I was driving down a road along a swamp last night at around 10:30 pm, when I came across a trumpeter swan standing in the middle of the road. Upon seeing it, I began to slow down, but as soon as I got a bit closer, it lifted and flew full speed into the front of my car, which was stopped at this point. I pulled over to check if it was alright, but stayed inside the vehicle until I saw what it would do in case it decided to charge me when I got out. Within around 10 seconds, it began to slowly get up, then stretched, splayed it's wings, and shook off. Once it was up, it began to walk around in a daze then fell into a ditch. I got out at this point to see what it was doing, but it took off through the bushes at a pretty high speed. I've been around birds of prey a lot, but my knowledge on swans is limited, although I know enough to know that this behaviour was very out of the ordinary. I've been looking for it today but have found no sign, other than the bushes parted where it went through them. Any idea what caused that behaviour?