Vasectomies for Feral Tomcats

A computer study of feral cat populations says that giving vasectomies to dominant males works better to reduce populations than trying to neuter all the males:

Feral cats live in groups that are controlled by a dominant male. A vasectomy cuts the tube that carries sperm without removing a cat's testicles, so a vasectomized cat retains its sexual hormones. Thus, it can also keep its dominant position in the colony, so it's able to mate with females without producing kittens. On the other hand, neutered or castrated—and thus sexually inactive—cats returned to a colony lose their position to the next most dominant breeding male. What's more, when a non-sterilized female cat mates with a vasectomized male, she undergoes a 45-day pseudo-pregnancy period, further reducing opportunities for reproduction, the study authors found.

This seems encouraging, but with 80 million feral cats in North America, that's a lot of vasectomies.