I got properly chased by one when I got too near its chick on top of Bynack More. Wouldnt have been there if I'd seen obviously, but basically ended up having to do my best football dodge to try and get away.
Can tell they are related to capers!
This one just squeaked piteously and then shuffled away a bit. It was in the middle of a track - the only track for tens of km in any direction!