Albatross species finds it easier to fly with changing winds near South Pole

Winds off the Southern Ocean, around Antarctica, are shifting, making it easier for a particular species of albatross to fly farther.

Winds over the Southern Ocean, around the continent of Antarctica, have shifted and picked up in recent decades, giving a lift to foraging albatrosses, scientists say.

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One species, the wandering albatross, can fly more than 2,175 miles (3,500 kilometers) looking for food, particularly dead squid floating on the ocean. During the summer, one breeding partner can travel for days or weeks at a time in search of food while the other incubates the egg.

Over the last two decades and possibly longer, changes in winds appear to have led to shorter, easier foraging trips, leading to heavier birds and more chicks for a population of wandering albatrosses on Possession Island, one of the Crozet Islands in the Southern Ocean, according to a study published in the Jan. 13 issue of the journal Science.

Winds of change

Over the past 50 years, summertime westerly winds over the mid-latitudes, within which Possession Island lies, have been shifting farther south, closer to the Pole, and strengthening.

The hole in the protective ozone layer ? which has expanded?above the Antarctic during recent decades but is expected to recover eventually ? is primarily responsible. The ozone hole decreases temperatures above the Pole. This creates a more significant atmospheric pressure difference between the polar region and the tropics, resulting in a shift and strengthening of the westerly winds, according to Judith Perlwitz, a research scientist at the University of Colorado, Boulder, who was not involved in the study. ?

Global warming is expected to have a similar effect, but by warming the atmosphere over the tropics. But the ozone hole has been the dominant driver behind the changes in winds so far, according to Perlwitz.

Flight of the albatross

Large seabirds and excellent gliders, the wandering albatross depends on the wind for its foraging trips, which have been recorded to last up to 35 days.?

To take off, they fly into the wind to reach gliding altitude, then the birds turn, and fly with side or tail winds. From there, they can glide for 1,640 feet (500 meters) at a time, according to Henri Weimerskirch, a study researcher and head of a marine predator group at Centre d'Etudes Biologiques de Chiz? in France.

Source: http://rss.csmonitor.com/~r/feeds/science/~3/cnNhlgua9nA/Albatross-species-finds-it-easier-to-fly-with-changing-winds-near-South-Pole

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