Found a bird? Be careful; larger birds can hurt you. Don't try to feed it or water it; birds have some pretty specific needs so just immediately call one of these bird places.
Flint Creek Wildlife Rehabilitation center has a bird hospital on Northerly Island. They even do bird pick-up; call 1-888-354-6827 to arrange. Here are their guidelines to what to do if you found a bird.
Chicago Bird Collision Monitors deal primarily with migratory birds that are injured, but they have a good network in place that can deal with domestic birds. Hotline: 773-988-1867.