Christmas Imperial Pigeon

The Christmas Island Imperial Pigeon, Ducula whartoni, also known by various names such as the Black Imperial Pigeon, Dusky Imperial Pigeon, and Wharton's Imperial Pigeon, is a majestic bird endemic to the remote Christmas Island. This large pigeon boasts a striking grey-blue plumage, with adults presenting a more vibrant hue compared to the juveniles' duller tones.

Identification Tips

Adult males of this species typically measure between 435-470 mm, while females range from 440-460 mm. The males' wingspan averages 250-264 mm, and females span 231-258 mm. Weights vary, with males between 383-700 grams and females 406-575 grams. The bird's plumage is predominantly grey-black, with a burgundy tinge on the breast and belly. A distinctive narrow white band adorns the base of the upper beak, and the eyes can range from yellow to orange. The nape and back shimmer with an oil-green gloss, and the wings have bluish-green tips. Juveniles share a similar appearance but lack the adults' glossy sheen and have brownish feet and a grey crown.

Habitat

The Christmas Island Imperial Pigeon thrives in the dense canopy of the island's tropical inland plateau, as well as in the widespread non-native Jamaican cherry forests.

Distribution

This species is exclusively found on Christmas Island in the northeastern Indian Ocean, a 135 km² tropical haven.

Behaviour

The Christmas Island Imperial Pigeon is known for its soft purring coos and deeper whoo sounds, reminiscent of a distant cow's moo. In flight, it is generally silent, save for occasional loud clapping sounds made with its wings.

Song & Calls

The pigeon's vocal repertoire includes a soft gurgling or purring coo, as well as a deep whoo or croo-croo-croo, which carries across the island's quiet landscape.

Breeding

Courtship involves a "perch coo" display, where the male puffs up its chest and emits a loud coo before assuming a near-horizontal position. Nests are built high in the forest canopy, and breeding season peaks from November to April. Typically, one glossy white egg is laid per brood, with the possibility of two broods per year.

Similar Species

While there are no similar species on Christmas Island, the Christmas Imperial Pigeon could be mistaken for other members of the Ducula genus, particularly the Pink-headed Imperial Pigeon, with which it was once considered synonymous.

Diet and Feeding

As one of only two major frugivorous animals on the island, this pigeon plays a crucial role in seed dispersal. It feeds on a variety of fruits, including those of the stinkwood, common fig, and Jamaican cherry, the latter being a significant food source.

Conservation status

The Christmas Island Imperial Pigeon is currently classified as Least Concern by the IUCN, with a stable population of approximately 5,000 mature individuals. Conservation efforts have been successful in stabilizing the species, which was once thought to be at risk of extinction.

Threats

Historically, hunting posed the greatest threat to the species, but this practice has been illegal since 1977. The invasive yellow crazy ant and scale insects have also impacted the pigeon's habitat, although control measures for the ants are in place. Feral cats and the Christmas goshawk are known predators, but the pigeon's population remains stable despite these challenges.