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Warmer winds a boost to albatross

Wandering albatross in flight over a rough sea.

The albatrosses are growing fatter, spending less time foraging, having more babies, and extending their range (Source: Paul Tixier)

Climate benefits Stronger winds over the Southern Ocean around Antarctica have helped the wandering albatross fly faster and breed more successfully, say European scientists.

However, the study published in the journal Science warns those benefits may be short-lived if the globe continues to warm and wind speeds shift more in the coming decades.

The study focused on four decades of data on a population of albatrosses on the windy Crozet islands, beginning in 1966.

Scientists began fitting the snow-coloured wind-riders - with the largest wingspans of any living bird averaging about three metres - with satellite transmitters in 1989 to track their movements.

Over time, they found that an increase in atmospheric pressure, likely a result of warming temperatures, has boosted wind speeds over this particular sector of the western Indian Ocean where the birds roam.

And the albatrosses have responded in kind, flying faster, growing fatter by an average of one kilogram, spending less time foraging for food, having more babies, and extending their range further southward.

"Wandering albatrosses appear so far to have benefited from wind changes occurring in the Southern Ocean, with higher speeds allowing for more rapid travel," write the study's authors, noting a marked change in the 2000s over the 1990s.

"In wandering albatrosses the probability of prey encounter and capture is related to the daily distances individuals are able to cover."

Gain in body weight

The birds' beefier size was "one of the most unexpected changes we observed over the past 20 years," they add.

An extra kilogram would add about 10 to 12 per cent of the bird's body weight, which is normally around 8 kilograms for females and 10 kilograms for males, the authors write.

The weight gain was likely due to improved access to food but could also be a structural adaptation by the birds, who may be exploiting their increased mass to maximize their flight ability in windier zones.

But if current trends continue, the winds could become too fast for the albatrosses and by 2080 their habit of foraging over the Crozet Islands may prove impractical.

"Travel and flight speeds will not respond linearly to the increase in wind speed, and too strong gales winds become unfavourable for dynamic soaring flights," the researchers write.

The study was led by Henri Weimerskirch and colleagues at the Centre d'Etudes Biologiques de Chize in Villiers en Bois, France; and Maite Louzao of the Helmholtz Centre for Environmental Research in Leipzig, Germany.

Tags: environment, climate-change, animals, birds