Wednesday, 19 November 2008

Bar-tailed Godwit creates new record

A Bar-tailed Godwit has achieved a new record for non-stop, muscle-powered flight, flying from Alaska to New Zealand in eight days. A study published in October reports that godwits can fly as many as 7,242 miles without stopping in their annual fall migration from Alaska to New Zealand. The previous record, set by an Eastern Curlew, was a 4,000-mile trip from eastern Australia to China.

The birds flew for five to nine days without rest, a few landing on South Pacific islands before resuming their trips, which were monitored by satellite in 2006 and 2007. As a feat of sustained exercise unrelieved by sleeping, eating or drinking, the Godwit's migration appears to be without precedent in the annals of vertebrate physiology.

As astounding as the feat is, it actually represents a highly evolved solution to a problem. The non-stop, over-water route is free of predators and substantially shorter than a hopscotching route down the eastern coast of Asia, which is the alternative. Landing and eating -- literally, refuelling -- would expose the birds to disease and parasites when they are probably somewhat immune-suppressed. Refuelling also would add weeks to the trip and itself take energy. All in all, flying non-stop across most of the north-south span of the Pacific Ocean is the safest thing to do. The death rate during the migration is unknown but presumably low, as the population of bar-tailed godwits, estimated at 100,000, has been stable and long-lasting.

"This system would not have perpetuated itself if mortality were a big problem," said Robert E. Gill Jr., a biologist with the U.S. Geological Survey, who headed the study, published in October by The Royal Society.

(Top marks to anyone who spotted my photo is of a Black-tailed Godwit; I haven’t got a picture of a Bar-tailed Godwit!)

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