Bee identification

Hi there, me and my mum recently found out that we have bees in one of our bird boxes. I have tried to google bees and have not found any that look like the ones we have. Does anyone know what kind of bees they are? 

these are the bees, there is about 20+ bees in this box and it looks as if it is filled with garden waste. 

this is a close up of the opening on the inside and looks like there might be tunnels?

if anyone knows what kind of bee this is it would help a lot! :)