Thursday, March 17, 2005

The Flight Of the Albatross And Other Frigatebird Tales

Source: Natural History Magazine

Albatrosses and frigatebirds spend most of their long lives soaring over the sea. Now miniature electronic trackers and sensors are telling the tales of their adventures. Natural History Magazine ran the story last October.

Frigatebirds live for decades, but albatrosses hold the record for seabirds, reaching ages of sixty to seventy years and continuing to reproduce into their fifties. The studies of the wandering albatross have repeatedly brought the writer to two of the most remote islands in the Southern Ocean, Crozet and Kerguelen, where the birds breed and nest.

The trackers found that during a single foraging trip, which typically lasted between ten and fifteen days, the birds flew more than 1,800 miles from their nests and covered as much as 9,300 miles. They traced huge irregular loops, and made smaller-scale zigzagging movements within the loops that added substantially to the total length of the trip. To save energy, they soared on tailwinds or side winds. When the winds died, they alighted and drifted on the sea until the winds picked up again.

Heart-rate monitors showed that albatrosses' heart rates during flight are only 10 to 20 percent higher than they are when the birds are at rest. In contrast, the heart rates of other birds in typical flapping flight can rise to as much as 200 percent higher than the baseline level.

The patchy distribution of prey requires long-distance foraging. Long-distance foraging means the chicks are fed at long intervals, and so they develop independence slowly. The nine months between hatching and fledging forces the adults to skip a year between breeding attempts. All in all, the bird's slow-paced life probably contributes to its lengthy life span. And perhaps the decade it takes an albatross to reach reproductive maturity is time spent learning how to find the right winds and ride them while keeping a weather eye out for prey.

Source: Natural History Magazine

For more on the mythical Albatross revisit Coleridge's The Rime of the Ancient Mariner.

1 comment:

Chris Moonbeams said...

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