Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
Department of Physiology, University of Arizona, Tucson, Arizona.
J Exp Zool A Ecol Integr Physiol. 2019 Jun;331(5):267-279. doi: 10.1002/jez.2267. Epub 2019 Apr 29.
Observations of animal thermoregulatory behavior are labor-intensive, and human presence may disturb the normal behavior of the animal. Therefore, we investigated whether a remote biologging technique could be used to detect orientation to solar radiation in savanna antelope. We predicted that when a mammal was orientated perpendicular to solar radiation, the subcutaneous temperature on the side of the body facing the sun would be greater than that on the opposite side, whereas when the mammal was orientated parallel to solar radiation, subcutaneous temperatures on both sides would be similar. A pilot study showed that the difference between left- and right-side temperatures under a pelt reflected orientation to solar radiation if a pelt-covered cylinder had been orientated for 15 min or longer. In addition, the rate of change in temperature difference could detect orientation that had changed within the previous 5 min. We implanted temperature-sensitive data loggers subcutaneously into the flanks of eight black (Connochaetes gnu) and eight blue (Connochaetes taurinus) wildebeest. By incorporating both the rate of change and subcutaneous temperature differences and excluding times when wildebeest were lying down, our predictions correctly matched behavioral observations of wildebeest orientation to solar radiation 71% of the time. Our technique tended to fail when wildebeest were lying down, wind speeds were high and the sun was overhead. But those are conditions in which the benefits of manipulating orientation to solar radiation is of diminishing importance to a free-living mammal. Therefore, subcutaneous temperatures provide physiologically relevant information on the importance of solar radiation to mammals.
对动物体温调节行为的观察是劳动密集型的，而且人类的存在可能会干扰动物的正常行为。因此，我们研究了远程生物遥测技术是否可以用于检测热带草原羚羊对太阳辐射的取向。我们预测，当哺乳动物垂直于太阳辐射时，面向太阳的身体一侧的皮下温度会高于另一侧，而当哺乳动物平行于太阳辐射时，两侧的皮下温度会相似。一项初步研究表明，如果一个覆盖有皮毛的圆柱体被定向 15 分钟或更长时间，那么皮毛下左右两侧温度的差异就可以反映出对太阳辐射的取向。此外，温度差的变化率可以检测出在过去 5 分钟内发生的取向变化。我们将温度敏感的数据记录器皮下植入到 8 头黑（Connochaetes gnu）和 8 头蓝（Connochaetes taurinus）角马的侧腹。通过同时考虑温度变化率和皮下温差，并排除角马躺下的时间，我们的预测正确地匹配了角马对太阳辐射取向的行为观察，准确率为 71%。当角马躺下、风速高和太阳在头顶时，我们的技术往往会失败。但这些都是自由生活的哺乳动物对太阳辐射取向的控制的重要性降低的情况。因此，皮下温度为哺乳动物对太阳辐射的重要性提供了生理相关的信息。
