The barn cat program we got our current barn cats from is fabulous. They bring a set up for the cats to keep them enclosed for at least a week, I think it may have been two. They give great instructions on what to do and cone back in a few weeks to pick up the.enclosure, litterbox, etc.
And I do recommend getting two. I think ours are sisters and they love each other
My two came as juveniles, in need of an instant home. As it was mid-of-a-nasty winter, they were shut in the tack room for ever. They were fed, petted and played with. Come spring they were allowed out, but at night they are fed, and tucked into the secure quarters. They are aging now, so I’m staying on good terms with the local humane society. I will get another pair.
There are a few ferals around who I’m sure work too, but are just vanishing tails, and an occasional spray. Phew!
Go to a high kill pound and save a life or two.