Live trap them, or ask a rescue for help. Their knowledge is normally free, some will even volunteer to help. They could hook you up. They can also be adopted out as barn cats. But I would say fix them so there isn’t an issue.

We have cat colonies here in Alaska. People dump their cats and don’t “fix” them. There was a colony that was 60+ cats in Palmer. Then there is one in Willow, and in Talkeetna.