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

吸热型海鸟在潜水或孵化期间禁食时，必须节省能量消耗。通过血液循环的变化来调节体温，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银嘴鱼(犀牛和厚嘴鸥)和孵化不同数量的卵(2-4枚)的黑尾鸥的体温变化。在1999-2000年夏天，我们植入了记录仪，并采集了三只潜水约20米深的犀牛的结核病变化。他们在进行20-30分钟的潜水比赛时，结核病降低了约4摄氏度。2000年夏天，我们在NY-Alesund植入了记录器，并从一只布伦尼奇鳄鱼身上采集了腹部体温和潜水行为的样本。这只鸟在潜水时，通过潜水到40米，持续一小时，平均降低了4摄氏度的结核病。然而，它在下降时增加了结核病，可能是因为它可能会频繁地对浮力进行翅膀拍打，然后在底部保持不变的结核病，然后在上升时逐渐增加结核病。当它到达海面时，它迅速降低了结核病。这种模式是出乎意料的，需要进一步研究。1999年夏天，我们测量了正在孵化2-4个蛋的黑尾鸥的结核病和蛋温。它们不会增加结核病，因此孵化4枚卵子的蛋温低于孵化2枚普通卵子的蛋温。

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.