Is it possible that a small plover, not described or illustrated in any modern literature or field guide occurs in southeast Asia? This is the question we were faced with following sightings of several small Charadrius plovers in Malaysia and Singapore.
In breeding plumage, the shape and extent of the lateral breast patches remains a useful and probably diagnostic character.
Males develop extensive, black patches at the sides of the breast in front of the carpal bend. Although variable in size and extent, typically these patches are quite long and deep, and extend forward towards the centre of the breast. Exceptionally, these patches can join to form a complete breast-band, although this is invariably narrow across the centre of the breast. On females, these patches remain dull brown, but are otherwise similar in size and shape to those of the male, and do not differ from their appearance in non-breeding plumage.
Like Kentish, males develop black patches at the sides of the breast. Importantly, these patches are invariably smaller, narrower and less extensive than those shown by Kentish Plover and, in extreme individuals, may be almost absent, with just a few blackish feathers visible immediately in front of the carpal bend. On females, these patches are generally slightly more extensive than on the males, but do not match those of Kentish Plover. Typically, they are similar in colour to the mantle and appear paler than the patches of female Kentish Plover. Almost all females show warm rufous-brown wash to these patches, which appear brighter than those of female Kentish Plover.
Figure 26. Two male ‘White-faced’ Plovers (front right and centre) with a male Kentish Plover (rear left), all in breeding plumage. Penang, 5th February 2007. David Bakewell
Comments for both Kentish and ‘White-faced’ Plovers remain as for non-breeding plumage.
Extremely distinctive and the single most useful feature for their separation, especially the males.
Males develop a strong and contrasting head pattern. The forehead and supercilium are white and contrast with the black lores and feathering behind the eye which, together with the black bill and eye, form a solid dark line extending along the side of the head from the bill tip to the rear of the ear-coverts. On some individuals, the entire ear-coverts may be blurred and appear smudged dull greyish-brown, while on others the distinction between the black feathering behind the eye and the white ear-coverts is well-defined. The frontal bar on the fore-crown is black and usually narrower than that of male ‘White-faced’ Plover. The crown itself varies in colour from pale orange-brown (generally western populations) to a darker burnt orange-brown or rich cinnamon-brown (in east Asian populations). The head pattern of the females does not differ significantly from that of females prior to the pre-breeding moult.
Males show a striking ‘white-faced’ appearance, with the black bill and large dark eye contrasting with the unmarked white lores and ear-coverts. The forehead is conspicuously and extensively white, while the black frontal bar on the fore-crown is variable in width but usually wider than shown by male Kentish. If narrower, the then white forehead often appears even more extensive. The entire crown is bright orange-orange, and always appears paler and brighter than that of the brightest male Kentish. This extends to the rear-crown where it hooks down and may form an indistinct line behind the eye.
The head pattern of females more closely resembles that of female Malaysian Plover than Kentish Plover. In particular, most females show a dull russet-brown line extending across the lores and behind the eye, which forms a conspicuous but rather blurred eye-stripe. This russet-brown tone extends over the entire crown but becomes duller towards the centre and brighter around the rear edges of the crown.
Figure 27. The same male ‘White-faced’ Plover as in figure 25, following completion of moult into breeding plumage, Penang, 5th February 2007. Note the greyer, paler mantle and small black lateral breast patches. David Bakewell
Figure 28. Female ‘White-faced’ Plover in breeding plumage, 6th February 2007. The extensive russet-brown on the crown, ear-coverts and lores is extremely bright and intense. Some females remain duller than this individual. David Bakewell
Following the pre-breeding moult, the shape, width and extent of the white collar remains unchanged in both species. Comments made under non-breeding plumage are equally applicable to birds in breeding plumage.
In both taxa, the pattern and extent of white in the outer rectrices remains unchanged from non-breeding plumage.
The pattern of the upperwing in both ‘White-faced’ and Kentish Plovers remains unchanged from the non-breeding plumage.
Figure 29. This rather dull and poorly marked ‘White-faced’ Plover, perhaps a first-summer male, was photographed at Penang on 5th February 2007. It shows the characteristic wing pattern including the broad wing bar that is particularly conspicuous across the inner primaries, the white trailing edge to the secondaries, and the white tips to the median coverts, which extends as a white ‘spur’ to the outer edge of the wing. David Bakewell
Invariably dark, similar to that shown by birds in non-breeding plumage.
Legs of some males darken to pale lead-grey, but remain slightly paler than shown by Kentish. Legs of females remain pinkish or flesh-coloured.
In both ‘White-faced’ and Kentish Plovers, the bill shape and colour remains unchanged throughout the year.
During low tide at the Penang site, the mixed flock would feed on the tideline, on or near an isolated sandbar in the middle of extensive mudflats. On occasion, ‘White-faced’ Plovers were seen to hunt prey (crabs?) in a manner typical of Greater Sand Plover; head lowered, dashing across the sand to seize the prey before it could retreat into its burrow. Kentish Plovers were not seen to feed in this manner, but may also do so. Typically, when feeding, the posture of Kentish Plover was rather horizontal, with the head held hunched into the ‘shoulders’. In contrast, ‘White-faced’ Plovers would often adopt a slightly more upright stance, with more of the neck visible. This had the effect of making ‘White-faced’ Plovers appear large-headed.
When roosting, the birds would congregate in a loose mixed flock, with ‘White-faced’ Plovers always preferring the sandier, drier areas. The birds would roost both on the foreshore and on the wasteland at the edge of the construction site. Typically, however, ‘White-faced’ Plovers tended to roost by lying on the sand, legs folded beneath and head held low. Often they would choose an area of larger stones that would conceal them wholly or in part. Kentish Plovers also roosted in this manner, but were as likely to roost standing up. When disturbed at the roost, ‘White-faced’ Plovers were more nervous and tended to run fast away from the disturbance, whereas Kentish would adopt a peculiar robotic mincing gait, but not retreat rapidly with ‘White-faced’ Plovers.
It is recognised that Kentish Plover is an extremely variable species, even within its Asian range where four or five races are described, depending on the taxonomy followed. Other races inhabiting North and South America may represent a different species – Snowy Plover C. nivosus. In addition, other populations of Kentish Plover, such as the distinctive small and pale birds breeding in the Persian Gulf, are still treated as synonymous with the nominate form.
Understandably, therefore, we are adopting a cautious approach towards the identity of these birds. But regardless of their ultimate identity, it is astonishing that these distinctive plovers have not been observed, commented upon or documented previously – although Wells (1999) did mention a bird with white lores at the Kapar Power Station roost in March 1993 (see above). What makes these events even more remarkable is that these birds have been overlooked for so long in Malaysia and Singapore; probably the two countries in the region with the longest history and strongest tradition of bird-related research, extending back almost two centuries to the founding of Singapore.
These observations establish beyond reasonable doubt that a ‘mystery’ plover does occur along the west coast of the Malay Peninsula south to Singapore between October and March. That it has only been noticed during the northern winter months, occurs with flocks of Kentish Plovers and, like Kentish Plover, appears to undertake a pre-breeding moult between January and March, suggests a northern origin.
In order to establish exactly what these plovers are, it will be necessary to compare the biometrics and DNA of these birds with that of known taxa to establish the phylogenetic relationship with other Charadrius. The best results will come from blood, feathers or fresh tissue taken from live birds, but can also be achieved using old tissue, typically toepad material, taken from old specimens held in reference collections. This work is currently in progress (Kennerley & Bakewell in prep), and details will be published in the near future.
By bringing these birds to the attention of a wider audience, it is hoped that further sightings will follow. We would be grateful for details of any other observations of these birds for inclusion in the above paper, which can be sent to either of the addresses below. All contributions will be fully acknowledged.
Our thanks go to Geoff Carey, John Howes, James Kennerley, Angus Lamont, Paul Leader, Phil Round, Brian Small, Subaraj Rajathurai and David Wells for their input on the text and comments on the photographs. Richard Chandler and Pete Morris/Birdquest generously provided the images of Malaysian and Javan Plovers which accompany this article. Chris Rose kindly supplied an image of a bird he painted at Kapar Power Station in 1993.
We are grateful to Mark Adams, Robert Pryˆs-Jones and Katrina Cook at the NHM, Tring, for allowing access to the specimen reference collection; to Wang Luan Keng and Kelvin K. P. Lim at the Raffles Museum of Biodiversity Research, Department of Biological Sciences, Faculty of Science, National University of Singapore for the loan of specimens; and to Brian Schmidt at the Smithsonian Institution, Division of Birds, Washington DC, USA, who kindly provided photographs of the type specimen of C. a. nihonensis.
Dr Tamas Szekely, Reader in Evolutionary Biology, Dept of Biology and Biochemistry, University of Bath, recommended methods by which we could work towards establishing the molecular phylogeny of these birds.
In Malaysia, Assistant Professor Shahrul Anuar bin Mohd Sah, School of Biological Sciences, Universiti Sains Malaysia, M. A. Muin, Unisains, Universiti Sains Malaysia, and Hasnan Yusop, Director, Department of Wildlife and National Parks, Pulau Pinang, supervised attempts to trap the birds in Penang.
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