Perhaps now, in this era, that's true, but chickens also evolved as foragers. I've read multiple stories about how the Buckeye breed in particular are excellent mousers, and my own chickens have caught quite a few field mice along with lizards and even young snakes, all of which they've devoured with glee. A friend of mine who keeps a pond has shown me photos of her chickens catching the small mosquito fish she stocks her pond with every year, and if you've ever watched chickens devour a roadkill carcass you'd swear they were more like vultures than the feathery little pets we've come to adore. My chickens LOVE blood, no matter the source, including an wound on my own skin.
As far as hanging around other livestock, I suspect that the insects attracted to their droppings or slopped feed present a more appealing and less labor intensive high-protein meal than hunting down mice, lizards, etc. Hence the reason for meal worm treats, or harvest Black Soldier Fly larva.
Ah, that makes sense. I'm still wondering about specific benefits that people see in their birds on an animal protein based feed versus vegetable.
@Georgia Boy 1970 your birds are cool!
Edited by Hholly - 2/11/16 at 4:27pm