Huddling in the heat? Rarely seen thermoregulatory behaviours as Southern Pied Babblers Turdoides bicolor compete for cool microsites

Abstract

Huddling is an important thermoregulatory behaviour used by many group-living endotherms to conserve energy during cold weather or periods of food scarcity. It is not typically considered a strategy for keeping cool during hot weather, largely because endotherms produce body heat which can aggravate heat discomfort. However, we recorded 423 instances of huddling behaviour at high temperatures in an arid zone endemic bird, the Southern Pied Babbler Turdoides bicolor (family Leiothrichidae), in the southern Kalahari Desert. Huddling was most often observed on the ground at the base of trees, and is likely to represent competition over access to limited cool microsites during extremely hot weather rather than being a specific thermoregulatory behaviour in itself.