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Subject: Common House Martin (?) at Tai Sang Wai today [Print This Page]

Author: John Holmes Time: 9/12/2012 14:45 Subject: Common House Martin (?) at Tai Sang Wai today

9th Dec 2012
ID Mk IV + 800mm lens.

Four poor "record" shots of what may be a Common House Martin.

There seemed to be only one "House Martin" around, so hard to give size comparison.

The bird in photo 1 is the same bird as in as 2,3, & 4 I think.

The amount of white on the rump (2,3) attracted my attention.

There seems little darkness on the flanks, (note shadow of wing in pic 4) I fancy that the white underside goes right up to the chin.

(I have noted the contents of Paul Leader's paper on p. 263 of the 2009-10 report, and offer these record shots for comments/discussion by anyone !)

Pic 5 is a "re-post" of an Asian House Martin I posted here last year

[ Last edited by John Holmes at 9/12/2012 19:12 ]

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Image Attachment: [Asian House Martin 2011] Martins_0218d.jpg (9/12/2012 14:45, 81.38 KB) / Download count 543
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Author: lpaul Time: 9/12/2012 19:22

I think this is a Northern House Martin. Whilst the tail fork looks too shallow for that species the extensive white rump which includes the uppertail coverts, the white underparts and lack of black on the chin are diagnostic of Northern House Martin and the eastern subspecies lagopodum.

Author: wgeoff Time: 9/12/2012 20:22

Great record John.

Wherever you go, this has been a spectacular autumn. Let's hope the winter keeps it going.

[ Last edited by wgeoff at 9/12/2012 20:47 ]

Author: kmike Time: 9/12/2012 23:38

Nice one John.

One question - the first paper suggests Northern House Martin should not show any black below the eye, which this bird does show. While the big white rump and very pale underparts are obvious I'd be interested to hear which features should predominate in deciding between Asian and Northern, or when the horrors of hybridisation need to be considered.

Cheers
Mike

Author: lpaul Time: 10/12/2012 10:11

Mike,

I think this bird clearly does not show black below the bill...

Author: ajohn Time: 10/12/2012 10:33

Mike's question is about the bird showing black below the eye, not the bill. I am not aware of this being a feature of Northern, it is not mentioned in the first paper, and the photos in the first paper appear to show black below the eye. Perhaps a misunderstanding?
The relevant feature is whether there is black below the bill, and I agree that the bird in question does not show black below the bill (the last photo does, of course, but that's a different bird!)

Author: brendank Time: 10/12/2012 11:23

Graham pointed out this thread to me, http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1 , and by the amount of black beneath the bill the lower bird in the photos should be a Northern House Martin too.

Author: lpaul Time: 10/12/2012 14:27

I have seen reference in the literature to the fact than nominate dasypus may lack black below the bill. However, I have not seen this any of the dasypus I have trapped (in HK and on the breeding grounds) or on skins I have examined so I'm not entirely convinced on this. That said nigrimentalis consistently exhibits more black below the bill than nominate (John's final image is a classic nigrimentalis). In terms of the extent of the white rump, it is worth noting that in the subspecies of Northern HM which breeds in NW China (and hence could occur in HK) the longest upppertail coverts are black rather than white (= lagopodum) and as such has a rump patch similar to that of nominate dasypus, however, that subspecies has a very deeply forked tail which should be obvious in the field.

The bird in the link provided by Brenden is probably Northern based on large body size, lack of black below bill and clean white underparts, but without information on rump pattern and tail structure I don't think it can id'd with any certainty.

Author: ajohn Time: 10/12/2012 15:51

The last photo in the lnik from Brendan shows dark-centred longest undertail coverts. Does this favour Asian over Northern? Of course, it may not be the same bird as in other photos.
Paul, I remember discussing this photo with you before. I think at the time you favoured dasypus for these. You were watching the martins at MP car park that day, and did not report any as being potential Northerns.

Author: handrew Time: 10/12/2012 19:23

Great find, John. Beats my Grey Bushchat :-(

Author: kmike Time: 10/12/2012 20:09

Many thanks for the clarifications.
Congratulations on a great find John.

Cheers

Mike

Author: John Holmes Time: 15/12/2012 12:17

Thanks to everyone who had a close look at the photos, and for the illuminating comments.

I'm going to be looking at House Martins even more closely in the future !

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