Sooty Shearwater - Distribution and Movements

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 June 1906 for example, two were shot near Guadalupe Island off Baja California (Mexico), several weeks before the bulk of the population would pass by. Likewise, the identity of numerous large dark shearwaters observed in October 2004 off Kwajalein in the Marshall Islands remains enigmatic; they might have been either Sooty or Short-tailed Shearwaters, but neither species is generally held to pass through this region at that time.

In the Atlantic Ocean, they cover distances in excess of 14,000 km (8,700 mi) 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.