Marathon flight of the godwit

ACCORDING to Wings, BirdWatch Ireland’s magazine, a new long distance flight record has been set.

In September, a bar-tailed godwit left its breeding grounds in Alaska and flew to New Zealand, where it will spend the winter, a distance of 11,600 kilometres. The bird, which had been ringed and fitted with a satellite tracking device, is believed to have flown non-stop for eight days, breaking its own record of the previous year when it travelled 10,200km in nine days.

“Over a nine month period”, says the report, “this bird clocked up over 29,000 km, flying from New Zealand to China, then over to Alaska, then back to New Zealand.” Bar-tailed godwits can live for up to 22 years, during which time a bird breeding in Alaska and wintering in New Zealand would have flown about 638,000km.

The name ‘godwit’ comes from Old English and means ‘good creature’, good to eat, that is! Sometimes called ‘half curlews’, godwits are smaller than the familiar wader of Irish bogs. Both species have very long bills; a curlew’s curves downwards, but a godwit’s is very slightly upturned. Female curlews and godwits have longer bills than their mates; the sexes probe the mud to different depths, avoiding competition with each other for food. The tip of the bill is flexible and sensitive; mud-dwelling creatures, such as ragworms, are located by touch.

This modification of the nose and mouth resembles an elephant’s trunk, a sort of nasal hand.

We have two godwit species in Ireland, the black-tailed and the bar-tailed. The former is slightly taller, but it’s difficult to tell the two apart when they are on the ground.

In flight they are very distinct; the black-tailed has a gleaming white wing stripe and a conspicuous black bar at the tip of a broad white tail. Its long legs trail behind it. The legs of bar-taileds protrude only slightly. Distinct plumages didn’t evolve for the benefit of bird-watchers. The two species don’t cruise at quite the same speed, and the colour patterns help a bird to find a flock of its own persuasion, so as to fly efficiently and comfortably, particularly at night. A flock of black-taileds is known as a ‘godliness’. For bar-taileds, the collective noun is ‘ungodliness’.

Black-taileds, compared to their bar-tailed cousins, lead fairly laid-back lives. They don’t travel so far north, staying well below the Arctic Circle when breeding. Iceland, a country warmed by the Gulf Stream, is their most northerly stronghold. A pair or two nest in Ireland each year and about 30 in Britain. Almost all of the black-taileds which visit us in winter come from Iceland. The journey here, a 1,000 km non-stop sea crossing, is demanding, but modest when compared to the ones the bar-tailed makes.

Bar-taileds may be less elegant to look at, but they are much more adventurous when it comes to migration. Breeding in the high Arctic, they undertake some of the most extensive flights of any bird. On this side of the Atlantic, migrating godwits fly down the west coast of Europe and on to Africa, stopping off to rest and feed along the way. Those heading south from Alaska face a daunting prospect; the open Pacific Ocean with only an occasional island between them and Australasia.

Did the record-breaking godwit stop off at Hawaii or the Marshall Islands on its way to New Zealand? It seems unlikely. Flying non-stop, its average speed would be 60km per hour. If it stopped to rest it would have fly faster to complete the journey in eight days and, with any significant delay, this would be impossible. But could a bird actually fly for eight days and nights without stopping? Small birds facing a long non-stop flight may double their body weight, but how does a bird contemplating an eight day journey lay on enough fuel?

Long-distance migrants have another trick up their sleeves; muscles not needed for flying are metabolised to provide extra energy. Birds, thin and emaciated at the end of such journeys, are little more than flying skeletons.