I also maintain  Feral Cat Colonies, in some of the most dangerous neighborhoods in SF

Some of These  people  want to know "what the F**k are you doing under my car??" at night kind of thing. which makes it harder to trap & feed. I'm always finding  new ways to do this.

I trap manually, with coat hanger (cut) & string to trigger the cage. It can take weeks to 'Trap Train' a cat to go fully into the cage. Or get lucky the first time (after a lot of prep). Some of my Cats have been returned  to owners from being lost, some are trapped for being damaged orabandoned . Most are Feral ... & TNRed.