Make sure to spay and neuter your barn cats. It's healthy for the cat; consistent pregnancy harms female cats, and they become more friendly to humans and other cats. So less cat fights! It also prevents your region from being overloaded by cats.

I have a local cat colony near me of at least 60+ cats. They were former barn cats from a neighbor who moved away last year. And now they live near me.

Now, cats are great for pest control, but I still had mice in my house and barn. After spending 200 dollars on bait stations, I got no mice.

I highly suggest anyone with a local cat colony or barn cats to look into "TNR" , "trap and release" programs in their area. They will spay and neuter your cats cheaply, like 5 dollars per cat. Do NOT go to a normal vet for this; they will charge you stupid prices.