Scientists still mystified by bird migration

BIRD migration is an extraordinary thing, in fact, in some cases, it verges on the unbelievable. Every autumn Aleutian bar-tailed godwits fly non-stop for nine days from Alaska to New Zealand, a distance of more than 11,000km.

Great shearwaters and sooty shearwaters, which are flying off our coasts at present, were hatched on remote islands in the Roaring Forties of the southern hemisphere. Miniature tracking devices attached to some have revealed that in the course of their world travels they fatten up on Canada’s Grand Banks and don’t feed again until they arrive off the east coast of Argentina.

Many long-distance migrants prepare for the journey by undergoing changes that seem as miraculous as Clark Kent’s transformation into Superman. All their non-vital organs, including their digestive systems, shrink in order to reduce weight and make space for the fat that fuels the flight. They reconfigure the amount of haemoglobin in their bloodstream so they can fly at high altitudes where the air is thin but there are beneficial tail winds. All this so that they can enjoy perpetual summer by flying from one hemisphere to another.