I have euthenized many animals. It is not pleasant but overpopulation is a problem for a species also. In areas where raccoons or skunks have no natural predators and their numbers increase to overpopulation, diseases naturally set in to reduce the lot. Parvovirus, Rabies, Tulermia ....
As gooberbean alluded to, we need to be managers of this world and that means wildlife also(and feral cats ARE wild). Many DNRs have very good strategies to keep wildlife numbers at a healthy level, but putting out the approval for a bunch of yahoos to be plinking critters at will is one of the dimmest ideas I have ever heard. There are going to be injured critters, people hurt, neighbor's dogs, cats, and maybe kids shot by accident. This is just silly.
You want to keep feral cats and other "nuisance" wildlife problems down? Bring back the larger predators. Where there are coyotes, the goose population is healthy. Where there are bobcats, Opossums are not under everybody's front stoop.
This use to be my profession and I have literally lived with my client base.
