Bullying behavior between each other
I've noticed there's one particular juvenile magpie that the rest of the group doesn't seem to like. Twice now I've seen that when one of the adults approaches, this little magpie crouches down and sticks its butt up, almost like a cat in heat. Then, almost immediately, the other bird attacks it or chases it off.
I just witnessed it again, and the little bird ended up on its back being attacked by two or three bigger birds. I had a look online, but couldn't really find an answer. Is this territorial behaviour? It almost looked like either a submissive posture or some kind of mating behaviour. Does anyone know what that posture means?