The identification of Chinese Egret and Pacific Reef Egret

by Colin M. Poole, Jin-Young Park and Nial Moores, from OBC Bulletin 30, November 1999.

In Birding Sites in Malaysia, supplement to OBC Bull. 20 (1), plate 4 is labelled as showing a Chinese Egret Egretta eulophotes feeding alongside a Pacific Reef Egret Egretta sacra (reproduced on page 39, photo 1). However, in our opinion, both birds in this photo are Chinese Egret, with the bird on the right being in non-breeding plumage. We believe that the same error is also made in the first edition of Birds: A Photographic Guide to the Birds of Peninsular Malaysia and Singapore (2), where the photograph labelled as Pacific Reef Egret (photo 3) shows a similar non-breeding plumage Chinese Egret. The photographer, Morten Strange, informs us that both pictures were taken over the period 8–10th April 1991, at the northern banks of the Seleta River estuary on the coastal side of Khtib Bongsu, Singapore.

It appears that the identification of both birds was based primarily on bare-part coloration. However, we believe this should not be relied on for certain identification and it should only be used to support observations of more consistent structural characteristics.

We base our re-identification largely on the following characteristics:

Bill shape
Chinese Egret typically has a more symmetrical bill, which is of a similar thickness for most of its length and only narrows in the last quarter towards the tip. This gives the bill a dagger-like profile. In Pacific Reef Egret the whole bill typically narrows gradually from the heavier-looking base. The culmen is rather more convex and the lower mandible straighter, with the upper mandible sometimes appearing to overlap the lower mandible at the tip. This gives the whole bill a rather more asymmetrical drooping, or droop-tipped, appearance.

Chinese Egret
(Morten Strange)

Leg length
Pacific Reef Egret has noticeably shorter legs than Chinese Egret, particularly in the tibia. In Pacific Reef Egret the tibia is significantly shorter than the tarsus so that all of the 'leg-length' appears to be in the tarsus. The legs also appear stouter, with chunkier knees in Pacific Reef Egret. In Chinese Egret the tibia is longer than that of Pacific Reef Egret, giving the slender legs a more balanced, proportioned appearance.

Jowl
Pacific Reef Egret often appears heavy-jowled, but Chinese Egret never appears to show this feature.

Pacific Reef Egret
(Morten Strange)

Eye position and loral shape
There appears to be a difference in the position of the eyes. In Chinese Egret the eyes are set noticeably above the gape. In Pacific Reef Egret they appear lower and closer to the bill. This difference is accentuated both by the apparent presence of a skeletal ridge above the eye in Chinese Egret, and by the difference in the shape of the loral skin. The latter appears narrower and more angled in Chinese Egret and broader and blunter in Pacific Reef Egret (often as wide as the bill at the bill-base).

| Chinese or Pacific Reef Egret?: 2 |