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Friday 15 December 2017

Magnificent flying machines

MANX shearwaters (puffinus puffinus) are well into their great migratory journey -- if not already completed -- to the far side of the world. Indeed, the tail of September would have seen the last of them leave (they start to move in July-August), and a proper bird-watching source I know might well chide me for missing the mass of dark birds flying close to chopping waves with the evening light falling and black clouds drawn up on the horizon like a cloak.

The Manxmen would have headed south and west, black-winged and white-breasted, gliding and shearing over the sea in wave troughs, sweeping and veering, guiding systems locked on for a journey of thousands of miles to Brazil

Ninety per cent of the world's population of these birds with hooked beak tip and tubed nostrils, 300,000 pairs, nest on secure island places off the Irish, Welsh and Scottish coasts, fishing by day and reclusively nesting at night in deep burrows in sand dunes and soft cliff faces.

The Manx shearwater is a tireless wanderer, sitting in high sea rafts and riding the rollers before nightfall when all join in a bedlam of screaming and howling while creeping into their tunnel homes. An old folk tale is that such a cacophony drove off in fear some Norse invaders from the Isle of Man 1,000 years ago.

These days few birds nest on Man, but up to 100 years ago there was a commercial trade by locals who harvested the single fat chicks from the burrows. Barrels of salted shearwaters often paid the croft rents!

However, enough survived to adapt to more secure locations and continue their great journeys to fish and feed their young. Ringed birds have travelled to Biscay to feed on the sardine shoals and return to these coasts with full crops -- a round trip of 1,200 miles.

Shearwaters have long lives. One bird, ringed on the Copeland Islands, Co Down, lived for 51 years. How many miles would it have travelled in such a long lifetime? There have been experiments to gauge navigation. A bird was taken by plane to Boston airport and released. Twelve days later it turned up at its burrow in Wales, having flown an average of 244 miles a day.

While the Manxmen were heading to South America, their cousins, the sooty shearwaters (puffinus griseous) were homing in here after flying 10,000 miles from the south Atlantic and Pacific. Like the Manx birds, they also utter eerie nightfall cries, described by one observer as "the most ghastly sound, like choking cats".

Scientists who fitted some sooties with electronic tags to trace their travels and fishing patterns found some birds made much longer journeys, going 46,000 miles from New Zealand and the Falklands to Japan and North America before crossing the Atlantic. En route they visited different areas of ocean to seek better fishing, diving to depths of up to 50 feet to feed.

Sooty shearwaters are the world's most abundant bird species, with about 20 million of them on the wing or giving off nightfall screams.

Other related species are Cory's, little and great shearwaters, with size and marking variations and visiting different breeding areas. All these magnificent flying machines are the world's most enduring and remarkable seabirds and, in their own way, unobtrusive travellers of the globe.

Sunday Independent

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