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Rediscovery of a long-lost Charadrius plover from South-East Asia

By Peter R. Kennerley, David N. Bakewell and Philip D. Round.
 
Note: This article was originally published in Forktail 20 (2004) the journal of the Oriental Bird Club (OBC) and was kindly submitted by Robert DeCandido.

Please support the OBC's conservation work by visiting the OBC website and becoming a member.
ABSTRACT
Several pale Charadrius plovers associating with Kentish Plovers Charadrius alexandrinus in Singapore, Malaysia, Thailand and Vietnam, which were presumed not to resemble any known taxon, have been recorded since 1993. Evidence is presented which establishes that these birds are Aegialites [Charadrius] dealbatus, described by Robert Swinhoe in 1870 as a species distinct from Kentish Plover. Subsequent confusion has resulted in this name being applied to the form of Kentish Plover that occurs in abundance in East and South-East Asia, while the true taxon dealbatus has been overlooked by almost all subsequent taxonomists, and mistakenly described and illustrated as Kentish Plover in all studies of this taxon. This paper suggests that this confusion arose, in part, due to misconceptions over the appearance of dealbatus, which resulted in many museum specimens of Kentish Plover from East Asia being incorrectly identified and erroneously labelled as dealbatus. Swinhoe did not designate a type specimen when he described dealbatus, and this was only done in 1896, from a composite series of Swinhoe’s specimens that comprised two taxa. Here, we formally select and describe a lectotype of Aegialites [Charadrius] dealbatus from Swinhoe’s pre-1870 specimens, list all known Swinhoe specimens of the composite taxa as paralectotypes of Aegialites [Charadrius] dealbatus and establish which specimens represent this taxon and which are Kentish Plover. Comparison with other small Charadrius plovers occurring in South-East Asia establishes the diagnosibilty of dealbatus as a distinct taxon that differs in aspects of plumage, behaviour, habitat preference and breeding distribution from the commonly occurring Kentish Plover in East and South-East Asia. Consistent morphological differences from Kentish Plover include a larger and heavier bill with a pale base to the lower mandible, pale pinkish-grey legs, light sandy-brown upperparts and a longer and more conspicuous wing-bar, particularly across the primaries. We describe plumage differences between sexes and age classes, and compare dealbatus with Kentish and Malaysian Plover C. peronii. The breeding range remains uncertain but probably lies in coastal South China, and evidence suggests that dealbatus is allopatric with Kentish Plover, which breeds in northern China. An investigation to establish the phylogenetic relationship between dealbatus and other small Charadrius plovers is currently in progress. If dealbatus proves to be distinct at the species level, we recommend that the name Charadrius dealbatus with the English name ‘White-faced Plover’ is adopted. The name Charadrius alexandrinus nihonensis is available for the larger-billed form of Kentish Plover breeding in north-eastern Asia. The true taxon dealbatus is believed to be rare but probably underrecorded
INTRODUCTION
Kentish Plover Charadrius alexandrinus is a common and familiar shorebird, breeding on coastal and inland wetlands throughout the warm temperate regions of Europe, Asia, and northern Africa, and also in North America and on the west coast of South America. Across its vast range there is considerable geographical variation, with five races recognised by del Hoyo et al. (1996). Within Asia, there is almost universal acceptance that three races of Kentish Plover occur. As a breeding bird, the nominate race is widespread from southern and western Europe, and North Africa, east across much of central Asia to the Nei Mongol Autonomous Region in north-eastern China. In China, the slightly larger-billed but otherwise similar form, C. a. dealbatus, is said to breed from the southern coastal provinces of Hainan, Guangxi and Guangdong, north to Liaoning (Cheng 1987). It is also generally accepted that C. a. dealbatus breeds in Japan from Honshu south through Kyushu to the Ryukyu islands (Vaurie 1965, Hayman et al. 1986, del Hoyo et al. 1996). However, Brazil (1991) referred to the Japanese breeding birds as belonging to the race C. a. nihonensis. In addition to these two migratory races, a smaller resident form, C. a. seebohmi, breeds in the coastal lowlands of Sri Lanka and the southern tip of peninsular India (Ali and Ripley 1969). A fourth taxon, previously treated as an insular race of Kentish Plover (Chasen 1938, Hoogerwerf 1967), is now widely recognised as a distinct species, Javan Plover C. javanicus, (Cramp and Simmons 1983, Inskipp et al. 1996, del Hoyo et al. 1996, Dickinson 2003, Clements 2007). Javan Plover is believed to be resident on Java, but was discovered to be breeding at Kuala Penet, Lampung, Sumatra, in June 2007 (I. Londo/WCS in litt. 2008), and may also breed in Sulawesi, where it is regularly observed (P. Morris in litt. 2007).

Northern populations of Kentish Plover are migratory and winter to the south of the breeding range. In China, wintering birds remain as far north as the Yangtze River, and they are common in coastal regions in the southern coastal provinces of China. Small numbers also winter in southern Japan, and the species is numerous in winter from Taiwan, south through the Malay Peninsula to Singapore, as well as in the Philippines and Borneo (Cheng 1987, Wells 1999, Carey et al. 2001). Outside the breeding season, Kentish Plover moults into a drabber plumage, making racial separation of the migratory taxa problematic at this season.

This paper challenges this long-standing arrangement and presents evidence which establishes that the Kentish Plovers of eastern Asia, widely accepted as being C. a. dealbatus, are, in fact, largely indistinguishable from Kentish Plovers of the nominate form. We shed new light on the highly distinctive appearance of the taxon dealbatus, which has been overlooked in the field, confused and mislabelled in museum collections, and omitted from the published literature since the nineteenth century. We also comment on the validity of C. a. nihonensis as a distinct taxon.
THE DISCOVERY OF AN UNKNOWN PLOVER
Kentish Plover is a fairly common winter visitor to Singapore, where small numbers formerly over-wintered on a large land reclamation site at Tuas. In October 1993, PRK and others observed several small Charadrius plovers which were distinctly paler than the accompanying Kentish Plovers. When initially discovered, all were in nondescript non-breeding plumage and closely resembled Kentish Plover, although they consistently differed in their conspicuously paler sandy-brown upperparts and paler greyish or pinkish-brown legs, while in flight the white wing-bar appeared broader and more noticeable. Furthermore, the structure of these birds differed slightly from Kentish Plover: they were noticeably larger-headed and heavier-billed, and slightly longer-legged, particularly the tibia. Notes and field sketches were made and compared with illustrations and descriptions of Charadrius plovers in Hayman et al. (1986), which depicted one paler bird, described as a non-breeding adult, with the comment ‘...Some, like this individual, may become faded and worn in tropical winter quarters’. However, other than noting these apparently minor differences in plumage and structural characters, no further progress was made towards establishing their identity until February 1994, despite regular observations throughout this four-month period.

On 20 February 1994, PRK, together with Angus Lamont, spent several hours watching the roosting plover flock at Tuas. On this date, many Kentish Plovers had completed their pre-breeding moult, and with these were three extremely distinctive plovers, clearly males, that we could not identify. Like male Kentish Plovers, they showed a dark band across the fore-crown, an orange cap and dark patches at the sides of the breast. Unlike male Kentish Plovers, however, the lores were entirely white and there was only a small, dull spot behind the eye, so the dark eye appeared isolated within the white facial feathering, and seemed exceptionally large and conspicuous. The upperparts were pale sandy-brown, however, like those birds seen earlier in the winter. With these three males were up to five females with similar pale sandy-brown upperparts. As well as sharing structural similarities with the males, these females displayed a warm and fairly bright rufous-brown wash to the cap, and slightly duller rufousbrown patches at each side of the breast, and a variable loral line; on some birds this appeared as a small rufousbrown spot in front of the eye, while on others it formed a distinct loral line between the bill and eye. Reference to Hayman et al. (1986) again failed to reveal a plover with characters that matched these birds.

This plover flock remained at Tuas until 14 March 1994 when the last bird, a female, was present together with c25 Kentish Plovers. Shortly after this date, the Kentish Plover flock departed, presumably returning to their northern breeding areas. Although the Kentish Plover flock returned to Tuas in the following winter, the paler birds did not accompany them.

There were no further known or published sightings from Singapore or elsewhere until October 2006, when DNB noted an unusually pale Charadrius plover associating with a Kentish Plover on a land reclamation site at Tanjung Tokong, Pulau Pinang, Malaysia, on 11 October 2006, which he tentatively identified as a Malaysian Plover C. peronii. Following discussion with PRK, it was realised that these plovers could be the same as the birds seen in Singapore. By December 2006, numbers had increased to c22 Kentish Plovers and no fewer than 12 unusually pale Charadrius plovers. At least five of the latter birds remained until early March 2007, and during this period DNB was able to obtain many photographs. As with the Tuas birds, these birds underwent a pre-breeding body moult and by early February 2007 they had transformed into a distinctive plover displaying a suite of characters that did not correspond with any taxon described in the available literature. Furthermore, these images closely matched the birds that PRK had described and sketched at Tuas almost 13 years earlier. The last sighting at Tanjung Tokong was of a presumed first-summer male on 28 March 2007.

Observations of Kentish Plovers throughout their breeding and wintering ranges in central and northern Asia, combined with observations of Kentish Plovers of the race C. a. seebohmi in Sri Lanka, Javan Plover C. javanicus in Java, Indonesia, and Malaysian Plover in Singapore, Thailand and elsewhere in South-East Asia, have established that the field characters associated with these taxa differed significantly from the pale Charadrius plovers observed in Singapore and Malaysia.
THE SEARCH FOR SPECIMENS
Although it was suspected that these pale Charadrius plovers might prove to be an undescribed taxon, it seemed inconceivable that such a distinctive plover could have been overlooked in South-East Asia, which has a long history of bird-related research and shorebird studies. The possibility that similar birds may have been previously collected but lie unrecognised in museum collections was investigated.

Raffles Museum of Biodiversity Research, Singapore
PRK examined Kentish Plover specimens held in the Raffles Museum of Biodiversity Research at the National University of Singapore in early 1994. Here, two birds in non-breeding plumage that resembled the pale birds seen at Tuas were located. Both were labelled Charadrius alexandrinus dealbatus by the same unknown collector, and were collected at Batu, Selangor coast, Malaya [Malaysia], on 26 November 1906. Although both specimens were in non-breeding plumage, they had been sexed as males. The remaining 16 Kentish Plovers in this collection, from Japan (1), Sarawak (7), Vietnam (4), Malaysia (1) Singapore (2) and Thailand (1), were also labelled Charadrius alexandrinus dealbatus, but were indistinguishable from Kentish Plovers which winter in South-East Asia. The two pale specimens (specimen reference numbers ZRC 3.2540 and ZRC 3.2541) were sent on loan to the NHM, Tring, in June 2007 for further detailed examination and comparison with Kentish Plover specimens held in that collection. These specimens are listed in Appendix 1.

Natural History Museum (NHM), Tring, U.K.
Examination of Kentish Plover specimens held in the NHM, Tring, by PRK revealed no fewer than 30 Charadrius plovers showing plumage and bare part characters consistent with the pale plovers observed in Malaysia and Singapore. All were collected at locations ranging from central Vietnam to coastal southern China. Significantly, 15 of these specimens, collected by Robert Swinhoe prior to 1870, came from localities along the south coast of China, which Swinhoe (1870) identified as the type locality for the bird he named Aegialites dealbatus, (hereafter referred to as ‘Swinhoe’s dealbatus’). Furthermore, all specimens matching the description of ‘Swinhoe’s dealbatus’ from the type locality were dated between the months of March and July, with the sole exception of a bird from Macau collected on 30 January 1906. With these, however, were a further 20 specimens of typically darker Kentish Plover, also collected by Swinhoe prior to 1870 from locations in southern China, hereafter referred to as ‘eastern’ Kentish Plover. All these darker birds had, however, been collected during the winter months between October and March, with the exception of a single August bird from Amoy [now Xiamen, Fujian province, China]. Those specimens identified as ‘Swinhoe’s dealbatus’ are listed in Appendix 1, and their locations are shown in Fig. 1.

Smithsonian Institution (USNM), Division of Birds, Washington DC, U.S.A.
The USNM collection holds 46 specimens of Kentish Plover collected in East and South-East Asia, including 41 from China (including Hong Kong), three from Malaysia and two from Thailand. Deignan (1941) examined these specimens and commented that this collection held several pale specimens including a series from Amoy collected in June and July, plus others from northern China, Thailand and Malaysia. B. Schmidt of the Smithsonian Institution, Division of Birds, photographed those specimens to which Deignan referred, enabling us to review the identifications. Based upon these photographs, the identification of nine specimens (five from southern China, one from Thailand and three from Malaysia) has been established as ‘Swinhoe’s dealbatus’ and these are listed in Appendix 1. The remainder are undoubtedly typical ‘eastern’ Kentish Plovers.

National Museum of Natural History (RMNH), Leiden, the Netherlands
H. van der Grouw of the RMNH, Leiden, located four Kentish Plover specimens collected by Swinhoe prior to 1870 in this collection, and photographed these on our behalf. Of these, two collected at Amoy in April 1861 belong with ‘Swinhoe’s dealbatus’ and are included in Appendix 1. The remaining two specimens are ‘eastern’ Kentish Plover.

Other collections
PDR examined the collections held at the Thai Natural History Museum, and the Thailand Institute of Scientific and Technological Research, but was unable to locate any specimens amongst the Kentish and Malaysian Plovers. In addition, the following collections responded to our request for information, but appear not to hold any relevant Swinhoe specimens: American Museum of Natural History, New York, U.S.A.; Museum für Naturkunde, Berlin, Germany; Manchester Museum, England; and Academy of Natural Sciences, Philadelphia, U.S.A.
WHAT IS ‘SWINHOE’S dealbatus’?
The conflicting appearance of these plovers from within the type locality, together with what appeared to be temporal separation of pale and dark birds, suggested that the bird hitherto recognised as Charadrius alexandrinus dealbatus could actually comprise two taxa. To establish whether the paler birds really were ‘Swinhoe’s dealbatus’, reference was made to Swinhoe’s original source material, plus his published works, and examination of the specimen designated as the type of dealbatus.

Swinhoe clearly recognised that two forms of Kentish Plover were occurring along the coast of southern China. Prior to formally describing these pale-backed plovers, Swinhoe (1863) commented that,
"the birds that stay to breed along the coasts and islands of South China and Formosa can at once be recognised by their flesh-coloured legs, which in the arrivals from the north are leaden. Our southern birds are, moreover, larger, very pale, in some cases almost white, and never, to my knowledge, attain aught but an indication of the bright rufous and black that adorn the head of the northern form."
Shortly thereafter, Swinhoe (1870) published a short paper in Ibis entitled ‘On the Plovers of the genus Ægialites found in China’ in which he formally recognised these paler plovers as distinct from ‘eastern’ Kentish Plover [then Aegialites cantianus], and which he named Aegialites dealbatus. Swinhoe (1870) also included the following description of dealbatus which supplemented the details which previously appeared in Swinhoe (1863) with the following description:
"Bill black, with an ochraceous-yellow spot at base of lower mandible. Legs light yellowish-brown or flesh colour. In other respects like a washed out Æg. cantianus... The male in summer plumage always has the latero-pectoral patch more or less black, as also the band over the white forehead. The loral streak sometimes shows in pale rufescentbrown, sometimes in black spots, and is rarely entirely wanting. The crown has generally some rufescence; and a rufescent tinge often washes over the back... The female in July has a slight rufescence on the head, and a rufescent brown breast-patch. She seldom acquires any of the dark markings of the male."
At the time, Swinhoe would have been extremely familiar with Kentish Plover, which he described in the 1870 paper as ‘coming down the Chinese coast in winter in great numbers’, a statement that still holds true today. Swinhoe’s conclusion was that dealbatus closely resembled ‘eastern’ Kentish Plover and he appears to have been readily able to distinguish the two taxa. Despite this, he noted that ‘the legs and the bill afford the only reliable characters for discrimination’, but then commented that ‘in some specimens of true Æg. cantianus I notice a paleness at the base of the lower mandible, and also in some a paleness of the tarse [sic], both of which by a little intensifying would produce the results characterizing our species’.

Swinhoe’s ability to distinguish between these two taxa did not extend to his contemporaries. When Swinhoe’s specimens were distributed into various collections, new labels were added that, in some cases, clouded the clarity which Swinhoe provided. For example, Seebohm correctly relabelled 12 of ‘Swinhoe’s dealbatus’ specimens (as Charadrius cantianus dealbatus), but also misidentified five ‘eastern’ Kentish Plovers, which he also labelled dealbatus. Similarly, Hume correctly relabelled two of ‘Swinhoe’s dealbatus’ specimens, but mislabelled an ‘eastern’ Kentish Plover as dealbatus.
SELECTION OF A LECTOTYPE AND IDENTIFICATION OF THE TYPE SERIES
Little more appears to have been published until Sharpe (1896a) provided a detailed description of the bird he considered to be Charadrius cantianus dealbatus. In this, he described the upperparts of the male as
general colour above pale earthy brown, with faint remains of paler margins to feathers
while the crown was described as
ash-brown, washed with light tawny-rufous, especially distinct towards the nape
He considered the
forehead and a distinct eyebrow white, with a broad black band separating the white of the forehead from the brown of the crown; eyelid and loral streak black; feathers below the eye and sides of face white, with a black patch on the hinder ear-coverts; cheeks and under surface of body pure white, with a patch of black on each side of the chest
Sharpe also described the female as appearing
similar to the male, but with less rufous on the head, this being represented by a tinge over the eye and round the nape, the black band on the fore part of the crown absent, the black patch on each side of the chest represented by a brown patch with a rufous tinge.
The above description, which mentions these birds showing a black loral streak, suggests that Sharpe may have included some male ‘eastern’ Kentish Plover, perhaps incorrectly labelled as dealbatus, within the series he was examining. Nevertheless, this was followed by a discussion in which Sharpe stated that,
"I do not see any advantage in upholding Ægialites dealbatus, which is supposed to differ by its paler legs. While admitting that most of the Chinese birds differ in this way, there are many birds, also from China, which have dark legs like the ordinary typical form, while it is equally certain that birds from other localities also have pale legs. In one instance I have seen a bird that had one dark leg and one pale one, so that apparently the skin of the leg dries in different colours."
As Swinhoe did not select a particular specimen to represent the type of Aegialites dealbatus, there is no specific type locality as such. Consequently, the type locality becomes the entire range of the species as defined by Swinhoe, i.e. ‘the South coast of China, including Formosa and Hainan’. Sharpe (1896b), with access to these same specimens (including the incorrectly labelled specimens), selected a specimen (BMNH 1896.7.1.559), to represent the type of Aegialites dealbatus, which is retained in NHM, and carries three labels. The first is in the handwriting of Robert Swinhoe, who collected the bird at Amoy in May 1861, and bears the name Hiaticula nivosa, Cass., but which has been subsequently changed, apparently in Swinhoe’s hand, to Hiaticula dealbata and noted as a female (although plumage characters suggest it to be an abraded male). This specimen later entered the collection of Henry Seebohm, who added a second label using the name Charadrius cantianus dealbatus. The third label, added by NHM when Seebohm’s specimens came to the collection shows this be the lectotype of Aegialitis dealbatus.

In selecting the lectotype from Swinhoe’s specimens, Sharpe (1896a, b) neglected to provide a description of this specimen. In these circumstances, Warren (1966) stated that the ‘listing of a syntype as “the Type”, as was often done in the Catalogue of Birds (BM 1874–1898), does not constitute its designation as lectotype; nor of course does its listing in the present work’. Thus, Warren argued that 1896.7.1.559 cannot be the lectotype of dealbatus as it is not accompanied by a description. To date, therefore, a lectotype of dealbatus as defined by Warren (1966) has not been designated. In order to fix the identity of Aegialites [Charadrius] dealbatus, a lectotype must be selected from the material which Swinhoe had available when he described dealbatus. The selection of a lectotype is necessary because dealbatus is presently represented by a composite series comprising two distinct taxa. There are 15 specimens of ‘Swinhoe’s dealbatus’ in NHM, Tring, together with 21 ‘eastern’ Kentish Plovers, all collected by Swinhoe from the coast of south China and Hainan on dates prior to 1870 (i.e. the material that Swinhoe would have had available to him when describing dealbatus). From these specimens, we hereby designate BMNH 1896.7.1.559 as the lectotype of Aegialites [Charadrius] dealbatus (Plate 1). Support for this decision is provided by reference to the characters which Swinhoe (1863, 1870) used to describe Aegialites dealbatus, and which apply to this specimen.

Plate 1. Lectotype of Aegialites [Charadrius (alexandrinus)] dealbatus
held in NHM, Tring, (BMNH 96.7.1.559), collected by Robert Swinhoe
at Amoy [Xiamen, Fujian province, China] in May 1861. In all plumages,
this taxon is characterised by its pale legs and pale base to the lower
mandible, larger, heavier bill structure, significantly paler upperparts
and longer and more conspicuous wing bar, particularly across the
inner primaries, than Kentish Plover. (Peter Kennerley © NHM, Tring)
The 14 remaining specimens of ‘Swinhoe’s dealbatus’ together with the lectotype, plus a further 21 ‘eastern’ Kentish Plovers collected by Swinhoe prior to 1870 from the type locality and held in NHM, Tring, form part of the composite series and become, by default, paralectotypes of Aegialites dealbatus. In addition, all additional Swinhoe specimens collected prior to 1870, including ten held in USNM, Washington, and the four in the RMNH, Leiden, also become paralectotypes. Appendix 2 provides details of all known paralectotypes of Aegialites dealbatus and identifies those specimens that are correctly assigned to ‘Swinhoe’s dealbatus’ and those which are ‘eastern’ Kentish Plovers, incorrectly placed within this taxon. This list is not exhaustive, and others may come to light in the future.
DESCRIPTION OF THE LECTOTYPE OF AEGIALITES [CHARADRIUS] DEALBATUS
The lectotype (BMNH 1896.7.1.559) was collected at Amoy [Xiamen, Fujian province, China] in May 1861 by Robert Swinhoe, and is housed in the NHM, Tring. Although the data on the label states that this specimen was sexed as a female, plumage characters strongly suggest this bird to be a male.

Slightly larger than Kentish Plover. Bill black with a pale base to the lower mandible, appearing slightly longer than that of Kentish Plover with prominent ‘culmenary bulge’ at the tip. Tarsus and tibia rich tan-brown on dried specimen. Toes dark brown. Claws black. Forehead and supercilium white, lores white, sparsely flecked with small, pale brown spotting. Ear-coverts lightly washed pale greyish-brown. Fore-crown marked with a broad, dark brown band. Crown pale sandy-brown, becoming warm orange on the lower edge of the rear crown. Collar white. Mantle and scapulars pale sandy brown with thin, dark brown shaft streaks and slightly paler, narrow tips. Greater coverts pale greyish-brown, slightly darker than the median coverts and broadly tipped white. Median coverts pale greyish-brown lacking broad white tips. Lesser coverts dark brown, becoming darkest towards the carpal bend. Primary coverts dark brown, narrowly tipped white, and appearing as the darkest part of the closed wing. Alula dark brown at the tip, paler brown towards the base. Inner primaries (P1–P6) mid brown with white panel on the basal half of the outer web, becoming darker towards the tip, although each narrowly tipped creamy-white. Outer primaries (P7–P10) dark brown and unmarked but with creamy-white shafts. Secondaries mid brown as the inner primaries, with narrow white tips to the outermost, these tips becoming progressively broader and whiter towards the body, and extending along the outer web on the inner secondaries. Tertials pale sandy-brown and heavily worn. Tail with central two pairs of rectrices (T1–T2) dark brown, becoming darker, colder brown towards the tip; this being the darkest region of upperparts. Feather shafts blackish. Rectrix T3 dull creamy-white at the base, becoming pale grey-brown towards the tip, this being more extensive on the outer web than the inner. The outer web also showed a narrow white fringe extending along the feather to the tip but there was no similar pale fringe along the inner web. Fourth outer pair (T4) creamy-white apart from a faint brown, lozenge-shaped spot near the tip of the inner web. Outer two pairs of rectrices (T5–T6) entirely creamywhite and unmarked. Entire underparts from the chin to the undertail-coverts white with a faint cream tinge, and unmarked. Sides of the breast marked by small, dark brown lateral breast patches, extending from the carpal bend to the sides of the breast but not reaching onto the breast. Wing 113 mm; tail 47 mm; tarsus 28.6 mm; bill length to feathering 18.5 mm.

Additional details, including descriptions of other known plumages and features which define the distinctive character of ‘Swinhoe’s dealbatus’, are detailed in Diagnosis (below).
CONFUSION BETWEEN SWINHOE'S DEALBATUS AND EASTERN KENTISH PLOVER
The status quo was maintained until Hartert and Jackson (1915) undertook a review of the plovers comprising the genera Charadrius, Aegialites and Eudromias, which they combined into the single genus Charadrius. With Swinhoe’s specimens of dealbatus available to them at NHM, they realised that Sharpe’s (1896a) decision to treat Kentish Plover as a monotypic species was unsound, but they appear unaware that a ‘type’ specimen of dealbatus had been selected by Sharpe (1896b). Even with this series available to them, they apparently failed to appreciate fully the differences between ‘Swinhoe’s dealbatus’ and ‘eastern’ Kentish Plovers. Furthermore, they appear not to have referred to the original descriptions provided by Swinhoe (1863, 1870), as the issue of leg colour was still problematic. For example, Hartert and Jackson commented that birds obtained by Alan Owston’s collectors in Japan, which they believed to be dealbatus, were described on the specimen labels as showing black legs. They did, however, recognise that the larger, stouter bill of ‘Swinhoe’s dealbatus’ set it aside from ‘eastern’ Kentish Plover, and they considered this character to be sufficiently distinctive to reinstate dealbatus as a race of Kentish Plover, which they named Charadrius alexandrinus dealbatus. It is surprising, however, that they did not acknowledge the distinctive appearance of dealbatus, in particular the paler upperparts and lack of a dark loral line, as in the same article they used these same features in the diagnosis of C. a. nivosus as a race of Kentish Plover. This treatment of dealbatus, as being larger-billed but otherwise very similar to the nominate race of Kentish Plover, was followed by all subsequent authorities throughout the twentieth century. At this point, Hartert and Jackson also mistakenly included Taiwan, the Ryukyu Islands and southern Japan within the range of dealbatus when they wrote:
"This form is resident in south China, Hainan, Formosa, and the Riukiu (Loo-Choo) Islands, and Japan at least as far north as Yokohama, where in winter C. a. alexandrinus also occurs as well. In the British Museum, a specimen from Amherst in Burma; also a female from Zaidam in Central Asia belongs to this race."
The treatment of dealbatus by Hartert and Jackson (1915), which correctly described it as being larger-billed, but erroneously concluded it to be otherwise very similar to the nominate race of Kentish Plover, has become widely accepted. Furthermore, the inclusion within its distribution of extensive regions of eastern Asia from which it is in fact unknown (there are no specimens or substantiated reports from any of these countries or regions mentioned above) has given rise to the misconception that dealbatus is the widely occurring form of Kentish Plover in eastern Asia. ‘Swinhoe’s dealbatus’ then vanished from the public perception, and subsequent taxonomists and authors throughout the twentieth century overlooked its distinctive appearance, assuming all ‘eastern’ Kentish Plovers to be dealbatus.
COMMENTS ON ADDITIONAL SPECIMENS OF "SWINHOE'S DEALBATUS" IN NHM
Following Hartert and Jackson’s (1915) treatment of Kentish Plover, it appears that little attention was paid to the separation of ‘Swinhoe’s dealbatus’ and ‘eastern’ Kentish Plover, as there was little or no perceived difference between the two taxa. So when further specimens of what are clearly ‘Swinhoe’s dealbatus’ were registered at NHM, including eight specimens from the Delacour and Jabouille Collection, taken at the former French colony of Kouang-Tcheou-Wan [Zhanjiang, Guangxi province, China] in 1932, and four collected during the Franco-British second expedition to Indo- China by Delacour and Lowe, mostly from Thuan An, near Hué, Vietnam, in September (2), November 1925 (1), and April 1926 (1), all were correctly labelled as dealbatus. However, with the four from Thuan An, but not distinguished from them, are nine ‘eastern’ Kentish Plovers, also labelled dealbatus and collected in November 1925. Consequently, the two taxa were included together in museum trays without any attempt to separate the pale-mantled and dark-mantled birds, resulting in dealbatus becoming a composite comprising two taxa.
WHAT ARE "EASTERN" KENTISH PLOVERS?
If the name dealbatus can be applied only to those birds matching the description given by Swinhoe, then the darker-mantled, dark-legged Kentish Plovers that occur in abundance along the coasts of East and South-East Asia must be something else. In fact, these latter birds are not readily separable from the nominate race of Kentish Plover, although some individuals show a tendency towards a larger and heavier bill, which can approach that of ‘Swinhoe’s dealbatus’.

When reviewing the extensive material available from East Asia in the US National Museum, Deignan (1941) remarked that he
arrived at conclusions rather at variance with those of the most recent revisers
He commented that
A good series from Amoy (June, July) are decidedly paler than birds from Europe, have a longer and more massive bill, and in every case have the upperparts suffused with rufous. Swinhoe’s description of dealbatus as a “washed out”, rufescent tinged alexandrinus fits these specimens perfectly
He goes on to note that
Another series of badly worn birds from Chihli (July) are probably dealbatus. In addition, I have seen examples of this race from Hong Kong (October, November), and Hainan (March)
Outside China, he commented that
Two birds from Thailand (November, March) and two from Malaya (December), all in winter dress, are so remarkably pale above that they stand out from all other Old World specimens I have seen and can be fairly compared with nivosus and tenuirostris of the New World
It seems clear that what Deignan had discovered was a series of specimens that matched ‘Swinhoe’s dealbatus’. Deignan then compared these paler specimens with a series of birds from breeding locations in Japan, which he described as having ‘the upperparts without the least rufescent wash and quite as dark as European specimens, but differ from the latter in having the bill as long and as massive as dealbatus’, although this statement is not quantified or supported by measurements. Deignan proposed the name Charadrius alexandrinus nihonensis for the Kentish Plovers featuring this larger, heavier bill structure, with an adult male selected as the type specimen (USNM 95938), taken at Aomori, Hondo [Honshu], on 23 April 1876 by Captain T. W. Blakiston. We have examined photographs of the type specimen of nihonensis (Plate 2) and can confirm that it is a dark-mantled, darklegged male Kentish Plover in breeding plumage, and closely resembles the nominate form, other than its marginally larger bill.

Plate 2. Type specimen of Charadrius alexandrinus nihonensis described
by Deignan (1941), and held in US National Museum, Washington
DC, USA (USNM 95938), collected by Captain T. W. Blakiston at
Aomori, Hondo [Honshu], Japan, on 23 April 1876. Birds assigned to
this form closely resemble the nominate race of Kentish Plover but are
distinguished by a slightly heavier bill structure, marginally darker
upperparts and a richer cinnamon-orange crown. (Brian Schmidt
© USNM, Washington DC)
Deignan also noted, however, that birds taken in China to the north of the range of dealbatus are ‘dark backed and have a bill somewhat smaller than nihonensis but nevertheless larger than alexandrinus’. While recognising there is substantial variation in bill size in Kentish Plover, and also that young birds tend to have smaller bills than their parents, Deignan concluded that ‘even the shortest billed examples from the Pacific coasts of Asia have the bill rather more massive than European birds of the corresponding age and sex—a difference that must be seen to be appreciated—and are thus better called nihonensis’.

Comments by Nechaev (1988), who examined Kentish Plover specimens collected during the breeding season from all parts of the territory of the former Soviet Union (FSU), support Deignan’s findings. Nechaev concluded that nominate alexandrinus occupied the breeding range of Kentish Plover throughout the FSU, with the exception of Sakhalin, and Kunashir and Moneron in the southern Kuril Islands. Here, he established that breeding birds differed from nominate alexandrinus in their larger bill structure, and, to a lesser extent, longer wing length. He considered the Sakhalin and Kuril birds to be otherwise identical in appearance to the nominate form and concluded they belonged to the race dealbatus. In fact, these slightly larger birds fit the description of C. a. nihonensis, which was (and mistakenly still is) treated as a synonym of dealbatus. Nechaev also recognized that the Kentish Plovers breeding in the southeast Russian region of Primorsky, bordering the Sea of Japan, had a bill structure that was, on average, slightly smaller than that of the birds breeding on Sakhalin and Kunashir, but marginally larger than that of nominate alexandrinus from elsewhere in the FSU. This suggests that an imperceptible change from nihonensis to alexandrinus occurs in this region but there is no convenient geographic division which separates the two races.

Deignan (1941) went largely unnoticed, and was certainly overlooked by those familiar with Kentish Plover in Asia, who continued to refer to ‘eastern’ Kentish Plovers as dealbatus. All recent accounts of Kentish Plover have incorrectly treated nihonensis as a junior synonym of dealbatus. Other than bill structure, there are additional minor differences that set nihonensis apart from nominate alexandrinus, although it is not known to what extent the intermediate populations on the adjacent mainland also exhibit these characters. It is marginally darker on the upperparts and, most conspicuously, the males display a dark, rich cinnamon-orange crown that nominate birds rarely approach. In addition, ‘eastern’ Kentish Plover shows a greater tendency towards displaying a narrow but complete breast-band across the upper breast, particularly in females (and males in non-breeding plumage?), a feature rarely encountered in nominate alexandrinus (Chandler and Shirihai 1995, Leader 2001).

Outside the breeding season, it is uncertain which races of Kentish Plover occur in South-East Asia. It seems probable that birds breeding over an extensive region of northern Asia, and probably within the range of nominate alexandrinus, may be occurring alongside larger-billed birds resembling nihonensis from the east of the range. In juvenile, first-winter and adult non-breeding plumages, however, separation of the races of Kentish Plover using bill structure alone has proved impossible. Although a small minority of Kentish Plovers wintering in South- East Asia, including birds observed in the field and specimens from this region examined in museum collections, do appear to differ from Kentish Plovers occurring to the west, many are identical and only an insignificant minority are slightly larger-billed; and there is no way to establish their place of origin.
ETYMOLOGY
The species was named Aegialites dealbatus by Swinhoe. Species previously forming the genus Aegialites, which is no longer recognised, are now included within Charadrius. The genus name Charadrius is believed to have its origin in the ancient Greek word kharadrios meaning ‘a nocturnal waterbird’, while dealbatus is derived from the Latin verb dealbare, meaning ‘to whiten’. This was presumably the term which Swinhoe thought best described the pallid appearance of this plover when compared with the Kentish Plovers with which he was familiar.
DIAGNOSIS OF "SWINHOE'S DEALBATUS"

Size and structure
Similar in size to migratory forms of Kentish Plover occurring in Asia, but slightly and consistently larger and heavier-bodied. In addition, the head appears proportionately larger than that of Kentish Plover and this, together with the more substantial bill structure, gives the head a robust and heavier appearance. In this respect, the bill structure and head shape of dealbatus appear closer to that of the slightly larger Lesser Sand Plover C. mongolus than to Kentish Plover. In addition, the tibia appears to be consistently longer than that of Kentish Plover, but it has not been possible to substantiate this by measurement from specimens.

To investigate possible structural differences, a series of measurements was taken from specimens of ‘Swinhoe’s dealbatus’, Asian C. a. alexandrinus, C. a. seebohmi and C. peronii (see legend in Table 1 for details).

Although there is extensive overlap with Kentish Plover on all measurements, these demonstrate that ‘Swinhoe’s dealbatus’ is, on average, slightly longer-winged and longerlegged, and also that it consistently shows a slightly larger, heavier bill than Kentish Plover (Table 1). These apparently minor structural differences can be surprisingly apparent in the field where, in particular, the bill structure of dealbatus appears more massive and blunt-tipped, and more parallel-edged and ‘tubular’ in shape than that of Kentish Plover. In dealbatus, the ratio of ‘nail’ length to exposed culmen length has a mean value of 0.49, compared with mean values of 0.47 in ‘eastern’ Kentish Plover, 0.43 in C. a. seebohmi and 0.51 in C. peronii (Table 1). Although these mean values are quite similar, when viewed on birds in the field, they translate to the short, stubby appearance to the bill of Malaysian Plover and to the short and relatively slender bill of C. a. seebohmi. Even between ‘Swinhoe’s dealbatus’ and ‘eastern’ Kentish Plover the visible difference can be striking. This feature is particularly noticeable when the bird turns slightly away from the observer, fore-shortening the bill length.
Table 1. Comparison of wing and tarsus length, and bill structure taken from specimens at NHM, Tring, of ‘Swinhoe’s dealbatus’, Kentish Plover C. a. alexandrinus from locations in East and South-East Asia, Kentish Plover C. a. seebohmi from Sri Lanka and Malaysian Plover C. peronii from locations throughout South-East Asia. Measurements of sexes are combined. Wing length (maximum chord) was measured to nearest mm, with measurements of tarsus and bill structure taken to nearest 0.1 mm. The term ‘nail’ here refers to the dertrum, this being the ‘culmenary bulge’ or distal bill swelling found on the upper mandible. Nail length is defined as the distance from the bill tip to the point where the ‘culmenary bulge’ meets the culmen, and nail depth is the maximum bill depth measured over the ‘culmenary bulge’. Figures in parentheses represent limits, standard deviation and sample size.

"Swinhoe's dealbatus" C. a. alexandrinus C. a. seebohmi C. peronii
Wing
113.1 (105–121; 3.20; 32)
111.7(104–117; 3.05; 101)
101.4(96–106; 3.13; 10)
98.8(94–102; 2.28; 41)
Tarsus
28.2(25.6–29.7; 0.87; 32)
27.2(24.6–29.4; 1.30; 97)
26.2(24.9–26.8; 0.74; 10)
28.8(26.0–31.0; 1.29; 40)
Bill length (to skull)
23.7(21.1–25.7; 1.07; 32)
22.3(19.5–24.4; 1.02; 101)
19.5(18.8–20.7; 0.60; 9)
20.8(19.4–22.8; 0.81; 40)
Bill length (to feathering)
17.8(16.4–19.5; 0.87; 31)
16.5(14.1–18.7; 1.16; 100)
15.0(14.1–15.9; 0.76; 9)
15.0(13.7–16.8; 0.55; 40)
"Nail" length
8.8(8.1–10.2; 0.50; 32)
8.0(6.2–9.5; 2.14; 94)
6.5(5.7–6.7; 0.34; 9)
7.4(6.5–8.0; 0.31; 40)
Bill depth at "nail"
3.8(3.4–4.4; 0.24; 30)
m
3.6(3.0–4.0; 0.57; 91)
3.1(2.8–3.4; 0.21; 9)
3.8(3.4–4.1; 0.19; 38)
Bill width at feathering
4.9(4.1–5.6; 0.39; 29)
m
4.7(3.7–5.6; 0.34; 94)
4.3(3.8–4.8; 0.31; 10)
4.9(4.3–5.6; 0.28; 39)
Mean ‘nail’ length/bill
length to feathering
0.49
0.47
0.43
0.51
Plumage
All birds observed, and the specimens examined to date, have been on dates ranging between late September and mid-July. Criteria used to establish ages referred to below are those used to age and sex similar Charadrius plovers, as described by Prater et al. (1977). Body moult occurs from late December to early February, and during this period birds appear transitional in appearance, between presumed first-winter and first-summer breeding plumages described below. A selection of images that illustrate a wider range of plumages than appear here can be found in Bakewell and Kennerley (2007, 2008).

Plate 3. Adult male Charadrius [alexandrinus] dealbatus, breeding plumage (early February onwards), Tanjung Tokong, Penang, Malaysia, 6 February 2007. (David Bakewell)

Plate 6. Adult female Charadrius [alexandrinus] dealbatus, breeding plumage (early February onwards), Tanjung Tokong, Penang, Malaysia, 6 February 2007. (David Bakewell)

Plate 4. Presumed first-winter male Charadrius [alexandrinus] dealbatus (October to late December), Tanjung Tokong, Penang, Malaysia, 24 November 2007. (David Bakewell)

Plate 7. Presumed adult female Charadrius [alexandrinus] dealbatus, non-breeding plumage (October to late December), Tanjung Tokong, Penang, Malaysia, 21 November 2007. (David Bakewell)

Plate 5. Presumed first-summer male Charadrius [alexandrinus] dealbatus, breeding plumage (early February onwards), Tanjung Tokong, Penang, Malaysia, 6 February 2007. (David Bakewell)

Plate 8. Presumed juvenile Charadrius [alexandrinus] dealbatus, Karon Beach, Phuket, Thailand, 15 November 2003. (Petteri Lehikoinen)

Wing and tail pattern
Both sexes share a similar wing and tail pattern, which does not appear to differ with age. Although ‘Swinhoe’s dealbatus’ shares with Kentish Plover a conspicuous white wing-bar extending across the centre of the upperwing, the overall upperwing colour and pattern differs substantially. The upperwing-coverts (except the primary coverts) are much paler than those of Kentish Plover and therefore provide a greater contrast with the dark alula, primary coverts and outer primaries than Kentish shows. This pallid appearance is further enhanced by the extension of white along the outer webs of the inner primaries, which is longer than on Kentish, while on the inner wing broad white tips to the greater coverts enhance the wing-bar width towards the body, so that the wingbar appears both broader and more conspicuous when compared to that of Kentish Plover.

Unlike Kentish Plover, the outer greater coverts and the outer median coverts of dealbatus, which are also tipped white, contrast against the sandy-brown lesser coverts and slightly darker mid-brown, white-tipped inner primary coverts to form a short, narrow bar which branches from the greater coverts and curves towards the alula, but does not reach the outer edge of the wing. In addition, fairly broad and conspicuous white tips to the dark brown secondaries create a third white bar in the wing, along the trailing edge of the wing in flight.

Also visible in flight, the white in the tail appears more conspicuous than that of Kentish Plover, with the outer three pairs of rectrices being almost entirely white, and only the inner two pairs being dark brown and lacking white.

At rest, differences in the colour of the fringing to the lesser and median coverts on the closed wing are apparent. On Kentish Plover these fringes are buff-brown and show subdued contrast with the feather centres, while on dealbatus they are whitish and show a distinct contrast, although this becomes less apparent with time as a result of feather wear. This difference can also be apparent on birds in flight, with the paler lesser and median coverts of dealbatus contrasting with the darker brown marginal coverts, and forming a noticeable dark bar along the leading edge of the inner wing. In Kentish Plover, the inner wing appears much darker and there is little or no trace of the darker marginal covert-bar.

Adult male breeding plumage (early February onwards). Plate 3
Pattern resembles male Kentish Plover, with white forehead and supercilium, orange crown and dark lateral breast-patches. Unlike Kentish Plover, the crown is purer, brighter orange, the loral region and ear-coverts largely or entirely white—although some birds do show scattered darker feathering or a dark smudge immediately in front of the eye, this being most conspicuous when worn but occasionally visible on birds in fresh plumage in February. Exceptionally, a male observed by DNB (February in Singapore) showed a narrow, dark line extending from the eye to the bill-base. The white forehead is broader and more extensive than in Kentish Plover, so the dark eye is isolated and surrounded by white feathering, resembling Snowy Plover, and the supercilium is broader and longer, with white extending well behind the eye. The blackish frontal bar across the fore-crown is wider than in male Kentish, and the crown bright orange rather than dull orange. The nape is white, forming a complete white collar separating the orange crown from the mantle, whereas on Kentish a narrow brown line extending down from the crown divides the white collar. The entire upperparts, including the mantle, scapulars, wing-coverts and tertials, are uniform pale sandy-brown, and clearly paler than the corresponding darker, wet-sand tone to the upperparts of Kentish Plover. The darker primaries project slightly beyond the longest tertial. A conspicuous blackish-brown patch on the side of the breast in front of the carpal bend is narrower, smaller and shorter than the equivalent patch on male Kentish Plover, resulting in the extent of white between the breast-patches being consistently wider than shown by Kentish Plover. Otherwise, the entire underparts from chin to undertailcoverts are white.

Presumed first-winter male non-breeding plumage (October to late December). Plate 4
Resembles the adult male breeding plumage but the head pattern is subdued, with the supercilium behind the eye lightly washed diffuse grey, and light grey around and below the lower edge of the eye, forming a dark ‘shadow’. In front of the eye, this appears as a small grey spot, but otherwise the lores remain white. The forehead is white, but the dark fore-crown bar is largely obscured with whitish tips, and appears pale grey. The crown is pale sandybrown like the mantle, but the sides to the crown and hind-crown are dull orange-brown. The dark patches on the sides of the breast appear slightly greyer and paler than those of the breeding male.

Presumed first-summer male breeding plumage (early February onwards). Plate 5
Similar to adult male in breeding plumage and some may not be separable (e.g. see leg-flagged male in Bakewell and Kennerley 2008, plate 11, which was aged as a firstwinter when trapped in October 2007). Other birds assumed to be this age differ from the adult male in showing a narrow and broken dark frontal bar on the fore-crown, which in some individuals can be almost absent. The crown is duller than bright orange of the adult, particular towards the centre where it is usually similar in colour to the mantle, but becoming brighter at the sides and across the lower rear-crown. The lateral breast-patches are usually smaller and less obvious than those of the adult male, varying in colour between sandy-brown (as the mantle) and dull blackish-brown, but at this age often two age classes of feathers are present, creating a mottled appearance to these patches. The replaced mantle and scapulars are slightly warmer and darker than in the adult male, and contrast with the retained, worn and paler juvenile wing-coverts.

Adult female breeding plumage (early February onwards). Plate 6
The overall appearance of the upperparts is consistently paler than in Kentish Plover, while the crown and breastpatches are sandy-brown with a fairly bright rufous or orange wash, and recall female Malaysian Plover. It usually lacks the entirely white-faced appearance of the male, although the forehead and supercilium are white. However, the lores and ear-coverts are pale sandy-brown with a light rufous or orange wash, forming a distinct eyestripe. The crown is sandy-brown with a rufous or orange wash, hooking down behind the supercilium to join the eye-stripe behind eye. The nape is white, forming a complete collar separating the crown from the pale sandybrown mantle. The entire upperparts are pale sandybrown as in the male, although indistinct dull chestnutbrown fringes may be apparent on the scapulars, giving them a slightly warmer and richer appearance compared with the mantle. The lateral breast-patches are pale sandybrown with a rufous or orange wash, similar to the crown colour or slightly duller and browner and, as in the male, not as deep or extensive as on female Kentish Plover. The entire underparts from chin to undertail-coverts are white, and the extent of white between the two breast-patches is consistently wider than shown by female Kentish Plover.

Presumed adult female non-breeding plumage (October to late December). Plate 7
Differs from the adult female breeding plumage by its lack of reddish-brown on the crown and breast-patches. The extent of the loral line is variable; on some birds this forms an indistinct sandy-brown line reaching to the bill, while on others the loral region remains white or shows an indistinct sandy-brown spot immediately in front of the eye. The dark coloration on the ear-coverts is much less extensive than shown by Kentish Plover, not extending onto the lower ear-coverts. The upperparts including the crown and mantle are uniform pale sandy-brown. However, scapulars usually contrast with the paler-fringed wing-coverts when visible.

Juvenile. Plate 8
Closely resembles the adult female in non-breeding plumage but differs in appearance by the presence of narrow but conspicuous pale fringes to the mantle and scapulars, giving the upperparts a slightly scaled appearance.

Bare parts
Legs: variable in colour. Adult males vary from dull midgrey with a slight pinkish tinge to pale flesh, the legs appearing darker on freshly moulted males in February and March. The legs of adult females are distinctly paler than those of most males, with grey tones almost or entirely absent, and replaced with dull pink or flesh tone, sometimes with a hint of ochre. Importantly, however, the legs are invariably and conspicuously paler than the bill. Only the most extreme Kentish Plover will occasionally show leg colour approaching that of dealbatus, and no dealbatus has been noted with legs approaching the dark grey of Kentish Plover. Bill: in both sexes black, apart from the base of the lower mandible which is yellowishbrown, similar in pattern and colour of the lower mandible of Malaysian Plover. Eye: black, and appearing proportionately larger than the eye of Kentish Plover.

Moult and wear
The moult strategy has not been studied in detail, but is believed to be similar to that of Kentish Plover. All birds appear to undertake a pre-breeding moult between December and January, during which the distinctive breeding plumage is acquired, although in second calendar year birds the brighter tones of the breeding plumage may be subdued. As no male specimens (collected between May and July) show the distinctive orange cap seen in the wintering areas, it is assumed that this abrades fairly quickly to reveal the pale brown feather-bases, possibly as early as May, when some small, dark feathering may appear on the lores, very occasionally forming a solid loral line.

Following the breeding season, it is assumed that a complete moult takes place although the timing for this has not been established. What is currently uncertain is why some birds wintering in Singapore and Malaysia adopt a pale, nondescript plumage outside the breeding season, while birds wintering in Vietnam retain the breeding plumage throughout the winter months. It now seems likely that at least some of these early-arriving birds in nondescript plumage are first-winter birds, which moult into a ‘first-summer’ plumage the following spring. This would accord with other Asian Charadrius plovers, which are either resident in the tropical regions or short-distance migrants which retain the same ‘breeding’ plumage throughout the year, including Malaysian Plover, Javan Plover, Kentish Plover C. a. seebohmi and Little Ringed Plover C. dubius of the south Asian form jerdoni. Further observations should provide answers to these questions.

COMPARISON WITH SIMILAR TAXA

Kentish Plover

Migratory races of Kentish Plover are similar in size to ‘Swinhoe’s dealbatus’, but invariably show dark lores and dark feathering around and behind the eye. In all plumages, the upperparts of both sexes of Kentish Plover are dull brown and appear considerably darker and browner than dealbatus. Both sexes of Kentish Plover also show larger and more extensive dark patches at the sides of the breast, appearing wider and usually extending well forward of the carpal bend, on some individuals even meeting across the centre of the breast (Chandler and Shirihai 1995, Leader 2001), particularly in ‘eastern’ Kentish Plovers. Another significant differentiating character, particularly useful on birds in first-winter plumage, is the extent of dark coloration on the lower earcoverts below and behind the eye, which is always greater in Kentish Plover. Male Kentish Plovers in breeding plumage display a dark frontal bar on the fore-crown but this is usually narrower than that shown by ‘Swinhoe’s dealbatus’, and the orange crown is slightly duller, more subdued and shows a distinct cinnamon tone.

The resident race C. a. seebohmi occurring in Sri Lanka and southern India is a distinctive taxon that is significantly smaller than the northern migratory form of Kentish Plover, overlapping in size with Javan and Malaysian Plovers. Prior to the pre-breeding moult, males can show restricted black feathering on the lores, with most birds retaining a small patch of dark feathering immediately in front of the eye or a narrow, dark line across the lores, flecked with white feathering. Following the pre-breeding moult, in late February, all males from a sample of over 80 observed in Sri Lanka showed a narrow but solid dark line across the loral region. Compared with other races of Kentish Plover, the head pattern of freshly moulted male seebohmi is dull, subdued, poorly marked and without the warm orange and cinnamon tones to the crown, resulting in an appearance that is like a washed-out version of the northern, migratory races. Female seebohmi are similar in size to the males, but closely resemble female Kentish Plovers of the nominate form, and so are darker than ‘Swinhoe’s dealbatus’.

Javan Plover
The appearance of Javan Plover is poorly documented, but observations of breeding birds at the Muara Angke reserve, on the western outskirts of Jakarta, Java, have established that their appearance is quite different to that of ‘Swinhoe’s dealbatus’. In size, it is relatively small and compact, and comparable in size to C. a. seebohmi. The upperparts vary from dark brown to a paler dull sandybrown, similar in colour to ‘eastern’ Kentish Plover, while males show a warm rufescent-brown wash to the lower crown and rear of the supercilium, which extends back over the ear-coverts where it drops slightly. Importantly, the lores are entirely dark, the patches at the sides of the breast are rufescent-brown, not black, and the legs are dull greenish-grey.

Malaysian Plover
Malaysian Plover is a relatively small Charadrius plover that overlaps in size with C. a. seebohmi and Javan Plover, but is significantly smaller than ‘Swinhoe’s dealbatus’ and the migratory races of Kentish Plover (Table 1). Bill coloration and structure and upperwing pattern are strikingly similar to ‘Swinhoe’s dealbatus’. It also shares the dark fore-crown bar and bright orange crown, and some males show entirely white and unmarked lores, and appear uncannily like some male ‘Swinhoe’s dealbatus’. In most, however, a narrow line of dark feathering extends from the eye to the bill-base. Male Malaysian Plover always shows a dark collar across the upper mantle, below the white collar, that joins with the dark patches at the sides of the breast. These patches are usually longer and deeper on Malaysian Plover, and on some individuals can almost meet across the breast. In addition, although the upperpart feathering of both sexes of Malaysian Plover is paler than shown by dealbatus and Kentish Plover, the feathers on the mantle and scapulars show a broad, pale fringe with a darker centre and a conspicuous dark shaft-streak, so the upperparts lack the relatively uniform appearance of dealbatus. Females more closely resemble female dealbatus, but the smaller size and pattern to the mantle and scapulars remain constant differences. There is a difference in the crown coloration between female Malaysian Plover and female ‘Swinhoe’s dealbatus’. Typically, female Malaysian shows orange on the fore, rear and sides of the crown, while the centre is sandy-brown, while female ‘Swinhoe’s dealbatus’ shows an even sandy or orange-brown colour.
DISTRIBUTION AND STATUS

Accounts from the early decades of the twentieth century described ‘Swinhoe’s dealbatus’ as a common breeding bird along the coast of eastern China from Hainan north to Chihli [Hebei province]. But this statement is confused by the belief at that time that all Kentish Plovers breeding in coastal China were dealbatus, and not just those along the south coast of China. For example, La Touche (1931– 1934) described dealbatus as breeding ‘in large numbers both on the coast of South-East China and on those of Shantung [Shandong province] and Chihli [Hebei province]’. He also describes finding nests at Swatow Bay [Shantou, Guangdong province], and near Amoy (within the type locality of dealbatus) but commented that he did not find any nests at Chinwangtao (Qinhuangdao, Hebei province], although he had no doubt that it bred there, as Wilder and Hubbard (1924) had described it as being abundant at Peitaiho [Beidaihe, Hebei province] from early April to early September. It is possible that La Touche’s description is an amalgamation of northern and southern Chinese breeding birds, passage migrants and wintering birds, based on the misconception of the appearance of dealbatus and erroneous distribution comments by Hartert and Jackson (1915), which included Taiwan, the Ryukyu Islands and southern Japan north to Honshu within its range.

An earlier account by Jones (1911) described Kentish Plover as ‘one of the commonest breeding birds on the sandy wastes which border the Yellow Sea and Gulf of Pechili [Gulf of Bohai] in so many parts of Shantung Promontory’. Jones clearly assumed these northern breeders to be the same birds which La Touche found breeding in Swatow, but he did not provide a description of the birds he saw. Crucially, however, he did include the comment that all Kentish Plovers here have black legs and none was seen with pale legs. This strongly suggests that the birds Jones was observing were ‘eastern’ Kentish Plovers rather than ‘Swinhoe’s dealbatus’.

Outside the breeding season Swinhoe considered dealbatus to be resident in south China, although there is little evidence to support this. In fact, the only report from south China to date outside the breeding season relates to a female mentioned by Vaughan and Jones (1913), who stated that one was obtained on mudflats at Macao [Macau, China] on 30 January 1906, but provided no supporting details. However, what is presumably this specimen is held in NHM (BMNH 1910.5.2.57) and is clearly referable to ‘Swinhoe’s dealbatus’.

An unsubstantiated report was included in Seebohm (1893), who referred to a female shot at Nagomagiri, Choda, Okinawa in the Ryukyu Islands, Japan, on 9 February that showed ‘very pale legs’. Based on this single character, he considered this bird belonged with the Chinese race Charadrius cantianus dealbatus. But without additional supporting evidence, there is nothing here to suggest that this was anything other than a Kentish Plover with unusually pale legs. In fact, a female Kentish Plover, also with pale legs that may possibly resemble Seebohm’s bird, was photographed at Okinawa on 20 March 2002, and can be seen at http://homepage2.nifty.com/stints/ ploveretc/kentishplv-awC.html

All specimens of Kentish Plover that we have examined from northern China, Taiwan and Japan, together with photographs of breeding birds taken in these countries clearly establishes them as Kentish Plovers. While it is possible, even likely, that ‘Swinhoe’s dealbatus’ bred to the north of Fujian province, we have not seen any evidence to support this. Outside the breeding season, it is generally believed that dealbatus ranges widely throughout coastal East and South-East Asia. However, examination of specimens and photographs from this region clearly shows that all are Kentish Plovers, with the exception of those listed below and in Appendix 1.

With such apparent confusion in the historical literature and museum specimens, it is unwise to assume that any published distribution data relating to the range of ‘Swinhoe’s dealbatus’ can be accurate unless supported by specimens or photographs. In an attempt to establish the true distribution, all specimens of Kentish Plover from eastern Asia held at NHM, Tring, and the Raffles Collection, University of Singapore, were examined. Although most were labelled dealbatus, the vast majority were found to be ‘eastern’ Kentish Plovers. Only those supported by specimens, photographs, field notes and sketches are included in the country summaries below. Appendix 1 details the location of all specimens which have been identified as ‘Swinhoe’s dealbatus’, and these are shown in Figure 1.

In an attempt to gather additional distributional data, Bakewell and Kennerley (2007) published a photo-essay on the Surfbirds website (http://www.surfbirds.com/ Features/plovers1108/malayplovers.html). In addition to bringing these birds to the attention of a larger audience, this article included a review and comparison of those characters considered to be most useful when separating ‘Swinhoe’s dealbatus’ from Kentish Plover. After publication, several additional reports were received involving birds seen and photographed in China, Vietnam, Thailand and Singapore. These, together with specimens, form the basis of the individual country summaries below.

China
Specimens examined are dated from the period spanning April to July, which would be the likely breeding season. These include 18 from Amoy [Xiamen, Fujian province], one from Swatow [Shantou, Guangdong province], nine from Kouang-Tcheou-Wan [Zhanjiang, Guangxi province], plus four birds collected on Hainan in March, which could also be breeding birds. In addition, there is the specimen from Macao [Macau] dated 30 January 1906, representing the only winter record from China. Recent reports from China depict what appears to be a worn adult, photographed at Sanya, at the southern tip of Hainan, on 12 July 2007 (see http://www.wwfchina.org/birdgallery/showpic.shtm?id=41638 and http://www.wwfchina.org/birdgallery/showpic.shtm?id=41639), while J. Wilkins (in litt. 2008) reported two birds at Sanya on 19 May 2000. In addition, a photograph of a male at Beihai, Guangxi, on 25 May 2005, appears at http://www.wwfchina.org/birdgallery/showpic.shtm?id=9234.

Currently, Xiamen marks the northern limit of the known range of ‘Swinhoe’s dealbatus’, although there are no recent reports from there. There are also no reports from Hong Kong, which lies approximately 500 km to the south-west of Xiamen. Migrant shorebirds have been studied extensively in Hong Kong since the late 1970s, and the lack of recent reports suggests few, if any, occur there.

Vietnam
Four specimens collected at Thuan An, Hué, Central Annam, Vietnam, during the Third Expedition to French Indo-China, in September and November 1925, and April 1926 (Delacour et al. 1928), are housed in the collection at NHM. In addition, photographs show at least seven birds at Phan Thiet, South Annam, on 27 December 2005 (B. Anderson in litt. 2007) and at least nine were photographed there on 20 November 2007 (H. Stamm in litt. 2008).

Thailand
We have examined one specimen from Thailand, collected at Khao Sam Roi Yot, Prachuap Khiri Khan, on 8 November 1932 and housed in the USNM collection, Washington DC. Following the publication of Bakewell and Kennerley (2007), several reports supported by photographic evidence were received. These include a male photographed at Nopparat Thara Beach, northwest of Krabi, Krabi province, on 17 February 2003 (P. Backman in litt. 2008), followed by a flock of seven, photographed at Karon Beach, Phuket, 15 November 2003 (P. Lehikoinen in litt. 2008). In the Gulf of Thailand, several reports have come from Laem Phak Bia, Phetchaburi, where R. Wardle (in litt. 2008) photographed a male on 29 January 2004. Next came a male in March 2007 (G. Bakker and R. van der Vliet in litt. 2007), followed by one, supported by photographs, from S. Daengphayon and Somchai Nimnuan on 15 December 2007. Up to three birds remained here until February 2008 (P. Ericsson, PDR, Pinit Saengkaew, K. Sutasha, C.-J. Svensson, C. Thomas and D. Walsh in litt. 2008) and at least one was still present on 23 March (V. Picken in litt. 2008). Other recent sightings from Thailand include one at Bang Berd Bay, Patiu district, Chumphon, east coast of peninsular Thailand, on 26 January 2008 (Smith Sutibut in litt. 2008), four at Thai Muang Beach, Phang Nga area, south Thailand on 22 February 2008 (C. Thomas in litt. 2008), a male at Nopparat Thara Beach, Krabi, on 26 and 29 March 2008 (J. Buckens in litt. 2008) and a male at Ko Libong, Trang, on 6 and 7 April 2008 (Somchai Nimnuan and PDR).

Figure 1. Map showing location of all documented occurrences of ‘Swinhoe’s dealbatusCharadrius [alexandrinus] dealbatus up to April 2008. Documented sightings (open circles) have been reported from the following locations: 1 Beihai, Guangxi province, China; 2 Sanya, Hainan, China; 3 Phan Thiet, Vietnam; 4 Laem Phak Bia, Phetchaburi, Thailand; 5 Bang Berd Bay, Patiu district, Chumphon, Thailand; 6 Thai Muang Beach, near Phang Nga, Thailand; 7 Karon Beach, Phuket, Thailand; 8 Nopparat Thara Beach, Krabi, Thailand; 9 Ko Libong, Trang, Thailand; 10 Tanjung Tokong, Penang, Malaysia; 11 Kapar Power Station, Selangor, Malaysia; 12 Tuas, Singapore; 13 Changi Cove, Singapore. 14 Cemara, Jambi province, Sumatra. Specimen records (solid circles) have come from: A Amoy [Xiamen, Fujian Province, China]; B Swatow [Shantou, Guangdong province, China]; C Macau; D Kouang-Tcheou-Wan [Zhanjiang, Guangxi province, China]; E Hainan, China; F Thuan An, Hue Vietnam; G Khao Sam Roi Yot, Prachuap Khiri Khan, Thailand; H Pulau Langkawi, Malaysia; I Batu, Selangor, Malaysia.
Malaysia
We have located five specimens from Malaysia. Three specimens, collected from Pulau Langkawi in the extreme north-west of the country are housed in USNM, Washington DC. Two were collected here on 1 December 1899 and the third was collected on 14 November 1963. The remaining two specimens are held in the Raffles Collection at the University of Singapore, and were collected on 26 November 1906, and labelled Batu, Selangor, Malaya. Although the location of Batu is uncertain, D. Wells (in litt. 2007) comments that Batu refers to a ‘rock’ or ‘milestone’, and he had also attempted to locate this site. Although he could not be certain, he considers it most likely to refer to a location on the northern Selangor coast, to the seaward side of Sungei Buloh, and to the north of Jeram beach, where there is a large limestone outcrop.

The first recent record, supported by a field sketch, was made by C. Rose who watched a bird in the roost at Kapar Power Station, Selangor, in March 1993. Observations by DNB during winter 2006–2007, supported by photographs, established that a flock of up to 12 birds wintered on an extensive land reclamation site at Tanjung Tokong, Pulau Pinang. The first bird was noted on 11 October 2006, after which numbers increased to a peak of 12 in December, followed by a decline to five in February, and the last bird was seen on 28 March 2007. The first returning bird was located on 21 September 2007, and up to six were present in January 2008.

Singapore
Up to four birds which spent the winter on the extensive land reclamation site at Tuas, at the western extremity of Singapore bordering the Straits of Malacca, from late October 1993 to 14 March 1994, were described and sketched by PRK. There were no further reports from Singapore until J. Cheah (in litt. 2007) photographed two males at Changi Cove, on 12 February 2007, and posted images on his website (http://www.pbase.com/wkcheah/ kentish_plover). A visit to this site on 8 February 2008 revealed eight birds, and at least 14 there on 17 February, falling to three on 13 March and just one on 22 March 2008 (M. Kennewell, S. Cockayne and Wang Luan Keng in litt. 2008).

Sumatra, Indonesia
A male was trapped at Cemara, Jambi province, Sumatra on 12 February 2008. (I. Londo/WCS in litt. 2008).

Breeding and wintering ranges
Based on the established identifications above, the breeding range of ‘Swinhoe’s dealbatus’ remains uncertain. There is no evidence to suggest that breeding occurs outside the range given by Swinhoe, i.e. the south coast of China including Hainan. But with no evidence of passage through Hong Kong, breeding may no longer occur in Guangdong or Fujian provinces. There is no evidence to suggest that ‘Swinhoe’s dealbatus’ has occurred in Taiwan and observers there are unfamiliar with it (S. Liao verbally 2007), contra Swinhoe (1863) who included Formosa [Taiwan] within the range of dealbatus.

Outside the breeding season, recent photographic evidence has established that ‘Swinhoe’s dealbatus’ winters locally along the coast from southern Vietnam, through the Gulf of Thailand and south along the west coast of the Malay Peninsula to Singapore, and the east coast of Sumatra, Indonesia. Undiscovered wintering sites may exist along the sandier east coast of the Thai-Malay Peninsula, and the underwatched coasts of Vietnam and Sumatra may holder larger wintering populations.
HABITAT
Outside the breeding season, ‘Swinhoe’s dealbatus’ appears to show a distinct preference for coastal sites with an open aspect, which it requires for roosting and feeding. Natural sites such as the sandy spit at Laem Phak Bia, Thailand, are favoured for both roosting and feeding, and birds are present there throughout the day. Land reclamation sites with a sandy substrate and little or no emergent vegetation, such as Tuas and Changi Cove, Singapore, are presumably unsuitable for feeding and are used for roosting during the day. However, these birds depart the site at dusk and return the following morning, presumably to visit unknown feeding sites (DNB pers. obs.). At Tanjung Tokong, Penang, Malaysia, the preferred habitat was a fine sandy substrate, almost completely devoid of vegetation, which was used as a high tide roost for shorebirds. When not roosting, however, these birds fed on the adjacent intertidal mudflats.

It seems likely that land reclamation sites represent a suboptimal habitat, and observations in Thailand and Malaysia show that ‘Swinhoe’s dealbatus’ prefers sand beaches to mudflats.
BEHAVIOUR AND ECOLOGY
At both Tanjung Tokong and Tuas, dealbatus usually associated with Kentish Plovers when feeding and roosting, although they tended to feed on harder, sandier substrates, while Kentish Plovers would feed in softer mud along tidal channels. During low tide at Tanjung Tokong, the mixed plover flock would feed on the tideline, on or near an isolated sandbar in the middle of extensive mudflats. On occasion, they were seen to hunt prey (possibly crabs) in a manner typical of Greater Sand Plover C. leschenaultii: head lowered, dashing rapidly across the sand to seize the prey before it could retreat into its burrow. P. Ericsson (in litt. 2008) also commented that at Laem Phak Bia, Thailand, ‘Swinhoe’s dealbatus’ seem to prefer the more isolated sandy beaches also frequented by Malaysian Plovers. One male observed for over an hour was very aggressive and would promptly chase off any Kentish Plover or Sanderling Calidris alba which approached it too closely. When feeding, both ‘Swinhoe’s dealbatus’ and Malaysian Plover are more active than Kentish Plover, and often run almost non-stop while foraging along the tide edge, where they have been observed chasing down and eating small crabs (M. Andrews in litt. 2008).

Differences in feeding posture may also be significant. When feeding, Kentish Plover assumes a rather horizontal stance, with the head held hunched into the ‘shoulders’. In contrast, ‘Swinhoe’s dealbatus’ often adopts a slightly more upright stance, with more of the neck visible.

On the rising tide, feeding shorebirds at Tanjung Tokong congregated in a loose mixed flock, prior to roosting. As the mudflats were covered, the flock selected the same roost site each day, with ‘Swinhoe’s dealbatus’ always preferring open areas devoid of vegetation and with a sandier, drier substrate. Roosting occurred both on the foreshore and on bare reclaimed land at the edge of a construction site. When roosting, dealbatus showed a propensity to sit on the sand, legs folded beneath the body and head held low. Frequently, they selected an area with larger stones and hollows into which they could crouch and which would conceal them wholly or in part. In contrast, while some Kentish Plovers also roosted in this manner, they were as likely to roost standing up. When disturbed at the roost, dealbatus appeared more nervous and tended to run away fast from the disturbance, whereas Kentish would adopt a peculiar robotic mincing gait, not retreating as rapidly as ‘Swinhoe’s dealbatus’.
VOCALISATIONS
Our observations suggested that dealbatus is largely silent during the non-breeding months. Three birds disturbed by DNB on 19 January 2007, gave an alarm call as they took flight, described as ‘a high-pitched tip, sometimes tee’, very similar to that of Kentish Plover. All vocalisations heard were similar to those of Kentish Plovers and markedly distinct from the more trilling calls of Malaysian Plover. Like other Charadrius, it is likely that they will have a ‘display song’ which is given on the breeding grounds, but this has not yet been recorded.
CONSERVATION
With all recent reports coming from outside the breeding season, it is unclear whether ‘Swinhoe’s dealbatus’ faces any immediate threats. With many coastal land reclamation schemes in Asia, there would appear to be a plentiful supply of suitable, albeit temporary, wintering sites. Circumstances in the breeding areas are unknown. But with massive coastal degradation occurring in coastal southern China, it seems inevitable that breeding areas must have been lost. Furthermore, if beaches are the preferred habitat during the breeding season, these will come under increasing pressure from China’s developing tourist infrastructure, particularly in Hainan and Guangxi provinces. The rapid and on-going destruction of much of the coast of southern China does not bode well for the long-term future.
CONCLUDING REMARKS
Few birds can have had such a confused history as Aegialites [Charadrius] dealbatus. It is remarkable that this rather distinctive plover has been overlooked for so long in such a well-watched region. Both Singapore and Malaysia have a long history and strong tradition of bird-related research, extending back almost two centuries to the founding of Singapore. Similarly, it is surprising that this plover has been overlooked for so long in Thailand, also a centre for bird research and a popular destination for visiting ornithologists and birders since the 1970s. Undoubtedly, the close resemblance of ‘Swinhoe’s dealbatus’ to ‘eastern’ Kentish Plover in non-breeding plumage, and passing similarity to Malaysian Plover when in breeding plumage, has contributed to this confusion and masked its true status. Furthermore, its omission from modern field guides has not encouraged observers to question the appearance of those ‘funny’ Kentish Plovers they have encountered.

What has become apparent from the above discussion is that the taxon referred to here as ‘Swinhoe’s dealbatus’ has completely disappeared from the modern ornithological literature, and its place taken by ‘eastern’ Kentish Plover. Consequently, the name dealbatus has been erroneously applied to ‘eastern’ Kentish Plover by almost all authorities and authors throughout much of the twentieth century. Currently not a single taxonomic authority, handbook or field guide recognises the distinctive appearance of ‘Swinhoe’s dealbatus’.

Based on comparisons of morphological, structural and behavioural differences, ‘Swinhoe’s dealbatus’ is consistently diagnosable from Kentish and Malaysian Plovers at all ages and in all plumages. At present, the breeding ranges of ‘Swinhoe’s dealbatus’ and ‘eastern’ Kentish Plover in eastern China are believed to be allopatric. However, contemporary accounts, including that of La Touche (1931–1934), allude to the possibility that the breeding ranges may have overlapped in northeast China, and further work is required to establish whether this is the case. Research to investigate the phylogenetic relationships of ‘Swinhoe’s dealbatus’ with Kentish and Malaysian Plovers is currently proceeding and the results will appear shortly.

It is hoped that the publication of this paper will rectify these taxonomic, historical and nomenclatural errors and reinstate ‘Swinhoe’s dealbatus’ as the distinctive taxon described here. If ‘Swinhoe’s dealbatus’ proves to be a valid species, it is recommended that the name Charadrius dealbatus be reinstated with the English name White-faced Plover applied for popular usage. Furthermore, it is also
recommended that the available name Charadrius alexandrinus nihonensis be reinstated for the large-billed ‘eastern’ Kentish Plovers breeding in northern Japan, Sakhalin and the southern Kuril Islands.

Finally, we repeat the appeal in Bakewell and Kennerley (2007, 2008) for anyone with past or future records and photographic evidence of ‘Swinhoe’s dealbatus’ to contact us, particularly from the period spanning March–July, and from anywhere in China.

Note added in proof
On 7–9 June 2008, members from the Hong Kong and Fujian Bird Watching Societies visited the Minjiang River mouth near Fuzhou, Fujian province, China, where several pairs of ‘Swinhoe’s dealbatus’ were found to be breeding (M. and P. Wong, and K. C. Lee in litt. 2008).
ACKNOWLEDGEMENTS
We are particularly grateful to Geoff Carey, Richard Chandler, Nigel Collar, John Howes, James Kennerley, Angus Lamont, Paul Leader, Brian Small, Subaraj Rajathurai and David Wells for their suggestions, comments, advice and enthusiasm during the preparation of this paper. Our thanks also go to Robert Prys-Jones, Mark Adams and Katrina Cook who kindly allowed access to the specimen collection at NHM, Tring, to Alison Harding for locating many of the more obscure references quoted, and to Chutammas Sukhontapatipak for help in preparing the map. Robert Prys-Jones, Edward Dickinson and Steven Gregory clarified nomenclatural issues associated with the selection of a lectotype and the naming of dealbatus, and Mike Wilson provided Russian reference details. Wang Luan Keng and Kelvin K. P. Lim, (Raffles Museum of Biodiversity Research, Department of Biological Sciences, Faculty of Science, National University of Singapore), kindly arranged for the loan of specimens to NHM. Brian Schmidt (Smithsonian Institution, Div. of Birds, Washington DC, USA), and Hein van der Grouw (National Museum of Natural History, Leiden), kindly provided images of Kentish Plover specimens collected by Swinhoe and held in their respective collections. Without their help, the listing of paralectotypes would be incomplete. In addition, Margaret Hart and Mary LeCroy (American Museum of Natural History, New York), Iris Heynen (Museum für Naturkunde, Berlin), Henry McGhee (Manchester Museum) and Nathan H. Rice (Academy of Natural Sciences, Philadelphia) responded to our requests for information. Professor Tamás Székely and Clemens Küpper from the Biodiversity Laboratory of the University of Bath, and Dr Pat Lee, Department of Biological Sciences Swansea University, recommended methods by which we could work towards establishing the molecular phylogeny of these birds. Thanks also go to Andy Birch who agreed to publish the earlier article on the Surfbirds website (Bakewell and Kennerley 2007), which encouraged observers to seek out these birds and submit their sightings to us.

In addition, we are extremely grateful to the many people mentioned below who provided details of their observations, together with comments and opinions, in response to our request for information, with apologies to anyone inadvertently omitted. Singapore: Jonathan Cheah provided details of his February 2007 sighting. Wang Luan Keng (NUS), Ramakrishnan and Lin Yangchen (National Parks, Singapore), together with Martin Kennewell and Simon Cockayne, supplied details of sightings made at Changi Cove, and are also thanked for their efforts to try to trap birds there. Malaysia: Chris Rose provided details and a sketch of a bird at Kapar Power Station Ash Lagoons. Associate 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, are thanked for their help in attempts to trap the birds at Tanjung Tokong. Indonesia: Iwan Londo/WCS provided details and photographs of a male trapped at Cemara, Jambi province, Sumatra. Thailand: Peter Backman, Garry Bakker, Johan Buckens, Suchart Daengpayon, Peter Ericsson, Petteri Lehikoinen, Somchai Nimnuan, Verity Picken, Pinit Saengkaew, Smith Sutibut, Carl-Johan Svensson, Craig Thomas, Rinse van der Vliet, David Walsh and Robert Wardle provided details of their sightings, some dating back to 2003. Vietnam: We thank Bjorn Anderson and Hanno Stamm for providing details of sightings at Phan Thiet. China: John Wilkins supplied details of his sighting at Sanya, Hainan. Bjorn Anderson and Jesper Hornskov provided links to websites which included photographs of Kentish Plovers, including breeding birds in China, and also shared their opinions on these birds. We also thank an anonymous correspondent in China who provided details of a bird photographed at Beihai, Guangxi province. Others: Ed Keeble and Frederic Jiguet commented on, and provided links to images of pale Kentish Plovers photographed in the Middle East.

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APPENDIX 1
List of all known specimens of Charadrius [alexandrinus] dealbatus. Examined specimens are at NHM, Tring; USNM, Washington; the National Museum of Natural History (RMNM), Leiden, and the Raffles Museum of Biodiversity Research at the National University of Singapore, and identification verified. All locations denoted appear as written on the original collection labels. Note that location names have changed as follows: Amoy [Xiamen, Fujian province, China]; Swatow [Shantou, Guangdong province, China]; Kouang-Tcheou-Wan [Zhanjiang, Guangxi province, China]; Sam Roi Yot, Siam [Khao Sam Roi Yot, Prachuap Khiri Khan, iThailand]; Pulo Lankawi [Pulau Langkawi, Malaysia].

Specimen No. Collection Location Date Sex/Age Collectors (s)
16D NHM, Tring Amoy 1861 Male Swinhoe
91.10.1.692 NHM, Tring Amoy June 1866 Male Swinhoe
91.10.1.693 NHM, Tring Amoy August 1861 Male Swinhoe
93.1.25.193 NHM, Tring
Amoy
May 1861 Male Swinhoe
93.1.25.194 NHM, Tring Amoy May 1861 Female Swinhoe
96.7.1.559 NHM, Tring Amoy May 1861 Male Swinhoe
96.7.1.560 NHM. Tring
Amoy
May 1861 Male Swinhoe
96.7.1.561 NHM, Tring Amoy June 1866 Male Swinhoe
96.7.1.562 NHM, Tring Amoy June 1866 Male Swinhoe
96.7.1.567 NHM, Tring Amoy June 1866 Female Swinhoe
96.7.1.568 NHM, Tring Amoy 4 July 1866 Male Swinhoe
96.7.1.569 NHM, Tring Amoy 4 July 1866 Female Swinhoe
96.7.1.573 NHM, Tring Hainan March 1868 Male Swinhoe
96.7.1.574 NHM, Tring Hainan March 1868 Male Swinhoe
96.7.1.575 NHM, Tring Hainan March 1868 Male Swinhoe
1908.1.8.222 NHM, Tring Swatow 2 July 1888 Female Styan
1910.5.2.57 NHM, Tring Macau, China 30 Jan 1906 Female Vaughan
1926.9.8.203 NHM, Tring Thuan An, Hue, Vietnam 22 Sep 1925 Juvenile Delacour & Lowe
1926.9.8.204 NHM, Tring Thuan An, Hue, Vietnam 25 Nov 1925 Juvenile Delacour & Lowe
1926.9.8.212 NHM, Tring Thuan An, Hue, Vietnam 22 Sep 1925 Male Delacour & Lowe
1927.6.5.256 NHM, Tring Thuan An, Hue, Vietnam 11 Apr 1926 Male Delacour & Lowe
1935.10.23.74 NHM, Tring Kouang-Tcheou-Wan 17 May 1932 Female Delacour and Jabouille
1935.10.23.75 NHM, Tring Kouang-Tcheou-Wan 17 May 1932 Female Delacour and Jabouille
1935.10.23.76 NHM, Tring Kouang-Tcheou-Wan 18 May 1932 Male Delacour and Jabouille
1935.10.23.77 NHM, Tring Kouang-Tcheou-Wan 25 May 1932 Female Delacour and Jabouille
1935.10.23.78 NHM, Tring Kouang-Tcheou-Wan 18 May 1932 Male Delacour and Jabouille
1935.10.23.79 NHM, Tring Kouang-Tcheou-Wan 29 June 1932 Male Delacour and Jabouille
1935.10.23.80 NHM, Tring Kouang-Tcheou-Wan 1 Jul 1932 Juvenile Delacour and Jabouille
1935.10.23.81 NHM, Tring Kouang-Tcheou-Wan 3 Jul 1932 Female Delacour and Jabouille
1935.10.23.238 NHM, Tring Kouang-Tcheou-Wan 27 Jul 1933 Female Delacour and Jabouille
107075 USNM Amoy Jun 1866 Male Swinhoe
113342 USNM Hainan Mar 1868 Unknown Swinhoe
113345 USNM Amoy 4 Jul 1866 Female? Swinhoe
113346 USNM Amoy 4 Jul 1866 Male? Swinhoe
113347 USNM Amoy 1861 Unknown Swinhoe
332671 USNM Sam Roi Yot, Siam 8 Nov 1932 Male Smith
172915 USNM Pulo Lankawi 1 Dec 1899 Female Abbott
172917 USNM Pulo Lankawi 1 Dec 1899 Unknown Abbott
486810 USNM Pulau Langkawi, Malaysia 14 Nov 1963 Female Gill
155918 RMNH Amoy April 1861 Female Swinhoe
155919 RMNH Amoy April 1861 Female Swinhoe
ZRC 3.2540 Raffles Batu, Selangor, Malaya 26 Nov 1906 Male Unknown
ZRC 3.2541 Raffles Batu, Selangor, Malaya 26 Nov 1906 Male Unknown
APPENDIX 2
List of paralectotypes of Aegialites [Charadrius] dealbatus held at NHM, Tring; USNM, Washington DC, and the National Museum of Natural History (RMNH), Leiden. All specimens were collected by Robert Swinhoe prior to 1870 from the type locality (i.e. ‘the South coast of China, including Formosa and Hainan’), and form the basis of his recognition of Aegialites dealbatus as a distinct taxon (Swinhoe 1870). The lectotype (BMNH 1896.7.1.559) is marked with an asterisk. Due to past confusion, the taxon dealbatus is a composite, comprising both Aegialites [Charadrius] dealbatus and Kentish Plover C. alexandrinus. This table distinguishes between those specimens identified as Aegialites [Charadrius] dealbatus, listed here as dealbatus; and those identified as ‘eastern’ Kentish Plover, listed as alexandrinus. All locations denoted appear as written on the original collection labels. Note that some location names have changed as follows: Amoy [Xiamen, Fujian province, China]; Talienwan [Dalian Bay, Liaoning province, China]; Takow, Formosa [Kaohsiung, Taiwan]. The location of Oseukeo cannot be traced but may be in Taiwan where Robert Swinhoe lived from 1856 to 1866.


Specimen No. Location Date Sex/Age Collection Taxon
16D Amoy 1861> Male NHM, Tring dealbatus
91.10.1.692
Amoy
June 1866 Male NHM, Tring dealbatus
91.10.1.693
Amoy
August 1861 Male NHM, Tring dealbatus
93.1.25.193 Amoy May 1861 Male NHM, Tring dealbatus
93.1.25.194 Amoy May 1861 Female NHM, Tring dealbatus
*96.7.1.559 Amoy May 1861 Male NHM, Tring dealbatus
96.7.1.560
Amoy
May 1861 Male NHM. Tring dealbatus
96.7.1.561 Amoy June 1866 Male NHM, Tring dealbatus
96.7.1.562 Amoy June 1866 Male NHM, Tring dealbatus
96.7.1.567 Amoy June 1866 Female NHM, Tring dealbatus
96.7.1.568 Amoy 4 July 1866 Male NHM, Tring dealbatus
96.7.1.569 Amoy 4 July 1866 Female NHM, Tring dealbatus
96.7.1.573 Hainan March 1868 Male NHM, Tring dealbatus
96.7.1.574 Hainan March 1868 Male NHM, Tring dealbatus
96.7.1.575 Hainan March 1868 Male NHM, Tring dealbatus
107075 Amoy Jun 1866 Male USNM dealbatus
113342 Hainan Mar 1868 Unknown USNM dealbatus
113345 Amoy 4 Jul 1866 Female? USNM dealbatus
113346 Amoy 4 Jul 1866 Male? USNM dealbatus
113347 Amoy 1861 Unknown USNM dealbatus
155918 Amoy April 1861 Female RMNH dealbatus
155919 Amoy April 1861 Female RMNH dealbatus
4.25 Amoy 1861 Male NHM, Tring alexandrinus
4.3 Amoy Aug 1861 Male NHM, Tring alexandrinus
5.55 Amoy Jan 1860 Male?
NHM, Tring
alexandrinus
91.10.1.694 Amoy 1861 Unknown
NHM, Tring
alexandrinus
91.10.5.157 North Formosa Mar 1862 Unknown
NHM, Tring
alexandrinus
93.1.25.195 Amoy Oct 1866 Female
NHM, Tring
alexandrinus
93.1.25.196 Amoy Oct 1866 Unknown
NHM. Tring
alexandrinus
93.1.25.197 Amoy Jan 1867 Juvenile
NHM, Tring
alexandrinus
93.1.25.198 Talienwan Jul 1860 Unknown
NHM, Tring
alexandrinus
93.1.25.199 South-west Formosa 1861 Male?
NHM, Tring
alexandrinus
93.1.25.233 Amoy Nov 1866 Unknown
NHM, Tring
alexandrinus
93.1.25.234 Amoy Nov 1866 Unknown
NHM, Tring
alexandrinus
93.1.25.235 Amoy Nov 1866 Female
NHM, Tring
alexandrinus
93.1.25.236 South-west Formosa 1861 Female
NHM, Tring
alexandrinus
96.7.1.558 Oseukeo 14 Nov 1857 Female
NHM, Tring
alexandrinus
96.7.1.563 Amoy Jan 1860 Unknown
NHM, Tring
alexandrinus
96.7.1.564 Amoy Nov 1866 Unknown
NHM, Tring
alexandrinus
96.7.1.566 Amoy Nov 1866 Unknown
NHM, Tring
alexandrinus
96.7.1.570 Amoy Nov 1866 Unknown
NHM, Tring
alexandrinus
96.7.1.572 North Formosa Mar 1862 Unknown
NHM, Tring
alexandrinus
93.1.25.192 Oseukeo 14 Nov 1857 Unknown
NHM, Tring
alexandrinus
107076 Amoy Oct 1866 Unknown USNM alexandrinus
113343 Amoy Oct 1866 Unknown USNM alexandrinus
113344 Amoy Jun 1866 Unknown USNM alexandrinus
113348 Amoy Jan 1860 Unknown USNM alexandrinus
113349 Takow, Formosa Oct 1865 Unknown USNM alexandrinus
155916 China April 1861 Female RMNH alexandrinus
155917 China Feb 1861 Unknown RMNH alexandrinus
Kindly submitted by:

Peter Kennerley, 16 Coppice Close, Melton, Suffolk, U.K. IP12 1RX. Email: peterkennerley@onetel.net

David N. Bakewell, c/o Whimbrel Cottage, Wilby, Eye, Suffolk, U.K. IP21 5LE.

Philip D. Round, Regional Representative, The Wetland Trust and Assistant Professor, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.
   
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