If you have a cat, keep it indoors and have it neutered, especially if the cat goes outdoors. The biggest problem occurs when cats breed indiscriminately and create colonies of feral cats. Most Humane Societies advocate catch and release programs where they catch feral cats, sterilize them, and release them back in the wild.
The problem with such catch and release programs is that unless they manage to sterilized at least 75 percent of the feral cats in the area, they fertile ones will simply breed some more. Even when the majority of feral cats get sterilized, feral cat colonies can last another 10-15 years before dying out.
Perhaps the best solution for dealing with feral cats is to sterilize your cat, keep your cat indoors if possible, and avoid feeding feral cats to keep them from congregating in one area. Cats may be fun, but colonies of feral cats are not always wanted, so enjoy your cat and don’t contribute to the feral cat problem in your neighborhood.