Feral Cats -- Scourge of Birds?

There's a lot of good stuff in the latest Audubon magazine, and I'll be doing a big post later, but I wanted to get this out there first.

I love cats. I had them the whole time I was growing up, and I wish I had one now, but it just wouldn't work. And my cats have always been at least partially outdoor cats. I never thought about it too much, and my mother firmly believes that it is wrong to keep a cat indoors all the time, for the cat's sake. But this article has made me really think about that theory.

Apparently, according to this Audubon article, cats, both totally feral and those somewhat dependent on humans, kill millions of birds a year.

The American Bird Conservancy estimates that 150 million free-ranging cats kill 500 million birds a year in the United States.

Many people believe that Trap, Neuter, Return (TNR) is the answer. Feed the feral cats, trap them, neuter them, and then return them. But apparently it doesn't work.

According to a peer-reviewed study published February 24, 2009, in Conservation Biology, TNR causes “hyperpredation,” in which well-fed cats continue to prey on bird, mammal, reptile, and amphibian populations so depressed they can no longer sustain native predators.

The article focused mainly on Hawaii, an area of particular concern because of the many indigenous and unique bird species there that are threatened with extinction, but the points made also apply to the mainland, too, Wisconsin and Florida being cited in particular.

Honestly, I knew cats kill birds, but I never thought the problem could be so terrible. And I never thought about this:

Wildlife biologists and law-enforcement officials contend that in most situations feeding feral cats violates federal law because it facilitates “take” of species protected by the Migratory Bird Treaty Act and/or the Endangered Species Act.

But that isn't usually enforced, due to the power of the feral cat lobby.

Last year, for example, it squashed federal legislation to remove exotic species from national wildlife refuges because feral cats might be among them. In Hawaii legislation to ban the feeding of cats on state property is invariably shouted down. “TNR advocates are very well organized and funded,” declares Steve Holmer, director of public relations for the American Bird Conservancy. “They’re getting ordinances passed all over the place.”

The article was fascinating, and contains much more data and facts than I am providing here. I highly recommend reading the whole article. What do you think? Should all cats be caged or kept indoors? Why doesn't TNR work? It seems like it should: sterilize the cats in a colony, and natural causes of death should do the rest. Is it impossible to trap all the cats in a colony? Does in-migration to a food source bring in unneutered cats?

cross-posted at Lizbeth's Garden