Nicobar Pigeon
Encyclopedia
The Nicobar Pigeon, Caloenas nicobarica, is a pigeon
Dove
Pigeons and doves constitute the bird family Columbidae within the order Columbiformes, which include some 300 species of near passerines. In general terms "dove" and "pigeon" are used somewhat interchangeably...

 found on small islands and in coastal regions from the Nicobar Islands
Nicobar Islands
The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean...

, east through the Malay Archipelago
Malay Archipelago
The Malay Archipelago refers to the archipelago between mainland Southeastern Asia and Australia. The name was derived from the anachronistic concept of a Malay race....

, to the Solomons and Palau
Palau
Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...

. It is the only living member of the genus Caloenas.

It is a large pigeon, measuring 40 cm in length. The head is grey, like the upper neck plumage, which turns into green and copper hackles towards the breast. The breast and remiges are dark grey. The tail is very short and pure white. The rest of its plumage is metallic green. The cere
Cère
The Cère is a long river in south-western France, left tributary of the Dordogne River. Its source is in the south-western Massif Central, near the mountain Plomb du Cantal...

 of the dark bill forms a small blackish knob; the strong legs and feet are dull red. The irides
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...

 are dark.

Females are slightly smaller than males; they have a smaller bill knob, shorter hackles and browner underparts. Immature birds have a black tail and lack almost all iridescence
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...

. There is hardly any variation across the birds' wide range. Even the Palau subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 C. n. pelewensis has merely shorter neck hackles, but is otherwise almost identical.

It is not a very vocal species, giving a low-pitched repetitive call.

Systematics

Based on cladistic analysis of mtDNA cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...

 and 12S rRNA sequences
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...

, the Nicobar Pigeon is sometimes called the closest living relative of the extinct didines (Raphinae), which include the famous Dodo
Dodo
The dodo was a flightless bird endemic to the Indian Ocean island of Mauritius. Related to pigeons and doves, it stood about a meter tall, weighing about , living on fruit, and nesting on the ground....

 (Raphus cucullatus). But the original study only yielded this result as just one possibility of several even from a rather limited sample of taxa, and not with a very high confidence either. In any case, nDNA β-fibrinogen intron
Intron
An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...

 7 sequence data agrees with the idea of the Raphinae as a subfamily of pigeons (and not an independent family, as was previously believed due to their bizarre apomorphies) that was part of a diverse Indopacific radiation
Evolutionary radiation
An evolutionary radiation is an increase in taxonomic diversity or morphological disparity, due to adaptive change or the opening of ecospace. Radiations may affect one clade or many, and be rapid or gradual; where they are rapid, and driven by a single lineage's adaptation to their environment,...

, to which the Nicobar Pigeon also belongs.

C. nicobarica is a quite singular columbiform
Columbiformes
Columbiformes are an avian order that includes the very widespread and successful doves and pigeons, classified in the family Columbidae, and the extinct Dodo and the Rodrigues Solitaire, long classified as a second family Raphidae. 313 species, found worldwide, comprise the Columbiformes order....

 (though less autapomorphic than the flightless
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...

 Raphinae), as are for example the Tooth-billed Pigeon
Tooth-billed Pigeon
The Tooth-billed Pigeon also known as Samoan Pigeon, is a medium-sized, approximately 34 cm long, dark pigeon with reddish feet and bare skin around eye. The underparts, head and neck are blackish with a slight blue-green iridescence, and the tail, wings-coverts and tertials are chestnut,...

 (Didunculus strigirostris) and the crowned pigeons (Goura), which are typically considered distinct subfamilies. Hence, the Nicobar Pigeon may well constitute another now-monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...

 subfamily. And while any of the semi-terrestrial
Terrestrial animal
Terrestrial animals are animals that live predominantly or entirely on land , as compared with aquatic animals, which live predominantly or entirely in the water , or amphibians, which rely on a combination of aquatic and terrestrial habitats...

 pigeons of Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

 and the Wallacea
Wallacea
Wallacea is a biogeographical designation for a group of Indonesian islands separated by deep water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as Lombok, Sumbawa, Flores, Sumba, Timor, Halmahera, Buru, Seram, and...

 cannot be excluded as possible closest living relative of the Raphinae, the Nicobar Pigeon makes a more plausible candidate than for example the group of imperial-pigeons and fruit-dove
Fruit-dove
The fruit doves are a genus in the pigeon and dove family . These colourful, frugivorous doves are found in forests and woodlands in Southeast Asia and Oceania...

s, which seems to be part of the same radiation.

Whether it is possible to clarify such deep-time phylogenies without a comprehensive study of all major lineages of living Columbidae remains to be seen. The primitive molecular clock
Molecular clock
The molecular clock is a technique in molecular evolution that uses fossil constraints and rates of molecular change to deduce the time in geologic history when two species or other taxa diverged. It is used to estimate the time of occurrence of events called speciation or radiation...

 used to infer the date the ancestors of the Nicobar Pigeon and the didines diverged has since turned out to be both unreliable and miscalibrated
Calibration
Calibration is a comparison between measurements – one of known magnitude or correctness made or set with one device and another measurement made in as similar a way as possible with a second device....

. But what little evidence is available still suggests that the Nicobar Pigeon is distinct from all other living lifeforms since the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...

 – most likely some time between 56-34 million years ago during the Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

, which makes up the bulk of the Paleogene period.

From subfossil
Subfossil
Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....

 bones found on New Caledonia
New Caledonia
New Caledonia is a special collectivity of France located in the southwest Pacific Ocean, east of Australia and about from Metropolitan France. The archipelago, part of the Melanesia subregion, includes the main island of Grande Terre, the Loyalty Islands, the Belep archipelago, the Isle of...

 and Tonga
Tonga
Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...

, an extinct species of Caloenas, the Kanaka Pigeon
Kanaka Pigeon
The Kanaka Pigeon is an extinct pigeon. It was probably hunted to extinction by the early settlers of New Caledonia and Tonga. It was also called the Great Green Pigeon or the Greater Maned Pigeon and was related to the Nicobar Pigeon, but was about one quarter larger in size...

 (C. canacorum) was described. It was about one-quarter larger than the Nicobar Pigeon. Considering that it must have been a good source of food, it was most likely hunted to extinction by the first human settlers of its home islands. It probably was extinct by 500 BC. The Liverpool Pigeon
Liverpool Pigeon
The Liverpool Pigeon or Spotted Green Pigeon is a presumed extinct pigeon species from an unknown provenance.-Description:...

 ("C." maculata) is a more recently extinct species from an unknown Pacific locality; it probably disappeared in the 19th century and most likely succumbed to introduced Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

an rat
Rat
Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, Rattus norvegicus...

s. It is placed in Caloenas as the least awkward possibility; its true affinities are presently undeterminable and it is perhaps more likely to represent a distinct genus of the Indopacific radiation of Columbidae.

Ecology

The Nicobar Pigeon's breeding range encompasses the Andaman and Nicobar Islands of India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

, the Mergui Archipelago
Mergui Archipelago
The Mergui Archipelago is an archipelago in far southern Myanmar . It consists of more than 800 islands, varying in size from very small to hundreds of square kilometres, all lying in the Andaman Sea off the western shore of the Malay Peninsula near its landward end where it joins the rest of...

 of Myanmar
Myanmar
Burma , officially the Republic of the Union of Myanmar , is a country in Southeast Asia. Burma is bordered by China on the northeast, Laos on the east, Thailand on the southeast, Bangladesh on the west, India on the northwest, the Bay of Bengal to the southwest, and the Andaman Sea on the south....

, offshore islands of south-western Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...

, Peninsular Malaysia
Peninsular Malaysia
Peninsular Malaysia , also known as West Malaysia , is the part of Malaysia which lies on the Malay Peninsula. Its area is . It shares a land border with Thailand in the north. To the south is the island of Singapore. Across the Strait of Malacca to the west lies the island of Sumatra...

, southern Cambodia
Cambodia
Cambodia , officially known as the Kingdom of Cambodia, is a country located in the southern portion of the Indochina Peninsula in Southeast Asia...

 and Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...

, and many of the small islands between Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...

, the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

 and the Solomon Islands
Solomon Islands
Solomon Islands is a sovereign state in Oceania, east of Papua New Guinea, consisting of nearly one thousand islands. It covers a land mass of . The capital, Honiara, is located on the island of Guadalcanal...

. On Palau
Palau
Palau , officially the Republic of Palau , is an island nation in the Pacific Ocean, east of the Philippines and south of Tokyo. In 1978, after three decades as being part of the United Nations trusteeship, Palau chose independence instead of becoming part of the Federated States of Micronesia, a...

, the only distinct subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...

 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 seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s, fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 and buds, and it is attracted to areas where grain
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

 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 beind 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
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

.

Nicobar Pigeons are hunted in considerable numbers for food, and also for their gizzard stone which is used in jewelry. The species is also trapped for the local pet
Pet
A pet is a household animal kept for companionship and a person's enjoyment, as opposed to wild animals or to livestock, laboratory animals, working animals or sport animals, which are kept for economic or productive reasons. The most popular pets are noted for their loyal or playful...

 market, but as it is on CITES Appendix I, such trade is generally illegal. Internationally, captive breeding
Captive breeding
Captive breedingis the process of breeding animals in human controlled environments with restricted settings, such as wildlife reserves, zoos and other conservation facilities; sometimes the process is construed to include release of individual organisms to the wild, when there is sufficient...

 is able to supply the birds demanded by zoo
Zoo
A zoological garden, zoological park, menagerie, or zoo is a facility in which animals are confined within enclosures, displayed to the public, and in which they may also be bred....

s, 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
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

 is decreasing. For one thing, the offshore islets which it requires are often logged
Logging
Logging is the cutting, skidding, on-site processing, and loading of trees or logs onto trucks.In forestry, the term logging is sometimes used in a narrow sense concerning the logistics of moving wood from the stump to somewhere outside the forest, usually a sawmill or a lumber yard...

 for plantation
Plantation
A plantation is a long artificially established forest, farm or estate, where crops are grown for sale, often in distant markets rather than for local on-site consumption...

s, destroyed by construction activity, or polluted by nearby industry
Industry
Industry refers to the production of an economic good or service within an economy.-Industrial sectors:There are four key industrial economic sectors: the primary sector, largely raw material extraction industries such as mining and farming; the secondary sector, involving refining, construction,...

 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 being jeopardized. For these reasons, the IUCN considers C. nicobarica a Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...

 species.

On the Nicobar Islands
Nicobar Islands
The Nicobar Islands are an archipelagic island chain in the eastern Indian Ocean...

 (which are referred to in its common
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...

 and scientific names), the most significant colony in our time was found on Batti Malv, a remote wildlife sanctuary between Car Nicobar
Car Nicobar
Car Nicobar is the northernmost of the Nicobar Islands. It is also one of two local administrative divisions of the Indian district of Nicobar, part of the Indian union territory of Andaman and Nicobar Islands....

 and Teressa
Teressa (Nicobar Islands)
Teressa is one of the Nicobar Islands, India. Austria and Denmark claimed Nicobar Islands as colony. Teressa is named after the Austrian Arch-duchess Maria Theresia....

. The 2004 Indian Ocean tsunami caused massive damage on the Nicobar Islands, and it is still not quite clear to what extent Batti Malv was affected. But while everything on some islets in the Great Nicobar Biosphere Reserve
Great Nicobar Biosphere Reserve
The Great Nicobar Biosphere Reserve encompasses a large part of the island of Great Nicobar, the largest of the Nicobar Islands in the Indian Union Territory of Andaman and Nicobar Islands. The Nicobars lie in the Bay of Bengal, eastern Indian Ocean, 190 km to the north of the Indonesian island of...

 was destroyed, Batti Malv lighthouse
Lighthouse
A lighthouse is a tower, building, or other type of structure designed to emit light from a system of lamps and lenses or, in older times, from a fire, and used as an aid to navigation for maritime pilots at sea or on inland waterways....

 – a skeletal tower
Skeletal tower
Skeletal Frame Light Towers are lighthouse towers that have only an open frame. They are commonly built as aids to navigation; most of them are not considered to be lighthouses. However, during the late nineteenth century and the first years of the twentieth, larger skeletal towers were installed...

 a dozen metres high, standing a few metres ASL
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

 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
Indian Coast Guard
The Indian Coast Guard is a branch of the Indian Armed Forces. Its mission is the protection of India's maritime interests and maritime law enforcement with jurisdiction over both territorial and international waters....

 vessel ICGS Vikram found the lighthouse tower "totally covered" in vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...

s, 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
Ecological succession
Ecological succession, is the phenomenon or process by which a community progressively transforms itself until a stable community is formed. It is a fundamental concept in ecology, and refers to more or less predictable and orderly changes in the composition or structure of an ecological community...

stages, while a photo of the lighthouse taken before the tsunami shows rather mature forest.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK