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Everett’s White-eye Zosterops everetti in KhaoYai, north-east Thailand

By Andrew J. Pierce and Philip D. Round

Note: This article was originally published in Forktail 22 (2006) the journal of the Oriental Bird Club (OBC) and was kindly submitted by Philip D. Round.

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INTRODUCTION
Two white-eyes caught and banded at Mo-singto, Khao Yai National Park (14°26'N, 101°22'E) on 14 July 2004 at 728 m were identified as Everett’s White-eye Zosterops everetti. This provides the first confirmed evidence of the presence of this species in north-east Thailand, and is a significant extension of the species’s known range, which was previously considered to extend from the Philippines and the Greater Sundas, northwards through the Thai-Malaya Peninsula and south-east Thailand to c.13°N (King et al. 1975, Lekagul and Round 1991, Robson 2000).

The two birds were caught between 14h30 and 15h45 in a mist-net placed at the side of a stream. They were ringed and colour-ringed, and their biometrics were recorded (Table 1). Both birds were photographed using a digital camera (Plates 1–2). The salient features of both individuals were the extent of the yellow on the underparts, and the lack of yellow on the forecrown. The entire upperparts from the crown to the uppertail-coverts were uniformly cold olive-green. In particular, the crown, forehead (extending to the base of the bill) and the earcoverts were uniform olive-green. There was a sharp demarcation between the olive-green ear-coverts and the yellow throat. The remiges and rectrices were blackishcentred, with bright, narrow, yellow-green fringes. A broad white spectacle was interrupted by a blackish loral line. The undertail-coverts, hind flanks and thighs were all yellow, and the yellow extended as an evenly broad, unbroken median stripe onto the belly and lower breast. The upper breast was whitish-grey, so that the yellow midline was cut off short of the throat. The flanks were whitishgrey. The iris was reddish-brown; the legs were blue-grey and the soles of the feet fleshy-horn (see Plates 1–2).

Table 1: Biometrics of two Everett’s White-eyes Zosterops everetti ringed in Khao Yai National Park, Thailand, in July 2004.

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Plate 1 : Everett’s White-eye Zosterops everetti, July 2004, Khao Yai National Park, Thailand. Photograph: A. Pierce.

Plate 2 : Everett’s White-eye Zosterops everetti, July 2004, Khao Yai National Park, Thailand. Photograph: A. Pierce.

Although none of the standard field guides (e.g., King 1975, Lekagul and Round 1991, Robson 1999) mentions the extent and broadness of the yellow median stripe as a diagnostic feature, this feature was shown by all Everett’s White-eye specimens examined at the Natural History Museum, Tring, U.K. Specimens of Oriental White-eyes Z. palpebrosus (other than Z. p. melanurus and some Z. p. siamensis, both of which may be completely yellow below) showed, at most, a narrow broken yellow median stripe along the belly that extended to neither the yellow on the vent nor the throat. In many Oriental White-eye specimens there was barely any yellow on the mid-line, and in all specimens the upperparts were more yellowish-green, with extensive yellow on the forecrown.

Bearing in mind the difficulty of distinguishing the upperparts colour (colder green in Everett’s, more yellowgreen in Oriental White-eye) or the precise shade of greyish-white on the flanks, the extent of yellow on the belly is possibly the best field character for distinguishing these species.

So, how many species of white-eye are resident in Khao Yai and the Dong Phaya Yen Forest Complex of northeast
Thailand, and do Oriental and Everett’s White-eyes occur there together? In fact, Deignan (1963) did not list Oriental White-eye for anywhere in the north-east, or away from the coast in eastern Thailand. Although Dickinson (1963), Dickinson and Tubb (1964) and McClure (1974) all listed Oriental White-eye for Khao Yai, there were no Zosterops spp. among the small number of bird specimens collected in Khao Yai during the 1960s (Dickinson and Chaiyaphun 1968). The listing of Oriental White-eye was based on conversation between E. C. Dickinson and H. G. Deignan, in which the latter supposed that Oriental White-eye was the most likely white-eye species to be found in Khao Yai. However, in 1968, Dickinson identified a flock of 12 white-eyes in Khao Yai as Everett’s White-eye on the basis of their ‘very dark flanks’, and all white-eyes he saw subsequently were likewise identified as Everett’s White-eye (E. C. Dickinson in litt. 2005). White-eyes in Khao Yai were also independently identified as Everett’s by S. Tantidapitak (verbally 2005), from comparison of video images of both Oriental and Everett’s White-eyes in other parts of their Thai range, especially in the peninsula.

Thailand’s Dong Phaya Yen forest complex supports two other species that, like Everett’s White-eye, are mainly Sundaic in distribution: Scaly-crowned Babbler Malacopteron cinereum and Moustached Hawk Cuckoo Hierococcyx vagans (Lynam et al. in press, Lekagul and Round 1991). These species, however, are known elsewhere in Indochina, in south Laos (both), Cambodia and Annam (M. cinereum only: Robson 2000). Although Everett’s White-eye has now been confirmed in Khao Yai, there are, as yet, no records from elsewhere in Indochina other than from Khao Soi Dao, Chanthaburi province, south-east Thailand. This strongly suggests that further surveys may reveal as yet undiscovered, outlying populations of Everett’s White-eyes in moist evergreen hill-slope habitats in Indochina, almost certainly in the Cardamom Mountains of south-west Cambodia, and perhaps elsewhere.

Thus, in addition to further surveys for Everett’s White-eye, more work is also required to elucidate the range of Oriental White-eye in north-east and eastern Thailand and possibly elsewhere in the Indochinese region. Although Oriental White-eye is apparently widespread in Indochina (King et al. 1975, Robson 1999, Dickinson 2003), in the absence of specimens or photographs the presence of this species in Khao Yai and elsewhere in Dong Phaya Yen must currently be considered as unconfirmed. If it does occur, it is perhaps more likely to be found at lower elevations, in disturbed habitats or deciduous woodland around the park boundaries.

REFERENCES
Deignan, H. G. (1963) Checklist of the birds of Thailand. U.S. Nat. Mus. Bulletin 226.

Dickinson, E. C. (1963) A preliminary list of the birds of Khao Yai National Park. Nat. Hist. Bull. Siam Soc. 20: 183–204.

Dickinson, E. C. (1967) A further contribution on the birds of Khao Yai National Park. Nat. Hist. Bull. Siam Soc. 22: 173–184.

Dickinson, E. C., ed. (2003) The Howard and Moore complete checklist of the birds of the world. Third edition. Princeton, U.S.A.: Princeton University Press.

Dickinson, E. C. and Chaiyaphun, S. (1968) Notes on Thai birds I. On a small collection of birds from in or near Nakhorn Ratchasima province, Eastern Thailand. Nat. Hist. Bull. Siam Soc. 22: 307–315.

Dickinson, E. C. and Tubb, J. A. (1964) Some additions and corrections to the preliminary list of the birds of Khao Yai National Park. Nat. Hist. Bull. Siam Soc. 20: 269–277.

King, B., Dickinson, E. C. and Woodcock, M. W. (1975) A field guide to the birds of South-East Asia. London: Collins.

Lekagul, B. and Round, P. D. (1991) A guide to the birds of Thailand. Bangkok: Saha Karn Bhaet.

Lynam, A. J., Round, P. D. and Brockelman, W. Y. (in press) Status of birds and large mammals in Thailand’s Dong Phayayen-Khao Yai forest complex. Bangkok: Biodiversity Research and Training Programme.

McClure, H. E. (1974) Some bionomics of the birds of Khao Yai National Park, Thailand. Nat. Hist. Bull Siam Soc. 25(3–4): 99–194.

Robson, C. (2000) A field guide to the birds of South-East Asia. London: New Holland.

Kindly submitted by:

Andrew J. Pierce, King Mongkut’s University of Technology Thonburi, School of Bioresources and Technology, Bangkhunthien, Bangkok 10150, Thailand. Email: andrew@pdti.kmutt.ac.th

Philip D. Round, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand. Email: frpdr@mahidol.ac.th