Pigeons

So, walking through the parking lot to get to the gym, look to my left, and there are two cars with pigeons all over the roofs. I counted 11 on one and 7 on the other (after one or two had flown down to the ground). I have never ever seen that before. I mean, why sit on a car roof? And why those two? Can you explain it to me?

My FB update was imagining them putting on a scene in West Side Story - the rival gangs building their masses for the big fight. Not sure how you determine which one wins - by the amount of poop on the roof?