The birds that just scream at home
SHEARWATERS are the world’s most abundant bird species with millions traversing the oceans to and from their breeding sites following the contours of the sea for thousands of miles.
Manx shearwaters (Puffinus puffinus), of which 300,000 pairs nest on British and Irish islands, have by now departed on their great winter migratory journey to Brazil.
The end of the month will have seen the last leave, heading south and west, black-winged and white-breasted, gliding and shearing over the sea. Ninety-per-cent of the world’s population of hooked beak and tubed nostril birds have been nesting on islands off the Irish, Welsh and Scottish coasts.
The Manxmen — though few pairs nest there — arrive in March to breed, deep in soft soil burrows in Kerry, Galway, Antrim and Down, Wexford and Dublin. Most are on Puffin Island, Skellig Michael and the Blaskets — about 10,000 pairs — fishing by day and joining in a bedlam of strange screaming and howling as darkness falls and they creep into their burrows to care for their sole chick.
There is an Isle of Man folk tale of Viking raiders 1,000 years ago preparing for an assault on Ireland, fleeing in terror at those blood-curdling screams in the night which they believed were from evil demons of the underworld!
More than 100 years ago, there were so many birds on the Isle of Man that there was a thriving commercial trade with locals who took the fat chicks which were salted in barrels for the London market. The chicks were easy to catch, plump (up to one pound in weight) and rich in fat. Half of this was oil and the bird was described as “the most delicious morsel in the world” or, by those who disagreed, “the most detested”.
About 10,000 were taken annually from the Calf of Man while on St Kilda, the Scottish isle, there was such a demand for eggs that the birds were almost wiped out.
Manx shearwaters travel far to seek food and ringed birds have been traced to the Bay of Biscay where they feed on sardine shoals before returning to Skellig and other sites with full crops — a round trip of 1,200 miles. The birds live long lives. One, ringed on the Copeland Islands, Co Down, was found dead at 51 years. It must have travelled 10 times round the moon and back again! There have been tests to judge navigation. A bird was taken to Boston by aircraft, released and 12 days later turned up at its burrow in Wales. It had flown an average of 244 miles a day.
As the Manx birds fly to South America, their cousins, Sooty Shearwaters (P. griseus), return from their breeding colonies in the South Atlantic and Pacific to spend winter here. Most will have travelled at least 10,000 miles but some birds make longer journeys from New Zealand and the Falklands to Japan and North America before crossing the Atlantic.
There are estimated to be about 20 million ‘sooties’, making it the world’s most abundant species. Like the Manx birds, they also utter weird screams in the night, described by one observer as “the most ghastly sound, like choking cats”. These global travellers save their pent-up frustrations until they arrive home. Just like some humans!
MIGRANT: Manx shearwaters