Christmas Island Imperial-Pigeon

Identificazione

An adult Christmas imperial pigeon male measures on average 435–470 mm (17.1–18.5 in), and females 440–460 mm (17–18 in). In males, the wing averages 250–264 mm (9.8–10.4 in), and in females 231–258 mm (9.1–10.2 in). The average male weighs 383–700 g (0.84–1.54 lb), and female 406–575 g (0.90–1.27 lb). It is rather large for imperial pigeons, though relatively lightly built. <p>It has an overall grey-black colour, with darker feathers on the top portion, and lighter feathers on the breast and belly with a burgundy tinge. The beak is black. There is a narrow white band on the base of the upper beak. The eye colour ranges from yellow to orange. The nape and back have a glossy oil-green colour. The wings have glossy bluish-green tips, and are greyish-brown nearer the base. The tail has broad, greenish-brown tips with a somewhat scalloped appearance, and the legs and underside of the tail have reddish-brown feathers. The feet are purple-red.<p>Juveniles look similar to adults, but have a duller colouration without the oil-green gloss from the lower back to the tail coverts, with a brown breast and belly, a dull grey crown, and grey-brown feet. Eye colour is dark brown.<p>The Christmas imperial pigeon is known to make a soft gurgling or purring coo sound. It can also make a deep whoo or croo-croo-croo sound which has also been compared to a cow mooing in the distance. It sometimes makes loud clapping sounds with its wings, but in flight, it is largely quiet.

Tassonomia

The Christmas imperial pigeon was first described by English ornithologist Richard Bowdler Sharpe in 1887 based on an adult male specimen collected by Captain John Maclear of HMS Challenger. The species name whartoni honours British admiral Sir William Wharton. It is unclear how Sharpe and Wharton are affiliated, but Wharton was made a Fellow of the Royal Society in the previous year, possibly somehow affecting Sharpe's thinking. Sharpe first classified it into the now-defunct genus Carpophaga. In 1933, English zoologist Frederick Nutter Chasen considered the Christmas imperial pigeon to be a subspecies of pink-headed imperial pigeon as D. rosacea whartoni. In 1937, American ornithologist James L. Peters synonymised Carpophaga with Drucula, and disagreed with Chasen, classifying the Christmas imperial pigeon as a distinct species, D. whartoni.<p>The Christmas imperial pigeon is a species of imperial pigeon (Ducula), which is widely spread out across Oceania, however it is the only imperial pigeon in the Indian Ocean. Likewise, its affinities are unclear. However, the Christmas imperial pigeon could be placed into the D. aenea species complex along with the green (nominate), island, grey, and pink-headed imperial pigeons. The latter is sometimes considered synonymous with the Christmas imperial pigeon.

Nome scientifico

Ducula whartoni

Autorità

(Sharpe, 1887)

Ordine

Columbiformi

Famiglia

Columbidae

Genere

Ducula

Areale e habitat

The species is endemic to the tropical 135 km2 (52 sq mi) Christmas Island in the eastern Indian Ocean. It predominantly inhabits the evergreen inland plateau, but is found throughout the island. Though about a third of this was cut down for phosphate mining, the introduced Jamaican cherry trees has recolonized many areas. It was introduced to the Coco Islands (probably Horsburgh Island) sometime between November 1888 and August 1890, with the last sighting made in 1906.

Migrazione

Specie stanziale

Comportamento

Comportamento migratorio: Specie stanziale.

Conservazione

Tendenza della popolazione: stabile.

Tendenza della popolazione

stabile