When I finally make the move, I'll definitely join the TNR (trap-neuter-release) group. I've done it up here in NY and have a humane trap. It made a big difference in the population of stray cats in the neighborhood!
Lovinganimals, a female cat needs to be held for a few days before being released. They can remain in the trap, but someone needs to keep the little patient in a quiet place during their convalescence. I've been nursemaid to a few.