I live on the 4th floor in NYC and there has been a squirrel sleeping on my window sill all night. We must have scared him a bit looking so he did get up and run into the fire escape. His arm appears to be injured. I called 311 and they said they don't help with squirrels. I don't know how or if I should help, but I'm an animal lover and hate to see them suffering. This window overlooks a courtyard between buildings (just cement, no trees) and I honestly don't know how he got inside, I'm sure there is a way to get in and out but not one anyone uses regularly. The squirrel is plump and looks well fed. Any ideas how to help the squirrel or who to call?