Lori, I've worked with Stanley Temple at UW-Madison who has done extensive research on free-ranging cats in Wisconsin; and has also been active on trying to get the word out to the public. Recently, the governor of Wisconsin turned-down a widely supported (in WI) bill to allow hunting of feral cats that don't have identification and are outside of city limits. PETA and other national groups lobbied heavily against it, it got a ton of media coverage, and the Governor decided (apparently) that it was too hot an issue for him to risk.
Here's what i've gathered from numerous lectures by Prof. Temple: 1) Yes, they are considered invasive by prominent ecologists. 2)They are the top predator (by far) in Wisconsin in terms of their impact on bird and small mammal populations. Interestingly, Temple found that supplemental feeding of cats (such as on farms where food is just left out for them, or cats that are allowed inside and outside the house) did NOT reduce the number of birds that they killed. They do it out of instinct, not because they're hungry. Although programs to spay and neuter are effective, they are extremely expensive and difficult to implement in large enough numbers to make a significant impact. Temple suggests that the best thing we can do to protect our song bird populations is to keep our cats indoors. I can't find the best references for #s of birds eaten right now, but here's a decent one on how common they are in Wisconsin. Rural Residents' Free-Ranging Domestic Cats: A Survey JS Coleman, SA Temple - Wildlife Society Bulletin, 1993 - JSTOR cheers, Lucas ------- Lucas Moyer-Horner PhD candidate Zoology Department University of Wisconsin-Madison
