For decades flipper banding has been the standard way to tag and monitor penguin populations, but a new study could be the death-knell of the practice.
A team of French and Norwegian researchers studied 50 banded and 50 non-banded free-roaming king penguins living on Antarctica's Possession Island over a ten year period, and say their research shows the practice impairs reproduction and reduces life-expectancy.
Some previous studies had concluded that the bands had no long-term ill effects on the birds. The new study, published today in the journal Nature, refutes the earlier assumption that penguins adapted to bands within a year.
The researchers, led by Claire Saraux of France's Universite de Strasbourg say that over a decade they found that flipper banded penguins produced 27 per cent fewer chicks, and had a 44 per cent lower survival rate.
During the ten-year study period, 80 per cent of the banded birds died, while only 64 per cent of the unbanded birds died, demonstrating a dramatically reduced life expectancy for those with bands.
Dr Andre Chiaradia, penguin biologist at the Phillip Island Nature Park, says the impressive thing about the research is that this is the first time a penguin population has been studied over such a long period.
He says that allowed all other factors to be equalised, and a valid comparison to be made between the banded and unbanded birds.
"The thing about this study is that they could look over time", he says, "and they could follow the same individual over ten years and say OK this is the effect of the band. What comes up quite clearly is that when you filter out all these factors is that birds with the bands are underperforming."
Interfering with hydrodynamic perfection
Penguins power their swimming exclusively with their flippers, and there had been increasing concern that the hydrodynamic drag which bands create would severely hamper the birds in the long run.
"Penguins are this perfectly streamlined machine for diving", Chiaradia says, "they have almost no turbulence, an amazing hydrodynamic structure. So, even a flipper band is going to have a huge drag effect."
Indeed, a study of captive Adelie penguins published in the journal Functional Ecology in 2002 showed that banded birds expended 24% more energy than their unbanded colleagues.
Chiaradia says that although the bird's performance is reduced, when food was plentiful, the extra energy may not make a huge difference to a bird's ability to feed itself and its chicks. But he says a bad season, where prey is not so abundant, can really make a difference.
"If the conditions get really tough and you go into survival mode, you have to search longer for your food, you have to work really hard," he says.
"You have to intensify your effort, and you have this handicap, this is going to affect your performance. You're not going to perform as well as the birds without the bands."
Studies in the 1970s on birds both in zoos and in the wild also found that bands often caused severe injury to flippers. Many researchers abandoned the practice during the 1980s. These days most research programs are using microchips or other alternatives, but some banding schemes are still being continued.
"In the past researchers thought the birds would get used to [the band] and compensate for it," Chiaradia says.
"But this study is the nail in the coffin for banding, because this is proving that there is a long-term effect. That's very impressive."