Flying high

For the science geeks: Ever wondered why some birds are able to fly at high altitudes and others aren't? Here's a peek into one probable adaptation.

For the bar-headed goose, migration is a high-altitude adventure. Spring and fall it flies between Central Asia and India, a route that takes it over the highest mountains in the world, the Himalayas. The bird has been known to reach altitudes of 30,000 feet.

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Mr. Scott and his colleagues examined pectoral muscles from bar-headed geese and compared them with those from related species, like barnacle geese, that don’t fly at extreme altitudes.

They found little difference among the birds in the amount and types of muscle fibers. But the bar-headed geese had more capillaries around the individual muscle cells. And within cells, more of the mitochondria — which use oxygen to supply energy to the cell — were nearer the cell membrane.