Despite impacts of breed and seasonal variation, there are advantages to having birds roosting up earlier than later. First, can allow detection of health issues that degrade mobility. Second, can enable more rapid counting which is often a good indicator somebody is gone. Thirdly, some predators like opossums, skunks and weasels that come by during the night are not the worlds best climbers. Those predators have been known to get into coops. Fourthly, getting birds up may help manage against problems caused by pest such as rodents. Finally, there can be advantages in having so birds do not sleep in their own feces.