I have many many wood pidgeons in my garden. There didn't used to be any even though I am quite rural but they have multiplied every year. Recently I noticed a pidgeon riding on another pidgeon's back. I initially thought they must be mating but this went on for a while and the underneath pidgeon seemed to be in distress. They didn't fly off when approached just kept moving around. The top bird was holding the other down by the back of its neck with its beak. This continued until the underneath bird died.
I have never seen pidgeons fighting before. Do you know why this would be happening?