Christmas Imperial Pigeon

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. 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. 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. 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. …

The species is endemic to the tropical 135 km2 (52 mi2) 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, introduced Jamaican cherry trees have recolonized many areas. The Christmas imperial pigeon was introduced to the Coco Islands (probably Horsburgh Island) sometime between November 1888 and August 1890, with the last sighting made in 1906.

The Christmas imperial pigeon, along with the Christmas Island flying fox, are the only 2 major fruit-eating (frugivorous) animals on the island. As such, the pigeon plays an important role in seed dispersal, seeds swallowed whole and remaining intact (imperial pigeons are able to stretch the base of the jaw to eat larger food items.) They have been reported feeding on smaller seeded plants such as the stinkwood Celtis timorensis, the common fig, the chinaberry tree, Syzygium nervosum, Tristiropsis acutangula, and the introduced Jamaican cherry. The latter has become a very important food source, with sightings of several hundreds of pigeons where the plant is common. It generally feeds in flocks in the canopy, isolated trees, or shrubs, and descends to drink from springs or puddles. It has also been observed feeding singly or in pairs. Though frugivorous, the pigeon has been observed repeatedly consuming the leaves of the introduced papaya plant (folivory), which may have been caused by an island-wide shortage of fruit or, less likely, for some therapeutic reason. Peak foraging time appears to be just before dusk. The Christmas goshawk has been observed preying on a Christmas imperial pigeon chick.