I have to concede that evolution failed deers... they really are dumb.

In the bike trail here, W&OD, there are a few stretches with chain-linked fences. Inevitably, deers would get trapped in there and don't know how to get back to the woods; they would just run left and right and hit the fences all over. Saw this many times as I commute to work, and got caught in it a couple of times. It was pretty scary.