I have a pair of Blue Tits nesting in an old security camera at work. I know there is chicks as Mam and Dad are really busy feeding and the chicks are demanding. The nest, I believe, is at the back of the camera as I could not see them.
The parents work non stop feeding the chicks.
They were at it all day and were still fetching food for their young as I left. They work much harder than I do.
I am looking forward to seeing the chicks when they decide to leave their home.