The identification of Chinese Egret and Pacific Reef Egret: 2 Neck shape and posture
Bare part coloration In our experience, non-breeding plumaged Chinese Egrets can show a wide variation in bare-part coloration. Recent observations in Korea, Japan and Singapore, and studies of photographs, indicate that the bill is typically largely blackish, with the basal half to two-thirds of the lower mandible sharply edged strongly orange or yellow, sometimes extending just above the cutting edge in the final third. The legs are greenish (with feet near-concolorous), often with some obvious blackish scaling on the shins. The lores are greenish through to greyish, and the irides are a pale whitish-yellow.
There is little or no information in the literature on the seasonal changes of bare part coloration of Pacific Reef Egret. However, our observations of dark-phase birds throughout the East Asian range (in all months) and white-phase birds in Singapore (in January) indicate that they show less clean-cut bills which are duller in dark-phase birds, with more extensively orangy-brown lower mandibles. In white-phase birds, the shins often lack the obvious scaling seen in Chinese Egret. Both phases have dark brown or yellow irides which appear duller than the pale irides of Chinese Egret. A more detailed appraisal of bare part coloration of Egretta species in North-East Asia is in preparation by NM and he would welcome comments and observations on this topic sent to the address below. Although outside the scope of this note, other features that can be useful when identifying Chinese Egret in the field are habitat preference and behaviour of the birds in question. Although Chinese Egrets utilise a variety of coastal habitats, they usually prefer feeding on intertidal mudflats. However, they roost on rocky shores, posts, islets or shingle banks and, where numerous, in tight groups. Pacific Reef Egrets prefer to feed on rockier shores or reefs, in areas influenced by wave action, often (though by no means always) occurring singly. Typically, Chinese Egret is more active when feeding and uses a variety of foraging techniques. One of these involves alternate walking and running through tidal-flat shallows, covering several hundred metres in a circuit. Others techniques include waiting (usually for shorter periods than other egret species) and, rarely, foot vibration. Pacific Reef Egrets appear more lethargic when foraging, usually carefully walking over smaller areas, waiting for long periods and rarely running. We hope these features shed some light on the problems that have long hampered the identification of non-breeding Chinese Egret, and in particular their separation from white-phase Pacific Reef Egret. Accurate identification of birds in non-breeding plumage is essential in determining the distribution and numbers of this globally threatened species. Acknowledgements References
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