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Biology & Medicine
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Dr. Polly Penhale
Program Manager
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B-031-M
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NSF/OPP Award 01-25608
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Station:
McMurdo Station
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RPSC POC:
Melissa Rider
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Research Site(s):
Cape Bird, Cape Crozier, Cape Royds, Beaufort Island, Franklin Island, Terra Nova Bay
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Dates in Antarctica:
Early November to early February
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Geographic structure of Adélie penguin populations: Demography of population expansion
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Geographic structure of Adelie Penguin populations: Demography of population expansion.
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Deploying Team Members:
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David G. Ainley
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Grant Ballard
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Jennifer Bloom
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Katie Dugger
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Chris McCreedy
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Viola Toniolo
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Research Objectives:
For several years now, this group has studied Adélie penguins. Specifically, they investigate the mechanisms responsible for the geographic structuring, the founding of new colonies, and the recent population expansion of the Adélie penguins of Ross and Beaufort Islands. It is an isolated group that comprises a single ‘metapopulation’ of interacting colonies. Population expansion in a similar fashion has been occurring throughout the Ross Sea, where 30% of this species’ World population resides, and is in some way related to ameliorating climate.
Only one of the colonies is limited by nesting space (Beaufort Island) and project researchers have shown how sea-ice extent and concentration affect diet, foraging effort (and ultimately chick growth and survival), and over-winter survival. The largest colony (Cape Crozier) affects the foraging patterns of smaller ones within foraging range and, perhaps ultimately, the sizes of those smaller colonies.
Researchers hypothesize, first, that age structure of the Cape Crozier colony has changed since the 1960s and 1970s when populations were declining, and does not represent the smaller colonies which have been growing much more rapidly. Based on recent analyses, researchers propose, second, that the Ross Island penguins winter in a narrow band of sea ice north of the Antarctic Circle (where daylight persists) and south of the southern boundary of the Antarctic Circumpolar Current (where food abounds). More extensive winter ice takes the penguins north of that boundary, with naïve juveniles incurring higher mortality than experienced adults. Finally, researchers hypothesize that higher annual mortality of adults from Cape Royds, the southernmost colony of all, and smallest in the study, is because of their late nesting season and subsequent problems with autumn sea-ice freeze up.
The extreme sensitivity of Adélie Penguins to climate change has been noted by geologists and glaciologists, as well as biologists. Not surprisingly the Adélie penguin is one of the most often studied wild vertebrates on earth. Therefore, understanding more thoroughly the demographic mechanisms behind this species’ sensitivity to climate change will contribute greatly to the recent, wide-spread interest in understanding the effects of climate change on antarctic marine organisms.
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