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Long before man worked out that the shortest distance between two points is not necessarily along a constant compass bearing, birds were already flying what amounts to "great circle" routes across the Canadian Arctic to their destinations in South America.
Brett spoke to Thomas Alerstam, Professor of Animal Ecology at Lund University in Sweden, at a recent conference on Animal Navigation held at the University of Reading. He explained that some waders like the Phalarope migrate from Siberia to Peru via the Arctic rather than at a compass bearing of South East. On a recent expedition to the Arctic, Professor Thomas Alerstam discovered that there are millions of birds that start their migration heading northwards and pass over this remote region of the world.
How are these birds able to navigate then if they initially start heading in the wrong direction? At such a northerly latitude during summer, there is continual daylight so the position of the stars in the night's sky is of no use. As Professor Thomas Alerstam explains, navigation must therefore be based on the movement of the sun and the earth's magnetic fields.