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

点击翻译按钮获取中文摘要

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.