Baby? Pigeon in garden


ive been watching what I think is a baby pigeon in my garden. First the pigeon was sat on a high wall, but has managed to walk across onto the fence now. 

It can stand up and stretch its neck. It will lift the top of its wings, but just won’t fly. 

I don’t know whether it has hurt itself or just can’t fly because of age. I’m scared to go outside in case it falls off the fence. Can anyone help?