Nicobar Pigeon

The Nicobar pigeon's breeding range encompasses the Andaman and Nicobar Islands of India, the Mergui Archipelago of Myanmar, offshore islands of south-western Thailand, Peninsular Malaysia, southern Cambodia and Vietnam, and many of the small islands between Sumatra, the Philippines and the Solomon Islands. On Palau, the only distinct subspecies C. n. pelewensis is found. The Nicobar pigeon roams in flocks from island to island, usually sleeping on offshore islets where no predators occur and spends the day in areas with better food availability, not shying away from areas inhabited by humans. Its food consists of seeds, fruit and buds, and it is attracted to areas where grain is available. A gizzard stone helps to grind up hard food items. Its flight is quick, with regular beats and an occasional sharp flick of the wings, as is characteristic of pigeons in general. Unlike other pigeons, groups tend to fly in columns or single file, not in a loose flock. The white tail is prominent in flight when seen from behind and may serve as a sort of "taillight", keeping flocks together when crossing the sea at dawn or dusk. The young birds' lack of a white tail is a signal of their immaturity clearly visible to conspecifics – to an adult Nicobar pigeon, it is obvious at a glance which flockmembers are neither potential mates, nor potential competitors for mates, nor old enough to safely guide a flock from one island to another. This species nests in dense forest on offshore islets, often in large colonies. It builds a loose stick nest in a tree. It lays one elliptical faintly blue-tinged white egg. In 2017, several individual Caloenas nicobarica were sighted in the Kimberley region of Western Australia with a juvenile captured at Ardyaloon (One Arm Point), near Broome - the first time the bird has been sighted on the Australian mainland.

On the Nicobar Islands (which are referred to in its common and scientific names), the most significant colony of Nicobar pigeons in modern times was found on Batti Malv, a remote wildlife sanctuary between Car Nicobar and Teressa. The 2004 Indian Ocean tsunami caused massive damage on the Nicobar Islands, and to what extent Batti Malv was affected is still not clear. But while everything on some islets in the Great Nicobar Biosphere Reserve was destroyed, Batti Malv lighthouse – a skeletal tower a dozen metres high, standing a few metres ASL at the highest point of the low-lying island – was little-damaged and put back in operation by the survey ship INS Sandhayak less than one month after the disaster. An April 2007 survey by the Indian Coast Guard vessel ICGS Vikram found the lighthouse tower "totally covered" in vines, indicating rampant regeneration of vegetation – but perhaps also that damage to the island's forest was severe, as a cover of creeping plants is typical of early succession stages, while a photo of the lighthouse taken before the tsunami shows rather mature forest.

Nicobar pigeons are hunted in considerable numbers for food, and also for their gizzard stone which is used in jewellery. The species is also trapped for the local pet market, but as it is on CITES Appendix I, such trade is generally illegal. Internationally, captive breeding is able to supply the birds demanded by zoos, where this attractive and unusual bird is often seen. Direct exploitation of the species, even including the illegal trade, might be sustainable on its own; however, its available nesting habitat is decreasing. The offshore islets which it requires are often logged for plantations, destroyed by construction activity, or polluted by nearby industry or harbours. Also, increased travel introduces predators to more and more of the breeding sites, and colonies of the Nicobar pigeon may be driven to desert such locations or be destroyed outright. Though the bird is widely distributed and in some locations very common --even on small Palau it is still reasonably plentiful, with an estimated 1,000 adult birds remaining—its long-term future is increasingly jeopardized. For these reasons, the IUCN considers C. nicobarica a near threatened species.