The nicobar pigeon, scientifically named Caloenas nicobarica, belongs to the pigeon family of birds, and scientists believe that it is the final remaining specimen of the genus Caloenas. Regarded as one of the most beautiful of all the pigeon species, the nicobar is a shimmering greenish blue in color with copper-toned streaks. Its most distinguishing feature is its white tail, which serves as a sort of taillight that helps keep flocks together when the light is low at dusk or dawn. Males and females resemble each other except that females are somewhat heavier and a little smaller. On average, the nicobar pigeon is about 16 inches (40 cm) long, with males weighing about 16-18 ounces (460-510g) and the female 17-21 ounces (490-600g).
Geographically, the distribution of the nicobar pigeon is limited to southeast Asia. They might be found on islands from India eastward through Myanmar, Thailand and New Guinea, to the Philippines, Indonesia and Malaysia. The species takes its name from the Nicobar Islands, which are a chain of islands found in the eastern Indian Ocean.
For habitat, the nicobar pigeon prefers lowland forests and mangroves on very small, wooded islands that are relatively close to either a larger island or a mainland. During the day, the nicobar pigeon is a nomadic bird that wanders in large flocks of as much as 85 birds from one island to another in search of food. While feeding, the nicobar pigeon will not avoid locations where humans are present and might seek them out because of better food availability. This bird feeds mostly on the ground of forests and likes to eat berries, insects, corn, hard seeds and nuts. Nicobar pigeons have a very muscular gizzard, which lets them grind extremely hard nuts that a human might need a hammer to open.
At dusk, after feeding, nicobar pigeons flock to uninhabited islands or islets because they refuse to roost or breed where there are humans. The nicobar pigeon breeds in dense colonies and mates for life. Breeding displays by males last for several days, after which the female selects her mate, with nest building following immediately thereafter. Male nicobars are responsible for selecting the site for the nest and gathering all of the materials, such as roots and twigs, to build it. The female assembles the nest and structures it so that the egg will be stable.
Clutches usually consist of just one egg. Incubation takes approximately 30 days and is shared by the female and male. The parents care for the chicks for about a month after hatching.