The Butler County Humane Society and the city of Butler tonight will start rounding up cats in the city.

From 5:30 to 8:30 p.m. in the Island neighborhood, humane society volunteers will set out humane traps in an attempt to catch about 30 cats for a spay/neuter/release program.

Marci Mustello, the humane society's director, asks cat owners who let their pets out for an occasional romp to keep them in tonight so they don't get caught.

Mustello said the two-year program is funded by a $22,500 grant from Petsmart Charities.

On Thursday, the cats that have been caught will be spayed or neutered in the Animal Friends of Pittsburgh's mobile clinic and returned to the neighborhood.

"First of all, we (the humane society on Evans City Road) only have so much room, and then many of the cats, while outdoor cats, are being taken care of by Island residents," Mustello said. "In fact, many residents are helping us catch the cats and have said they do want them back."

Mustello said she suggested the program because of reports of the large number of stray cats in the city.

Volunteers will replicate tonight's roundup in all city neighborhoods during the next two years. Mustello expects the grant will pay to spay or neuter about 750 cats.