HKBWS BBS 香港觀鳥會新聞組


    
      
        HKBWS BBS 香 港 觀 鳥 會 新 聞 組
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        Discussion Area 討論區 >> Bird Identification 鳥類辨識 >>   Unsure Terns again ?
        
(Message started by: Neil on Jun 5^th, 2006, 7:04am)

Title: Unsure Terns again ?
Post by Neil on Jun 5^th, 2006, 7:04am

This photo was taken on the 1st June. It looks like a Whiskered Tern in the centre but is it a Common Tern at the rear/right? Neil.

Mai Po Nature Reserve,
Hong Kong,
China.
01/06/06

Olympus 7070wz plus Swarovski STS80HD scope and Sw 30x eyepiece and DCA adapter

http://www.pbase.com/neilfif11/image/61313472.jpg

Title: Re: Unsure Terns again ?
Post by David_Diskin on Jun 5^th, 2006, 9:20pm

The tern in the centre of the picture is Common Tern and not Whiskered Tern. Whiskered Tern in breeding plumage shows greyer upperparts and much darker grey underparts that contrast with the white cheek. These features are evident in Allen’s original photo that began this thread. The bird in the centre is paler and has a longer, more slender bill than Whiskered shows.

Interestingly, this bird shows a red base to the bill and reddish legs, suggestive of the race tibetana or minussensis rather than longipennis – the latter seems to be commoner in Hong Kong and shows a black bill, blackish legs and greyer underparts, especially on the belly. However, the taxonomy of Common Tern is controversial, and there appears to be substantial overlap and intergradation between the various subspecies. (Indeed, some authorities consider minussenis not to be a genuine taxon!)

The second bird at the rear right is more problematic and, given the frontal view, does look very much like a Whiskered Tern. However, I'm not completely sure that this isn't a rather dark, rain-bedraggled longipennis Common Tern and would welcome other opinions.

Interesting photos from Allen, Owen and Neil …… Keep up the good work!

dave