The purpose of a brooder is to provide a safe and warm space for your birds. Most people keep their young birds in the brooder for six weeks. We got our birds in late spring/early summer, and were able to move them into a mobile chicken tractor after three weeks. We put the heating plate into the tractor but noticed the birds weren’t using it overnight. So evidently, they were warm enough. Of course, our chicken tractor is predator-proof to keep rats, snakes and raccoons out.