Huddling in the heat? Rarely seen thermoregulatory behaviours of the Southern Pied Babbler Turdoides bicolor

Huddling is an important thermoregulatory behaviour used by many small 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, 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 a specific thermoregulatory behaviour in itself.

拥挤取暖是一种重要的体温调节行为，众多群居的小型恒温动物在寒冷天气或食物稀缺时期用以节约能量。这一行为通常不被视为在炎热天气中降温的策略，主要原因是恒温动物会产生体热，这可能会加剧热不适感。然而，我们在南卡拉哈里沙漠的干旱地区特有鸟类——南方山鹛 Turdoides bicolor 中记录了423起高温下的拥挤取暖行为。拥挤取暖通常发生在地面、树木底部，这很可能代表了在极端炎热天气下对有限凉爽微生境的竞争，而非一种本身具有特定体温调节功能的行为。