Barn cats are actually pretty important. rodents can be terrible, and spread disease due to the conditions they often live in. Cats help with snakes and certain bugs as well (larger bugs they can swat at. Usually just kill them and play with them, but I've seen cats eat them too)

But is still absolutely essential to spay/neuter barn cats, and provide them with safe places to get away from coyotes. Spay/neuter is to prevent them from making more cats, which can quickly get out of hand. For getting away from coyotes, raised areas they can quickly climb to are good. Yes coyotes can jump, but I've never seen a coyote climb. Their front legs just dont bend the right way to let them grab the tree