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L'Antàrtida, molt més que gel C. Pedrós-Alió. Els
ocells de la fi del món. Antarctica has one of the most extreme environments of the planet. The Southern Ocean however, provides a moderate and constant temperature, and seasonally many light hours. Antarctic seabirds, therefore, are a particular case of seabirds. They have to travel long distances with low energy consumption, orient themselves and find the food sources dispersed as patches in a very wide and diluted ocean. They also must find appropriate snow-free areas to build nests and breed. Recent developments in instrumentation have revolutionized our understanding of their life at sea (up to 70% of the time in the case of albatrosses) and of their strategies to find food, as well as their diving and navigating capabilities. The number of species is relatively low. More than 800 species breed in the southern part of the South American, African and Australian continents. Only a few dozens do so in subantarctic islands. And only four nest exclusively or mostly in the Antarctic continent: the Emperor and Adelie penguins, the Antarctic Petrel and the Snow Petrel. Each one of these species has developed particular adaptations to take advantage of the constantly changing ice pack. Current increases in temperature due to global change are of concern for Antarctic seabird populations, especially those dependent on sea ice. Up to the present, however, trends in population abundances are different in separate areas of Antarctica. Further refinements in our knowledge of their ecology will be needed to ascertain their status. |
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