Birdbox

My new favourite thing it to see what our little blue tit is doing in the bird box.  She's currently fast asleep but will be off and out tomorrow morning at around 7.00am.

I was wondering what motivates birds to get up at the crack of dawn and be 'out' all day - does anyone know?  Is it hunger, or the need to attract a mate?  

This is what the birdbox location looks from the outside, near to a fabulous Garrya.