I've seen a woodpecker (I think it was) and a crow combine to challenge a falcon, in Edmonton repeatedly; although not in the air. The competition was for tree tops in the ravine and lasted a while with the smaller birds zooming up to harrass the sitting falcon then diving down to lower perches the falcon had trouble getting at. Eventually the falcon had enough and left.
Over the last 5 years I've realized that there are a pair of crows which essentially own the airspace above our house and in front of it.
Each time a hawk or owl or crane flies into this airspace, it will be hounded by these 2 crows. And it happens pretty often.
(One of the crows only has 1 leg - that's why I know its the same 2 each time. We've named him Blackbeard.)
I imagine there is so much of nature we just blindly miss.