ajohn

Hong Kong leg flags (using the colour combination White over Yellow) have been used for about 10 years. In this time, we have received some useful information about the movement of waders from Hong Kong due to resightings of birds here and overseas.

Because all waders from Hong Kong use the same flag combination, however, it has not previously been possible to recognise individual birds in the field. This limits the potential information which can be gained about the movements of individual birds and the duration for which an individual remains in Hong Kong. For example, we still do not know whether Marsh Sandpiper individuals remain in Hong Kong all winter or whether there is passage through Hong Kong, despite the fact that good numbers of this species have been flagged.

During this summer, the Hong Kong Ringing Group (HKRG) has obtained some engraved leg flags. These will allow individual birds to be recognised, so that we can gain this additional information. Engraved leg flags like these have been used successfully elsewhere for several years, and some Australian birds with engraved flags have been resighted in Hong Kong.

Last night, the HKRG was able to trap waders at Mai Po and we have fitted the first of the Hong Kong engraved leg flags. So far, 39 birds have been ringed: 22 Common Redshank, 9 Marsh Sandpiper, 5 Common Greenshank, 2 Greater Sand Plover and 1 Common Sandpiper. As usual,all have been fitted with the Hong Kong combination of White over Yellow. Both flags are engraved with a single letter followed by a single number (e.g. A1, B2, etc.) - the combination is the same on both flags. Photos are attached for Common Redshank, Common Greenshank and Marsh Sandpiper.

If anyone is at Mai Po over the coming weeks and months, I would like you to look out for these waders (and for any waders with leg flags). You can report them on the website, or by contacting me directly (jallcock @asiaecol. com.hk) All reports will be useful to gain a pattern of the birds behaviour in Hong Kong, and to see how long birds stay in this area. We hope that there will also be sightings from overseas. We plan to continue trapping over the course of the autumn and winter, so expect to see more of these birds (hopefully including more species) turning up in coming months.

As always, thank you to WWF-HK and Mai Po staff for their help with managing the reserve and giving permission for us to visit the site to conduct this research.

ajohn

Samuel,
As you guessed, your bird is a Common Redshank. It is a young bird (hatched this year), which often are not particularly red on the bill. Can you please let me know when and where you photographed the bird, so that I can add it to the list of resightings.
Thanks, John

ajohn

Thanks John. In fact, A0 was the first Whimbrel combination - about 30 minutes before A1 was used (on 14th September)

ajohn

Thank you for continuing to update the records. Please continue to post sightings of these leg-flagged birds. The Common Greenshank has been in Hong Kong now for about 2 months (flagged on 26 August) and the Greater Sandplover for over 1 month.

ajohn

Sze, thank you for drawing this to my attention. I have looked at the photos on HKWildlife. The flag number is very difficult to read, but appears to be A2 - this is another Greenshank ringed in late August.

ajohn

Thank you for the resightings John. The Redshank and Greenshank were flagged in September and the Godwits were flagged in January.  The Broad-billed Sandpiper resighting is perhaps the most interesting of your observations: only 11 have ever been flagged in Hong Kong, all in April 2004. I have not heard of any previous resightings of flagged individuals of this species.

Please keep these records of engraved flags coming, as they will provide interesting information on the behaviour of waders in the Deep Bay area. We hope to put more flags on over the next few weeks as waders stop over in Hong Kong.

[ Last edited by ajohn at 21/03/2011 09:12 ]

ajohn

Thank you for the suggestion, Captain. One reason I have not been doing this is that I am concerned that by providing the information publicly, people may just look up the date on which their bird was flagged and may not report the details to me. If this happened it would be counter-productive, as we could end up receiving less details about the observations. I will reconsider this position and may post something in future.

I am also considering ways in which we can make it easier for people to report resightings and increase observer awareness of the various marking schemes taking place in Hong Kong and elsewhere along the flyway. For the moment I am happy to respond to any observations which are reported to me, and if anyone has any questions about a particular individual I can provide details directly. Either post questions here or send me a PM. I will respond to any PM (or email) and will also respond on the website for any sighting which I consider to be significant.

I intend to post an update summary on the engraved flags in the coming weeks, to let people know about the resightings received so far and what these tell us about the waders in Deep Bay.

ajohn

I agree, it will be interesting to see how long some individuals stay.
For example, Black-tailed Godwit B1 was flagged in late January, so we know that this is an individual from the wintering population - does this mean it will depart earlier than the passage migrants currently arriving?
In this respect, keep a look out for Curlew Sandpipers. I am surprised that Bena's sighting is the only report so far - we flagged a large number of these earlier this week (so hopefully more sightings this weekend).  These are obviously migrants and it will be interesting to know how long they stop over in Hong Kong.

ajohn

I saw the following at Mai Po today:
Pond #11
Black-tailed Godwit B1
Common Greenshank A5
Also another Godwit with engraved flags (but I couldn't see the combination) and at least 2 Marsh Sandpipers with plain Hong Kong flags.

Pond #16/17
Curlew Sandpiper D3
Curlew Sandpiper E2
Common Greenshank A1

ajohn

Thanks for the continued sightings being posted here. We have now flagged over 250 birds using the engraved flags, and there are plenty to see.
Yesterday (5th April) at Mai Po I saw:
Boardwalk:
Pacific Golden Plover J0
Greater Sand Plover E8
Marsh Sandpiper A8, B0
Common Greenshank A6
Red-necked Stint A5
Curlew Sandpiper A4, B9, D7, J1, J5, L8, M4

Pond 16/17
Curlew Sandpiper B9, C2, J7, L1, L5, L8

ajohn

Thanks for the sightings Katherine.
Marsh Sandpiper B0 is interesting - it was flagged at the end of August 2010 and was not reported between August and April. Perhaps it has spent the winter elsewhere and is now returning north.

ajohn

Thank you for the sighting Paux. This is a bird flagged in September 2010, and is now returning on northward migration through Hong Kong.

ajohn

Today I have received news that three Curlew Sandpipers with engraved leg flags from Hong Kong have been resighted in Bohai Bay, China. Bohai Bay is almost 1900km from Hong Kong, on the shores of the Yellow Sea.  All three individuals were flagged in Hong Kong on 21st March and were resighted between 1st and 6th May (one was also resighted in Hong Kong on 2nd April).

These are the first sightings of our engraved flags reported from outside Hong Kong. We already knew that the Yellow Sea was an important stop-over site for waders migrating through Hong Kong, and there have been previous resightings from the area.

We have also now passed the landmark of 100 individuals resighted in Hong Kong (thanks to Katherine's last update). To date, over 400 birds have been fitted with engraved leg flags of 20 different species. Please continue to post records of any flags you see to help us build up a picture of the movement of these birds.

ajohn

Another significant observation reported to me is a Black-tailed Godwit (B6) photographed at Cheongli County, near Beidaihe (Hebei province) in early April. This bird was flagged at Mai Po on 22 January. This is only the second time a Black-tailed Godwit with Hong Kong flags has been resighted outside Hong Kong. At about 1980km, it is also the furthest resighting for any of the HK Engraved Leg Flags.

I have also received a report of Whimbrel A2, which was flagged last September and is now passing back through Hong Kong on northward migration.

ajohn

Southward wader passage is already apparent at Mai Po and surrounding areas, with moderate numbers of Redshank, Greenshank and Wood Sandpipers already present. The birds ringed with engraved flags last year may start to move through at any time now. At Mai Po yesterday, I noted one Redshank and one Greater Sand Plover with plain HK flags, both presumably on southward migration. I would like to remind any visitors to Mai Po to keep a look out for the engraved leg flags and report their sightings, either by posting here or by reporting to me directly (by PM or by email to jallcock AT asiaecol.com.hk). Thank you.

Of interest, at least two leg-flagged birds have spent the summer at Mai Po: Grey Plover C1 (which has been reported and photographed here) and Whimbrel A2 (which seems to have avoided most photographers!). Both are in their first summer (i.e. hatched in 2010) and it is not unusual for birds at that age not to return to the breeding grounds. Interestingly, the Whimbrel was flagged in September and obviously spent last winter further south before returning as far as Mai Po to spend the summer.

ajohn

Thanks Bena. This is the first resighting of a bird with engraved flags which appears to be returning south.
A6 was flagged last September and resighted twice in April. It is a first-summer bird so perhaps didn't breed this year, which may explain the early return date.

[ Last edited by ajohn at 20/07/2011 13:59 ]

ajohn

Thanks for posting this sighting - I would have missed this on the Chinese website. U6 was flagged at Mai Po in April and resighted at Mai Po in early May. The bird has presumably been to the breeding grounds and is now on southward migration.
This is now the greatest distance for one of the engraved leg flags (over 2000km).
If anyone is able to post to the website, I wonder if you could ask the photographer too submit the sighting to the Australian Wader Studies Group, who keep a list of leg flag reisghtings on the East Asia - Australia flyway. The contact e-mail is mintons @ ozemail.com.au

ajohn

Thanks for posting the photos hilldog and kenneth. It is interesting to see all these birds now migrating southwards, and the observations will hopefully help us to biuld a picture of the movements of birds in Hong Kong and beyond.

So far I am aware of 15 birds which have been seen on southward migration (9 Common Redshank, 4 Common Greenshank and 2 Black-tailed Godwits). There are also two flagged birds which spent the summer in Hong Kong (1 Whimbrel and 1 Grey Plover) and, of course, the Black-winged Stilt chick which Katherine resighted which was hatched at Mai Po.

I hope to write a more comprehensive summary of the initial findings from the engraved leg flags soon, but in the meantime please keep reporting any sightings.

ajohn

Late, were you able to confirm that this bird was B7? It's difficult to see the number on the photos but I agree that B7 looks like the most likely number. B7 was seen at MP in August.

Of interest, I resighted a Wood Sandpiper (A1) at Kam Tin on Monday which had been flagged at Mai Po 10 days earlier. The engraved flags will hopefully allow us to understand more about the local movement of wader species within Hong Kong, as well as the longer-distance movements along the flyway.

ajohn

Thank you all for continuing to post your sightings. These should be useful in understanding the movements of waders in the bay, and beyond.
Most of the recent sightings are (not surprisingly) of recently-flagged birds, the exception being Common Redshank B6 (photo'd by Paux) which was flagged back in August 2010, and has not been reported since last November.

hilldog, the birds you have reported as Greenshank are in fact Marsh Sandpipers. Note the very thin, straight bill and the long, slender legs.

Steve, it would be great if you did manage to find any of our birds at Olango. We have never had a bird from HK reported in the Philippines, but I always wonder whether some of our birds end up over there.

John

ajohn

It's great to see the returning Black-tailed Godwits from last winter - all of the 'B' flags in Kinni's post were flagged in January last year.

ajohn

Sorry, that was a bit unclear. I have a tendency (especially with birds like this) to think of birds in winters rather than calendar years.

Those godwits were flagged in January 2011 (i.e. last winter 2010/11). The bird with plain flags was flagged in a previous year (most likely in winter), but it is not possible to know exactly when.

[ Last edited by ajohn at 5/10/2011 07:30 ]

ajohn

As John's link should show, single yellow flags come from North-west Australia (but they are usually on the Right leg I think?)
The Broad-billed Sandpiper is probably a very good record, possibly the stint as well - I don't know how many reports they get from Philippines, but I think not many.
Report your sightings (or any flag sightings) to the Australian Wader Studies Group - the best e-mail contact is Heather Gibbs: mintons (at) ozemail.com.au

I'm glad you are getting some resightings - there must be many flagged birds passing through the Philippines but not recorded.

ajohn

Thanks for the resightings puppymic. Both C4 and E5 are Redshank which were flagged in 2010, and both birds have not been reported for over a year!

I managed to pick up a few flag sightings yesterday
Common Redshank A4, D3, R3
Common Greenshank A0, A1, A5, D4, D8
Marsh Sandpiper P9
Black-tailed Godwit B3
Lesser Sandplover A2.

The Lesser Sandplover is interesting - we have only flagged 2 with engraved flags, and this is the first resighting. The bird was flagged in September 2010. It is from the 'atrifrons' group, which is not often reported in Hong Kong. The bird is now in winter plumage - if anyone is able to get photos of this bird, it may help to understand the field ID of this species in Hong Kong in winter.

ajohn

Thanks Katherine. All are birds from September this year.

Meanwhile, from the other hide I saw
Marsh Sandpiper R4, S4
Common Greenshank A0, A9, E1

Greenshank A0 now has the longevity record for the engraved flags - 429 days since flagging (in August 2010). It probably overwintered last year (seen in November, February and March) and I expect will do so again this winter.

ajohn

Thanks Andrew. The photos aren't needed, as you have provided the flag numbers, location and date.

ajohn

Thanks Katherine and all others who have recently reported sightings.

The slightly higher daytime tides are obviously helping record flags. I managed to pick up a total of 18 combinations on Saturday, including (surprisingly) one Pacific Golden Plover and another PGP on which I could not get the complete combination.

It is interesting that GRey Plover C1 has reappeared - this bird oversummered in HK last year but hadn't been seen since September!

ajohn

Thanks for providing the link Sze.

I have heard from various sources that there is an overwintering Terek Sandpiper with engraved leg flags. I have not seen this bird. So far, no-one seems to have been able to read the engraved flags. It would be very interesting if someone was able to read the flags or photograph the bird, so that we are able to tell which individual has overwintered in Hong Kong.

I would also be particularly interested for anyone to keep a look out for Avocets with engraved flags. We have put engraved flags on 47 Avocet so far but have had relatively few resightings of this species (only 5 individuals), perhaps because it is difficult to pick out the flags among the large numbers of birds present.

ajohn

Thanks for reporting the Terek Sandpiper, Brendan. If this is the individual which has been overwintering, it is not the individual I expected - it is an adult flagged in September 2011 (I was expecting the overwintering bird to be a first-winter flagged in November).

Thanks to all for continuing to post the latest sightings. It seems there has been alrge number of resightings recently, perhaps with better tides. Of particular interest are the two Great Knot. These are the only two with engraved flags so far, and both were fairly late autumn (October and November) migrants last year but it is still surprising that both overwintered rather than moving south with most birds of this species. It's good to have received a few more observations of the flagged Avocets as well.

Wader migration should pick up in the next few weeks and it will be interesting to look out for sightings of north-bound migrants as they pass through. I hope that the engraved flags will allow us to look at the duration of the stop-over of individual migrants in Hong Kong, so all resightings would be of use.

ajohn

See my earlier post (#126 on 14 Feb). There has been an overwintering Terek Sandpiper with leg flags, reported to me by several observers who were unable to read the engraving. I had assumed Brendan's bird was the same, but it is possible that it is an early migrant (although it is still rather early for Terek Sandpiper migration).

ajohn

Thanks for these latest sightings. I am particularly pleased that Ho-fai managed to see the Curlew Sandpiper flag - I saw this bird in three different places on Saturday, but still couldn't manage to read the flag combination! P3 was flagged on 18 April 2011, and this is the first resighting.
In addition to these sightings, I managed two Terek Sandpipers with flags on Saturday (A2 and C7, both from last autumn). There were at least 3 flagged Avocets on the scrape at high tide, but frustratingly I could only read the combination on one of these.

I have also realised that one of two Black-tailed Godwit flags I read on Saturday (B6) is the bird seen last April near Beidaihe. This was the first bird with engraved HK leg flags to be seen outside Hong Kong, and is now also the first to be resighted back in Hong Kong after an observation elsewhere.

By the way, the combination E5 has not been used on a Marsh Sandpiper. This bird is in fact a Greenshank, but I agree that the photo is deceptive and makes the bird look slim-billed like a Marsh Sand.

[ Last edited by ajohn at 12/03/2012 14:26 ]

ajohn

Only waders will get coloured flags, so that we can follow the movements of these birds along the flyway when they are seen. /this is part of a scheme involving several countries along the flyway, each with it's own colour scheme. Waders are ideal for this study because the flags are easy to see in the field at a long distance, and provide information about the movement of the bird.

Other bird species are not routinely given colour rings. Certain species are the subject of particular study involving colour ringing (e.g. White-shouldered Starling in Hong Kong) but these species are exceptions. Most birds are only given metal rings with an individual identification number. It is these rings which you would have seen on the Chinese Bulbuls. It is usually not possible to read these in the field and information about the particular bird is usually not obtained unless the bird is retrapped. There have been a few cases in Hong Kong, however, when the ring has been read in the field or from photographs which have allowed the individual to be recognised.

ajohn

Thanks for these sightings. You obviously had a very good day at the Boardwalk!
Nice to see some returning Curlew Sandpipers. Coincidentally, 2 of these birds (E9 and H5) were flagged exactly one year ago, on 21 March 2011.
Great Knot L3 and Greater Sand Plover C7 are actually birds which have been here over the winter rather than returning individuals

If possible, please check the report of C3 on Greater Sand Plover - this flag has not yet been used on this species. It may be a different flag number.

With the returning waders, there may be many more reports to come in the next few weeks. Please continue to post any resightings. To date, we have received resightings of 269 individual birds with engraved flags (out of 689 flagged).

ajohn

Some interesting resightings again today. You may be particularly interested to know that Curlew Sandpiper H1 was last reported on 5th May 2011, in Bohai Bay (on the Yellow Sea near Tianjin), about 1900km from Hong Kong!

Richard's reports also include two presumed migrant Pacific Golden Plovers (H8 and H9, not seen since last spring - the others were seen here in February).
In addition to these I had another Curlew Sandpiper not yet reported here (E3) and a Greater Sand Plover (H1)

ajohn

Ho-fai, The Curlew Sandpiper you posted has an orange flag (rather than red). This indicates that the bird was flagged in Victoria, SE Australia.

ajohn

A couple of new arrivals at MP today were Greater Sand Plover K4 and Curlew Sandpiper R3, both on #16/17 at high tide.
Also a noticeable increase in Great Knot today, but no leg-flagged birds.

ajohn

There have been a few species in HK flagged with the combination E4. Given the information that you thought the bird was a Greenshank, I think this limits the possibilities to only three birds: Common Greenshank, Common Redshank or perhaps Terek Sandpiper. The other species flagged with E4 (Red-necked Stint, Curlew Sandpiper, Greater Sandplover and Pied Avocet) should not be confusable with Greenshank. The usual confusion species with Greenshank is Marsh Sandpiper, but this has not yet been flagged with the combination E4.

Common Greenshank E4 was flagged in September 2011 and has been resighted twice at Mai Po in mid-March 2012. Common Redshank E4 was flagged in September 2010 and has never been reported. Terek Sandpiper E4 was flagged in September 2011 and has also never been reported. On balance, I think you are probably correct and the bird you saw was the Common Greenshank.

Thank you for reporting this sighting - we have had surprinsingly few resightings from Nam Sang Wai.

ajohn

The numbers on the flags allow each individual bird to be recognised in the field. The white over yellow flag combination indicates that the bird was flagged in Hong Kong, and since 2010 we have been using these engraved flags so that individuals can be recognised (there are still some birds around with plain white over yellow flags). The actual letter/number combination dones't really mean anything, except to allow us to identify the individual (all of these birds also have a number metal ring, but this cannot be read without retrapping the bird).

We mostly follow a sequence A0-A9, B0-B9, etc. but some species have not been used strictly in sequence. This is the reason for example that Marsh Sandpiper has not used E4, despite there being other individuals with later letter/number combinations - E4 will be used later on this species. For some species (especially Curlew Sandpiper) we have nearly run out of letter-number combinations and will soon move onto letter-letter combinations.

The information from these flags allows us to know more about the movement of individual birds, including the length of time they spend in Hong Kong, their movements around the Deep Bay area, and in some cases their movements overseas. Since 2010 we have had resightings of engraved Hong Kong flags in northern China, Australia and Indonesia. Different colour combinations indicate different flagging locations, and birds can be seen in Hong Kong with flags from overseas, especially Australia (single yellow or orange flags) and Chongming, China (Black over white flags).

I hope this sufficiently explains the background to the flagging system.

ajohn

Thank you all for continuing to report sightings. Most of the recent reports have been of recently-flagged birds, but it is interesting that we are getting some older reports - some Greenshank and Redshank flagged in 2010 have been seen recently. There are also returning Curlew Sandpipers, Terek Sandpipers and Grey-tailed Tattlers which were flagged in 2011 (not all sightings are posted on this website). It is interesting that we are also getting sightings away from Mai Po reserve, including the Long-toed Stint which spent much of last week along the Mai Po Access Road (the bird photographed by Samuel).

We have also just received an observation away from HK - a Grey Plover (J3) resighted at Nanpu, Bohai Bay (Hebei province) in mid-April. This is the first resighting of a Grey Plover with engraved flags outside Hong Kong, but we have previously had reports of birds with plain Hong Kong flags at Yalujiang. J3 was flagged at Mai Po in early March.

ajohn

Interestingly Terek Sandpiper K2 was back at Mai Po this morning.
Other leg-flagged birds still present this summer include Terek Sandpiper L0, Greenshank D7 and a Marsh Sandpiper (I think N0, but it was slightly too distant to be sure).

ajohn

Thanks for posting this sighting John. It is indeed a returning bird. A3 was flagged on the first day that engraved flags were used in Hong Kong, on 26th August 2010 - making this our oldest resighting to date (690 days). It had not been reported since 5 September 2010!
The same bird was present on the Mai Po Scrape today, along with four other Redshank with engraved flags (D3, P1, P5 and S2) and one Greenshank (A5).

[ Last edited by ajohn at 18/07/2012 09:12 ]

ajohn

Greater Sandplover C7 is an interesting resighting. It was originally flagged in September 2010, but the only sightings since then were in February and March 2012, suggesting it may have overwintered in Deep Bay last year. It will be interesting to see if it stays in the bay now or moves on.

ajohn

Thanks Richard.
The godwit is L0. So far the only engraved flags used in Hong Kong have been one letter followed by one number, with the exception of a few Curlew Sandpipers, on which we have now switched to a letter-letter combination.

ajohn

Hello hkbear.
Your bird is a Common Redshank. Note the long, reddish legs, very different from Curlew Sandpiper.
U6 was flagged on 20th August 2012, but surprisingly has only been since once since then (on 11th September), so thank you for reporting it.

ajohn

The metal ring on each bird is unique - no other bird of any species will have the same number/letter combination.

But the engraved leg flags can be used on more than one species. But the code will only be used once on each species, so that we can identify the individual involved. It is therefore important that you provide not only the letter/number combination, but also the species involved. The combination U6 has been used on Common Redshank and Curlew Sandpiper (but no other species yet). Others are used on more species, e.g. A0 has already been used on 10 different species!

This is largely because the combination of one letter plus one number only gives around 200 combinations - we would very quickly run out of combinations if each could be used only once. In order to get more combinations, you need more letters/numbers. This adds extra weight to the flag, and requires that the writing is smaller - which would make them difficult or impossible to read in the field (much like the metal rings).

ajohn

R5 has not yet been used on an Avocet. Is it possible this was another combination (maybe K5?)
The other two avocets reported are interesting - neither has been resighted previously. K2 was flagged in December 2011, but A6 was flagged back in January 2011 - I wonder where it has been since then?

ajohn

Interestingly P2 was reported at Nam Sang Wai in October and December last year (including one sighting by a certain J Holmes), suggesting that it favours this area. We get surprisingly few reports of flagged birds at NSW.

The PGP was flagged on 19 October 2012, so perhaps not as surprising an observation as it may first seem, but still useful data.

ajohn

One interesting observation over the last couple of weeks is the arrival of several leg-flagged Avocets (not all reported here) that have not been reported earlier in the winter. This is surprising because most were flagged in November or December of last winter (i.e. late 2011).
It is not clear if these have been in Hong Kong but not observed (e.g. due to lower tides), or whether they have spent the early part of the winter further north. Observations of two HK-flagged birds in Taiwan this winter suggests at least some birds may not have come as far south as HK until February.

ajohn

Wilson, note that the Great Knot (VYR) in the photograph has a yellow flag only. This shows that the bird was flagged in Western Australia. I have received details back from the wader studies group in WA, and have posted a summary of sightings of this bird at: http://www.hkbws.org.hk/BBS/viewthread.php?tid=16234&page=3

ajohn

Interestingly, Richard's resighting of Terek Sandpiper E1 comes a year to the day after the only other sighting of this bird, on 19th April 2012.

There have been some interesting reports of our birds from overseas in recent days - a Grey Plover in Jiangsu on 7th April, Curlew Sandpiper in Taiwan on 17th April, Grey Plover in Bohai Bay (Hebei) since 11th April, Black-tailed Godwit in Bohai Bay (Hebei) on 19th April and Eurasian Curlew in ohai Bay (Hebei) on 18th April.

The Eurasian Curlew is our first overseas report for this species, allowing us to get more information about the migration route of our wintering population.