Small bird leaves scientists gobsmacked
By MICHAEL FIELD - Fairfax Media | Thursday, 23 October 2008
Scientists are marvelling over a small female bar-tailed godwit somewhere in New Zealand who has a world record for non-stop flying – an epic 11,200 kilometres.
A major international study into the birds has been published in the journal Proceedings of the Royal Society B and it offers an explanation as to why the godwits fly so far from Alaska to New Zealand in a single bound.
The birds flew non-stop for up to and covered more than 11,200km. The flight path shows the birds did not feed en route and would be unlikely to sleep.
The study, which involved scientists from around the world, electronically tagged godwits and tracked them, both from New Zealand to Alaska, via Asia and, more recently, from Alaska back to New Zealaqnd direct.
One of the birds, a female called E7, set the record of flying the furthest in eight days across the Pacific.
"These extraordinary non-stop flights establish new extremes for avian flight performance and have profound implications for understanding the physiological capabilities of vertebrates," the report said.
The international media have hailed the achievement.
In Britain’s Guardian quoted Theunis Piersma, a biologist at the University of Groningen in The Netherlands.
"There is something special going on here. For a vertebrate this kind of endurance is just extraordinary."
Piersma said the birds would have flapped their wings non-stop for the entire journey, and that the resulting energy requirement was the greatest in the animal kingdom.
The birds would have gobbled up energy at some eight times their resting basic metabolic rate (BMR) during their week-long exertion, he said.
Professional cyclists an only manage about five times BMR for a few hours.
"Lance Armstrong would be no competition for these birds," he said.
The Washington Post quoted Robert F Gill, a biologist with the US Geological Survey, who headed the study.
"The human species doesn't work at these levels. So you just have to sit back in awe of it all," he said.
Said Kimberly A. Hammond, a physiological ecologist at the University of California: "What this suggests to me is that we haven't yet mined the depths, we really don't know what the extremes are."
The nonstop, over-water route is free of predators and substantially shorter than a hop-scotching route down the eastern coast of Asia, which is the alternative.
Landing and eating would expose the birds to disease and parasites when they are probably somewhat immune-suppressed.
Flying non stop – north to south – across the Pacific was 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 Gill
The Post said a major mystery is how high the birds fly.
Gill said that since word of his research has spread, researchers on boats in the Pacific have told him of seeing godwits 1000 metres high and "smoking by at deck level."