McKechnie A E, Lovegrove B G
School of Botany and Zoology, University of Natal, Scottsville, South Africa.
J Comp Physiol B. 2001 Aug;171(6):507-18. doi: 10.1007/s003600100201.
We investigated normothermic thermoregulation and heterothermic responses to restricted food in the speckled mousebird Colius striatus, in the context of the widely accepted distinction between normothermia, rest-phase hypothermia, and torpor. Normothermic thermoregulation differed from typical endothermic patterns in that rest-phase body temperature (Tb) was not maintained with respect to a constant setpoint. Instead, Tb decreased during the course of the rest-phase, with the highest cooling rates observed at moderate ambient temperatures (Ta). Restricted food was associated with significant reductions in rest-phase Tb and metabolic rate. The lowest Tb recorded in a bird which was able to arouse spontaneously, was 18.2 degrees C. However, we were unable to clearly discern between normothermic, hypothermic and torpor Tb ranges. Furthermore, heterothermic responses did not accord with the patterns typically observed in birds and mammals. Metabolic suppression normally associated with entry into torpor and the defence of a torpor Tb setpoint was largely absent. The mousebirds significantly reduced their energy expenditure when heterothermic at moderate TaS only. We suggest that the observed patterns of thermoregulation in C. striatus, as well those previously reported in Colius colius, are associated with plesiomorphic clustering behaviour in the Coliiformes, and the tandem evolution of behavioural and metabolic thermoregulation.
在正常体温、静息期低温和蛰伏这一被广泛认可的区分背景下，我们研究了斑纹鼠鸟（Colius striatus）的常温体温调节以及对食物受限的异温反应。常温体温调节不同于典型的恒温模式，即静息期体温（Tb）并非相对于恒定的设定点维持稳定。相反，Tb在静息期过程中会下降，在中等环境温度（Ta）下观察到最高的降温速率。食物受限与静息期Tb和代谢率的显著降低有关。在一只能够自发苏醒的鸟身上记录到的最低Tb为18.2摄氏度。然而，我们无法清晰区分正常体温、低温和蛰伏的Tb范围。此外，异温反应并不符合鸟类和哺乳动物中通常观察到的模式。通常与进入蛰伏和维持蛰伏Tb设定点相关的代谢抑制在很大程度上并不存在。鼠鸟仅在中等Ta时处于异温状态时显著降低了它们的能量消耗。我们认为，在斑纹鼠鸟中观察到的体温调节模式，以及之前在红脸鼠鸟（Colius colius）中报道的那些模式，与鼠鸟目动物的原始集群行为以及行为和代谢体温调节的协同进化有关。
