglings, sitting hens and other vulnerable offspring they reduce the survival rate for entire populations, which may eventually condemn a local species to extinction. If the young are constantly preyed upon and reproductive failure is routine, the population will disappear within a short time. Tragically, already scarce reptiles and amphibians, such as frogs, turtles, salamanders, lizards and snakes have succumbed to cat predation. One SUNY-WCC professor remarked, "Reptiles are virtually extinct south of Route 287 in Westchester County."
One of the biggest problems facing efforts to control the numbers of free-roaming cats is that they are capable of up to 3 litters per year, with 6 kittens per litter. Calculations by the Humane Society of the United States (http://www.hsus.org/) determined that a single female with her offspring could produce up to 420,000 cats in seven years. The exploding population of cats survives because people feed them, whether they feast on wildlife or not. Very often hunting skills are not essential to their longevity. In addition, owners immunize their outdoor cats from disease, helping ensure their survival. Cats will often form "colonies" that effectively destroy wildlife. In Australia, within a 10-kilometer area, it is not uncommon to find 30 cats perched in one tree. These Australian cats are responsible for the extinction of dozens of species!
Besides damage done through killing, cats destroy wildlife indirectly as well. Native predators like the hawk, fox and ferret are facing starvation today as the small prolific feline hunters deplete their natural prey. Rabbit, squirrel and voles are among feral cats' favorite catch, but these are also important food sources for native predators. What's more, cats often puncture their victims without killing them, and will even "play" with their prey. Once injured by the cat, the victim is an unsafe meal for other predators. Minor cuts or bites are usually lethal to prey since cat saliva is loaded with bacteria and parasites that can be transmissible to other predators. There is no question as to the success of feral and outdoor cats at the expense of native wildlife.
According to the U.S. Centers for Disease Control, cats are the animals most often infected by rabies. In addition, feline distemper and leukemia are rampant in outdoor cat populations. Feral cats are being blamed for the spread of the feline leukemia virus found in a California mountain lion and distemper in a Florida panther. Native mountain lion and lynx have been found with feline infectious peritonitis, and a Florida panther and bobcat with feline immunodeficiency virus; the likely source being feral cat contamination which may occur from sharing a kill or even direct physical contact.
With an average of 98 cats per non-farm square mile in just one state, the number one pet in America has enjoyed unbelievable success. But loss of native wildlife habitat to housing developments or commercial sites pressures species into concentrated and fragmented nesting sites, making their survival even more precarious.
Picture this scenario: forested or wild areas are cleared, rivers and streams are diverted, new homes are built surrounded by lush green lawns sprung up after a judicious application of fertilizer and pesticides, obliterating and then replacing the native landscape. New homeowners arrive, bringing their pet cats, which they allow to roam outside. Whatever has survived the environmental upheaval during these massive construction projects the housecats easily finish off. Besides here at home, it is a scene played out all over the world where the combination of development and housecat is wiping out wildlife populations at a terrifying pace. As scientists have determined, cats make the developed areas essentially uninhabitable to most wildlife.
The prevailing attitude in society is that cats will kill, it is their nature, and they belong outdoors. When cats bring home prey items as "gifts," their owners often think it's funny or even "cute." But in the face of overwhelming wildlife destruction, it is clear that this has to change.
Some believe it is not fair that cat-lovers are allowed to let them roam outside freely while birdwatchers and others who hope to enjoy native wildlife grieve the destruction they are forced to witness, often in their own backyards. Perhaps it is even less fair to force them to petition lawmakers for cat leash laws or other restrictive legislation. It may even be argued that a violation of rights is occurring.
Because as many localities have discovered, cat owners cannot be trusted to keep their pets inside or remove strays that they feed from the outdoor environment, legal action is necessary.
Many counties, cities and even nations have already enacted cat-leash laws. For example, Marin and Columbia Counties in Florida, Cleveland, Ohio, Gaithersburg and Rockville, Maryland as well as parts of North Carolina, California, New Jersey and Louisiana all have cat leash laws. Violations of the cat leash law result in anything from a small fine to the loss of ownership rights. Cat leash legislation is pending in many states, including Virginia, West Virginia, Connecticut and New York.
The problem is so serious that one community, Akron, Ohio, passed an emergency "trap and kill" ordinance, and collected and euthanized over 1000 cats. This extreme measure need not have occurred had residents kept their cats inside and helped prevent the outdoor and feral cat population explosion.
The easiest remedy to this problem is to keep cats indoors. The benefits to owners are simple. Indoor cats live on average five times longer than outdoor cats. Inside, cats are protected from wild dogs or coyotes, cars, deadly epidemic feline disease, or poisonous toxins in the environment. Nuisance activities that infuriate neighbors and create hostility, such as attacking birds at birdfeeders, urinating on doors, digging up gardens and fighting with other cats, would be eliminated as well. Having cats spayed or neutered is a must for all owners. Enacting restrictive legislation and keeping cats indoors will ultimately protect the cat and our wildlife as well.
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