A new study determined that, over a ten year period, flipper-banded penguins have a 16% lower survival rate and produce 39% fewer chicks than non-banded penguins.
The study was performed by a team of researchers led by Yvon Le Maho, CNRS researcher at the Institut Pluridisciplinaire Hubert Curien (CNRS / Université de Strasbourg) and member of the Académie des Sciences. They obtained their results through electronic monitoring of 100 king penguins on Possession Island in the southern hemisphere.
Supported by the Institut Polaire Français Paul-Émile Victor, this work was carried out in collaboration with Oslo and Tromsø universities in Norway, the Tour du Valat biological station and the Muséum National d’Histoire Naturelle and has been published on 13 January in Nature, also featuring on the cover of the journal.
Penguins are known to be excellent indicators of the state of the health of marine ecosystems and can be used to better understand the impact of climate chage on biodiversity.
They are the top predators of the southern ocean and are at the summit of the food chain. Any changes in their breeding or survival reflect the impact of the climate on links lower in the food chain.
Unlike other birds, it is not possible to fit bands on penguins’ feet so instead, researchers fit them on their flippers. The bands can be read at a distance which allows researches to obtain data without recapturing and further stressing the birds.
There has been debate about the use of such flipper bands because they can have negative effects on the animal. They can injure flipper tissues or increase energy expenditure while swimming or fishing due to hydrodynamic drag. Short-term studies (maximum of one year) have previously concluded that bands have no impact but some researchers stopped banding penguins as a precaution. French researchers have stopped banding penguins since 1990; however, many researchers still rely on data from bands.
This is the first time a long-term study has been conducted. The French-norwegian team’s objective was to monitor one hundred king penguins with electronic tags implanted under the skin, half of which were also fitted with a flipper band, for ten years. The penguins were indentified individually by radiofrequency using antennas burried between the colony and the sea. This system was developed by Le Maho’s team at the Institut Pluridisciplinaire Hubert Curien (CNRS / Université de Strasbourg).
The researchers focused on two key parameters for monitoring the evolution of this penguin population: mortality rate and breeding success. Their results proved the significant impact of flipper banding, which effects both the survival and breeding of the penguins in the medium and long term. Over the ten year period, the 50 banded penguins produced 39% fewer chicks and their mortality rate was 16% higher than non-banded birds.
The banded birds arrive later at their reproductive sites and after being banded for ten yeaers, they continue to have a delayed breeding cycle because of their longer foraging trips. The study refutes the fact theory that penguins get accustomed to their bands. Another important result is that banded penguins do not react the same way to climatic variability as non-banded penguins. This is why the effect of banding is more or less perceptible.
“In favorable conditions, when the sea temperature is low and food resources are abundant, there is virtually no differece between abnded and non-banded animals,” explains Claire Saraux, the leading author of this article. “On the other hand, when the sea temperature is higher, the penguins need to forage further to find their food and banded birds then stay longer at sea.” These results show the need for long-term studies to test possible effects of methods used to monitor animal populations.
From an ethics point of view, the study questions numerous on-going banding campaigns. These results are specific to penguins and cannot be generalized to birds with foot- bands. Furthermore, since banded and non-banded penguins react differently to changes in sea temperature, the study demostrates that flipper banding introduces a bias in the study of climatic effect on the dynamics of penguin populations.
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC