Huddling and a drop in metabolism allow penguins to survive the South Pole cold

Huddling and a drop in metabolism allow penguins to survive the South Pole cold February 01, 2007 - (Bethesda, MD) — March of the Penguins, the Oscar® winning documentary, showed how the emperor penguins endure their incubation and fast for four dark and bitterly cold months each year. The tight huddling among these South Pole penguins is a key energy-saving mechanism that allows them to endure their extremely harsh conditions. A team of scientists that had already shown that emperor penguins who are free ranging in their colony spend about 50 percent of their time in dense huddles and drop their average metabolic rate by 25 percent has questioned whether this drop is due to a process similar to hibernation. Entering into the colony with bulb thermometers, earlier investigators had indeed found that huddling penguins maintain a lower rectal temperature than birds which were isolated from the colony (35.7°C vs. 37.9°C, respectively). However, a sustained drop in deep body (core) temperature would be in direct conflict with the requirements for successful egg incubation. Therefore, energy savings accrued from huddling might rely on mechanisms other than a lower body temperature.To better understand this mechanism, the researchers conducted the first recordings of deep body temperatures in free ranging birds throughout their breeding cycle by using long-term implanted data loggers. The researchers sought to assess whether male emperor penguins lower their deep body temperature during breeding and incubation. Additionally, using external devices during pairing and visual observations of implanted males during incubation, they sought to study deep body temperature variations when the birds were huddling.Study Published in American Journal of Physiology-Regulatory/ComparativeThe authors of the study entitled "Body Temperature Changes Induced by Huddling in Breeding Male Emperor Penguins," are conducted by Caroline Gilbert, Yvon Le Maho and André Ancel, all from the Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie and Département Interactions Physique, Chimie et Vivant, Centre National de la Recherche Scientifique and Université Louis Pasteur, Strasbourg; and Martine Perret at the Département d'Ecologie et Gestion de la Biodiversité, Centre National de la Recherche Scientifique and Muséum National d'Histoire Naturelle, Brunoy, France. Their findings appear in the January, 2007 edition of the American Journal of Physiology–Regulatory, Integrative and Comparative Physiology.