More commonly called Pigeons. They are everywhere in the city. A lot of people call them flying rats. I find them strangely compelling somehow, and I prefer to think of them as Rock Doves - the urban, hip counterparts to Mourning Doves.
These guys were hanging out in the cold on Wabash Avenue, all puffed up to stay warm. You're not supposed to feed them, but people always do, and as I walked toward them, others that were on the ground walked towards me, thinking I had food. I didn't, and they walked back, waiting for someone else to bring them their breakfast.