I saw a small group of sparrows watching a single one peck at a dead one on the road today. As I drove by, the whole group, including the supposedly dead one, took off and landed a short distance away, where the scene was repeated.

I have no idea why this is. Birds generally don't like being on their backs. Mating occurs with the male facing into the female's back. So why was one on its back with another pecking at its neck?