Grandfather once kept a pair of rat terriers that lived in the coops with the chickens. Never lost a chicken for a few years until he sold the dogs. They kept things like badgers to coons to rats and snakes and mice and even hawks and owls away
They were wild dogs (given up and never played with from a chitty dog owner) that pretty much just watched "their" birds.
Now bears... LOL! That may be a different issue LOL

Now bears... LOL! That may be a different issue LOL