Tracked in godwits

Apr 5, 2007 11:05 GMT  ·  By

A marathon is like a warm-up exercise for some animal species.

Their endurance capacities can amaze, like they would be driven by engines.

Now, a new record for endurance has been tracked in four bar-tailed godwits for a non-stop flight of over 10,000km (6,000 mi) from New Zealand to the Yellow Sea (eastern China).

The birds were followed-up employing satellite transmitters, and did not stop to eat or drink on the first leg of their migration to the north, to the breeding places in Alaska.

"It had been suspected that the birds could fly such distances but now it had been proved. No other animal had shown such endurance," said Dr Phil Battley, an ecologist at Massey University's Palmerston North campus.

Dr Battley said: "It is the first time transmitters have been implanted in New Zealand into the female birds, which took from 6 to 7 days to cover the route, flying up to 2km (1.3 mi) high at an average speed of 56 km (35 mi)/h."

One bird covered 10,063km and another 10,205km.

But not all the monitored godwit individuals which started the migration in the middle of March displayed such stamina.

"Of the 10 godwits tracked so far, three had made stops - in Papua New Guinea, the Philippines and Micronesia. Interestingly, they were male birds, which had instead been fitted with backpack tracking devices, worn on the outside and fitted with a harness. While those transmitters, at 9.5g, were lighter than the implanted devices, weighing 22g, they appeared to create drag problems which could explain the need to stop on the way," said Battley.

"Godwits flew in reasonably small flocks of 30 to 70 birds, and if one touched down it was probable that the flock had landed."

Godwits set out from New Zealand with a huge fat reserve (they are clinically obese), but they lose about 50 % of their bodyweight in each leg of their journey.

When they arrive at the tidal flats of the Yellow Sea, off eastern China and South Korea, they remain here for a month or two to refuel.

"It's the equivalent of riding the Tour de France but keeping it up for a week nonstop."

After that, the godwits fly to Alaska where they arrive by mid-May.

In September they make the journey back, in a straight line across the Pacific Ocean to the New Zealand coast.

"The project would provide crucial information about the migratory behavior of declining species," he said.

Throughout East Asia and Australasia, 85 % of shorebird populations were decreasing, and 40 % of the species were assessed as threatened or near threatened.

"Annual population counts at major sites in New Zealand showed a decline in numbers." said Battley.

The growing reclamation of tidal mudflats in Korea and China and dams, like that of the Three Gorges Dam, will affect birdlife.

"We are entering a critical decade for these birds, so the research is timely and crucial."

Photo Gallery (2 Images)

The route of the tracked godwits
Bar-tailed godwits
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