Tagging wild penguins with flipper bands threatens their chances of survival and has skewed data on the effects of climate change, biologists said Wednesday.
Researchers at the University of Strasbourg in France followed 50 banded adult King penguins and 50 non-banded penguins with under-the-skin transponders for 10 years.
Conducting their research on a French island in the southern Indian Ocean between Africa and Antarctica, they found the flipper-banded penguins had 39 percent fewer chicks and were 16 percent likelier to die than their untagged counterparts.
Study author Yvon Le Maho theorizes that the metal bands, which are tied around the top of the flipper, increase drag on the penguins when they swim.
“The picture is unambiguous,” Le Maho told news agency AFP. “Among banded penguins, the least-fit individuals died out in the first five years of the study, which left super-athletic birds.
“In the remaining five years, the mortality rate between the two groups was the same, but the reproductive success of banded penguins was 39 percent lower on average.”
Le Maho said this is the first study showing the long-term detriments of penguin tagging practices, and disproves the long-held assumption that the birds adjust to the bands.
He said banded birds respond differently to the climate, arriving later (16 days later on average) on the island to breed. This tardiness endangers the survival of their offspring, because late chicks face harsher weather conditions and more predators.
Consequently, studies that use banded penguins to measure the impact of global warming on marine life need to be reviewed, researchers said. Although climate change is still harming penguin populations, the data may be skewed.
“…[W]hen there was a rise in sea temperature and food was less abundant, the penguins had to swim farther, and banded penguins stayed longer at sea to forage compared with non-banded birds,” said Claire Saraux, like Le Maho a member of France’s National Centre for Scientific Research (CNRS), according to AFP.
The findings were published in Wednesday’s edition of the Nature science journal.