Newell's Shearwater

Identificazione

It is a fairly small shearwater, 33 centimetres (13 in) in length. The wing is 223–249 millimetres (8.8–9.8 in) long and the tail is 78.9–88.8 millimetres (3.11–3.50 in). The bird weighs 0.340–0.425 kilograms (0.75–0.94 lb). The upperparts are black with a brown tinge while the underparts are white. The dark colouration on the face extends below the eye and is sharply separated from the white throat. There is a white patch on the flanks, extending onto the sides of the rump. The underwings are mainly white with a dark border. The undertail-coverts have a black and white pattern and appear white in the field. The bill is dark grey or brown and the legs and feet are mainly pale pink. The bird flies low over the water on stiff wings with a mixture of short glides and periods of rapid flapping. It utters a donkey-like braying call around the breeding areas. Townsend's shearwater (P. auricularis) is very similar but has dark undertail-coverts, a shorter tail and a less sharp boundary between the black and white on the face.

Tassonomia

It was described as a new species Puffinus newelli in 1900 by the American ornithologist Henry Wetherbee Henshaw using specimens obtained by Brother Matthias Newell from residents of Maui. It was later included by some authors in the Manx shearwater (Puffinus puffinus) as was Townsend's shearwater (Puffinus auricularis). Later, Townsends's shearwater was raised back to species status with Newell's shearwater as a subspecies of it. This taxonomy was followed by the American Ornithologists' Union from the sixth edition of its checklist onwards.<p>However Newell's differs from Townsend's shearwater in various measurements and has a different breeding season and marine habitat. It is now often treated as a separate species, e.g. by BirdLife International following Brooke (2004). In 2004, a study of mitochondrial DNA sequences suggested a close relationship between Rapa shearwater (Puffinus myrtae) and Newell's shearwater and the authors proposed that Rapa shearwater be treated as a subspecies of P. newelli pending further study. The Rapa shearwater is now treated as a full species.

Nome scientifico

Puffinus newelli

Autorità

Henshaw, 1900

Ordine

Procellariformi

Famiglia

Procellaridi

Genere

Puffinus

Areale e habitat

It breeds in at least 20 colonies on mountain slopes in the Hawaiian Islands. The main colonies are on Kauaʻi, on slopes around the Alakaʻi Plateau and probably in the Mokolea Mountains. Its distribution on the other islands is uncertain but it is known to breed on Molokaʻi and the island of Hawaiʻi and may breed on Oʻahu, Maui and Lānaʻi. From April to November it can be seen in the waters around the Hawaiian Islands, particularly around Kauaʻi. Outside the breeding season it disperses into the tropical Pacific Ocean. Its distribution at sea is little known but many move south and east into the waters of the Equatorial Counter Current. It has been recorded as far west as the Mariana Islands. In the south there are records from Samoa in September 1977 and American Samoa in January 1993.

Areale riproduttivo

PO : Lehua (n of Nihau), montane Kauai, Molokai and Hawaii (main Hawaiian Is.)

Areale non riproduttivo

to waters s of Japan and Mariana Is. (nw Micronesia) and to sw Pacific near New Caledonia, Solomon Is. and Vanuatu

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in diminuzione.

Tendenza della popolazione

in diminuzione