"The Spay Today fee for spaying or neutering runs more than $90 at some vet's offices in the county - and that's for a single animal," Bonvillain said. "Animals that are being fixed have to get a rabies shot, too, so that's another $10 or more."
So what's the solution?
Bonvillain, who regularly feeds the homeless animals that camp out down the street and tries to socialize kittens so that they might be candidates for adoption someday, also spends time trying to think of ways to combat the area's feral cat overload.
She'd like to see a greater understanding in the community about the problem so that pet owners who let their cats outside realize the importance of getting their animal fixed.
"If young people who have to complete community service hours could spend some time in an animal shelter, there would start to be a much better appreciation for the need to keep this population under control," she said.
Another idea of Bonvillain's is to create a problem to manage feral cat populations by borrowing ideas from the biologists working on deer overpopulation.
"In some communities in Maryland, deer are given what is basically the birth control pill - and they've been able to keep the deer population in check," she said. "What if pet food companies were required to include hormones that block female cats from reproducing or keep male cats from wanting to reproduce?
And then consumers who wanted their pets to breed could buy a more expensive cat food made without the birth control component."
Bonvillain also hopes more animal lovers in the community begin to pressure shelters in the region to do more to tackle the problem rather than merely react to it.
"There are so many people in our community who want to do the right thing," she said. "They want to help but it's hard to know just what to do."