ddavid

When and where was the photo taken?

david

ddavid

I'm no expert but I think this a very difficult bird to ID. I can see why Richard suggested Sandwich Tern - the wing pattern fits 1st-summer Sandwich and there does seem to be pale tip to the bill in the photos. However, the "jizz" doesn't seem quite right to me (very subjective) and, as Richard points out, the leg colour in one of the photos is wrong for Sandwich.

Also, of course, HK is way out of range for Sandwich, which doesn't usually occur east of Sri Lanka - although Mark Brazil includes the species in Birds of East Asia on the basis of  a record from Taiwan.

My own personal feeling is that this is an odd Roseate Tern in non-adult plumage (1st-summer? 2nd-summer?) -  but I wouldn't bet my life, for what it's worth, on that assessment.

david

[ Last edited by ddavid at 21/08/2010 23:16 ]

ddavid

I'm not sure. If Sandwich Tern can turn up in Taiwan, then it could turn up in HK. Also, if say your 4th photo was the only photo you had, then I would probably say it was definitely a Sandwich Tern!!

It is a very difficult bird to ID - but I'm sure, given your photos, it will be pinned down in the end.

All the best

david

ddavid

Olsen & Larsson in Terns of Europe and North America (1995) write that Roseate Tern adults have a complete moult to winter plumage from June-July. Therefore any adults seen in August should (theoretically) already be in full winter plumage. Hence this bird may well be, as John suggests, a winter plumage adult Roseate Tern. I also agree that the wing pattern does not fit Common Tern.

david

ddavid

Apparently there are records of hybridisation between Common and Roseate terns in the USA and Europe. However, in this part of the world, I think there is little overlap (if any) in their breeding ranges.

I think the difficulty with this bird is, as John points out, simply because we aren't very familiar with the winter plumage of Roseate Terns. Most birders/photographers in HK see them in summer plumage on their breeding islands. The terns seem to leave the territory fairly early - I don't recall seeing any on the boat trips organised by the HKBWS in September - Common Terns & Aleutian Terns yes, but not Roseate.

So, all in all, an instructive set of photographs and an interesting discussion.

david

[ Last edited by ddavid at 22/08/2010 17:58 ]