An Apparently New Species of Rallina Crake from Great Nicobar Island, India S
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44 BirdingASIA 17 (2012): 44–46 DISCOVERY An apparently new species of Rallina crake from Great Nicobar Island, India S. RAJESHKUMAR, C. RAGUNATHAN & P. C. RASMUSSEN Great Nicobar Island (7.0°N 93.75°E) about 1,045 Porphyrio porphyrio (although no specimens or km² in area and the largest island of the Nicobar other evidence traced). group, is the southernmost point of India, lying On 21 November 2011, at around 06h00 (about about 150 km north of Sumatra, Indonesia, and 2 hours after dawn) SR found a single crake at about 1,300 km south-east of the Indian mainland. Govind Nagar tsunami shelter on the east coast of The climate is tropical and the annual rainfall is Great Nicobar, 6 km from Campbell Bay. The area high (3,000–3,800 mm) due to the monsoons. was occupied recently by people displaced by the Vegetation is typically divided between coastal 2004 tsunami. The bird was observed foraging for mangrove forest and interior evergreen and insects in the open for about 15 minutes at a range deciduous moist broadleaf forest (although some of 4 m and provided good views. It was islands contain extensive interior grasslands photographed both in short grass and on gravel. thought to be the result of human intervention). The bird was silent throughout the encounter, and The 885 km² Great Nicobar Biosphere Reserve set when disturbed, ran away quickly up a steep slope up in 1989 incorporates two national parks, and and hid rather than taking flight. The bird was several endemic birds and mammals are found on initially thought by SR to represent an odd plumage the islands. BirdLife International has designated of Band-bellied Crake Porzana paykullii, in which the Nicobar islands an Endemic Bird Area. The case it would have been the first record for the islands were severely affected by a 10–15 m high Indian subcontinent of this migratory species. tsunami on 26 December 2004 in the aftermath of Further study in collaboration with PCR has the 2004 Indian Ocean earthquake and there have revealed that the crake differs from any known been subsequent earthquakes in July 2005, species (e.g., Taylor & van Perlo 1998) in numerous November 2009 and June 2010. respects, and must surely represent a new species Four species of rallid have been reported from that has gone completely undetected by science the Nicobars (Rasmussen & Anderton until now. Here we provide a preliminary diagnosis 2005, Grimmett et al. 2011): Slaty-breasted Rail based on comparisons of photographs of living Rallus striatus, White-breasted Waterhen birds, and describe the circumstances of this first Amaurornis phoenicurus, Watercock Gallicrex record. For convenience we henceforth refer to this cinerea (sight records) and Purple Swamphen taxon as the ‘Great Nicobar Crake’. Formal Plate 1. First image of the new Great Nicobar rallid foraging in Plate 2. The ‘Great Nicobar Crake’ quickly crossing gravel, short grass, at Govind Nagar tsunami shelter, Great Nicobar, by Govind Nagar tsunami shelter, Great Nicobar, 21 November 21 November 2011. 2011. S. RAJESHKUMAR S. RAJESHKUMAR BirdingASIA 17 (2012) 45 designation as a new species should await pale green bill (instead of bluish-horn or dusky- availability of type material. horn with greenish base of lower mandible) that is Our preliminary diagnosis indicates that the relatively shorter and blunter; a larger, redder eye; Great Nicobar Crake is a medium-sized crake most a rounder head and thinner, more distinct neck; a similar to some Asian members of the genus Rallina deeper, relatively shorter body with more erect and almost certainly pertaining to this genus as posture; and orange-red instead of dark bluish-horn presently constituted. Although its size cannot be or dark grey legs, which are heavier with shorter accurately estimated from the images, SR believes toes. In plumage it differs by having a much paler, it is about the size of an adult White-breasted more rufescent dorsum that lacks contrast with the Waterhen—i.e. about the size of an Andaman Crake head and neck, in the presence of narrow black- Rallina canningi. The bill is rather thick and short, and-white barring on the secondaries closest to the neck moderately long, legs rather heavy with wing edge, narrower white barring on the lower moderate length toes and short claws, and the tail underparts, and the dark, very narrowly banded fairly short. The plumage is generally rich rufescent, thigh feathering. the back browner, the wing-coverts narrowly black- From the Red-legged Crake R. fasciata, the Great and-white barred, the underparts below breast with Nicobar Crake differs in being (probably much) broad black and narrow white bands, and the larger and lankier, with relatively smaller eyes, a thighs very narrowly barred, appearing blackish. pale green instead of dark bluish-horn bill, probably The iris is bright red, fleshy eye-ring orange-red; without a red gape, and longer, heavier, more bill entirely very pale green except for slightly orange-red (vs pinkish-red) legs and proportionately reddish-tinged tip, tarsi bright orange-red with shorter toes. On the upperparts, spots are lacking duskier claws. No other species of Rallina has a on the upperwing-coverts, only the marginal wing- combination of pale green bill, broadly black- coverts being barred, and these much more narrowly banded underparts, and heavy orange-red legs. and less obviously barred than in R. fasciata; the The Great Nicobar Crake differs in shape and underparts have much broader black bands and proportions from Andaman Crake in having a much narrower white ones, and the thigh feathering relatively larger head and eye, less triangular bill is dark instead of white. that is more evenly deep from base to near tip, The Great Nicobar Crake differs from Band- with more curved distal culmen; less hunched back; bellied Crake in having a rounder head and longer more laterally compressed, less barrel-shaped body; neck, a much more uniformly and paler green bill, and much shorter, less prominent tail. In the Great a more obvious bare eye-ring, and brighter orange- Nicobar Crake, the bill appears pale greenish rather red, longer and thicker legs and much shorter toes. than yellow (some descriptions of R. canningi In plumage it differs most obviously in having the indicate the bill as apple-green, but photographs whole head and nape rufous-brown, lacking the of several birds show it to be pure yellow or strongly contrasting brown crown and nape of greenish-yellow in that species); the iris is more paykullii, and the entire dorsum is much more obviously red and fleshy eye-ring much more rufescent in the Great Nicobar bird; it also has much prominent than in canningi; legs and toes are broader dark bands and narrower white ones on similarly heavy but appear proportionately shorter, the underparts, and dark rather than white thighs. and are orange-red instead of dull pale greenish, The extent and nature of barring on the wing- with darker instead of pale claws as in canningi. coverts is more similar to that of paykullii than to The main plumage colour of the Great Nicobar any of the aforementioned species, but it is Crake is paler and more orange-brown on face, narrower and blacker. neck and breast, with crown and dorsum It is possible that the photographs of the Great (including tertials and scapulars) fairly dark Nicobar Crake could be misleading in certain rufescent brown, much darker posteriorly than on respects, but the two were taken in different the upper mantle (not uniform rich dark maroon- habitats and lighting conditions and many chestnut as in canningi). The wing-coverts near photographs of all the other taxa were consulted, the wing edge of the Great Nicobar Crake are and yet the differences mentioned here are narrowly black-and-white barred, looking mostly consistent. Even if one or a few of the differences black, not plain maroon-chestnut as in canningi. mentioned above are found to be variable in series, The underparts below the breast are much more there is still no known candidate species to which broadly banded black, not narrowly and this bird could belong. Important plumage features approximately equally black-and-white barred as not visible on either of the two existing photographs in canningi. of the bird include the mid-belly pattern (whether The Great Nicobar Crake differs from Slaty- fully barred or white), the wing pattern, the tail legged Crake R. eurizonoides in having an entirely and the undertail-coverts. 46 An apparently new species of Rallina crake from Great Nicobar Island, India The possibility of a hybrid has been considered. Dr. Kailash Chandra, Additional Director, Zoological However, the particular combination of characters Survey of India, for providing the necessary facilities. shown by the Great Nicobar bird seem highly Thanks also go to Dr. Gopinathan Maheswaran, unlikely to be exhibited in a hybrid (assuming Officer-in-Charge, Zoological Survey of India, common genetic patterns) from any two of the (APRC), Itanagar, and to Dr. Mazhar Sultana, Head, above possible parental species in any part of their Dept. of Zoology, Presidency College, Chennai, for range, much less on an island group from which her support and encouragement. none has ever been recorded. Now that it is clear that there is an unknown References species of rallid on Great Nicobar Island, SR will Grimmett, R., Inskipp, C. & Inskipp, T. (2011) Birds of the Indian attempt to locate and study further individuals and subcontinent. London: Christopher Helm. describe it to science as soon as possible. This Rasmussen, P. C. & Anderton, J. C. (2005) Birds of South Asia: the Ripley finding of course raises questions as to its total guide.