Cats Protection will lend you traps to catch them, they will neuter them and return them, so if you want to feed them you can. We did this with some feral cats round the greyhound kennels, we used to chuck them the trimmings of the turkey meat we collected from the local turkey farm, and I found one of the kittens abandoned at a few days old, which my dog reared till it was rehomed at 6 weeks. They all used to come running for the food but you could not get near them. Someone once left an open cat food tin, and one got its head stuck. Shouldn't laugh, but it was hilarious seeing this half cat/half tin running round like a mad thing - we eventually cornered it and pulled the tin off its head and for our sins we got scratched and bitten, before it shot off like a, well, a scalded cat.