Columba livia  

It's the most popular kind of pigeons, which you can see in towns, in parks, markets, old towns. They're entirely fed by people. Owing to this way of feeding they haven't any natural opponents. They multiply on such a large scale that their excrements are demaging the remains.

My own observations of rock-pigeon I have made at the railway station of Gdynia Glowna, but one can do it at any other station, because it's a place, where people throw pieces of bread or cakes for rock-pigeons. As a result rock-pigeons are tame and I could approach them. During the observation of two pigeons, which were chasing themselves I saw that after one catching the other they started pecking themselves. I think that it could be some kind of courtship, but it could be fighting between two individuals of the same sex as well.