Owls get my vote.

While I was hunting in Kansas I got accosted by a large owl. I was sitting on the side of a ditch in a hedgerow watching a field when I caught movement on my left. Doh, I thought the one spot I couldn't see and a deer has snuck in on me, I turned my head just in time to catch a large owl winging its way at eye level towards me, when he saw my face he veered off, not that big of a deal.

I was kinda spooked but I sat there for a few more minutes waiting on the sun to completely set, got up and headed back to where I was going to meet up with my ride when I caught movement above me!!! That damn owl was circling low over my head in a tight pattern waiting for its chance to come in for the kill. So here I am, 270 in hand walking backwards in the dark across a wet field trying to fend off what was in my eyes an owl the size of a pterodactyl while trying to make it back to the truck.

The owl/pterodactyl gave up the hunt and let me be, but I know he is out there somewhere waiting.