Felines gone wild: feral cats (Discovery)

Okay, people! Read it right here. Do you help or harm our environment?

David Pimentel, a Cornell University professor who studies the effects of parasitic creatures on ecosystems, says there is no question that domestic cats are killers — and costly ones at that. In fact, a recent study of his found that cats kill about $6 billion (U.S.) worth of birds each year! By his calculations, that's 200,000 birds every year at about 20 bucks a pop.
It surely seems unusual to attach a dollar figure to each dead sparrow or finch that Patches presents to you on the living room floor. But it does highlight the enormous damage the house cat does in North America — a continent that never had these tiny predators before the arrival of Europeans.
"And it's not only birds. It's squirrels, chipmunks and things like that," Pimentel says. "I was talking to a friend last week and his pet cat, in a ten year period, killed 143 squirrels."
Pimentel minces few words, summing up the impact of the house cat.
"I just don't think they are a real benefit to the environment, very frankly. They're a pest, similar in a way to rats and feral dogs. In fact I can't think of any way in which they benefit the environment."