April0617
Songster
No idea if this would help or not, as I'm on my first batch of chicks ever and they haven't done this... But do they have somewhere to roost in their brooder box? Mine are 5 weeks and don't sleep under their heart plate anymore, most of them sleep on a branch I put in the box and a couple sleep on top of their plate. A total uneducated guess but maybe, because they are getting older and are outside during the day, the instinct to roost at night is kicking in?