Long-term trends in the population size and breeding success of emperor penguins at the Taylor Glacier colony, Antarctica
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The population size of emperor penguins at the land-based Taylor Glacier colony was monitored over 54 years from 1957 to 2010 by intermittent ground counts from 1957 to 1975 and annual photographic counts from 1988 to 2010 of males attending the colony in winter and chicks in early summer. The breeding population in the early years averaged 3,684 ± 492 pairs compared with 2,927 ± 320 pairs from 1988–2010, a reduction of 20.5 %. The exact timing and magnitude of the change is unknown because there was a 13-year gap between the end of the historical counts and start of the contemporary counts. From 1954 to 2010 no real or inferred warming event that may have been linked to the decrease was evident at Australia’s Mawson station, 95 km from Taylor Glacier colony. From 1988 to 2010, variation in breeding population size and breeding success were not related to variation in the distance between the colony and open water. In this period, the number of pairs breeding fluctuated annually and overall showed signs of a gradual decrease. The Taylor Glacier colony is one of only three emperor penguin colonies where populations have been monitored in winter over the long term. Given the threat of climate warming to the future of this ice-dependent species it is imperative that the annual monitoring programme at Taylor Glacier continues well into the future.
KeywordsEmperor penguins Population trends Breeding success Distance to open water Climate warming
We are grateful to the members of the Mawson overwintering parties in the eight early years and the 23 years from 1988 to 2010 for conducting the counts and photography at Taylor Glacier. We thank Gary Miller for the photograph in Fig. 1 and three anonymous referees for improvements to the manuscript. This project was completed under permit ATEP-MM-YY 0484 Taylor Glacier of the Antarctic Treaty Environmental Protection Act.
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