Biology of King and Emperor Penguins While at Sea

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Penguins are an important component of antarctic ecosystems, and represent 88-98% of the bird biomass of the Southern Ocean. Considerable information has been gathered on penguin activities within colonies, but little is known about activities after they have left the colony and are foraging at sea. The diving behavior and energetics of King and Emperor penguins is of specific interest, since these species dive much deeper than other penguins and presumably utilize a distinct food resource. It has been impossible to study the at-sea behavior of these birds until very recently. Kooyman proposes to study the diving behavior of Emperor and King penguins at sea using microprocessors developed in his laboratory to store data on dive duration, dive depth, and swimming velocity. Information will be obtained on the diurnal pattern of dives, prey depth distribution, and swim speeds during travel to food patches and while catching prey. Energetics at sea will be determined indirectly by first obtaining laboratory measurements of oxygen consumption and carbon dioxide production at antarctic environmental temperatures and at various swim velocities. Using these values, a time budget estimate of energy production will be validated by conducting a controlled laboratory experiment using doubly labelled water for the energy determination. Both the behavior and energetic results will be used for interspecies comparisons of hunting strategy, success rates, and energy inputs per trip between King and Emperor Penguins, and to test several hypotheses regarding diving physiology. Data should be of value to various broad programs concerned with antarctic food webs.