Winter torpor in a large bird

Abstract

Torpor is a natural state in which animals show a substantial and controlled reduction of body temperature to conserve energy^1,2. A few small birds (weighing less than 80 g) are known to use it as a survival strategy in winter, but we have discovered that a large bird, the Australian tawny frogmouth, which weighs 500 g, can also enter this state. This surprising finding increases the size of birds known to use natural torpor by almost tenfold, suggesting that avian torpor is more widespread than is commonly believed, enabling birds to stay in their territory throughout the year.