Nicobar Pigeon
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| Caloenas nicobarica Linnaeus, 1758 |
The Nicobar Pigeon, Caloenas nicobarica is a pigeon which is a resident breeding bird on small uninhabited islands in Indonesia and the Nicobar Islands. It is the only living member of the genus Caloenas.
This is a large, heavy pigeon at 40cm in length. It is mainly metallic green with green and copper hackles on the neck. The head and upper neck, flight feathers and breast are dark grey. The tail is very short and pure white. There is a black knob on the base of the bill, and the strong legs are dark red. This is not a very vocal species, but the call is a coo-coo-coo.
Females are slightly smaller than males; they have a smaller bill knob, shorter hackles and browner underparts. Immature birds have a black tail.
The Nicobar Pigeon roams in flocks from island to island, including inhabited sites, seeking its food of seeds, fruit and some invertebrates, and is attracted to areas where grain is available; usually, it sleeps on offshore islets where no predators occur and spends the day in areas whith better food availability. Its flight is quick, with the regular beats and an occasional sharp flick of the wings which are characteristic of pigeons in general. Peculiarly, groups tend to fly in columns or single file, not in a loose flock as most other pigeons do; the white tail seems to serve as a sort of "taillight" when crossing water at dawn or dusk. These observations are also supported by inexperienced birds, which could lead a group astray, lacking this feature.
This species nests in dense forest, building a stick nest in a tree and laying one elliptical, faintly blue-tinged white egg.
[edit] Systematics
Following comparison of mitochondrial cytochrome b and 12S rRNA sequences (Shapiro et al. 2002), the Nicobar Pigeon has been proposed as the closest living relative of the Dodo and the Rodrigues Solitaire. Note however that this does not imply an actually close relationship; it simply means that all other living species seem to be more distinct still. In addition, the phylogeny inferred from the data is spurious; molecular phylogenies of the Indo-Australian pigeons have yielded wildly differing results depending on the gene sequence analyzed (compare e.g. with Johnson & Clayton 2000).
From subfossil bones found on New Caledonia and Tonga, an extinct species, the Greater Maned Pigeon (Caloenas canacorum) was described. It was a sizeable bird, 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 the islands where it occurred.
The Liverpool Pigeon, another more recently extinct species from an unknown Pacific locality, is also placed in Caloenas, but this is just the least awkward possibility; its true affinities are presently undeterminable.
[edit] References
- BirdLife International (2004). Caloenas nicobarica. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes a brief justification of why this species is near threatened
- Grimmett, Richard; Inskipp, Carol, Inskipp, Tim & Byers, Clive (1999): Birds of India, Pakistan, Nepal, Bangladesh, Bhutan, Sri Lanka, and the Maldives. Princeton University Press, Princeton, N.J.. ISBN 0-691-04910-6
- Johnson, Kevin P. & Clayton, Dale H. (2000): Nuclear and Mitochondrial Genes Contain Similar Phylogenetic. Signal for Pigeons and Doves (Aves: Columbiformes). Molecular Phylogenetics and Evolution 14(1): 141–151. PDF fulltext
- Shapiro, Beth; Sibthorpe, Dean; Rambaut, Andrew; Austin, Jeremy; Wragg, Graham M.; Bininda-Emonds, Olaf R. P.; Lee, Patricia L. M. & Cooper, Alan (2002): Flight of the Dodo. Science 295: 1683. DOI:10.1126/science.295.5560.1683 (HTML abstract) Supplementary information
