Perhaps, the driver was unaware that they had even hit the chicken. I hit a dog years ago that ran right into the wheel of my car, basically hitting ME, not the other way around. I didn't even realize I'd hit the animal until I stepped out of my car to see what the screech and bump was. I was horrified to see my neighbor's dog crawling around under my car. The dog survived the incident with only minor injuries, but I almost kept driving not knowing I had hit an animal. Chickens are very light-boned and wouldn't make much of a thump, so I can't help but think maybe the driver was completely unaware that they had hit the chicken. I'd hate to think someone would knowingly strike an animal and then leave without explanation.