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Subject: Terns Today - id needed [Print This Page]

Author: Beetle Time: 28/09/2008 18:50 Subject: Terns Today - id needed

i am very confused with the terns we saw on the boat today.
I will be very happy if somebody can tell me how to identify these birds which have highly varying plumage. (the photo arranged roughly in time order)

1.common tern?

2.common?

3.Aleutian?

4.common?

10.

Author: lchunfai Time: 28/09/2008 19:17

Quote:

Original posted by Beetle at 28/09/2008 18:50
i am very confused with the terns we saw on the boat today.
I will be very happy if somebody can tell me how to identify these birds which have highly varying plumage. (the photo arranged roughly in t ...

#5 little tern???
#9 gull-billed tern???
#10 right aleutian???

thx

[ Last edited by lchunfai at 28/09/2008 19:22 ]

Author: ddavid Time: 29/09/2008 11:44 Subject: Tern ID

Yes, terns can be very confusing. My thoughts are below - open to correction, of course.

1. 1st-Winter Common Tern. Dark edges to the front and rear of the inner wing with a pale rectangular area in the middle of the wing.

2. Left hand bird = Aleutian Tern attaining winter plumage. White looking crown and a conspicuous white line in the grey wing caused by white fringes to the median coverts. The right hand bird = juv Aleutian Tern (?).

3. Aleutian Tern. Conspicuous dark edge to the secondaries on the underwing. Also note on the right upperwing the conspicuous white line formed by white tips to the median coverts (as for Pic 2).

4. Juv Aleutian Tern (?) (same as in pics 2 & 10). Very dark upperparts.

5. Aleutian Tern. Head pattern.

6. Aleutian Terns left and right, Common Tern centre. Head pattern & jizz indicate Aleutian Terns. Common is smaller, not so long-winged and has a conspicuous dark (carpal) mark on the wing.

7.White-winged Black Tern. Face pattern with (almost) isolated dark smudge behind eye.

8. Common Tern. Dark carpal patch on wing.

9. White-winged Black Tern. Face pattern with isolated dark smudge behind eye. Also dark markings on covert tips on underwing.

10. Adult & juv (?) Aleutian Terns. The adult still retains an almost summer head pattern.

[ Last edited by ddavid at 29/09/2008 16:30 ]

Author: tmichael Time: 2/10/2008 20:58

I agree with DAD's id of these birds, which is in line with how we identified at the time on the boat.

These and other shots taken that day are very informative with regard to combinations of features which help to separate what are often surprisingly similar species in autumn, either as juvenile/1st winter birds or as moulting adults.

The HY (hatching year) Aleutian Tern - it seemed there was just the one, which was attended by an adult - is I believe just the second such record for HK.

Mike Turnbull

Author: lchunfai Time: 2/10/2008 21:54

...我只有一是對

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