I've been pretty lucky NOT to hit anything substantial, but I like to also think I'm very good at scanning for things, and being lucky as well. In the West here, there are ALL kinds of big critters to avoid, and I've had a couple semi-close encounters, luckily after slowing down considerably. The scariest NON-collision was me and a buddy doing 75+ southbound on the 101 near the Hollywood bowl back in about '87-ish in basically bumper-to-bumper traffic. We came around the blind left turn (blind because of the concrete barriers) in the fast lane and there was an 8' aluminum ladder in our lane! Mikey sweved left, and I swerved right, and we both missed it. Good thing because if either or both of us had fallen we'd have been splattered by countless cars that were right behind us......
As far as actually hitting something, a few years back at over 100, SOMETHING hit me hard on the right pectoral muscle. It was like getting punched hard, but I had my leathers on so it didn't hurt too bad. I thought it was a bird, but I didn't see any feathers like I did when I hit a dove with my truck. I should have stopped, and looked around to see if maybe it wasn't a couple kids throwing rocks, but I didn't.
Many years before that in the mid-'90's, I remember ripping my KX500 down a fire road up North of Peterborough Ontario when I was at a friends cottage for a week, and hitting some sort of pheasant or something. I was tail out going around a right-hander and suddenly out of the bushes this big bird flies out.....into my left fork leg. Biff! Feathers everywhere. I stopped, and went back. The poor thing had it's neck broken or something and was squawking and flopping around. I wanted to put it out of it's misery and not suffer anymore so I stomped on it's head with my big motocross boot. There was a sickening crunch, but it died pretty quickly after that. I was still bummed though. I went back to my buddy's place and told him what happened, and he jumped up to go get it in his truck. Said it was good eating and he was going to cook it up! Well, we got there, and found the spot (blood and splatter from me stomping the poor thing) and it was already gone. He was bummed, and I was kind of relieved. We figured maybe the reason the thing had ran suicidally in front of me in the first place was that a predator was chasing it, and when I left, came and got it's fresh dinner. Either that or another local had found it and took it home to eat. Ah well.