Malaysia's Mystery Plover

Cover Photo: Female ‘White-faced’ Plover, 5th February 2007 © David Bakewell

By David Bakewell and Peter Kennerley

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.
Bakewell and Kennerley

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. Regular and detailed observations of up to four birds in Singapore in winter 1993–94, and of 12 birds in Malaysia in winter 2006–07, combined with a series of photographs illustrating both non-breeding and breeding plumage, have established that these birds possess a unique suite of plumage and structural characters which make them readily recognisable but, as yet, not identifiable to a specific taxon.

Our initial thoughts were that they must represent one of the commoner southeast Asian species such as Kentish Plover Charadrius alexandrinus or Malaysian Plover C. peronii in an aberrant or undescribed plumage. As these ‘mystery’ plovers occurred alongside typical Kentish Plovers during the northern winter months, observations of the two taxa, often side by side, were made over the period spanning October to March. In addition, observations of nesting Malaysian Plovers in Singapore were made between January and March, often on the same day as the ‘mystery’ plovers were seen, but at a different location. The possibility of a hybrid origin between these species was considered but the numbers involved, together with consistent plumage features and structural differences, ruled out both the aberrant and hybrid options. From late January onwards, following the pre-breeding moult and acquisition of breeding plumage, the appearance of these ‘mystery’ plovers was transformed to such an extent that it became difficult to believe they could be just a distinctive race of Kentish Plover.

As yet, it remains uncertain where these birds go after they leave the Malay Peninsula. Their departure from the Singapore and Malaysian wintering grounds coincides with that of wintering Kentish Plovers. The coincident timing of moult (and that of other Charadrius species such as Greater Sand Plover C. leschenaultii), suggests they may originate from breeding grounds that lie to the north of the Malay Peninsula. But the fact that there were no observations between the initial sightings in the winter of 1993-94 and those in 2006-07, despite being looked for, makes it likely that the overall population may be very small and widely dispersed.

Being so distinctive, we coined the name ‘White-faced Plover’ for these birds and for clarity, this term is used throughout the text below. It is hoped that by publishing this photo-essay, observers will be encouraged to check through wintering and migrating flocks of Kentish Plovers in east and southeast Asia in the hope that new wintering areas and passage stopover sites can be found and, ultimately, the breeding area discovered.

Events in Singapore

In the winter of 1993–94 PRK, together with Angus Lamont, was regularly observing a flock of up to 30 Kentish Plovers which was wintering on the extensive landfill area at Tuas, at the western tip of Singapore. Much of this site comprised a sandy substrate with little covering vegetation, and small, scattered pools formed by rainwater. With the Kentish Plovers were up to four similarly sized plovers which it was not possible to put a name to. Although these birds resembled the Kentish Plovers they associated with, they were readily separable, even at distances of 200 metres or more, by the distinctly paler brown upperparts; described at the time as resembling the colour of ‘milky-tea’.

When initially discovered in November 1993, they lacked any trace of rufous or warmer brown tones to the crown, nape and lateral breast patches. These birds were slightly but consistently larger than the Kentish Plovers, while other differences included the heavier and deeper bill structure compared with that of Kentish, and the legs were longer than those of Kentish and often showed a distinct pinkish tone, while in flight, the wing-bar appeared broader and more conspicuous.

Thoughts turned to the most likely possibility; Malaysian Plover, a species breeding at Changi, another extensive coastal reclaim area at the eastern extremity of Singapore. The initial similarity between ‘White-faced’ and Malaysian Plovers was obvious; they shared similar pale upperparts, pink-toned legs, and a broader and more conspicuous wing-bar than shown by Kentish. Yet, there were differences. ‘White-faced’ Plovers were consistently slightly larger and longer-legged than Kentish Plovers, yet all Malaysian Plovers are clearly smaller than Kentish, a fact supported by measurements. Consistent differences in several plumage features also suggested these were not Malaysian Plovers, in particular in the patterning of the mantle and scapulars. On ‘White-faced’ Plovers, these feathers appeared relatively uniform and unmarked, or with just a dark shaft streak, yet all Malaysian Plovers of both sexes showed distinctly contrasting upperparts, with a dark and relatively broad streak along the feather shaft, a pale brown feather centre and a wide, whitish fringe, giving them a characteristic variegated ‘moth-eaten’ appearance to the upperparts. In addition, the lateral breast patches of ‘White-faced’ Plovers were shorter and narrower than shown by both Kentish and Malaysian Plovers, and lacked the rufous tones characteristic of females of the latter species. Furthermore, all male Malaysian Plovers examined showed classic male features, including the blackish collar across the lower nape, while the females showed a distinctly rufous-brown wash to the nape and ear-coverts. It seemed incongruous that Malaysian Plovers breeding in eastern Singapore could appear smaller and in a different plumage to the birds in western Singapore, separated by a distance of approximately 40 km, if they were the same species.

On 20th February 1994 an adult male ‘White-faced’ Plover in breeding plumage was discovered. This bird was associating with the mixed flock of Kentish and ‘White-faced’ Plovers at Tuas and, like the accompanying Kentish Plovers, it had apparently recently moulted into an adult-type breeding plumage. Any thoughts of this being a Malaysian Plover evaporated. Here was a stunningly attractive plover that was so different to anything previously encountered that we were completely mystified as to what it could be. As before, the upperpart colour remained uniform milky-tea in colour, and lacked the contrasting, variegated appearance of Malaysian Plover, but it was the striking appearance of the head pattern that really had us stumped.

This bird had acquired a unique head pattern which gave it a striking ‘white-faced’ appearance; the forehead, lores and feathering surrounding the eye were entirely white, while behind the eye there was just a hint of a brownish eye-line. Above the white forehead was a solid black frontal bar that was wider than that of male Kentish. The crown had moulted to a most attractive bright orange, as bright or brighter, and more extensive than the brightest of all the male Kentish Plovers present. This extended as a cap down to the upper nape and hooked around to partially encircle the rear edge of the ear-coverts. Like male Kentish Plover, the nape remained white and black patches had appeared on the sides of the breast, although they were more restricted than on the male Kentish. Unlike male Malaysian Plover, there was no hint of a black collar across the lower nape.

Up to four ‘White-faced Plovers’, including the male, remained at Tuas until early March 1994, and the last sighting was made on 14th March when 25 Kentish Plovers were still present. The wintering plover flock must have departed shortly after this date and there were no further observations. The following winter, the wintering flock of Kentish Plovers returned but no ‘White-faced Plovers’ were with them. In subsequent winters, vegetation on the site became established, the sandy substrate became inaccessible and unsuitable for plovers, and the wintering Kentish Plover flock failed to return.

Events in Malaysia

When DNB discovered an unusually pale and nondescript plover associating with a Kentish Plover at Penang, Malaysia, on 11th October 2006, he tentatively identified it as a Malaysian Plover. On checking the available literature, however, he was perplexed to discover that Malaysian Plover was not known to assume a nondescript plumage outside the breeding season. Although there appeared to be no alternative options, he posted some photographs of the bird on his blog, but received little feedback, and nothing to suggest an alternative identification.

Figure 1. The first ‘White-faced’ Plover (right) seen in Penang, together with a Kentish Plover, 11th October 2006. Non-breeding plumage. Note the sandier tones of the upperparts and more restricted breast patches compared to the Kentish. (Please note that this photo was cropped so both birds appear closer together for a better comparison). David Bakewell

Figure 2. Female ‘White-faced’ Plover (left) seen alongside a female Kentish Plover. 5th February 2007. David Bakewell

Coincidentally, DNB was contacted at this time by PRK, and he invited PRK to view the images. On viewing the blog, PRK was surprised to see a bird almost identical in appearance to the ‘White-faced’ Plovers which he had previously seen at Tuas, Singapore. These images showed birds that appeared quite different in structure, plumage and bare part colouration to the Kentish Plovers they stood alongside. When compared with wintering Kentish Plovers, the overall paler appearance of the Penang plovers was striking, and their distinctive appearance was enhanced by the slightly larger and heavier structure than the accompanying Kentish Plovers together with longer and paler legs – particularly the tibia, and a slightly longer and heavier bill which was pale at the base of the lower mandible.

Figure 3. Two of 12 ‘White-faced’ Plovers present at the Penang roost on 21st November 2006. Non-breeding plumage. The white lores of both these birds may indicate that they are males. Note also the whitish fringes to the lesser coverts, the leg colour, and the limited extent of the breast patches. David Bakewell

As with the Singapore birds, these birds moulted into breeding plumage between January and February. Fortunately five birds, three males and two females, remained into February. By 6th February, their moult had progressed to a point where their appearance had transformed, and they now appeared quite different to the nondescript appearance of their non-breeding plumage. The males were characterised by the bright orange cap, white unmarked lores and ear-coverts with contrasting dark eye set within white feathering, small black lateral breast patches and pale, relatively uniform upperparts. Females proved to be equally distinctive, with a strongly rufous-toned crown and lateral breast patches, and similarly pale, and relatively uniform upperparts. Although there was limited individual variation, both the males and females resembled their Singapore counterparts and were readily separable from female Kentish Plovers.

Figure 4. Female ‘White-faced’ Plover, 5th February 2007. Breeding plumage. Note the conspicuous orange tone to the crown, ear-coverts, lores and breast patches, as well as the rather conspicuous pinkish legs. David Bakewell

Figure 5. The brightest of the three male ‘White-faced’ Plovers following completion of moult into breeding plumage, Penang, 5th February 2007, together with a Kentish Plover. David Bakewell

The birds were equally distinctive behaviourally, preferring areas with a drier, sandier substrate to the soft mud favoured by the Kentish Plovers. Though they associated with Kentish Plovers and other species on occasion, they were more likely to found in a distinct feeding or roosting group.

What are ‘White-faced Plovers’?

Malaysian Plover

After the Kentish and ‘White-faced’ Plovers had departed from Singapore, observations of several breeding pairs of Malaysian Plovers at Changi continued. Although Malaysian and ‘White-faced’ Plovers were not seen together, it was felt that Malaysian was a distinctly smaller and shorter legged species. In addition, plumage differences, particularly between the male plumages, were so great and consistent that they could not possibly be the same species. Furthermore, Malaysian Plover is a monotypic species, largely resident and believed to retain breeding plumage throughout the year, i.e. they do not have a distinct non-breeding plumage (Hayman et al. 1986). Attention then turned to other options.

Figure 6. Pair of Malaysian Plovers, Thailand, 21st November 2002. Malaysian Plover is distinctly smaller than ‘White-faced’ Plover and similar in size and proportions to Javan and seebohmi Kentish Plovers. Throughout the year, both sexes retain breeding plumage, unlike Kentish and ‘White-faced’ Plovers. Richard Chandler

Figure 7. Female Malaysian Plover, Thailand, 21st November 2002. Although the rufous tones to the crown, nape and lateral breast patches are reminiscent of female ‘White-faced’ Plover, Malaysian Plover shows characteristic variegated upperparts, unlike the uniform upperpart appearance of ‘White-faced’ and Kentish Plovers. Note also the proportionately short and stubby bill compared to that of ‘White-faced’ Plover. Richard Chandler

Other races of Kentish Plover

Between six and eight races of Kentish Plovers are recognised, with four or five occurring in Asia and the remainder restricted to the Americas. The races which occur in Asia include the nominate form C. a. alexandrinus which breeds from Western Europe to northern China; the east Asian race C. a. dealbatus which is described by Vaurie (1965) as having a distinctly more massive bill that averages only slightly longer, but is otherwise not well differentiated from the nominate form. Similarly, Hayman et al. 1986 described dealbatus as being very similar to the nominate race but averages longer-billed, and that it intergrades with this form over a broad zone.; C. a. seebohmi which is a small race resident in coastal Sri Lanka and southernmost India; and C. a. javanicus (now treated as a distinct species, Javan Plover C. javanicus, by most authorities including Inskipp et al. 1996; Dickinson 2003; Clements 2007) which was believed to be restricted to Java, Indonesia, as a resident species, but has recently been discovered on Sumatra and Sulawesi, and may possibly occur further to the east. In addition, the race C. a. nihonensis, described by Deignan (1941) from Aomori, Japan, is generally treated as being synonymous with dealbatus (i.e. Vaurie 1965), and is not recognised, or even commented upon by current taxonomic authorities. We have examined photographs of the type specimen of nihonensis held at the Smithsonian Institute, Washington. This male in breeding plumage is a typical dark mantled Kentish Plover with dark lores. It resembles the many thousands of typical Kentish Plovers we have observed throughout east and southeast Asia, and is quite different to ‘White-faced’ Plover.

Figure 8. Male Kentish Plover in breeding plumage, Penang, 6th February 2007. The appearance of this male and, in particular, the dark brown upperparts are typical of many of the Kentish Plovers that winter throughout coastal east and southeast Asia and breed in northern China, Japan and the Korean peninsula. David Bakewell

Observations of seebohmi at Yala National Park, Sri Lanka, where it is resident, reveal this to be a distinctive race that is slightly smaller than the northern migratory forms of Kentish Plover, with a proportionately shorter and finer bill. It occasionally shows unmarked white lores, but more frequently displays a narrow line of dark, broken feathering in front of the eye but not extending all the way to the bill. However, seebohmi is also a dull race, resembling a washed out version of the northern, migratory races, with a poorly defined male plumage which shows only show slight warmth to the crown. This combination of smaller size and dull appearance clearly established that the ‘White-faced’ Plovers are not seebohmi.

Figure 9. Male Kentish Plover of the race seebohmi, Bundala National Park, Sri Lanka, 26th November 2006. This diminutive race typically shows reduced black feathering on the lores which may form a narrow loral line or, perhaps more typically, appear broken with dark feathering restricted to the front of the eye. Peter Kennerley 

Figure 10. Male Kentish Plover of the race seebohmi, Bundala National Park, Sri Lanka, 26th November 2006, same bird as depicted in figure 9. Unlike other races of Kentish Plover, male seebohmi does not develop a rich cinnamon or rufous tone to the crown, although this can appear slightly warmer than the mantle, which remains dull brown, and the frontal bar, ear-coverts and lateral breast patches are washed dull brown. Peter Kennerley