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    Winter distribution of chinstrap penguins from two breeding sites
    in the South Shetland Islands of Antarctica

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    W.Z. Trivelpiece, S. Buckelew, C. Reiss and S.G. Trivelpiece (USA)
    Agenda Item(s)

    Satellite telemetry was used to determine the winter movements and distributions of eight chinstrap penguins known to breed at one of two colonies in the South Shetland Islands, Antarctic Peninsula region during the 2000 and 2004 austral winters. Six birds from a breeding site in Admiralty Bay on King George Island (620 10’ S, 580 27’ W) were instrumented with satellite tags following their annual molt; similarly, two birds were tagged at their breeding site on Cape Shirreff, Livingston Island (620 28’ S, 600 46’ W). Chinstrap penguins were tracked successfully for one to six months following dispersal from their respective breeding colonies using the ARGOS satellite system. Data analyses revealed that 4 of the birds instrumented in the 2000 winter, two from each colony, foraged largely on the shelf to the north and northeast of the South Shetland Islands. Similarly, two birds tagged at Admiralty Bay in 2004 also dispersed to the Drakes Passage side of the South Shetland Islands. In contrast to the inshore locations utilized by all the penguins in 2000, both of the 2004 winter birds foraged well offshore, 350 to 500 km north of the Islands. Bathymetry and hydrological data, including SST and geostrophic velocities, suggest that the chinstrap penguins used markedly different winter foraging habitats in the 2000 and 2004 winters. The final two chinstrap penguins from Admiralty Bay, one from each winter, proceeded directly to the Elephant Island area and spent the next 2-5 months continually migrating eastward. Both of these penguins followed the Scotia Arc with the chinstrap penguin tagged in 2004 tracked to the vicinity of the South Orkney Islands where its signal was lost in April, a distance of 800 km from its breeding colony. The bird tagged in the 2000 winter continued towards the South Sandwich Islands until its signal was lost at 580 30’ S, 360 10’ W in late July, over 1300 km from its breeding colony. The migration path of both these birds was remarkably similar to the only other record of a chinstrap penguin’s winter migration reported by Wilson et al. (1998). Our results suggest that chinstrap penguins breeding in the same colonies during the summer have different migratory routes and winter habitats. The different migratory routes may reflect individual ties to different ancestral epicenters of chinstrap populations; one older and local in the South Shetland Islands and one relatively recent, arising from the emigration of chinstrap penguins that occurred during the expansion of this species in numbers and range in the middle of the past century.