Radar observations of northbound migration of the Arctic tern, Sterna paradisaea , at the Antarctic Peninsula

An intensive migration of Arctic terns was observed from 7–9 March 1989 in Marguerite Bay (67°50'S 67°30'W). The movement pattern and speed of tern flocks were analysed from time-lapse films of a marine navigation radar. The terns migrated north at altitudes 30–60 m asl along the inner coa...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Gudmundsson, Gudmundur A., Alerstam, Thomas, Larsson, Bertil
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 1992
Subjects:
Geology
Ecology, Evolution, Behavior and Systematics
Oceanography
Arctic
Antarctic
The Antarctic
Antarctic Peninsula
Weddell
Marguerite
Marguerite Bay
Bourgeois
Bourgeois Fjord
Pourquois-pas
Antarc*
Antarctic Science
Arctic tern
Ice cap
Sterna paradisaea
Online Access:http://dx.doi.org/10.1017/s0954102092000257
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102092000257
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Summary:An intensive migration of Arctic terns was observed from 7–9 March 1989 in Marguerite Bay (67°50'S 67°30'W). The movement pattern and speed of tern flocks were analysed from time-lapse films of a marine navigation radar. The terns migrated north at altitudes 30–60 m asl along the inner coast of Marguerite Bay. When approaching Pourquois Pas Island, the majority veered to the NNE flying into Bourgeois Fjord. Mean flock size was 11.6 (s.e. = 1.9). The estimated total during the three observation days was about 7600 migrating terns. Analysing flight speed in relation to wind showed that the terns increased their airspeed when flying into headwinds and decreased it with following winds. The terns' airspeeds, with an estimated mean of 11.3 ms -1 (s.e. = 1.3) with no wind effect, were significantly faster than the predicted maximum range speed. It is suggested that the terns were migrating on a connecting route between the pack ice of the Bellingshausen and Weddell Seas, involving a flight across the Antarctic Peninsula. Topographical conditions are favourable for such a passage close to the observation site in Marguerite Bay, where the distance across the 1500 m high ice cap of the Antarctic Peninsula is only 37 km. It remains to be clarified if the suggested migration route is of importance for regional tern populations only, or if it is part of a circumpolar Antarctic migration pattern.

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