A friend of mine hit a deer last year on her bike. Her husband was shocked that she did not go down. The back of the deer made contact right above the headlight on the highway. Cracked the windshield and sheared bolts around the headlight, and caused her to almost lose control. Amazingly she pulled out of it and they quickly pulled off the road. The deer was killed in the accident, but the bike was still functional and after a cool down period they finished the 20 mile drive to town. Take my word... this is an exceptional case. A deer can do a ton of damage to a car, so a motorcyclist is in big trouble.
Another friend had a close call last week. He saw a deer cross ahead of him while riding at night so he quickly slowed down. Right before he made it to where the deer had passed a second one appeared right in front of the bike. By this time he had slowed considerably so a collision was avoided. The best part is that he was reviewing a new headlight for his motorcycle site and got it all on video. Seeing the deer so far out was a great testimonial for the headlight.
I live near Yellowstone and we had a couple that hit a grizzly near here last season on a motorcycle and they were messed up bad. They are alive but they are both still in full body casts or traction as far as I know. The same thing could be caused by a deer strike, especially out west where we have large mule deer, elk, and moose in abundance.
Another grizzly strike occurred years ago and was actually a bit amusing. Guy comes around a corner on his HD touring bike and hits something BIG. Brushes off the side and he ends up in the grass twenty feet from the bike. He thought he hit a deer or moose and jumped up to shut off the bike... that's when he saw the grizzly. It was standing by the side of the road, shaking it's head back and forth.. "shaking it off" if you will. The rider lifted the enormous bike in seconds and got back on the road pronto. I heard he rode 10 miles before pulling over to check the bike and himself for injuries.