Not entirely related, but I saw a greydwarf kill a bird the other day. I didn't think there was any way to kill a bird other than with a bow, but there was the greydwarf with a puff of feathers around it, and a pile of feathers on the ground when I went to investigate.

It could be that they just happened to spawn at the same spot and the greydrwarf won the contest for the space, but it seemed to be too close to me to be a spawn location.