Posted: July 16, 2013, 11:15 a.m. PDT
Experts agree that indoor cats live longer, healthier lives.
Many human-related factors contribute to bird declines, including habitat loss, pesticide poisoning and collisions with windows and other structures. One important cause that is also one of the easiest to remedy might be curled up in your lap right now — your cat.
This might shock you, but experts estimate that domestic cats may be responsible for killing 3 million to 5 million wild birds per day in the United States. [In 2013, a study showed that feral cats might kill wildlife in the billions. — Eds.] This staggering number is backed up by a growing body of research suggesting that cats contribute to bird declines.
Studies Of Cats As Predators
Some of the earliest research about bird predation by cats took place in England, where scientists chronicled the predatory habits of outdoor cats in the village of Bedfordshire. Although the primary items in the British cat's diet were small mammals, songbirds like House Sparrows, Song Thrush, blackbirds and robins accounted for more than one-third of all captures. These scientists estimated that Britain's 5 million cats probably killed about 20 million birds annually. They speculated that outdoor cats were responsible for one-third to one-half of all mortality for House Sparrow, a preferred prey!
Closer to home, Dr. Stanley Temple and his students at the University of Wisconsin in Madison studied outdoor cats' predatory behavior in rural areas of Wisconsin. Temple estimated that there were about 1.7 million free-ranging cats in rural areas of Wisconsin and that about 23 percent of their prey were birds.
From their research and that of others, Temple found that the number of animals killed by any individual cat varied widely. Some killed no wild animals, but others captured one per day. Accounting for this variation, Temple estimated that free-ranging rural cats killed between 7.8 million and 219 million wild birds per year — in Wisconsin alone! And these numbers don't include predation by the state's urban cats.
It's not just common feeder birds that take a beating from outdoor cats. Ground-nesting birds like meadowlarks are particularly vulnerable. Cats contribute to the endangerment of populations of birds such as Least Tern, Piping Plover and Loggerhead Shrike. On Marion Island in the subarctic Indian Ocean, cats introduced to control mice now kill an estimated 600,000 seabirds annually.
Convincing Cat Owners
Now, before we go any further, you need to know that I am a cat lover! Two inhabit our house, and they often perch next to my binocular, which rests on the table overlooking my 11 feeders. As a lifelong cat owner, however, I can attest to their hunting proficiency. In the late 1980s, when we lived in rural South Carolina, I documented the "trophies" that our two cats brought to our doorstep.
I was amazed at the number of animals they caught and at the diversity. They captured species I had never seen in the yard, including glass lizards, shrews and, of course, birds.
I stopped their acvtivities the day they brought home a Fox Sparrow, a very unusual visitor to that part of the country. The sight of that beautiful bird on our welcome mat was a sobering experience, and it changed my perspective about cats and their behavior.
Scientists involved in cat research often find owners to be in denial about their pets' behavior and the resulting impact on wildlife. Others rationalize the predation as natural. I know I certainly did. After all, cats are naturally predators, so it seems appropriate for them to go out and catch things, right?
Wrong! First of all, domestic cats are not native to this continent. Following domestication by the Egyptians, cats spread around the world and were brought to North America by European colonists. Cats are no more part of our natural ecosystem than cows or dogs.
Free-ranging cats are sometimes found at densities much higher than native predators. For example, Temple found as many as 114 cats per square mile in rural Wisconsin, a density several times higher than the combined densities of similar sized mammalian predators such as foxes, raccoons, opossums and skunks.
Finally, because most of us go to great lengths to attract birds and other wildlife to our yards and neighborhoods, it hardly seems fair that we unleash these predators into the very sanctuaries that we hope to create.
What You Can Do
So what's a cat lover to do? Fortunately, there is good news. Dramatically reducing and even eliminating cat predation in your yard is as simple as keeping your cat indoors. This elegant solution is the focus of the American Bird Conservancy campaign called "Cats Indoors!"
Keeping your cat indoors is good for birds and for your cat. The Humane Society of the United States, a partner in Cats Indoors!, found that indoor pets live up to 17 years, but free-ranging cats typically live less than five years. Other hazards for free-ranging cats include: cars (an estimated 1.5 million cats are hit by cars each year in the United States); diseases such as rabies, feline leukemia virus, Lyme disease, worms and a host of other undesirables; poisons such as rat and mice bait, spilled antifreeze and chemicals used to treat lawns and gardens; other animals such as dogs, cats and wildlife; human abuse including stealing; traps set for other animals; starvation; and overpopulation.
This latter hazard pulls at any cat owner's heart strings. HSUS estimates that clost to 8 million cats and dogs are euthanized in the United States every year. With more than 35,000 kittens born in this country each day, we should work to prevent unwanted animal pregnancies. Think about it this way: The humane society calculates that one female cat and her offspring can produce 420,000 cats in just seven years! Cat overpopulation takes a tremendous toll on wildlife and encourages suffering by cats.
Keeping cats indoors isn't as hard as it sounds. Linda Winter, director of Cats Indoors!, recommends providing plenty of recreational opportunities inside the house, including simple toys like ping pong balls, posts for scratching, greens for nibbling and empty paper bags or boxes. She also suggests a leash for outdoor strolls. Make the adjustment indoors gradually. Cats are creatures of habit, so slowly replace the old routine with the new one.
One of the prickliest situations occurs when a neighbor's cat shows up in your yard and starts feasting on your feeder birds. Most reasonable cat owners are approachable about this subject, but if you need additional help, Cats Indoors! offers a list of suggestions on its website here.
Some traditional "solutions" to cat predation don't work. For example, declawed cats can still pin their prey and dispatch it with a quick bite. Collar bells may sometimes help, but stealthy cats sometimes spring before the bell tolls — it may be the last sound the bird hears. In fact, in one study, cats with bells killed more birds than those without! Well-fed cats are also no less dangerous. The urge to hunt is not related to hunger. Well-fed cats just tend to hunt closer to home!
It's not surprising to me that the majority of cat owners are also bird lovers and vice versa. There is no reason why the two interests can't be perfectly complementary. It's as simple as you and your cat enjoying the birds together — indoors!