A bar-tailed godwit has been crowned the endurance champion of the animal kingdom after completing an epic 7,200 mile nonstop flight across the Pacific Ocean from Alaska to New Zealand.

The wading bird's journey lasted more than eight days with no rest or food, and took it into a place in the record books. Scientists tracking the bird's flight said it was unprecedented.

Theunis Piersma, a biologist at the University of Groningen in the Netherlands who worked on the study, said: "There is something special going on here. For a vertebrate this kind of endurance is just extraordinary."

The long-haul flight of the godwits, from their breeding to feeding grounds, was first reported last year, but scientists have now analysed the journeys and have reported their findings in the journal Proceedings of the Royal Society B.

Led by Bob Gill of the US Geological Survey, the scientists say: "These extraordinary nonstop flights establish new extremes for avian flight performance and have profound implications for understanding the physiological capabilities of vertebrates."

Curious about the role migratory birds play in spreading avian influenza, the scientists captured godwits in 2006 and 2007 and fitted them with satellite transmitters to track their journeys. On the southward leg, the birds flew nonstop for up to nine days and covered more than 7,000 miles. The scientists say the flight path shows the birds did not feed en route and would be unlikely to sleep.

Piersma said the birds would have flapped their wings nonstop 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.

Peak human performance is measured in professional cyclists, who can only manage about five times BMR for a few hours. "Lance Armstrong would be no competition for these birds," he said.

The scientists suggest that the central Pacific may act as a ecological corridor because, unlike coastal routes, there are few predators or diseases. But they say climate change could alter its suitability by changing the strength and frequency of winds.