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Some Riparia martins from Taiwan (September 2018)

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Old Tuesday 10th September 2019, 07:21   #26
SteveMM
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Originally Posted by johnallcock View Post
This has been an interesting thread so far.

The Riparia martins in Hong Kong have a complicated history - initially thought to all be Sand Martins, they were then reassessed and thought to be Pale Martins, but birds trapped in recent years have all turned out to be Sand on DNA analysis. At the moment we only know that Sand definitely occurs, but there is no clear reason why fokiensis wouldn't occur here as well.

Checking the trapping records, we have trapped first year birds in suspended moult (inner primaries replaced, outers retained) in October/November, and birds in active wing moult in April. I'm not sure whether any of these were confirmed for species from DNA analysis.
Hi John,

How about the migration there now? Are there Sand Martin-types moving through Hong Kong in September? My intuition (which is frequently wrong) would tell me that, if this is post-fledging dispersal of fohkienensis Pale Martin, it might only be a local phenomenon (i.e. just across the Taiwan Strait).

Mac's posts above show that Sand Martins are on the move in the region right now, and there's no reason why they couldn't have penetrated this far south already.

As regards the trapping records, my current 'mental model' (which is subject to constant revision) would tell me that the April birds would have to be first-year Sand Martins which had migrated as juveniles and not managed to complete the post-juvenile moult on the wintering grounds. The April dates would fit in well with the April/May migration of northbound Riparia through outlying islands here at that time (birds that I assume to be Sand Martins).

As for the autumn first-years.....?

Steve
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Old Tuesday 10th September 2019, 07:39   #27
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It's interesting that you get movements of Grey-throated Martins. Do you know where they go? They are extremely rare here - only two records, one of which was in early October, which fits well with your observations.

Maybe knowing about the movements of Grey-throated could reveal more about fokiensis Pale Martins. If Grey-throated don't move much, perhaps the same is true of [i]fokiensis[/I], which may explain why they are rarely seen far from the breeding areas.
The Grey-throated Sand Martins are resident and all the movements are local.

The area I find these birds in floods at this time of year, and thousands of birds of various types (waders, herons etc) congregate there, hence my interest in watching it. Once it dries out, it's just barren dried up mud/dust, with nothing of interest to see.

There's a vast network of private fishponds to the north, south, and inland of here, and I suspect the Grey-throated Sand Martins disperse amongst these to spend the winter months there (with big flocks of Striated and other swallows). As these are concrete-sided, deep, and always full, they're a very poor environment for birding in so I spend no time there.

As regards fohkienensis, I also wonder if this taxon might not essentially be resident.

Last edited by SteveMM : Tuesday 10th September 2019 at 08:19. Reason: Comment added
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Old Thursday 12th September 2019, 03:16   #28
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this thread (and to put it back on topic)
I suppose that after this rap on the knuckles from Steve, I should retire from this thread.

However, at the risk of seeming selfish, I'll ask one more question. (I've often learned a lot from threads on BF that I've followed without posting once, so maybe there are a couple of people who will get the same benefit from this thread.)

Yesterday, I went back to my usual patch which was very quiet.

(The weird weather we have had this year, as for the last three years when all sorts of records have been broken and by a lot, must also be changing bird behaviour a bit. I don't want to bore you, but to give an example, this week we have had the four hottest September minimum daily temperatures in our prefecture since records began in 1953 - the hottest of which (26.3C) beat the previous record from 2010 by 1.2C.)

Anyway my question has nothing to do with the weather really. As I was leaving, I took some photos of the hirundines just in case there was something interesting. Again, the number of Red-rumped Swallows was large.

The two photos that I attach must surely be a Sand Martin (I think; I didn't notice at the time).

My question is about the tail. On both the underview and the overview, there are clear white spots across the tail. I have seven books which purport to describe this bird (including Birds of Europe) - and not one of them shows these white spots in their photos or illustrations; most, indeed show a closed tail on all illustrations. But those that seem to show an open tail also don't seem to show these spots. (But I've seen this on Rock Martins in Africa.)

All my photos in this place are taken with a handheld 300mm lens.

Assuming that these spots are a Sand Martin feature, then I wonder if I have been underestimating the numbers (still small, and only on migration) of these birds where I am in central Japan. Because if I saw in this patch and with my naked eye a slightly forked tail with white spots like these, then I would assume it was a regular Barn Swallow, and wouldn't bother to take any photo, since I can take photos of Barn Swallow three metres from where I am typing this.

Anyway, are these spots a Sand Martin feature, or am I missing something (agaiN)?
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Old Thursday 12th September 2019, 04:36   #29
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I suppose that after this rap on the knuckles from Steve, I should retire from this thread.
Hi Mac,

Apologies if you interpreted my comment that way, it wasn't meant as a reprimand. I just took it that the thread had already run out of steam given that we had moved on to talking about pylons!

The birds you post are in fact Barn Swallows. Some juveniles don't acquire much blue gloss or red in the throat in their first year and can appear otherwise brownish. I've read somewhere that this is more frequent in Asian populations than it is elsewhere.

It is interesting to see that neither of these (northern) birds (assuming there to be two) is in primary moult. The first-year Barn Swallows that are currently arriving here are also not in primary moult.

Steve

Last edited by SteveMM : Thursday 12th September 2019 at 04:54. Reason: One afterthought!
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Old Thursday 12th September 2019, 05:22   #30
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How about the migration there now? Are there Sand Martin-types moving through Hong Kong in September? My intuition (which is frequently wrong) would tell me that, if this is post-fledging dispersal of fohkienensis Pale Martin, it might only be a local phenomenon (i.e. just across the Taiwan Strait).
Sorry, I realise I didn't reply to this. No, there's very little or no Riparia migration here at the moment. Most migration is during October-November and again in April-May, with a small number of birds in winter. I've seen very large flocks of hundreds or thousands in southwest Guangdong (a couple of hundred km to west of here) in winter but not many here.

To add to the confusion, I've seen a post-typhoon bird here in late July - maybe that was genuinely a Pale Martin?! Unfortunately I don't have more details - it wasn't the best of viewing conditions
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Old Thursday 12th September 2019, 09:07   #31
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Apologies if you interpreted my comment that way, it wasn't meant as a reprimand. I just took it that the thread had already run out of steam given that we had moved on to talking about pylons!
I know.

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The birds you post are in fact Barn Swallows. Some juveniles don't acquire much blue gloss or red in the throat in their first year and can appear otherwise brownish. I've read somewhere that this is more frequent in Asian populations than it is elsewhere.
Well until this thread I would have put this bird (just the one) down as a rare pale juvenile Barn Swallow. But now it's interesting (to me) that the face pattern is so like the Sand Martin, including the slight hook below the eye mask. If you cut off the tail part of the photo, what feature would show the difference?

I don't normally bother to photograph Barn Swallows because there are thousands here.

Looking back through my records, from two years ago I have one other bird as pale as this, and which I had noted as a specially pale Barn Swallow. It was at the very beginning of migration (I guess, though 10th August is actually a bit soon), but the reason I got a shot of it was that it was on a wire with a bird that I ID'd as a 'saturata' bird (not tytleri, I think), and this was the bird that stood out. The pale bird was something I noticed accidentally. Such pale birds are not in any way common. Young (even with a yellow gape) birds here usually have significant colouring as you can see from the later attached photo (this photo is actually from mid-May, and therefore an early brood; the swallows usually arrive here from mid-March (though this year we saw one bird on 3rd January).

Do you think that there's any possibility that juvenile saturata are actually especially pale? Incidentally, I've never noticed another saturata before or since, so maybe I'm wrong about this also (but, as I said, I don't really look closely at Barn Swallows).
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Old Thursday 12th September 2019, 13:24   #32
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Sorry, I realise I didn't reply to this. No, there's very little or no Riparia migration here at the moment.
Thanks, John. I've also today asked a friend on Kinmen (a very active birder who would notice if there was any kind of vis mig going on) if he has seen any Sand Martins yet this autumn, and he reports that he is still looking for his first.

If these birds in SW Taiwan are Sand Martins, then they really do represent the vanguard of the migration!
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Old Thursday 12th September 2019, 13:53   #33
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If you cut off the tail part of the photo, what feature would show the difference?
They are indeed very similar and do catch people out, e.g. http://orientalbirdimages.org/search..._ID=&Location= (as indeed do Grey-throated Sand Martins: http://orientalbirdimages.org/search..._ID=&Location= ).

They are longer-billed, though, larger and larger-headed, and generally dark blackish-brownish above. The white frame to the rear ear coverts should be more prominent in all but a worn Sand Martin, and once they take wing the colour of the underwing coverts helps! And, I'm a bit confused, why ignore the tail part anyway when that's where a very salient identification feature lies?

I can't help you with the various races of Barn Swallow, Mac, as I really have not given this species (and all its variation) the attention it deserves.

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Old Thursday 12th September 2019, 15:24   #34
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Ban Swallows are very variable in this part of the world - underparts varying from pale whitish to strong orange-buff. I think that this is partly geographical variation, but is also related to age, gender, wear and body condition (so they are more likely to have darker underparts if they are fit, fresh, adult and male). We get occasional birds that attract attention as possibly tytleri, but have never had a definite tytleri here. There is more work to be done on this species and I think someone may be working on the genetics.

Regarding Barn Swallow moult, I've just been through our ringing database. We've trapped a few adults with suspended moult in September-November, a couple of adults in active moult in December, and a few first-winter in active moult in February - early April. But most birds trapped do not show moult contrast. We have fewer around in mid-winter, so probably most birds moult somewhere further south at that time. Adults can be back at breeding sites from February.
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Old Thursday 12th September 2019, 22:30   #35
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Thanks Steve and John. Sorry for damaging your thread. I learned a lot. I knew I didn't have a good 'eye' for birds unlike many of the contributors here on BF, but it seems its even worse than I thought!
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