Skinny seals eat more, sleep less

Sleep is essential for animals, but it comes at an energetic cost if they still haven’t consumed enough food. New research on northern elephant seals (Mirounga angustirostris) reveals how animals manage this trade-off. Using sensors attached to the seals’ jaws and their backs, researchers tracked movement, foraging and sleep, finding that seals adjust their behavior—sleeping less and foraging more—when energy is limited. By examining the activity data, researchers found that thinner seals in poorer body condition often spend more time looking for food and burning additional energy, which can worsen their condition. These seals are also less efficient and take longer at finding food. The consequence of spending more time looking for food? Less time available for sleep. If seals do not increase their foraging time, their condition may worsen, so they reduce the amount of time sleeping to compensate. The finding demonstrates how animals can alter their behavior to deal with energetic demands and ecological dynamics, an important insight into potential population changes under changing ocean and food conditions.

Read more in Current Biology.