Where are these magical wild cats that don't have any diseases that kill them? URIs, distemper, feline leukemia, feline infectious peritonitis, feline immunodeficiency disease, to say nothing of heart disease, diabetes, and other congenital conditions. In the absence of a TNR program, most of these won't prevent an adult cat from reproducing AT ALL, but they WILL reduce the frequency and success of reproduction. And if you've never seen a litter of kittens born of a mother already infected with FIV, well, all I can say is, I hope you remain that lucky. It's heartbreaking. Your coyotes may not kill ferals. Here, they do. Cars kill ferals, too. Both foxes and hawks will take kittens when they get the chance. Fleas, ticks, mosquitoes, and the parasites they carry reduce the health of affected cats, and reduce both lifespan and reproductive success. So, sorry, no, you don't get maximum theoretical possible reproduction from urban feral cats. Or anything close to it.

I agree that Trap-Neuter-Release is the way to go with feral cats. However, in my urban, cat-loving neighborhood, the constraints on cat population OTHER than TNR include: 1. Traffic. Cats get hit by cars. 2. Coyotes. A cat makes a nice snack for the whole family, or a full meal for one. 3. A pair of hawks--those birds of prey you think don't figure into the predator/prey balance in cities. They loves them some tasty kittens, just like the coyotes, do, and they also directly compete with the cats for the cats' preferred prey, rodents. 4. Foxes. Also direct competitors with cats for the same prey. 5, Disease. 6. Failed litters--kittens born dead or deformed or otherwise weak. Also, your comment that "left unchecked [cats] will decimate a bird population---sorry, but that's another phony, widely-circulated statistic. From the "Damn Lies and Cat Statistics" article that this references: "Take the estimates of how many birds are killed each year by cats," he said. "A 1993 article usually called 'the Wisconsin study' is constantly being cited, with an estimate that between 8 and 219 million birds were killed by free-roaming rural cats in that state." But 15 years ago, study co-author Stanley Temple told the Sonoma County Independent, "The media has had a field day with this since we started. Those figures were from our proposal. They aren't actual data; that was just our projection to show how bad it might be." Read more: http://www.sfgate.com/cgi-bin/article.cgi?f=%2Fg%2Fa%2F2010%2F08%2F18%2Fpetscol081810.DTL#ixzz0xek8PyCj You can't use one bad statistic to support another bad statistic.