The stormy weather of late has cast another large wreck of birds on the beach here. This time it is mainly the sooty shearwater. Over the course of several days, several hundred have been cast ashore on the short stretch I walk along every morning. This is, apparently, a fairly common occurrence with sooty shearwaters as they migrate backwards and forwards from the Northern Pacific.
The name shearwater is applied to that sub–division of the Procellariidae, petrels, family whose members have a skimming flight pattern, a flap and rapid glide, close to the surface of the sea. There are five known in New Zealand waters, the sooty shearwater being the most common and in season the most numerous sea–bird in southern New Zealand waters.
The sooty shearwater is quite heavily built, almost the size of a mallard duck but more streamlined. It is dark brown above, black–looking in flight and a little paler underneath with conspicuous silvery white linings to the under part of the narrow wings. The upper bill is curved to a sharp hook. The webbed feet are a surprising shade of lilac with brown markings. As it only comes to land to breed, the legs are feeble so that on land the bird is never erect but always in a squatting position. The melting dark brown eye and the classic shape and poise of its fine neck and head are things of great beauty.
The sooty shearwater is found in oceans throughout the world but its only known breeding areas are in the Southern Hemisphere. It breeds in the sub Antarctic and temperate zones on islands off the coast of Chile and around Cape Horn, on Kidney Island, Falklands, on Tristan da Cunha, on islands off Tasmania and New South Wales and on numerous New Zealand islands and some headlands on the mainland. Sub fossil and midden evidence, as well as historical records, suggest that sooty shearwaters formerly bred in large colonies on the mainland. In the Bay of Plenty a few still breed on Whale Island.
Charles Darwin in The Voyage of the Beagle, noted that; “the sooty shearwater generally frequents the inland sounds [of southern Chile] in very large flocks: I do not think I ever saw so many birds of any other sort together, as I once saw of these behind the island of Chiloe. Hundreds of thousands flew in an irregular line for several hours in one direction. When part of the flock settled on the water the surface was blackened, and a noise proceeded from them as of human beings talking in the distance.”
The breeding pairs mate at an average age of six years and lay a single egg in a three week period during the last week in November and the first two weeks of December. Like most other petrels they dig a burrow in the ground to lay their egg. The cunning slope of the burrow, downward from the entrance before lifting upwards, must help drain the ground and keep the nest dry. According to Oliver, the evidence suggests that they return to the same burrows year after year.
The nightly homecoming of countless numbers of these birds on bird islands of southern New Zealand has been described as one of the marvels of the world. An observer seated on shore will notice before 9pm in mid–summer the birds collecting in hundreds on the water off shore. Soon they will rise and begin to circle the island or the area containing their burrows in their thousands. As one watches a thud is heard followed by a soft rustle. The first bird has arrived to be followed by countless numbers.
The parents take turns in incubating, the bird on the nest fasting during its spell sometimes for up to 16 days. They raise their young during the southern summer months, both parents being providers to the chick which is left during the day while the parents fish at sea. By the autumn the young birds are ready for departure, that is, if they escape the rats, stoats and long reaching human arms that descend on the colonies in March to gather chicks so fat they are larger than their parents.
The young are fed on regurgitated oil digested from the fish eaten by the parents. Pilchards, shrimps, sprats, small squid are some of the catch. The parents do not come home every night but when the chick, which may have been on its own for up to ten nights, is ultimately fed by regurgitation, its intake is tremendous. Its growth is spectacular and seems to thrive on the irregular diet.
After the breeding season most adults depart on migration to the northern Pacific between late March and early May, moving along the east coast of the South and North Islands of New Zealand. The migration path seems to be directly north over a broad front to sub arctic waters between Japan and the west coast of North America, some drifting north to reach the Gulf of Alaska. They return directly south in August and arrive back in New Zealand waters around September. It is on the migrations in spring and autumn that they are often wrecked in large numbers on our beaches.
The sooty shearwater, together with other petrels, forms the basis of a considerable industry in which Maori of the southern part of New Zealand are interested. At present 500,000 of the grossly fat young birds are taken from their burrows annually and exported for sale throughout the country. Adult birds also used to be taken in nets as they came in of an evening to the inland breeding grounds. However, these birds no longer visit the old inland breeding grounds of the North Island, Maori blaming the imported European rat for the change.
The saying, he manawa titi, seems to refer to the powers of flight possessed by the titi and so a man possessed of a good staying power may be described as manawa titi.
Other common names: —
44 cm., 800 g., dark brown above, black–looking in flight and a little paler underneath with conspicuous silvery white linings to the under part of the narrow wings, upper bill is curved to a sharp hook, webbed feet are a surprising shade of lilac with brown markings.
Where to find: —
The main breeding colonies in the New Zealand region are on the islands off Stewart Island, The Snares, Auckland, Chatham, and Campbell Islands.
Credit for the photograph: —
Illustration description: —
Godman, Frederick du Cane, Monograph of the Petrels, 1907–1910.
Dresser, Henry E., Birds of Europe, 1871–1896.
Heather, B., & Robertson, H., Field Guide to the Birds of New Zealand, 2000.
Oliver, W.R.B., New Zealand Birds, 1955.
Otago University Titi Project
Page date & version: —
Thursday, 28 October, 2010; ver2009v1