“Why not have them captured by groups and then have them spayed and neutered and clip their ears.”
If they’re going to live out their days at your place then fine. But spaying and neutering and then letting them go doesn’t solve the problem of cats annihilating local bird populations.
Feral cats have obliterated bird populations in Australia and the one thing the Aussies relaxed their gun controls for is cat hunting. They’re very serious about ridding their country of feral cats and they’re not so particular if the family tabby gets killed while hunting local birds.
Ok I must be down the rabbitt hole now, cats can't fly.