Paris, February 11, 2008
How to track penguins in their natural environment?
For years, a numbered band attached on a flipper was used to track individually penguins, but these bands increased the drag of pengouins when moving into water. The "Écologie fonctionnelle" team, led by Yvon Le Maho at IPHC, observed that adult king penguins wearing a flipper band had their breeding success reduced by half. They also showed that the survival of unbanded chicks was increased by half. To avoid this bias on the scientific data, the IPHC team put together an innovative system allowing long-term tracking of the king penguins with no impact on how the penguins interact with their natural environment. The new system is based on individual electronic identification. The study was initiated 9 years ago, covering a population of 450 king penguins who had had an 0.8 g electronic tag implanted under their skin. The tagged birds could then be identified thanks to antennas buried along the “Penguin highways”. The research was carried out on Ile de la Possession in the Crozet Archipelago, where 2/3 of the world population of king penguins is breeding (some 2 million penguins). The data are thus representative for the entire population.
Why king penguins?
Being able to predict the impact of climate change on biodiversity is vital, but the effects on marine productivity in the Southern Ocean are still poorly understood. Furthermore, it is difficult to determine the impact of climate on marine food chains. One of the advantages of pelagic birds is that they are predators, and thus at the top of the food chain, and as a result, their population dynamics reflect the change in marine resources. As penguins obviously do not fly, great numbers of them can be identified and localized on their usual routes. Additionally, it is only king penguins that commute regularly all throughout the year between the colony and the ocean, where they find food for themselves and their chicks. During the summer, the penguins forage at a distance between 300 and 600 km from their colony, the distance being directly correlated with the warming of the Ocean: the warmer the surface water, the fewer fish prey close to Crozet and the further the penguins must go. In winter, when marine resources are more difficult to come by, the penguins must go some 2000 km from the colony, near the ice seas off of Antarctica.
© Nicolas Chatelain / IPHC (photo available at the CNRS photo library, firstname.lastname@example.org).
A colony of King Penguins on île de la Possession
King penguin population threatened by Southern Ocean Warming. Céline Le Bohec, Joël M. Durant, Michel Gauthier-Clerc, Nils Chr. Stenseth, Young-Hyang Park, Roger Pradel, David Grémillet, Jean-Paul Gendner and Yvon Le Maho. PNAS. 11 February 2008. (Article available online at www.pnas.org).
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