Sleeping unsafely tucked in to conserve energy in nocturnal migratory songbirds

Sleeping with the head tucked in the back feathers is a common behavior exhibited by most species of birds. In a recent study, scientist from the Vetmeduni Vienna and the University of Vienna found, that the hiding of the head during sleep reduces heat loss and conserves energy reserves. However sleeping with the head tucked is risky for the birds. Due to the reduced metabolic rate and the slower reaction time, their risk of being predated is increased. Even penguins with modified feathers that do not cover their head sleep this way. Interestingly, fossils suggest that birds inherited this behavior from their feathered dinosaur ancestors. Several studies suggest that by hiding the poorly insulated head and bill in their feathers, birds reduce heat loss and thereby conserve energy.