Either a crow, raven, or a vulture/ buzzard as we call them down here. I'd vote for the later but I've never known them to nest in barns. You should stake out the barn from a distance wait for the parent to return with groceries.
If it is as big as a chicken, maybe it taste like chicken.
They're buzzard chicks, sure not pretty, but I feed mine regular. Coons from the sweet corn patch and turtles from the pond. I've counted up to 14 setting on the fence posts around the pond after I fish out a big snapper.