Scientific name: Oceanodroma leucorhoa (Vieillot, 1818)
Bird group: Shearwaters and Petrels
Field characters. Length 19-22 cm; wingspan 45-48 cm. Larger and browner than European Storm-petrel, with longer wings and with distinct whitish band across upperwing which is absent in Storm-petrel. Dark forked tail and smoky grey centre of white rump. Flight distinctive: boyant and erratic, frequently glides with abrupt changes in speed and direction; does not follow vessels. During breeding season only comes ashore during dark nights.
Voice. Usually silent; during night on breeding ground a rhythmic series of purring notes, interrupted by a staccato "wicka, wicka".
Distribution. Locally common breeding bird; breeds in large colonies.
Habitat. Breeds on undisturbed offshore islands. Outside the breeding season pelagic species.
Food. Mainly planktonic crustaceans, molluscs, and small fish. Feeds usually during day-time by picking up prey from the water surface.
Eggs. Without markings or with lilac/reddish bands of minute spots towards large end, ground colour white. Shape quite variable, short subelliptical <-> long oval. Size 33 x 24 mm (30-36 x 22-23), weight 9 g (8-10).