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Marine Ecology Progress Series

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MEPS 491:253-264 (2013)  -  DOI:

‘Stepping stone’ pattern in Pacific Arctic tern migration reveals the importance of upwelling areas

Aly McKnight1,*, Andrew J. Allyn2, David C. Duffy3, David B. Irons1

1US Fish and Wildlife Service, Anchorage, Alaska 99503, USA
2Department of Environmental Conservation, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
3Pacific Cooperative Studies Unit, Department of Botany, University of Hawai’i Manoa, Honolulu, Hawaii 96822, USA

ABSTRACT:  Arctic terns Sterna paradisaea are noted for their extraordinary migration between Arctic and sub-Arctic breeding grounds and Antarctic wintering areas. Until recently, few data existed to document this migration, and none existed for North Pacific breeders. In this study, we tracked 6 Alaskan Arctic terns tagged with combined light geolocation and saltwater immersion tags through their fall migration. During fall 2007, these birds used several highly productive stopover locations to refuel during their southward migration: the California Current, the northern and southern Humboldt Current, and the Patagonian Shelf. At least 3 of the birds went on to winter in the Weddell Sea region of Antarctica, where Arctic terns from several Atlantic populations are also known to winter. Analysis of the first ever post-breeding behavioral data collected on this species showed that the birds foraged extensively in these staging areas, spending more time foraging on days when they were located within staging areas during the fall migration. We also found that the birds were exclusively diurnal foragers, spending their nights standing out of the water and/or flying. Arctic terns likely face strict time constraints throughout the migration, timing stopovers to match production while simultaneously aiming to arrive at the wintering grounds with sufficient time remaining to complete the winter molt before returning north. Ecological disturbance at any of these locations could have serious consequences for many birds. Further, predicted effects of climate change in the Weddell Sea region could have repercussions throughout the global Arctic tern population.

KEY WORDS:  Arctic tern · Sterna paradisaea · Migration · Geolocation · Activity sensor · Staging area · California Current · Humboldt Current · Patagonian Shelf · Weddell Sea

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Cite this article as: McKnight A, Allyn AJ, Duffy DC, Irons DB (2013) ‘Stepping stone’ pattern in Pacific Arctic tern migration reveals the importance of upwelling areas. Mar Ecol Prog Ser 491:253-264.

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