That ain't no joke. My mom tells stories about a rooster that they had when she was a kid. I also have a friend that owned a house with a small pond where a goose adopted it as home, and it would attack if you strayed off the path.
My grandpa, when my mom was a kid, used to raise chickens. On hot days, they would sometimes roost up in a low tree. He'd have to climb the trees to knock them out, to corral then into the coop for the night to keep them away from coyotes and foxes.
One time, a whole bunch if the chickens must've gotten spooked or something, but they rushed him up in the tre, and knocked him out and he fell to the ground, breaking multiple ribs, and his leg.
He's also been gored by a dairy cow, and trampled by a couple sheep. A tough (if not unlucky) S.O.B., my grandpa was.
I'm always wary of cows in fields, the other week I took a long detour around a cow with a calf when I was walking on a footpath through a field. I wouldn't usually be bothered by sheep but I suppose if they get you to the ground they could do a load of flocking damage.