Found baby pigeon

[pigeon_rules]

Hello again,

My partner found a baby pigeon. He was walking on the street, wandering. My partner took him. He is very thin and I think he was cold, You can see he is really thin around the chest area. I gave him, like I did for the last one some pigeon food and water. Can you tell me how old he is? Should I do anything else?
I put him in a pet cage and he just stands there, he is not moving. Maybe he's afraid.....

I forgot to say that here it's quite cold, for a few days now, today there were about 4-5 degrees.

Thank you in advance.