Vancouver, July 30 - Little bar-headed geese tame the world's highest mountains of the Himalayas to fly between India, China and Mongolia annually. Canadian scientists now say they have found why these birds are able to outperform the world's most accomplished athletes in stamina.

Researchers at Vancouver's University of British Columbia (UBC) say these geese have a higher density of blood vessels and other unique physiological features in their flight muscles.

This allows them to do what even the most accomplished athletes struggle to achieve, exert energy at high altitudes, according to a university statement.

The geese, which are identifiable by the dark stripes on the backs of their heads, fly over the world's highest peaks to migrate annually between India and China and Mongolia.

'They fly at altitudes up to 9,000 metres. That is the equivalent of humans running a marathon at the altitudes commercial airlines fly,' said zoology research student Graham Scott, who was part of the research team comprising scientists from the UBC and the University of Birmingham in Britain.

As part of their research, they compared the physiology of bar-headed geese to low-altitude waterfowl such as barnacle, pink-footed and greylag geese.