Thursday, January 13, 2011

Penguins tagged by scientists with metal armbands 'die quicker and have less chicks'


Damage: New research shows metal bands used to monitor penguin populations affect death and birth rates

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.

Visible signs: Researchers say penguins who wear the bands look haggard

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.

Thousands of penguins have been fitted with the armbands in the last decade

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.

Options: There are several different types of armbands, and they do not produce the same results

The researchers followed 50 banded adult penguins and 50 unbanded birds for 10 years, tracking them with under-the-skin transponders.

Thirty six per cent of the non-banded survived for 10 years, compared to only 20 per cent of the band-wearing birds.

Penguins generally live for around 20 years although King penguins - among the largest penguins at 3ft tall - can live even longer.

The non-banded penguins had 80 chicks, while the banded seabirds produced 47 chicks, a 41 per cent drop.

The penguins were studied on a French island in the Indian Ocean between Africa and Antarctica.

Penguin researchers have long debated the use of bands. The bands weigh just under an ounce and are a bit more than an inch wide.

The scientists singled out potential problems with research on global warming's effect on penguins.

Banding may have skewed the data, but climate change is still harming and will harm penguins, they said.

Saraux said a study she did a couple years ago - without bands - showed harm to penguins from global warming.

source: dailymail

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