Pattinson Nicholas B, Smit Ben
Centre of African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa.
Centre of African Conservation Ecology, Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth 6031, South Africa.
Physiol Behav. 2017 Oct 1;179:268-275. doi: 10.1016/j.physbeh.2017.06.018. Epub 2017 Jun 27.
Many arid-zone animals have to forage under extremely hot conditions to maintain water and energy balance. The effect of high air temperatures (T) on the behavioral patterns of small endothermic animals-characterized by their high energy and water demands-will provide a valuable framework for understanding species vulnerability to climate warming. We determined the seasonal behavioral responses to changes in T in a~10-g arid-zone passerine, the rufous-eared warbler (Malcorus pectoralis), in the Karoo semi-desert, South Africa. Rufous-eared warblers showed significant temperature-dependence in their behavior in summer, but not in winter. During summer, the warblers frequently experienced T exceeding 40°C in the shade. For all observations <26°C compared to >36°C, the warblers showed reductions in preening (40% decrease), foraging effort (56% decrease), and foraging success (15% decrease), as well as a significant increase in time spent engaged in evaporative cooling behavior. Moreover, as T increased the warblers shifted increasingly off the ground and out of the full sun, into microsites in the shade (131% increase) and in shrubs (23% increase). In this regard, behavior varied seasonally, with the time spent in the shade 23% higher, and foraging effort 28% higher, in summer compared to winter across a range of moderate T (15-30°C). Our findings emphasize the link between behavior and temperature in small birds inhabiting hot, arid environments, as well as the importance of understanding these responses for predicting biologically meaningful responses (and hence, vulnerability) of arid-zone avian communities to climactic shifts.
许多干旱地区的动物必须在酷热条件下觅食，以维持水分和能量平衡。高气温（T）对小型恒温动物行为模式的影响——这类动物具有高能量和高水分需求的特点——将为理解物种对气候变暖的脆弱性提供一个有价值的框架。我们在南非卡鲁半荒漠地区，对一种体重约10克的干旱地区雀形目鸟类——棕耳鹪莺（Malcorus pectoralis），测定了其对温度变化的季节性行为反应。棕耳鹪莺在夏季的行为表现出显著的温度依赖性，而冬季则没有。在夏季，鹪莺在阴凉处经常经历超过40°C的气温。与所有温度>36°C的观察相比，在温度<26°C时，鹪莺的梳理行为减少（减少40%）、觅食努力减少（减少56%）、觅食成功率降低（降低15%），同时参与蒸发散热行为的时间显著增加。此外，随着温度升高，鹪莺越来越多地离开地面和阳光直射区域，转移到阴凉处的微生境（增加131%）和灌木丛中（增加23%）。在这方面，行为表现存在季节性差异，在一系列中等温度（15 - 30°C）下，与冬季相比，夏季在阴凉处停留的时间高23%，觅食努力高28%。我们的研究结果强调了栖息在炎热干旱环境中的小型鸟类行为与温度之间的联系，以及理解这些反应对于预测干旱地区鸟类群落对气候转变的生物学意义上的反应（进而脆弱性）的重要性。
