Most of the sooty shearwater’s life is spent out at sea, flying fast over the ocean with rapid wingbeats, or gliding low over the water’s surface (4). Feeding mostly on small fish, shrimp and other crustaceans, squid and jellyfish (2) (3), the sooty shearwater may snatch its prey from the ocean surface or plunge, from flight, into the water, and pursue its prey underwater. Propelling itself though the water with powerful beats of its wings, the sooty shearwater is known to reach depths of 67 metres (3).
Sooty shearwaters arrive at their breeding colonies at the end of September or very early October, with egg laying, at least in New Zealand, taking place between mid-November and early December (3). Burrows, measuring up to three metres long, are dug into the ground, under tussock grass, low scrub, or Olearia forest (3). Like all shearwaters, albatrosses and petrels, sooty shearwater females lay just a single egg into this burrow (6), which is then incubated for around 53 days (3). The chick hatches around the middle of January (3), and is then fed by both parents, who spend their days foraging at sea, returning at night to feed their chick. These night time visits are somewhat boisterous, with the parents crashing through the trees and landing on the island with a loud thump (2). At 97 days of age, in late April or early May, the chick fledges and leaves its nest to head out to sea. Sooty shearwaters generally start breeding at the ages of five to seven (3). They typically mate for life (2), attracting a partner through a duet of courtship calls and gentle mutual nibbling (3).
Upon the completion of breeding, sooty shearwaters commence their impressive migration north. From New Zealand, this bird travels to the regions off Japan, Alaska or California, before returning to New Zealand for the subsequent breeding season. Electronic tracking of this species has revealed that the sooty shearwater undertakes the longest migration of any animal tracked to date (9). Travelling in a figure-eight pattern across the Pacific Ocean, this small but intrepid bird covers an astounding 65,000 kilometres. Undertaking this great journey allows the sooty shearwater to exploit the greater abundance of prey found in the North Pacific at that time of the year (9).