I'm working on a feral project in a nearby area. My own ferals are neutered, and have both food and shelter from the weather, and they're looking sleek and healthy. So the local humane society asked me to help trap cats in this area, as the caretaker for the colony has no vehicle and can't take them to the clinic.
I have trapped, to date, 11 cats there. 4 were around a year old - last spring's surviving kittens - and the rest have been battle scarred old toms. Two of the young ones were pregnant females, and the clinic terminated those pregnancies.
But I'm continually missing the queens who have to be in that area. I'm putting traps in parts of the complex where cats have been seen traveling through. I'm using high quality bait - tuna and sardines, very stinky. The traps are covered with sheets to make them look more like boxes. The boys go in. The adult females do not.
I know that area has to have at least 2 queens, given the number of young cats in the neighborhood. If I don't catch them soon, I'll be running out there constantly to catch this spring's crop of kittens, and I really am not interested in that.