I used to work at a university that had a significant population of feral cats wandering around campus. Every evening several faculty members would dutifully go around feeding the cats. Their numbers increased. Finally, there were cats everywhere. One night when I was leaving campus after teaching a night class I saw a cat attack a nesting bird in a tree. In a few seconds the cat had killed the bird and the chicks in the nest. Afterwards, I noted that with the exception of great-tailed grackles there were fewer and fewer birds on campus.
I recall visiting Bentsen State Park west of Mission, Texas and when I arrived I saw many dozens of feral cats wandering around. I also realized the bird populations were down significantly. I contacted a biologist with the Texas Parks & Wildlife Department and told him he needed to close the park and get rid of all the feral cats. He drove out to the park and was shocked at the number of cats living there. The cats were multiplying and the birds were disappearing. So the park was closed for a few days so that TPWD trappers could come in and rid the park of the cats. I wonder what would have happened if no one had mentioned the situation to the biologist. The bird numbers had fallen precipitously.
Presently in a park in San Antonio there are dozens of cats in residence. I’m not sure about the status of those cats, whether they are neutered, but I don’t think they are de-clawed. I visited the park a few weeks ago and became concerned about bird numbers. I have no idea if bird numbers have gone down but wouldn’t be surprised if they have. Remember that a domestic cat is a killing machine. Left to wander around and cats will decimate the wild bird population in short order. One cat can wipe out several coveys of quail on five to ten acres in about ten days. The message here is if you own a cat then keep it indoors. Abandoned cats become lethal predators. They often kill for the sport of killing. Like a lot of people I might add. Interestingly, evidence is emerging that healthy coyote populations keep feral cat numbers under control. Here’s an interesting post from Field & Stream Magazine regarding how keeping coyotes around helps to protect your quail populations and other birds as well.