I've seen red winged black birds harass deer. They're extremely territorial. Particularly during their nesting season in the summer, but I saw a lone male red winged black bird dive bombing a nice buck in tall marsh grass last October. I don't think I would have seen the buck if I didn't look to see what the bird was messing with.
A couple years ago I was walking back to my truck on the main hiking trail after a late October morning hunt and heard a bunch of bluejays going nuts in a tree up ahead. I was walking at a brisk pace, looking up at the blue jays. When I got under the tree they were in I looked down and was face to face with a giant buck (for my area) standing there with a doe, about 20 yards broadside. He stood there staring at me like a dummy while I fumbled around trying to knock an arrow until the doe bolted, taking him with her. Now I ALWAYS pay attention when I hear blue jays harassing something.