Nesting in my balcony??

Last few days I was hanging my clothers at the balcony(night time), I heard some noise at the side of my balcony. I was scared. I am not sure it was a rat or something else. Although I live at 17th floor of a condo, I do experience a rat entering my house and eat our food. I can't imagine how the rat manage to climb until the 17th floor.

I come back home and remember to have a watch what actually is that thing moving at my balcony. Well, very obvious 2 pigeons. I ask my housemate, did you know there is pigeons at our balcony? One of them told me, he saw them lay eggs and hatch into pigeons. Omg.... I didn't know that. I thought those are pigeons was hurt and cannot fly. I didn't know they were baby pigeons. I didn't know pigeons are in black color when they are babies... I will let them stay there until they know how to fly. Hope they don't shit too much at my house balcony.