Nicobar pigeon

The Nicobar pigeon, known scientifically as Caloenas nicobarica, is a large and striking bird. It is a unique member of the pigeon family, called Columbidae. This species is currently the only living member of its genus, Caloenas. It is also considered the closest living relative to the extinct dodo and the Rodrigues solitaire. These extinct birds belonged to a group called the Raphinae. While some studies suggest this connection is a possibility, others use genetic data to show the Nicobar pigeon belongs to a diverse group of birds from the Indopacific region.

This bird has a very distinct appearance. Its plumage is a metallic green that can appear black in dim light. The head and upper neck are grey, but the neck features long feathers called hackles. These hackles are green and copper in color. One of its most notable features is a short, pure white tail. The bill is dark with a small blackish knob called a cere. Its legs and feet are a dull red color.

There is some difference between males and females. Males typically weigh between 460 and 525 grams. Females are slightly larger, weighing between 490 and 600 grams on average. Females also have a smaller bill knob and shorter neck hackles. They tend to have browner underparts than the males. Immature birds look quite different because they lack iridescence and have black tails. There are also two recognized subspecies. The first, C. n. nicobarica, lives across the Andaman and Nicobar Islands and the Malay Archipelago. The second, C. n. pelewensis, lives on Palau Island and is slightly smaller with shorter neck hackles.

Scientists have been documenting this bird for centuries. In 1738, the naturalist Eleazar Albin provided a description and illustrations of the species. In 1758, Carl Linnaeus included the bird in his Systema Naturae. He originally placed it in the genus Columba. Later, in 1840, the zoologist George Robert Gray established the genus Caloenas. The Nicobar pigeon serves as the type species for this genus. Research suggests this bird is distinct from all other living lifeforms since the Eocene epoch. This period occurred between 56 and 34 million years ago.

Nicobar pigeons have specific ways of moving and eating. They eat seeds, fruit, and buds. To help digest these hard items, they use a gizzard stone to grind the food. When they fly, they do not move in loose flocks. Instead, they fly in columns or single file. They usually fly at least 60 meters above the sea surface. The white tail acts like a taillight to help the group stay together during flight. This is especially helpful when they cross the sea at dawn or dusk.

These birds live in many coastal regions and small islands. Their range includes the Andaman and Nicobar Islands, Myanmar, Thailand, Malaysia, Cambodia, and Vietnam. They are also found in the Philippines and the Solomon Islands. They often sleep on offshore islets to stay safe from predators. In these islands, they build loose stick nests in trees within dense forests. They lay a single elliptical egg that is white with a faint blue tinge. Interestingly, they have been spotted far from home, such as in the Kimberley region of Australia.

The future of the Nicobar pigeon is a concern for conservationists. The IUCN lists the species as near threatened. They are hunted for food and for their gizzard stones, which are used in jewelry. They are also caught for the pet market, though international trade is prohibited by CITES Appendix I. Their natural habitats are also under pressure. Offshore islets are often lost to logging, construction, or pollution. Additionally, increased travel brings new predators to their breeding sites. These factors combined put the long-term survival of the species in jeopardy.