Until recently the shearwaters were devided in two genera Calonectris and Puffinus, but based on dna-analysis Penhallurick and Wink (2004) have proposed a splitting of the shearwaters into three genera: Calonectris for the large shearwaters of the Northern Atlantic, the Mediterranean and the waters around Japan, Ardenna for a group of large Southern Hemisphere breeders and Puffinus for the smaller shearwaters such as the Manx’ group, Audubon’s and Little Shearwaters. This new taxonomy is now widely accepted, but not by all and is stil subject of discussion.
formed by the contrasting pattern on back and wings. Tail wedge-shaped. Feet pale, but variable.
|wingspan min.:||97||cm||wingspan max.:||99||cm|
|size min.:||46||cm||size max.:||47||cm|
|incubation min.:||48||days||incubation max.:||52||days|
|fledging min.:||97||days||fledging max.:||103||days|
Tends to concentrate at areas of strong upwelling, or where warm and cool water currents meet, bringing food to the surface. Rarely comes close to shore. Nests on islands with soil suitable for burrows or with crevices among rocky cliffs.
Nest: Site is in burrow under tree r
oots or rocks, or in cave or rock crevice. Both sexes help dig burrow. Nest chamber is lined with leaves, twigs, pebbles. Where birds nest in Maori burial caves, may use human bones as nest material.
Clutch 1 per season. White. Incubation is by both sexes, roughly 51 days.
Young: Both parents feed young, by regurgitation. Period from hatching to departure from nest probably about 100 days, but not well known.
Behavior: Food is taken at or just below surface of water. Forages by dipp
ing to surface in flight, plunging into water from a few feet above surface, swimming with head submerged, sometimes upending with head down and tail up. Rarely dives underwater. May feed at night.
Video Bullers Shearwater
copyright: Peter Fraser
Breeding adults move north in May, common in parts of North Pacific in summer, returning to New Zealand by September. Seen off our Pacific Coast mainly June to November, most common September-
October; evidently these are mostly non-breeders and immatures.