White-faced Plover: August 31, Yubu Island, Geum Estuary

Nial Moores, September 7^th

On August 31^st, a day or so after the passage of Typhoon Bolaven, a small sandy-toned plover was found and photographed feeding by itself on Yubu Island by Kevin Johnson, Nial Moores, Vince Smith, Therese Catanach and Kazunori Yoshizawa. Identification (by NM) was made as a juvenile dealbatus White-faced Plover, “moving into” first-winter plumage. A selection of the series of images taken by Vince Smith (below, reproduced with permission) were forwarded to Jonathan Martinez, who has for the past year been conducting research on dealbatus in South China. JM supported our identification.

This becomes (at least) the second record of White-faced Plover in the ROK, and the first or second to be documented with photographs (see also “Fig. 3 (Aug 17) A second Kentish Plover, bottom image at https://www.birdskoreablog.org/?p=5710, suggested by JM as likely to be dealbatus. Both follow on soon after an adult male White-faced Plover seen by “Team Entomology”, also at Yubu, on August 18^th (see: https://www.birdskoreablog.org/?p=5693), and the bird of August 31st was followed two hours later by the discovery of the ROK’s first record of Western Sandpiper Calidris mauri!

Main features used for identification of this White-faced Plover can be seen in the following images (all copyright of Vince Smith):

Fig. 1: Seen from the rear, bird appeared heavy-billed and pale with contrastingly pale wing-coverts, in both respects suggesting a miniature Great Sand Plover Charadrius leschenaultii. While pale on the upperparts, rusty tones were strongly evident to the rear of the supercilium and onto the nape and neck sides.

Fig. 2: From the side, appeared almost white-lored and again very heavy-billed, with an obviously paler (pinky-grey) bill base which seems to be absent or at least far less apparent on thousands of nihonensis Kentish Plover seen in similar conditions at this and other sites. Held an odd posture in runs, appearing somewhat flat-backed.

Fig. 3 : When stretching (again an odd-looking posture, held several times), the white hind neck collar appeared rather narrow, and was edged greyer-brown above and greyer-brown below, with increasingly rusty or ginger tones towards the upper mantle. The tail looked longer than expected in nihonensis. Interestingly research by JM in coastal China indicates that dealbatus are consistently longer-tailed than nihonensis. Also of note, in shadow the legs showed some yellowish or paler tones.

Fig. 4: At most angles, the bare parts and the flight feathers were the darkest parts of the bird, with the pectoral patches (merging with the nape-sides) obviously warmer. Even more striking, the forehead, much of the supercilium and the lores appeared white, giving an obviously different impression from nihonensis Kentish Plover.

Fig. 5: Head-on, this individual appeared strikingly pale-fronted. The consistency of the pale fringes on the coverts indicates that this is most likely a juvenile moving into a First-winter plumage, thus appearing much paler than similar-aged nihonensis.

Fig. 6: Close-up, this bird again appeared strikingly different from “typical” nihonensis. Structurally, the bird looked long-legged (with obvious yellowish tones) and heavy-billed, with a paler-bill base (both upper and lower mandible) and an obvious gape-line (usually hard to see on nihonensis due to the dark feathering on the lores). It also showed a broad white forehead, a trace of a thin brownish loral-line, a darker patch in front of the eye, “hollow” ear coverts, and gingery-rust tones to the rear of the ear-coverts. The pectoral patches also appeared small, and similarly rust-toned.

Fig. 7: For contrast, a group of nihonensis photographed the same day by VS in rather different light conditions (including at least one juvenile – towards the centre) reveals the typical appearance of this taxon at this time of year. Compared to dealbatus, nihonensis appears less heavy-billed (some short-billed, others more obviously fine-tipped) and has much more contrasting plumage, including a typically well-defined dark loral line, a narrow white-forehead, dark pectoral patches (lacking rust) and no strikingly paler wing-panel.

Your comments, as always, are welcome…