Board logo

Subject: Po Toi Seawatch Autumn 2022 [Print This Page]
Author: badesc    Time: 13/09/2022 14:15     Subject: Po Toi Seawatch Autumn 2022

Here we are with the survey of the autumn, i.e. September, October and November. Of course, it will be interesting to compare results with last year, but not sure there will be as much surveys done this year. Anyway, with September being a pretty hot month and the forecast for easterly winds with cloudy skies, we headed out for our first autumn seawatch.

6 to 10 September

Arriving with the ferry, I started on 6 September at 11h45 and seawatched until 17h00. No clouds yet, as it was hot and sunny. Winds did come from the east, with force 2 to 3 (that breeze was just enough to cope with high temperatures). It turned out the be a very calm start of the survey.

Terns:
104 terns spec.
2 Little Terns
9 Common Terns
13 Greater Crested Terns

Passerines:
2 Eastern Yellow Wagtails

Checklist on eBird: https://ebird.org/checklist/S118544471
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220906

The clouds arrived on 7 September, with showers and thunderstorms in the morning, but mostly dry afterwards. Winds came from the northeast and turned east, with force 5. I watched from 06h00 until 17h00.

Egrets and herons:
39 egrets spec.
2 Eastern Cattle Egrets

Waders:
2 waders spec.

Terns:
433 terns spec.; many probably Common, some probably Aleutian
66 Greater Crested Terns
24 Common Terns
11 Bridled Terns
5 Aleutian Terns
5 Little Terns
3 Gull-billed Terns

Doves and pigeons:
1 Rock Dove

Swift(lets), swallows and martins:
4 Barn Swallows

Checklist on eBird: https://ebird.org/checklist/S118544605
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220907

The earlier forecast of cloudy weather already turned out to be a different reality on Po Toi on 8 September. Apart from some clouds in the morning, it soon became hot and sunny. Winds continued to come from the east, changing force during the day, from 3 to 5. Seawatching time was from 06h00 to 17h30.

Seabirds:
1 Parasitic Jaeger
26 Red-necked Phalaropes

Ducks:
11 Garganeys

Waders:
4 Eurasian Whimbrels

Terns:
673 terns spec.; mostly probably Common, few probably Aleutian
179 Greater Crested Terns
109 Common Terns
6 Little Terns
3 Gull-billed Terns
1 Bridled Tern

Swift(lets), swallows and martins:
1 Barn Swallow

Passerines:
3 Eastern Yellow Wagtails

Checklist on eBird: https://ebird.org/checklist/S118544776
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220908

And the same weather for 9 September: after a few early morning clouds, bright, hot and sunny. Winds continued to blow from the east, with only force 2 to 3. A full day seawatching again, from 06h00 to 17h30.

Seabirds:
1 jaeger spec.
1 Parasitic Jaeger
13 Red-necked Phalaropes

Ducks:
21 Garganeys

Egrets and herons:
1 Grey Heron
1 Eastern Cattle Egret 

Waders:
1 Black-winged Stilt
1 Eurasian Whimbrel

Gulls:
3 Black-tailed Gulls

Terns:
802 terns spec.; many probably Common, but most unidentifiable
155 Greater Crested Terns
112 Common Terns
4 Aleutian Terns
1 Bridled Tern

Swift(lets), swallows and martins:
2 Himalayan Swiftlets
4 Barn Swallows

Checklist on eBird: https://ebird.org/checklist/S118544985
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220909

And our last day, 10 September, it turned cloudy/overcast, with mist and limited visibility (less than 5 to 6 km.). Winds stayed the same: easter, force 2 to 3.

Seabirds:
25 Red-necked Phalaropes

Ducks:
7 Garganeys

Egrets and herons:
111 egrets spec.

Gulls:
1 Black-tailed Gull

Terns:
380 terns spec.; almost all probably Common
111 Greater Crested Terns
52 Common Terns
1 Bridled Tern

Passerines:
1 Eastern Yellow Wagtail
1 White Wagtail

Checklist on eBird: https://ebird.org/checklist/S118545355
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220910

Remarks:

Let’s turn to the most numerous birds by far, terns, and compare this year’s results with last year’s. Our survey in 2021 was a bit later, but the differences were noticeable, as is clear from this table.



Indeed, the number of terns this year was much lower than last year, and we also did not see any White-winged Terns. For example, we counted 999 terns on an afternoon last year, while only 1,074 on a full day this year. And 3,226 on a full day last year, but only 544 on a morning this year. If numbers would be similar, we would have counted much higher numbers during that morning (with unchanged weather for the whole day), as mornings are the traditionally peak (see further).

But we did count a new record for Greater Crested Terns this year, with 179 individuals (all flying west) on 8 September, while the previous highest count was 165 last year on 10 September.

Yet, our counts now lead to more and new questions. Were the numbers of terns exceptionally high last year? Or were they exceptionally low this year? And what caused the difference? Is the lower number caused by the very low counts of Aleutian Terns this year? Many of last year’s unidentified terns might have been this species, possibly explaining the different counts. These are question to which I do not have the answer. We still need to do more surveys in the future.

Another point is that we didn’t see any Swinhoe’s Storm Petrels so far this August/September, while there were certain ones last year on 29 August (from a boat) and 11 September (from Nam Kok Tsui), plus a possible one on 26 August (from Nam Kok Tsui). Maybe easterly winds were not strong enough or occurring over a large enough area? And maybe there is a link between so few Aleutian Terns and the absence of storm petrels this year? Again, questions without answers…

More on terns and weather. We’ve seen on many occasions in the past – and mentioned here a few times – that calm, dry weather seems to be their preferred circumstances to migrate. Interestingly, on 7 September, the day started rainy and turned mostly dry afterwards. While the traditional peak of tern movements in a day is from 06h00 to between 08h00 and 10h00, 80% of the terns on 7th appeared after 10h00, exactly when most rain was gone. Moreover, the peak on that day appeared between 10h00 and 14h00, which is usually the quietest part of the day. I think this largely confirms the relation between weather and tern movements, although there might always be exceptions.

The rarest bird on this survey was the Black-winged Stilt. Last year, also only one was seen, on 26 August.

Image Attachment: terns.jpg (13/09/2022 14:15, 125.06 KB) / Download count 328
http://hkbws.org.hk/BBS/attachment.php?aid=43279

Author: John Holmes    Time: 17/09/2022 17:06     Subject: Seawatch in Autumn

Thanks for an interesting summary, Bart !  

The weather conditions must really make a huge difference.  The Swinhoe’s Stormy on 29th August 2021 may have been driven closer to HK by heavy rainfall not far offshore....

Keep up the good work !
Author: badesc    Time: 18/09/2022 08:58

Quote:
Original posted by John Holmes at 17/09/2022 17:06
Thanks for an interesting summary, Bart !  

The weather conditions must really make a huge difference.  The Swinhoe’s Stormy on 29th August 2021 may have been driven closer to HK by heavy rainfall n ...
Thank you for your continuous support and encouragements, John! Very much appreciated.

Yes, weather is likely to have an influence on seabirds, but it remains a complex phenomenon which I still mostly don't understand. Sometimes it makes sense and sometimes it seems completely unexplainable (at least to us, humans). So many factors that might be in play, as well.
Author: badesc    Time: 6/10/2022 21:05

20 to 22 September

September is a pretty hot month in Hong Kong and with the forecast of some more cloudy and windy days, we planned another seawatch survey. Furthermore, onshore winds could produce some seabirds as well.

As usual in the week, the first day, 20 September, was only a half day of seawatching, from 11h40 until 17h3o. But as the results show, it was one of these half days that makes you wonder what passed during the other half… The weather was nicely cloudy/overcast, which means favourable light conditions, but no rain. Winds blew from the east and increased from force 4 to 5.

Seabirds:
2 Red-necked Phalaropes

Ducks:
1,007 Garganeys

Gulls:
1 gull spec.
3 Black-headed Gulls

Terns:
280 terns spec.; some probably Common, but most too far
16 Gull-billed Terns
4 Common Terns
60 Greater Crested Terns

Passerines:
1 Eastern Yellow Wagtail

Checklist on eBird: https://ebird.org/checklist/S119384451
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220920

The only full day of this survey, 21 September, turned out to be pretty good. Especially between 06h30 and 09h30 there was a constant, non-stop stream of migrating birds, mostly terns. I could seawatch from 06h00 until 17h30. Again a dry day, with just scattered clouds, but mainly sunny. Winds blew from the east again, but now force 6 decreased to 5.

Seabirds:
23 Red-necked Phalarope
9 jaeger spec.; most probably all Parasitic Jaegers

Ducks:
142 ducks spec.; probably Garganeys
67 Garganeys

Egrets and herons:
29 egrets spec.
1 Great Egret
1 Eastern Cattle Egret
1 Striated Heron

Raptors:
1 Eastern Marsh Harrier

Waders:
2 Eurasian Whimbrel

Gulls:
4 gulls spec.
1 Black-tailed Gull
6 Heuglin’s Gulls

Terns:
1,659 terns spec.; many probably Common Terns
1 Bridled Tern
2 Gull-billed Terns
59 Common Terns
201 Greater Crested Terns

Swift(lets), swallows and martins:
1 Himalayan Swiftlet
3 Barn Swallows

Passerines:
1 Black Drongo

Checklist on eBird: https://ebird.org/checklist/S119385446
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220921

We apparently picked that full they well. The last day, 22 September and a half day again, was much quieter. Seawatching was done from 06h00 until 13h45. The weather was mostly sunny, with some cloudy periods. And winds decreased further, from 5 to 4, and blew from the east to the northeast.

Seabirds:
1 Red-necked Phalarope
3 jaegers spec.; most probably Parasitic Jaegers

Ducks:
35 ducks spec.; probably Garganeys

Egrets and herons:
3 Great Egrets
2 Little Egrets

Waders:
6 Eurasian Curlews

Gulls:
1 Heuglin’s Gull

Terns:
264 terns spec.; probably mostly Common Terns
12 Common Terns
86 Greater Crested Terns

Swift(lets), swallows and martins:
9 Barn Swallows
Passerines:
1 White Wagtail

Checklist on eBird: https://ebird.org/checklist/S119385873
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220922

Remarks

21 September was by far the best day for terns this month. We even counted a new record high for Greater Crested Tern (201).

Another new record count was for Garganey on 20 September (1,007) and that was not even a full day of seawatching. Ducks flew exceptionally close, while light conditions were good. Most ducks are generally too far out to ID. Although more confirmation would always be a good thing for sure, our surveys indicate that Garganey is by far the most common duck species that migrates over sea off Po Toi. Most other duck species are rather scarce or even rare here.
Author: parrotkeen    Time: 7/10/2022 09:49     Subject: Rock safety?

How do we get on the rocks again? It feels kind of risky. Any trail that people can effectively watch from?
Author: badesc    Time: 7/10/2022 10:24

Quote:
Original posted by parrotkeen at 7/10/2022 09:49
How do we get on the rocks again? It feels kind of risky. Any trail that people can effectively watch from?
Just walk as far as you feel comfortable. The rocks are a popular destination for day trippers and hikers.

You can try, and if you feel it’s not safe and too risky for you, then don’t do it.
Author: badesc    Time: 7/10/2022 10:35

29 and 30 September

Again, easterly winds and clouds predicted, so we headed to Po Toi for another seawatch survey. It started to rain soon after the ferry had left on 29 September and continued to do so during the journey and after arriving at Po Toi. But on the “Loc-based Rain & Lighting Forecast” of the MyObservatory app, I saw an opening without rain. So a bit later than usual, I headed to Nam Kok Tsui, and, indeed, when I arrived there, it was dry. It mostly stayed dry for the remaining afternoon, with force 5 winds from the east. I watched from 11h50 until 17h00. Noteworthy is that Typhoon Noru had moved from east to west over the South China Sea, but it stayed well south of Hong Kong.

Seabirds:
1 jaeger spec.; very likely Parasitic Jaeger

Terns:
41 terns spec.; probably mostly Aleutian Terns
20 Aleutian Terns
2 Common Terns
15 Greater Crested Terns

Checklist on eBird: https://ebird.org/checklist/S119883741
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220929

The weather on 30 September wasn't particularly great: cloudy with only a few dry periods in the morning, and rain, squally showers and thunderstorms for the rest of the day. Winds blew from the east with force 4 to 5.

Seabirds:
1 jaeger spec.
4 Parasitic Jaegers
1 shearwater spec.; possible Wedge-tailed Shearwater

Egrets and herons:
2 Grey Herons
2 Eastern Cattle Egrets

Gulls:
1 Heuglin’s Gull

Terns:
108 terns spec.; most birds probably Aleutian, some probably Common.
28 Greater Crested Terns

Checklist on eBird: https://ebird.org/checklist/S119883828
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20220930

Remarks

Few remarks for these two days. But two points stood out. First, the vast majority of terns flew to the northeast, instead of the usual and southbound west. So, that’s actually in the wrong direction. And secondly, Aleutian Terns, which I only saw in tiny numbers (or was unable to identify) earlier in September, now moved through. Last year, I didn’t identify any Aleutian Terns after 17 September.

Both points might be a result of an influence of Typhoon Noru, but that’s just a guess.

Lastly, the shearwater was thus possibly/likely a Wedge-tailed Shearwater; dark morph going northeast between 07h07 to 07h13. All-dark bird, flying mostly low over the waves, with just a few shallow and short wheeling arks. Apart from colour, of course, quite similar to Streaked Shearwater. Effortless flight with regular, rather supple wingbeats, not stiff like Sooty/Short-tailed, which are both excluded based on flight and structure (underwings did not show any silvery shine either). Also not a Bulwer’s, as flight behaviour, structure, proportions, size, do not match at all. Landed at least once on the sea; one time seen landing; second time lost it when it might have landed again. Could be looking for food, hence low, unhurried flight (flight is typical for Wedge-tailed anyway). Could be observed for several minutes, but not close enough to see important characters (e.g. exact tail structure/length, colouration, etc.). Still one of the most anticipated and to be expected rarer seabirds here, of which I thought I would’ve see at least one by now. But note this is the second possible one; previous one was also a dark morph during a typhoon in July last year. Sooner or later, one will pass closer.
Author: badesc    Time: 16/10/2022 21:26

September 2022

Let’s wrap-up September, using data from Trektellen. There were 10 observation days during this month, five full days and five half/partial days. This resulted in 84 hours and 55 minutes of seawatching. By the way, we have now done more than 1,000 hours of seawatching, since we started in spring last year. Like last year, we didn’t go seawatching during a typhoon this month; it’s still the plan to do that in autumn, if circumstances are right.

Starting with the terns, for which September seems to be the very best month in Hong Kong. I mean numbers, not variety of species for which spring seems better. Remember we counted 10,143 migrating terns last year. But this year, the number was (only) 6,121. And the peak count was on 21st, while last year that was on 10th and 17th.

Alas, that leaves plenty of questions, but few answers. Did we simply miss the best day(s) this year? Was any count, high or low, exceptional? What caused the difference in counts? And so on and so forth.

Some other interesting statistics/species for September, with the totals of September 2021 between brackets:

1,113 Garganeys (1)
15 jaegers spec. (13)
6 Parasitic Jaegers (1)
5 Black-tailed Gulls (1)
8 Heuglin’s Gulls (3)
913 Greater Crested Terns (604)
1 Black-winged Stilt

Not only were the numbers of terns quite different from last year, some (other) species were seen in (much) higher numbers this year. Most noticeable, Greater Crested Tern (+51%). But also do take into account that observation time last year was 68 hours and 15 minutes, so a bit less. And September 2022 did not produce any rare or scarce (sea)birds. With the shearwater we came pretty close and that could have been the bird of the month, if I’d would have flown a bit closer. The rarest bird for Po Toi this year, actually was the Black-winged Stilt.
Author: badesc    Time: 18/10/2022 10:58

1 October

1 October was the last day of the survey that started on 29 September, which was reported above. This was thus just a half day, from 06h10 until 11h00. Some clouds, but mostly sunny weather, with winds blowing from the east with force 4. Not a particularly exiting day.

Ducks:
59 ducks spec.; probably Garganeys

Egrets and herons:
1 egret spec.
1 Little Egret

Waders:
1 wader spec.

Terns:
40 terns spec.; most birds probably Aleutian
17 Aleutian Terns
3 Common Terns
18 Greater Crested Terns

Checklist on eBird: https://ebird.org/checklist/S119883862
Count on Trektellen: https://www.trektellen.nl/count/view/3323/20221001

Remarks

No remarks this time, as there isn’t anything noteworthy or mentionable, as Walter Mitty would say.
Author: badesc    Time: 3/11/2022 11:04

October 2022

Besides posting reports on every survey, we’ve also posted a review of every month. But in this month, there was only one half day of seawatching. I had to take a break. So, there is nothing additionally to report for October.

This month (November) I’ll be traveling abroad – for seawatching from a rock, what else… – and there might not be any seawatching surveys from Po Toi. Be assured that there were and will be plenty of interesting stuff in October and November, we just will never now it in 2022.

December and especially January are rather quiet months, so don’t expect much surveys then either. Most probably, we’ll return from February onwards and do more surveys until May.



Welcome to HKBWS Forum 香港觀鳥會討論區 (http://hkbws.org.hk/BBS/) Powered by Discuz! 6.0.0