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Subject: Terns at Sai Kung Pier May 2016 [Print This Page]
Author: ((華仔))    Time: 25/05/2016 11:13     Subject: Terns at Sai Kung Pier May 2016

Sai Kung Pier HK May 2016
Is my first time saw such different kind of terns gathering at Sai Kung pier
Whiskered Tern,
Black-naped Tern,
Roseate Tern,
Gull-Billed Tern,
White-winged Tern

https://youtu.be/hTN9-Vh26pE


















[ 本帖最後由 ((華仔)) 於 25/05/2016 11:24 編輯 ]

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Author: ((華仔))    Time: 26/05/2016 12:12

Photo add..


















[ 本帖最後由 ((華仔)) 於 26/05/2016 12:16 編輯 ]

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Author: ajohn    Time: 30/05/2016 14:48

Do you have any more photos of the bird in the 12th picture of the second post? This bird looks very interesting, and doesn't look like a typical White-winged. Flight shots would be particularly useful.
Author: lpaul    Time: 30/05/2016 15:39

I agree - its clearly a Black Tern!! Which would be a first for HK!  When were the pictures taken?
Author: ((華仔))    Time: 30/05/2016 20:11

Quote:
原帖由 ajohn 於 30/05/2016 14:48 發表
Do you have any more photos of the bird in the 12th picture of the second post? This bird looks very interesting, and doesn't look like a typical White-winged. Flight shots would be particularly usefu ...
Sorry John, I have no kept watching on this bird at that time,
Only took a few same pictures while it stayed alone & close to me!
Author: ((華仔))    Time: 30/05/2016 20:15

Quote:
原帖由 lpaul 於 30/05/2016 15:39 發表
I agree - its clearly a Black Tern!! Which would be a first for HK!  When were the pictures taken?
Hello Paul,
Photo date : 21st May 2016 around 3:15P.M.

Kevin
Author: jsk_ppp    Time: 30/05/2016 21:14

Congratulations! Great find!
Author: ((華仔))    Time: 30/05/2016 22:42

I have found three more photos took at noon on the same day!
it wing's color look like the same but body was darker,
I cannot confirm is it the same bird, if yes,
would it be a hybird??





[ 本帖最後由 ((華仔)) 於 30/05/2016 22:50 編輯 ]

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Author: ((華仔))    Time: 31/05/2016 21:51

One more near the same time at 3:15PM
Is much closer to the above three pictures




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Author: ((華仔))    Time: 1/06/2016 00:20

Photo at 13:23PM
Found no similar tern



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Author: ajohn    Time: 2/06/2016 17:36

Thanks you for looking for the additional photos and for posting the ones you have. These all are clearly White-winged Terns - the black underwing coverts are absolutely conclusive on that ID.

I'm not entirely sure whether the bird in flight with grey upperwings is the same as the bird I originally asked about - there are certainly some similarities.

I'm now inclined to think that the bird I originally asked about is actually a White-winged Tern, rather than Black. Besides the fact that no further photos of Black have turned up, I think that the leg length fits better for White-winged (Black is very short-legged), and the bill is perhaps too strongly curved on the culmen. It is a shame that nothing shows the rump or underwing to help with ID.

I had always thought that these two species were relatively easy to separate in breeding plumage, so for me it is an interesting lesson that the ID of this individual is not straight-forward. I will need to pay more attention to variability in breeding White-winged Tern in future!
Author: msamuel    Time: 2/06/2016 21:47

I agree with John.
Since many terns were photographed but no one has white underwing covert, I incline to think that the standing one is also a White-winged Tern.  At least it is hard for me to conclude that it is a Black Tern.

[ Last edited by msamuel at 2/06/2016 21:49 ]
Author: mchristine    Time: 2/06/2016 23:29     Subject: Interesting findings

Finding No 1:

The differentiation between white-winged and black tern was depicted on P189 of Encyclopedia of European Birds as follows:

" These two species can be told apart very easily in summer plumage, however, because as its name suggests, the White -winged has prominent white wing coverts.  Even during the winter, whereas the Black Tern has a consistent black cap, the head markings of its white-winged relative are reduced to pale black streaks extending back behind the eye, with an isolated black spot on each side of the head behind the eye."

Based on the above way of differentiation, the photo taken should be a white-winged rather than black tern.

Finding No 2:

According to P.104 of A Checklist on the Classification and Distribution of the Birds of China(Second Edition)with ZHENG Guangmei as Chief Editor, Black Tern was found in Hong Kong as well.  So even if a Black Tern was found in Hong Kong, it was not a Hong Kong First.  What a mystery!!! Who was the person who had found the Hong Kong First Black Tern and when was that??????

Looking forward to hearing any expert advice.
Author: lrichard    Time: 3/06/2016 15:59

Christine raises an interesting point about Zheng’s checklist recording Black Tern for Guangdong.

The origin of the record is almost certainly an article by E.A. Aylmer, one of the leading writers on birds in Hong Kong in the 1930s. Entitled “The English Bittern”, the article describes the breeding behavior of Great Bitterns at a bird sanctuary in Norfolk and mentions other birds seen in the Norfolk Broads, including Black Tern (Hong Kong Naturalist Vol. 7, pages 222-224, December 1936). Unfortunately, the article does not make it absolutely clear that the Norfolk Broads are in the UK, not HK!

This lack of clarity led to confusion as T.H. Cheng, the great Chinese ornithologist of his generation, understood the locality to be somewhere in Hong Kong. Thus, Black Tern appears in his list of Non-passerines in Guangdong (Cheng 1940) with the text “Hong Kong, Aylmer 1936” and again with a similar text “Hong Kong - Aylmer” in his Synopsis of the Avifauna of China (Cheng 1987). Cheng is of course a major source for Zheng’s checklists.

I don’t know of any other records of Black Tern claimed for the Guangdong-Hong Kong-Macao region which might account for the species being listed for Guangdong by Zheng. Unless other credible records come to light, the species clearly should not be on the Guangdong-Hong Kong-Macao list. The only marsh terns with certain records for the region are Whiskered Tern Chlidonias hybrida and White-winged Tern C. leucopterus.
Author: mchristine    Time: 3/06/2016 17:16

Dear lrichard,

I am grateful to have the mystery solved.  You are indeed a valuable history book of HKBWS!!!!
Author: lrichard    Time: 3/06/2016 17:26

Thanks, Christine.

BTW I totally agree with John that the available photos show a White-winged Tern, and not a Black tern
Author: kkchang168    Time: 4/06/2016 10:54

Thank you all for all these in-depth researches. I am very happy to see those discussion. I think it is very helpful for me, a very green birdwatcher, to learn more. I would like to see more these kind of constructive discussion in HKBWS forum in the future. Solute



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