The Sooty Shearwater (Puffinus griseus) is a medium-large shearwater.
It appears to be particularly closely related to the Great and Short-tailed Shearwaters, all blunt-tailed, black-billed species, but its precise relationships are obscure. In any case, these three species are among the larger species of shearwater.
Description[]
Sooty Shearwaters are 40–51 cm in length with a 94–110 cm wingspan. It has the typically "shearing" flight of the genus, dipping from side to side on stiff wings with few wing beats, the wingtips almost touching the water. Its flight is powerful and direct, with wings held stiff and straight, giving the impression of a very small albatross. This shearwater is identifiable by its dark plumage which is responsible for its name. In poor viewing conditions it looks all black, but in good light it shows as dark chocolate-brown a silvery strip along the center of the underwing.
Usually loud, Sooty Shearwaters coo and croak while on the breeding grounds.
In the Atlantic, it is the only such bird, whereas in the Pacific part of its range, other all-dark large shearwaters are found. Particularly the Short-tailed Shearwater is almost impossible to tell apart from the present species at a distance.
Distribution and movements[]
Sooty Shearwaters breed on small islands in the south Pacific and south Atlantic Oceans, mainly around New Zealand, the Falkland Islands, Tierra del Fuego and also in the Auckland Islands and Phillip Island off Norfolk Island. They start breeding in October, and incubate their young for about 54 days. Once the chick hatches, the parents raise their chicks for 86 to 109 days.
They are spectacular long-distance migrants, following a circular route, travelling north up the western side of the Pacific and Atlantic Oceans at the end of the nesting season in March–May, reaching sub Arctic waters in June–July where they cross from west to east, then returning south down the eastern side of the oceans in September–October, reaching to the breeding colonies in November. They do not migrate as a flock, but rather as single individuals, associating only opportunistically.
In the Atlantic Ocean, they cover distances in excess of 14,000 km (9,000 miles) from their breeding colony on the Falkland Islands (52°S 60°W) north to 60° to 70°N in the North Atlantic Ocean off north Norway; distances covered in the Pacific are similar or larger; although the Pacific Ocean colonies are not quite so far south, at 35° to 50°S off New Zealand, and moving north to the Aleutian Islands, the longitudinal width of the ocean makes longer migrations necessary. Recent tagging experiments have shown that birds breeding in New Zealand may travel 74,000 km in a year, reaching Japan, Alaska and California, averaging more than 500 km per day.
In Great Britain, they move south in late August and September; with strong north and north-west winds, they may occasionally become 'trapped' in the shallow, largely enclosed North Sea, and heavy passages may be seen flying back north up the British east coast as they re-trace their steps back to the Atlantic over northern Scotland.
Ecology and status[]
The Sooty Shearwater feeds on fish and squid. They can dive up to 68 m deep for food, but more commonly take surface food, in particular often following whales to catch fish disturbed by them. They will also follow fishing boats to take fish scraps thrown overboard.
They breed in huge colonies and the female lays one white egg. These shearwaters nest in burrows lined with plant material which are visited only at night to avoid predation by large gulls.
Gallery[]
