Penguins tagged by scientists with metal bands 'die more quickly and have fewer chicks'

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Metal bands used to track penguins may inadvertently be killing the birds, according to a study by scientists.

Thousands of penguins have had the steel rings fitted around their legs and flippers over the last decade to monitor population numbers.

But a 10-year study among tagged King Penguins showed survival rates were 44 per cent lower than those without bands.

It also significantly affected birth rates among the birds, with banded penguins producing 41 per cent fewer chicks than their unbanded counterparts.

The French study, published in the journal Nature, theorise that the bands - made either aluminum or stainless steel - increase drag on the penguins when they swim, making them work harder.

Author Yvon Le Maho of the University of Strasbourg in France, said the banded penguins looked haggard, appearing older than their actual age.

Consequently, studies that use banded penguins - including ones about the effects of global warming on the seabirds - may be inaccurate, mixing up other changes in penguin life with the effects from banding, said Le Maho and colleague Claire Saraux.

'There is an ethical question: should we continue with banding penguins?' said Le Maho.