In 5000 hours I've had 4 bird strikes on different occasions, with no damage (other than bird bits to the plane). A number of evasive manuevers prevented more strikes.
Last year a local C172 hit a goose. It took out most of the windshield. The instructor landed safely, but he and the student were both in hospital for some time afterward. I saw the plane afterward, and in my opinion, it would have needed a complete new interior as well as a windshield.
Another friend hit a goose in a C150. It pushed the leading edge of the wing, outboard of the strut back so far that the spar was displaced. He said it would barely fly straight to land, but he got it down.
The little ones don't seem to do much harm, but goose sized birds are a problem...