Over 80 million pet cats reside in U.S. homes, and as many as 80 million more free-roaming cats survive outside. How to deal with this feline explosion has caused much debate, especially between cat lovers and wildlife advocates who are concerned that cats are regularly killing birds and other animal species.

(Related: "Writer's Call to Kill Feral Cats Sparks Outcry.")

Using a computer model, the researchers found that colonies of feral cats that were trapped, given vasectomies or hysterectomies, and released (TVHR) shrank faster than colonies that were trapped, neutered, and released (TNR), a method of feral cat control promoted by many cat advocates.

Feral cats live in groups that are controlled by a dominant male. A vasectomy cuts the tube