Adaptive significance of short-term hypothermia for energy saving in active endothermic animals

吸热海鸟在潜泳或孵育期间禁食时，必须节省能量消耗。通过血液循环的变化调节体温应该是其中一种短期的节能生理适应。我们测量了潜水的两种酸类物种（犀牛小海雀和厚嘴鸥）和孵化不同数量蛋的黑尾鸥的体温变化（2-4）。1999-2000年夏季，我们植入记录仪，采集了3只深约20 m的犀牛小海雀体内的结核菌变化。他们在进行20-30分钟的俯冲时降低了约4摄氏度。2000年夏天，我们在新奥勒松（new - alesund）植入记录仪，对一只布伦尼奇海鸠的腹部体温和潜水行为进行了采样。这只鸟在一小时内潜到40米的高度进行潜水时，平均体温降低了4摄氏度。但在下降过程中，由于可能会对浮力产生频繁的振翼，使Tb增大，然后在底部停留时保持不变，然后在上升过程中逐渐增大Tb。当它到达海面时，它迅速降低了结核。这种模式是出乎意料的，需要进一步研究。1999年夏天，我们测量了黑尾鸥在孵化2-4个蛋时的Tb和蛋温。它们没有增加Tb，因此孵育4个卵的卵温低于正常孵育2个卵的卵温。

Endothermic seabirds have to save energy expenditure while they are diving or fasting during incubation spell. Body temperature (Tb) regulation through the change in blood circulation should be one of short-term physiological adaptation for energy saving among them. We measured body core temperature change in diving two alcids species (Rhinoceros Auklets and Thick-billed Murres) and in Black-tailed Gulls incubating various number of eggs (2-4). In 1999-2000 summer, we implanted the logger and collected Tb change from three Rhinoceros Auklets diving about 20 m depth. They decreased Tb about 4 C while they were making 20-30 min dive bouts. In 2000 summer, we implanted the logger and sampled abdominal body temperature and diving behavior from a single Brunnich's Guillemot at Ny-Alesund. The bird decreased average Tb by 4 C while it was making dive bouts by diving to 40 m for an hour. However, it increased Tb while it was descending possibly because it might make frequent wing beat against the buoyancy, then it kept constant Tb while it was staying at the bottom, then gradualy increased Tb while ascending. When it reached the seasurface, it decreased Tb quickly. This pattern was unexpected and needs a further research. In 1999 summer, we measured Tb and egg temperatures in Black-tailed Gulls while they were incubating 2-4 eggs. They did not increase Tb hence had lower egg temperature when they incubated 4-egg clutches than they incubated 2-egg normal clutches.