Well, doves are actually the same exact bird a pigeon is, but they are white. I think those birds, realized those birds did not smell or acted natural, so they struck the doves. Like if a wolf or lion checking to see if something is eatable or not. Chances are, the doves had the scent of human food on them, and seagulls and crows as we know are natural hunters. It could also be confirmed both the seagulls and crows were hungry. Another thing is that many of the doves do not survive, and are eaten as food by the seagulls and crows, so by that a gene/instinct is passed down to attack the crows. Also the incident has been on going for sometime, so we should ask, is their anything in the area that has changed? A local food source for the birds? Something built? Radio waves?
A crow for that matter is an extremely smart bird, and when in a crowd they are called a "murder". While people could call the pigeon the rats of the sky, crows just like rats can be trained, for many purposes. Some people say a crow can challenges a parrots intelligence as well, make good pets, for people willing to train them. A seagull is known for being a thief, at the beaches. You can spot them swiping food from each other as well as peoples belongings.
I had a pet pigeon for awhile, we took the bird in, thinking it was something else, but it was really a baby pigeon, that boinked it's head. We released it, in the park and the first thing it did, was fly on top of a person who was jogging, that was something to behold. The bird was getting used to humans to the point where it could see them as friendly.