badesc

9 to 11 September

Here we are with the first survey of the autumn, i.e. September, October and November. There have been few seawatching surveys in the past during autumn and winter (much more during April and May) and I even don’t know of anybody ever doing seawatching a whole day long with a telescope at Nam Kok Tsui. So there is a lot of new data that we can gather.

The reason to go from 9 to 11 was the prediction of this weather system, which looked like a dream for a seawatcher:

windy friday.jpg (321.5 KB)

13/09/2021 11:32

This were the predictions for Friday 10th at 10 AM. Left is Severe Tropical Storm Conson and right is Super Typhoon Chanthu.

9 September was the first day of this survey, and I started soon after arriving with the ferry, as usual. I watched from 11h45 to 17h45. The weather was fine, with east to northeast winds, force 2 to 3. The afternoon saw the passage of mostly terns. It is likely that at least the same number passed during the early morning. Alas many were very far out.

Interesting is to note that I did not see a single tern from the ferry from Aberdeen to Po Toi. This strongly indicates that the ferry trip provides no indication for what to see at Nam Kok Tsui, as the migration route of birds is far away from the ferry route.

Gulls:
1 adult-type large white headed gull; very far also, but appeared to have a rather light mantle, lighter than Heuglin’s Gull

Terns:
866 terns spec.
80 Common Terns
32 Greater Crested Terns
20 White-winged Terns, 1 group
1 Little Tern

Here’s the checklist: https://ebird.org/checklist/S94539414

So Friday 10 September was the day that looked fantastic from the predictions, with winds up to force 6. It would be “mainly cloudy with occasional squally showers and thunderstorms”. Okay for me, as I’ve seen shearwaters in that kind of weather in Hong Kong, so bring it on.

Alas, the reality was quite a bit different. Apart from some scattered clouds in the morning but not a drop of rain, it turned-out to be hot and sunny for most of the day. Winds coming from the east and northeast, but only force 3 to 4. During noon, shortly force 5.

I had to make a construction with my umbrella against the sun, not against showers and thunderstorms.

20210909_133113.jpg (766.24 KB)

13/09/2021 11:35

Not a single tubenose was seen, but tern movement was massive. As soon as I put my scope at the sea, I witnessed these birds flying west. I think I counted over a 100 in the first 10 minutes and soon after up to 300 in just 15 minutes. My voice recorder proved to be very valuable, as I was able to count and record without taking my eye from the sea.

The peak of tern movement was between 06h00 and 09h30, but they kept on coming for most of the day.

I’ve probably missed some terns, as it happened frequently that when I zoomed-in to 70x from 30x to try to identify the distant birds, I discovered that there were even more terns passing further out that were invisible with 30x magnification.

Seabirds:
11 jaegers spec, groups of 2 and 9

Egrets:
21 white egrets spec.

Waders:
3 Red-necked Phalaropes, flying northeast

Terns:
2,969 terns spec.
165 Greater Crested Terns, 161 flying west, 4 to northeast
56 Common Terns
33 Aleutian Terns
3 Bridled Terns

There were also some passerines on the move and 1 swift, but I focused on the terns. Here’s the checklist: https://ebird.org/checklist/S94539495

11 September was again a pretty good day, but it appeared that the largest number of terns had moved through. The majority on this day occurred between 06h00 and 08h00, with very few afterwards. It was cloudy in the morning with one distant thunderstorm, but soon turned really very hot and sunny. Winds coming from the west now, force 2 to 3.

Seawatchers need FOPP – focus, optimism, patience and perseverance. Even though it turned really hot and there was not much movement, another good species flew-by at 10h37 and FOPP was rewarded. But I must admit that the weather and the observation that most terns passed-through at that point, eventually made me quit earlier than planned.

Seabirds:
1 Swinhoe’s Storm Petrel, flying to northeast at 10h37

Egrets:
47 white egrets spec.
46 Little Egrets
14 Eastern Cattle Egrets

Gulls:
2 Heuglin’s Gulls

Terns:
1,207 terns spec.
100 Greater Crested Terns, 96 flying west, 4 to northeast
37 Common Terns
22 Aleutian Terns
7 White winged Terns, 1 group
1 Gull-billed Tern
1 Bridled Tern

Here’s the checklist: https://ebird.org/checklist/S94539547

Remarks

Once more a very worthwhile and most enjoyable survey. I can only repeat that this place is awesome.

A total of exactly 5,600 terns were counted on one full and two half days (only!).

For Greater Crested Terns, we set a new record high count for Hong Kong with 165 individuals seen. The previous record was 105 last April, but only with counts during early morning and late afternoon, not during the whole day.

This species is one of the best examples of how the status of a bird can be different from reality. The status in Hong Kong up to now is “Common spring passage migrant through coastal waters with occasional summer and autumn records.”. What is really occasional in summer and autumn is not the occurrence of this species, but birders looking for them. Of course, the status of a bird can only be determined with what’s been seen and reported, but this illustrates that too few observation days can lead to an inaccurate status. Greater Crested Tern is common in spring, not uncommon in summer and it looks like to be common in autumn as well. But let’s first get some more observation days for the autumn.

Something similar can be said about terns in general. Record counts of Common Tern and Aleutian Tern have been reported during typhoons in spring (mainly typhoon Leo on 2 May 1999, from Cape D’Aguilar). But our survey here produced 5,600 terns without any typhoon near Hong Kong. The two storms mentioned above were actually quite far away and not even a storm signal 1 was issued in Hong Kong during the survey. Yet thousands of terns passed-through. Although weather conditions might have an effect, we don’t necessarily need a typhoon. More likely there was just a normal, regular passage at the right time in autumn.

It’s indeed a pity that so many terns flew very far out, and more so that I was unable to identify the majority. Firstly, when more Common Terns than Aleutian Terns (or vice versa) were counted, that doesn’t mean there were really more Common than Aleutian, just that the birds that flew close enough for a positive ID happened to be Common. But I did feel that Common were the majority, but can’t be really sure.

Secondly, on Saturday 11th and for a limited time, some terns suddenly flew a lot closer than on the previous days. Two fishing boats relatively nearby, with their nets in the water, seem to attract the terns.

20210911_062400.jpg (317.37 KB)

13/09/2021 11:35

It’s interesting to note that this caused the migration route to be different – after the boats were gone, terns flew far off again. It could be a useful fact when doing boat trips for observing birds: any kind of fish-based chum will most probably (at least) attract many terns, even more likely during migration time.

I’m looking forward to future autumn surveys and am expecting an increase in species of a broader variety of families of birds, like herons, egrets, gulls, ducks, grebes, waders, etc., but also swifts, swallows, passerines and raptors. I will miss most of the ones that fly high, as I will continue to focus on seawatching.

[ Last edited by badesc at 13/09/2021 11:35 ]

badesc

Additional thoughts on Swinhoe’s Storm Petrel

I wrote in a previous post, about spring (http://www.hkbws.org.hk/BBS/view ... amp;page=1#pid86924), that I believed Swinhoe’s Storm Petrels are too close to never appear in Hong Kong and should pass through like once a year or every two years. (I had and have the same thoughts on Bulwer’s Petrel, but here the jury is still out!). But it now looks like that I was very wrong. Not only does the end of May not seem to be the best time, but that could be early autumn instead. And the species does not seem to pass through “once a year or every two years”, but likely every year and in very small numbers, not just one individual.

It is well known that Swinhoe’s Storm Petrels pass through the Singapore Straight in September (e.g. https://singaporebirdgroup.wordp ... raits-of-singapore/). That’s roughly 2,600 km southwest of Hong Kong. Based on the below screenshots from eBird Singapore, the peak is in the third week of September.

SSP Singapore.jpg (67.89 KB)

13/09/2021 15:09

It makes sense to expect the species passes-by Hong Kong in late August/early September. This is just a provisional estimate, of course. But there is now some data to support this.

Not only have we done seawatching surveys from Nam Kok Tsui, Carrie Ma has organised three boat trips in Hong Kong Southern Waters this autumn (these are usually done only in spring). And Chris Campion and Michael & Elizabeth Leven have done seawatching with a telescope from Genting cruise ships, known as ‘cruises to nowhere’, so basically relatively close to Hong Kong. All efforts were made in the last two weeks of August and the first two weeks of September (so far), and everybody (!) has seen at least one Swinhoe’s Storm Petrel. Let’s sum them up below:

Swinhoe's .jpg (46.51 KB)

13/09/2021 15:09

Included is an older record from this century, of a very likely Swinhoe’s in 2000; I’ve included my possible Swinhoe’s on 26 August; the one on 29 August was found by Jemi Holmes and seen by more than 20 people.

During the previous century, other dark-rumped or (possible) Swinhoe’s Storm Petrels have been seen in Hong Kong, but more in autumn than in spring, measured by number of individuals. No Swinhoe’s Storm Petrels have been accepted by the RC so far.

On a map, the coordinates of the birds since 2000 are marked by the blue pointers:

Swinhoe's all.jpg (169.1 KB)

13/09/2021 15:09

Just for Hong Kong and zoomed-in a bit, they are marked by red circles:

Swinhoe's HK.jpg (84.14 KB)

13/09/2021 15:09

It seems logical that most of the presumably hundreds of Swinhoe’s move over sea in a south-westerly direction between the Taiwan Straight and the Singapore Straight and thus are too far away from Hong Kong. But we’re seeing evidence that some of these birds move a lot closer and even fly through Hong Kong Waters. Note that of the above observations, some birds flew west or southwest, while some flew to the northeast. And also, that they have been seen on days with no strong easterly winds.

So, let’s hope all these sightings will increase awareness and make more people looking for Swinhoe’s Storm Petrel during what could be the right time of the year for this species. When more efforts will be made, maybe more will be seen, and it could become obvious that they are at least a rare passage migrant in (early?) autumn. Whether we’ll see more this year as the autumn progresses, remains to be seen, so I am by no means drawing definite conclusions here. Just bringing it up.

A final thought on confusing species (hence there’s often talk of ‘dark-rumped storm petrel’). For Hong Kong that would be Tristram’s and Matsudaira’s Storm Petrel. I remember the time when together with Swinhoe’s, the ID of these species was considered extremely difficult or they even could not be separated in the field. Anno 2021 a lot more information is available and these are actually three pretty different species.

The most unlikely to ever occur in Hong Kong is Tristram’s Storm Petrel. It breeds only off Japan and on Hawaiian Islands and does not migrate outside an area between the breeding grounds. However, it has been recorded off Taiwan (https://cwbftaiwan.wixsite.com/cwbf/important-links), but not in Singapore. It’s the largest storm petrel, with a deep-forked tail and prominent upperwing bar, and has a different jizz and flight behaviour than Swinhoe’s.

Although it has never been recorded in Taiwan, nor is it on the Singapore list (https://singaporebirdgroup.wordp ... klist-2021-edition/), Matsudaira’s Storm Petrel breeds off Japan (Volcano Islands) and is a long-distance migrant that moves through parts of South-East Asia to the East coast of Africa. It is a large storm petrel as well, very dark-coloured (appearing blackish), has prominent white primary shafts, with deep-forked tail, different jizz and flight behaviour than Swinhoe’s.

But Swinhoe’s should by far be the most-likely storm petrel of the three to occur in Hong Kong. All the odds are in its favour. Actually, we all approach all-dark shearwaters in a way, that the first and obvious choice (certainly in April-June) is Short-tailed Shearwater. So almost all are reported as such. We then look for deviant features that could perhaps indicate a Sooty Shearwater (no records in HK as far as I know). But we’re not saying: it’s an all-dark shearwater that looks very much like a Short-tailed and all odds are in favour of this species, but we cannot 100% exclude Sooty, so it’s an all-dark shearwater spec. Maybe Swinhoe’s and Matsudaira’s can be approached in a very similar way.

badesc

16 to 18 September

The reason to go on these dates was not because the weather looked good for seabirds, but actually precisely because it did not particularly look good. Winds were predicted to come from the west or the south, with only force 2 to 3. Unlikely to make a number of seabirds occur in the Lema Channel. So with no expectations we went to see what’s out there.

It turned-out interesting, and even before I was at Nam Kok Tsui. I noted almost 170 egrets and herons on the move from the ferry from Aberdeen, some 40 Barn Swallows, 50 or so terns spec. and 5 Greater Crested Terns. Three points to put forward:

1.        I was on the lower deck, but on the upper deck Peter Ho and others saw a distant dark shearwater. As I did not see it, I cannot comment on it, apart from noticing that it is very interesting to still see a shearwater in what we consider to be unfavourable wind conditions for them to move through Hong Kong Waters.
2.        What I did notice was that some terns flew very far away from the ferry, but a decent number flew close and, most importantly, came from the waters between Beaufort Island and Hong Kong Island, and also from between Beaufort Island and Po Toi. So did one group of c150 white egrets. Needless to say, is that I miss all these birds from where I am on Po Toi. So what passes-by on some days can be even more numerous than what I see/report.
3.        What I did see on the ferry was a good indication for what I was about to see on Po Toi (except for shearwaters). This was the opposite of the survey from 9 to 11 September when I saw basically nothing from the ferry, but many terns from Po Toi.

16 September was the first day of the survey and I hurried to the seawatch point like never before, arriving 15 minutes earlier than usual. I was on duty from 11h30 until 17h30. It was mostly cloudy with limited visibility and with one distant thunderstorm (that hit Hong Kong elsewhere). Winds came from variable directions, from the west to the southeast, with force 2 to 3.

As soon as I looked through my scope, terns appeared moving west, and just like on the ferry, a good number of egrets and herons was on the move as well.

Egrets and herons:
174 white egrets spec.
30 Little Egrets
19 Chinese Pond Herons
7 Great Egrets
2 Grey Herons

Waders:
2 Red-necked Phalaropes

Terns:
1,490 terns spec.
21 Gull-billed Terns
57 Greater Crested Terns
2 Aleutian Terns
1 Bridled Tern

Swifts and swiftlets:
13 Himalayan Swiftlets, 6 seen moving south during the afternoon and 7 around the lighthouse in the evening
6 Pacific Swifts

Furthermore, a Common Kingfisher appeared briefly on the rocks. Here’s the checklist: https://ebird.org/checklist/S94915061

With seemingly quite a lot of birds – mostly terns – on the move, I was looking forward to the next, full day, 17 September. I watched and counted from 06h00 until 17h30. It was cloudy in the morning, but turned hot and sunny afterwards, with limited visibility. Winds blew from variable directions, from southwest turning to east, force 2-3.

20210917_061702.jpg (382.96 KB)

20/09/2021 17:38

Ready for the first sunlight, with scope pointing to the southeast

There was a bit more variety and the first migrating ducks appeared. 2,013 terns in total were counted, but 90% between 06h00 and 10h00.

Egrets:
56 white egrets spec.
4 Chinese Pond Herons

Ducks:
4 ducks spec., likely teals

Waders:
1 Eurasian Whimbrel, flying northeast

Gulls:
1 Heuglin’s Gull

Terns:
1,900 terns spec.
103 Greater Crested Terns
6 Gull-billed Terns
3 Aleutian Terns
1 Bridled Tern

Here’s the checklist: https://ebird.org/checklist/S94915253

18 September was already the last day, which is then usually a half day (morning to noon only). I watched from 06h00 until 11h00, but there were almost no birds after 8 o’clock. It was cloudy and rainy in the morning, afterwards hot and sunny with limited visibility. Eastern winds, force 2-3 (maybe up to 4).

Egrets:
89 white egrets spec.
1 Great Egret

Ducks:
34 Eurasian Teals
7 ducks spec., likely teals
1 Garganey

Waders:
Common Greenshank

Terns:
777 terns spec.
93 Greater Crested Terns
1 Bridled Tern

Swiftlets:
2 Himalayan Swiftlets

Furthermore, a local White-bellied Sea Eagle and the first migrating Eastern Yellow Wagtail. Here’s the checklist: https://ebird.org/checklist/S94915454

Remarks

Similar remarks as on the first September survey can be made, certainly with regard to terns. This time a total of 4,455 were counted. Sometimes they almost only occur in the morning, but the two Thursdays (9 and 16 September) saw good passage in the afternoon. Who knows how many came through in the morning, when I wasn’t yet there… Plus how many flew to the north of Po Toi, which I did not see…

It is difficult to ignore the fact that some tens of thousands of terns pass-through Hong Kong Waters in autumn. Autumn could be even better than spring. And I like to stress again, the complete absence of any storms during this survey as well.

Another point to make is indeed the total absence of seabirds (okay, you could perhaps call Red-necked Phalaropes seabirds), apart from the dark shearwater seen by others. No tubenoses, no boobies, no jaegers for me. Perhaps we could carefully make the point that we need the extra help of strong winds (perhaps at least force 5 from the east to the south) for a number of seabirds to appear in the Lema Channel during autumn. Yet, the 11 jaegers and 1 Swinhoe’s Storm Petrel of the previous survey did occur in much less than such ‘perfect’ winds. So you never can exclude anything. And that’s also the best attitude: anything can turn-up at any second, no matter which weather.

badesc

23 to 25 September

As we wanted 3 surveys in September, these 3 days were chosen; two half days and one full day. The weather was totally different from the previous survey, so that in itself was interesting. The prediction was for easterly winds, averaging force 5. It is usually associated with the chance for seabirds off Po Toi.

23 September started on the ferry with zero birds. The day on Po Toi was with sunny periods, but mostly cloudy and with a few short showers. Winds were blowing from the east, with force 4 to 5, maybe up to 6 at some point. I watched from 11h45 until 17h00. When I put my scope towards the south, to catch birds flying to the west as well as to the northeast, it was like on the ferry: zero birds. No migrants. No terns. Nothing, and this for quite a while. But one of the first birds was a Red-footed Booby, which saved the day.

Seabirds:
1 Red-footed Booby, flying northeast at 13h11

Waders:
1 Grey Plover

Terns:
2 terns spec.
3 Greater Crested Terns
1 Common Tern

There was a Richard’s Pipit near the lighthouse in the evening. Here’s the very short checklist of the seawatch survey: https://ebird.org/checklist/S95239129

24 September saw very similar weather, but after a cloudy morning it turned mostly sunny. Winds were the same. There was a some improvement, of course also because we started at 06h00, and watched until 16h30. The afternoon was very very quiet and it was ticking away the moments that make up a dull day, fritter and waste the hours in an offhand way…

Seabirds:
1 juvenile Long-tailed Jaeger

Egrets:
170 white egrets spec.
1 Great Egret

Ducks:
74 teals spec.
15 ducks spec.
5 Eurasian Teals

Gulls:
1 1st CY Black-tailed Gull

Terns:
6 terns spec.
18 Greater Crested Terns
2 Bridled Terns

Further over sea was an Oriental Dollarbird. Here’s the checklist: https://ebird.org/checklist/S95239199

25 September was the last day. After a short cloudy morning, it turned way too sunny. This is a disturbing issue, because when watching to the south, the light is very bad, certainly on a bright sunny day as this. I started at 06h00 but stopped at 12h00. Migration died down very early, but the morning was again better than the previous day.

Seabirds:
2 jaegers spec., Parasitic or Long-tailed
1 juvenile Parasitic Jaeger

Egrets & herons:
26 white egrets spec.
22 Eastern Cattle Egrets
9 Great Egret
1 Grey Heron

Terns:
21 terns spec.
33 Greater Crested Terns
1 Bridled Tern
1 Common Tern

Also a Black Drongo on the move. Here’s the checklist: https://ebird.org/checklist/S95239288

Remarks:

Although we encountered a handful of jaegers and a Red-footed Booby – so it was not disappointing – there were not many seabirds, and also no tubenoses. Terns seemed to have mostly gone.

September has been exceptionally hot and sunny this year (https://www.scmp.com/news/hong-k ... k-be-hottest-record), which, together with bad light, created an extra challenge at Nam Kok Tsui.

Lastly, one interesting ‘white’ tern was seen, but a bit too far out. After having seen more than 10,000 terns in September, this one stood out immediately (so not like the ones seen before). A very elegant bird and an elegant flyer, dark trailing edge to outer primaries of underwing though primaries did not appear clearly translucent. Tail appeared rather short, missing long streamers, or they were not visible. Greyish hint on underparts, but pale (i.e. white) cheeks. The only species that came to mind was Arctic Tern. Most noticeable was that the bird was in complete summer plumage, with full black cap. No photos were taken.

I’m not making any claims here, but it’s just a good reminder that Arctic Tern perhaps could actually turn-up in Hong Kong. The issue of its rarity along East Asian coasts was recently discussed by Limparungpatthanakij et. al. (2021)*. It is “an extremely widespread and numerous Holarctic breeder”, breeding alongside the in Hong Kong common migrant Aleutian Tern. So, it could occur here, although the forementioned article assigns its rarity along coastal waters because it’s a pelagic bird, on migraton. But in Europe that is not entirely the case, so we’d better be on the lookout. By the way, also for Chinese Crested Tern, as this is even more likely to occur in Hong Kong. First step is to pay attention to terns, with these species in mind, and the chance of finding one is greatly increased. That’s the main point here.

* Limparungpatthanakij, W., Ekkul, J., Aderik, K., Angkaew, R., Sutibut, S., Round, P.D. (2021) Terns in the Thai Gulf—a potentially important over-summering area for Aleutian Tern Onychoprion aleuticus and documentation of Thailand’s first Arctic Tern Sterna paradisaea. BirdingASIA 35: 92-96.

[ Last edited by badesc at 27/09/2021 20:25 ]

badesc

September 2021

Let’s wrap-up September. There were 9 observation days during this month, three full days and six half days. There were no typhoons in Hong Kong this year in September. It felt hotter than in summer.

What without a doubt stood out this month was the number of terns that we counted: 10,143 in total. We’ll never know the real total for the whole month. But if you add mornings of the half days and the afternoons of the other half days to the full days, we were counting on only 20% of the available days in this month. I don’t say you should multiply the actual counts by 5 to get an estimated number for the whole month, but it’s clear that thousands upon thousands of terns pass-through. And note that the tern migration starts to take-off by the end of August.

Some other interesting statistics/species for September:

1 Swinhoe’s Storm Petrel
1 Red-footed Booby
13 jaegers spec.
1 Parasitic Jaeger
1 Long-tailed Jaeger
1 Black-tailed Gull
3 Heuglin’s Gulls
604 Greater Crested Terns

badesc

16 to 19 October

October would be a very interesting month, as very few seawatching surveys have ever been done on Po Toi. There were also two storms in the first half of October, Tropical Storm Lionrock closely followed by Typhoon Kompasu. Both storms triggered a signal 8 and in theory you want to be on Po Toi for seawatching, then.

Alas, it turned out less favorably. To make a long story short, there simply was no ferry in between the two storms. My original plan to go for the first one had to be cancelled, because I was not sure if I could get back and the prospect of having to stay 10 days on Po Toi during two typhoons was not really ideal. I then tried to go before the second storm, but, indeed, no ferry.

So that’s why I had no choice to let these opportunities go. October typhoons or storms are rare in Hong Kong, although it seems they might get more regular in the future.

Before we go to our own sightings, let’s summarize what others did see during the storms.

* On 9 October a storm petrel was found on Shek O beach. The video clips that were shown indicated a Swinhoe’s Storm Petrel, but the rump was not visible so Leach’s could not be excluded.
* Graham Talbot and others did manage to get to Cape D'Aguilar on the day typhoon Kompasu passed-by, on 13 October. Graham’s results were fantastic:

Between 11h30 and 17h00, with most birds flying northeast.

5 Streaked Shearwaters
1 Bulwer’s Petrel; heading to Shek O bay
7 dark-rumped storm petrels, almost certainly Swinhoe’s
1 Swinhoe’s Storm Petrel
1-2 juvenile Sooty Tern(s), feeding; the same or another one seen 40 minutes later
10 terns spec.
3 Whiskered Terns

So, two storms in October (!) brought 9 storm petrels and 1 Bulwer’s Petrel to Hong Kong waters. And nobody was even at what is widely considered as the very best seawatching point: Nam Kok Tsui on Po Toi. We do have to keep in mind that there were no similar storms in September, so it doesn’t mean that October by definition is the best month or better than September.

Okay, let’s now move to our own sightings, starting with seawatching from Po Toi on 16 October. I watched from 11h45 to 17h15. The weather was bright and sunny, with force 5 winds coming from the north to northeast.

Egrets and herons:
2 Eastern Cattle Egrets

Raptors:
2 Eastern Marsh Harriers

Terns:
40 terns spec.
23 Greater Crested Terns
2 Common Terns

Swallows:
6 Barn Swallows

Here’s the checklist: https://ebird.org/checklist/S96212263

17 October showed this interesting weather pattern:

17.10.jpg (223.02 KB)

22/10/2021 16:20

So I was present at 06h15 and seawatched until 17h15. It was mainly cloudy, with some sunny periods. Winds were still coming from the north to northeast but had increased to force 6. The sea off Po Toi was rough and the waves were high.

Seabirds:
1 tubenose spec., to northeast at 06h50; too far and seen briefly, but likely Bulwer’s Petrel
2 Bulwer’s Petrel, to west, 1 at 13h14 and 1 at 15h05

Ducks:
66 duck spec.

Egrets and Herons:
4 white egrets spec.
1 Grey Heron

Raptors:
1 falcon spec.
2 Eurasian Hobbies
1 Osprey
1 Common Kestrel

Gulls:
1 Black-tailed Gull

Terns:
16 terns spec.
1 Greater Crested Tern

Swifts and swallows:
11 Barn Swallows
2 House Swifts

Interesting was that raptors, swallows and passerines flew to the northwest. Here’s the checklist: https://ebird.org/checklist/S96264204

18 October turned out to be a good day for ducks, but all groups were too far to identify. Quite a few terns passed through as well. I was again present at one of the seawatch-points, from 06h15 to 16h45. The morning was mostly cloudy, while it turned mostly sunny in the afternoon. Winds were blowing from the northeast, starting with force 5 and later with force 4.

I choose the southwest watch point again, as seen on this photo.

20211018_141200.jpg (408.4 KB)

22/10/2021 16:20

Ducks:
393 ducks spec.

Egrets and herons:
3 white egrets spec.
39 Eastern Cattle Egrets
1 Chinese Pond Heron

Gulls:
6 Black-headed Gulls, all adults
1 Black-tailed Gull

Terns:
124 terns spec.
13 Common Terns; 8 were hanging around
6 Greater Crested Terns
5 White-winged Terns
1 Caspian Tern

Swallows:
4 Barn Swallows

Here’s the checklist: https://ebird.org/checklist/S96456960

And 19 October was already our last, half day for seawatching. This time from 06h30 to 14h00. It was sunny with winds still blowing from the northeast, starting at maybe force 5 but mainly force 4. It was relatively quiet.

Ducks:
33 ducks spec.
2 Northern Pintails, males

Egrets and herons:
2 white egrets spec.
35 Eastern Cattle Egrets
14 Chinese Pond Herons
12 Great Egrets
7 Black-crowned Night Herons
2 Little Egrets

Gulls:
1-2 Gulls spec.

Terns:
2 terns spec.
5 Common Terns

Swallows:
5 Barn Swallows

1 Eurasian Hobby was present, hunting for dragonflies. Also, 1 Common Moorhen was seen at the very small pool at the watch point. This is a very rare occurrence in autumn on Po Toi and probably even the first autumn record ever. Here the checklist: https://ebird.org/checklist/S96457058

Remarks:
Most remarkable sightings were of course those of the two Bulwer’s Petrels that flew to the west. They interrupted their journey from time to time to feed. The sightings will be submitted to the Records Committee in due course.

Also, the 6 Black-headed Gulls on 18 October is the first autumn record for Po Toi. There is only one other record of this species off Po Toi: 2 birds on 22 February 2013. I saw another group of 11 on 19 October that were most probably also Black-headed Gulls, but they were much too far to be certain and this sighting has not been included in the above listing. But we’ll certainly keep an eye on these in the coming surveys.

Greater Crested Terns were still coming trough and all our sightings were new late dates, the previous late date was 3 October. So, the new one is now 18 October.

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28 to 30 October

For our last survey of October, we choose a period close to the final days of the month. Weather-wise there was not really anything special going on, but some cloudy weather was welcome.

On 28 October I seawatched from 11h45 until 16h45. It was both sunny and cloudy and winds were coming from the northeast, force 5 and later force 4.

Seabirds:
1 adult or 4th CY Parasitic Jaeger; coming from the open sea and flying north, sometimes circling around, at 16h24 and to the east of Po Toi

Gulls:
2 Black-tailed Gulls

Terns:
25 Caspian Terns; one group of 22

Here’s the (very short) checklist: https://ebird.org/checklist/S96797004

29 October was our full day and more birds were seen. I was present from 06h30 to 17h00. The weather was mostly sunny, but also cloudy. Winds blew from the east to northeast, with force 5 and later force 4.

Seabirds:
1 adult or 4th CY Parasitic Jaeger; seen at 06h30 around the same area as yesterday late afternoon, so this is likely the same bird that spent the night there.

Egrets:
1 Little Egret

Ducks:
44 ducks spec.
1 male Northern Shoveler

Raptors:
1 buzzard spec.
1 Eastern Buzzard
1 Common Kestrel
1 Peregrine Falcon

Gulls:
1 large white-headed gull spec.
4 Black-tailed Gulls
4 Heuglin’s Gulls

Terns:
30 Whiskered Terns, one group
12 Caspian Terns
5 Common Terns

Gulls or Terns:
35 gulls/terns spec.

Here’s the checklist: https://ebird.org/checklist/S96868959

And the last day was 30 October, when I was watching from 06h30 to 12h30. It was cloudy, but dry, with winds still coming from the northeast, force 4 to 5.

Ducks:
3 ducks spec.

Herons, egrets & bitterns:
2 heron/bittern spec.
10 Great Egrets

Gulls:
2 large white-headed gulls spec.
27 Black-headed Gulls; one group
1 Black-tailed Gull

Terns:
21 Caspian Terns
2 Common Terns
1 Little Tern

Gulls or Terns:
1 gull/tern spec.

Here’s the checklist: https://ebird.org/checklist/S96869091

Remarks

There are quite a few remarks to be made, this time, as there have hardly been any prolonged seawatching surveys in October.

The Parasitic Jaeger was the first October record for Hong Kong. Furthermore, note that the previous late date, pre-2021, was 19 June. During our surveys, we’ve seen them also in July, August, September and now October. By the way, I actually was expecting Pomarine Jaeger to show-up by now. Maybe in November…

The Northern Shoveler, a common bird in the New Territories, was the first ever record from Po Toi. So were our 2 males Northern Pintail seen on 19 October. I’m sure we’ll discover more new duck species for Po Toi during the remainder of this autumn and during the winter…

Never before have there been Black-headed Gulls seen in October from Po Toi and never – in any month – so many as have been seen during our surveys. This is a new discovery: some apparently fly via the Lema Channel and Hong Kong Southern Waters, possibly to Mai Po where they are an abundant winter visitor. Maybe the majority flies over land or at night. We’ll see, because peak counts at Mai Po are generally in January and February…

The Caspian Terns have been the largest numbers ever to been seen from Po Toi, more than anyone would have expected. In the past, there have been only a few autumn records involving singles or just a few individuals. As their numbers might still increase, we might see even more Caspian Terns in November…

The previous late date for Common Tern was 26 October. So this is now 30 October, but who knows we’ll see a few more in November…

There have been three unexpected circumstances in autumn. First, the fact that on sunny days, the light is really bad, as mentioned already. But this photo shows this very well, when looking southeast around noon. In the back, you barely can see Dangan Island.

20211029_114546.jpg (457.61 KB)

31/10/2021 20:46

The second point is that birds seem to fly further away from Po Toi than in spring. This makes sense, as they are ultimately flying on a route to the south. Even though you can see all of them coming from the northeast and then bend to the west, there is no reason to fly close to Po Toi (maybe except for strong onshore winds, which we have not experienced).

In spring, their route is to the north, so birds coming from the west have a tendency to fly northwards and thus pass closer to Po Toi when flying from the west to the northeast. Hence, I have no choice than to let go quite a lot of species and only report “spec.” in the autumn.

But very different from seabirds and terns/gulls is the peculiar route of migrating raptors (buzzards, Osprey, harriers, falcons) seen in October. All flew north or northwest. Perhaps that would make sense if they come from Taiwan, flying overseas with northeast winds and then eventually make a landfall to continue migrating along the coast. From the sea, the Wanshan Archipelago is clearly visible, so as Geoff Welch pointed out, they fly in that direction when coming from the sea and after that, Po Toi (and from there Hong Kong Island) is visible and they make their way to land.

The third point is that there is a time of the day during which really nothing flies by. It’s completely dead, unlike on many days in spring, summer (with local terns around or a booby passing through) or in September. This ‘dead zone’ seems to appear between 11h00 à 12h00 and 15h00. But shortly after 15h00 there are as much migrants as during the morning hours.

NB: the source for early or late dates is David Diskin’s website: https://www.birdinghongkong.com/ ... ng-birds-2021.html.

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October 2021

Let’s wrap-up October. There were only two surveys, with seven observation days: three full days and four half days.

There certainly were a lot less birds than in September. But terns still came through and new late dates for Greater Crested Tern (18 October) and Common Tern (30 October) were established. The 33 Black-headed Gulls was a new discovery for Po Toi, as were the large number of Caspian Terns by the end of the month. Good numbers of ducks and herons and egrets is also noteworthy. Furthermore, two new species for Po Toi were seen: Northern Shoveler and Northern Pintail. And we likely encountered the first Common Moorhen in autumn there. And last but certainly not least, the two Bulwer’s Petrels on 17 October were the absolute highlight.

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6 to 9 November

Like October, November is a month in which hardly any half or full day seawatching surveys from Po Toi have ever been done. So it’s prone to produce some interesting findings and maybe new discoveries.

The main reason we choose the above-mentioned period was for this:

temperatures.jpg (91.11 KB)

11/11/2021 13:56

On Monday 8 November a cold front would arrive over Hong Kong and it would be interesting to see what the impact would be on coastal migrants and perhaps seabirds.

As the emphasis was put on the day before, the day of and the day after the cold front, I arrived on Po Toi on Saturday 6 November in the late afternoon. I birded from 15h00 until 17h00, which is a very short time. It was bright and sunny with very clear views and there was hardly any wind: force 1 to 2 from the southwest.

It was the first day this year on which there was really nothing to see. Apart from a few birds foraging very very far out, which could have been gulls, terns or even Streaked Shearwaters (sometimes, with bright light and from a large distance, you only see the white on them). So, no checklist or anything.

7 November was the day before the cold front and we could perhaps witness certain birds being pushed out by the coming cold front. I was on duty from 06h30 until 17h00. It was mostly sunny, with some cloudy periods. Winds had turned to the east-northeast, only force 1 in the morning, but gradually increasing to force 4 in the late afternoon. There was certainly more going on this day.

Seabirds:
8 Streaked Shearwaters; all singles with wheeling arcs to northeast between 16h20 and 16h40; probably a few more which were not seen well enough.

Egrets:
25 egrets spec.

Ducks:
5 ducks spec.

Gulls:
1 large white-headed gull spec.
92 Black-headed Gulls

Terns:
72 Caspian Terns

Also 46 gulls/terns spec.

Furthermore about 300 Light-vented Bulbuls on migration, in four groups. Here’s the checklist: https://ebird.org/checklist/S97235533

The next day, 8 November, was the day of the cold front which had appeared overnight. It was indeed cooler in the morning, but after a cloudy morning, it turned (way too) sunny for the rest of the day. Too sunny means bad lighting. And there was also severe heat haze, which prevented me from finding birds that were further out (like the shearwaters the day before). Winds came from the north with force 5 to 6.

There was no noticeable effect of the cold front. On the contrary, and due to very few coastal migrants, the heat haze and the bad lighting, I birded from 06h30 to 11h00 and again from 14h15 to 17h00, and took the time in between to look for landbirds (https://ebird.org/checklist/S97285408).

Egrets:
1 white egret spec.
1 Great Egret

Ducks:
1 duck spec.

Gulls:
67 Black-headed Gulls

Terns:
8 Caspian Terns

Also 43 gulls/terns spec. (which are believe to be mostly Black-headed Gulls, but too far out)

9 House Swifts flew northwards and 2 Peregrine Falcons were hunting above the sea. Here’s the checklist: https://ebird.org/checklist/S97289528

And then there was the day after the cold front, 9 November. This turned out to be the best day, with noticeable more species and higher numbers. And I only birded from 06h30 until 14h00, in time to catch the ferry to Aberdeen. It was cloudy and overcast for most of the time, which provided good lighting conditions. There was a relatively short sunny period. Winds came from the north-northeast, force 4 to 5.

Cormorants:
1 cormorant spec.

Egrets and herons:
166 white egrets spec.
23 Little Egrets
20 Eastern Cattle Egrets
3 Grey Herons
1 Great Egret
1 Chinese Pond Heron

Ducks:
10 Northern Shovelers
1 male Eurasian Wigeon

Gulls:
6 large white-headed gulls spec.
322 Black-headed Gulls
1 Black-tailed Gull
1 Heuglin’s Gull

Terns:
37 Caspian Terns

Also 5 gull/terns spec.

240 Light-vented Bulbuls were migrating as well. Here’s the checklist: https://ebird.org/checklist/S97340487

Remarks:
Several remarks.

The days just before and just after the cold front were the best, but I’m not sure that should be a definite conclusion for all late autumn cold fronts. Other factors, such as wind force, could play a role as well.

Anyway, to summarize some numbers and species, see the below table.

cold front.jpg (19.15 KB)

11/11/2021 13:56

The Streaked Shearwaters were the first November record for Hong Kong and thus a new late date, the previous one was 27 October.

The 72 Caspian Terns were a new high count for Po Toi. In recent years, peak numbers were variable but usually in double digits (https://www.birdinghongkong.com/ ... ong-birds-2021.html), but this was only in spring. They’re presumed to be scarce in autumn, but our surveys in October and so far in November indicate that it is a rather common coastal migrant. (Of course, as in almost any species, populations can change, food sources can change, or wintering grounds might vary due to climate change or other reasons.) Note that the peak might be in the second half of November, so our next November survey might shed more light on this.

Also, amazing that Black-headed Gull was almost never recorded from Po Toi in the past and considered a “rare sighting” (source: Hong Kong Bird Report 2013) in southern waters. Actually, they pass in good numbers, even being the commonest coastal migrant! And as stated here earlier, the peak has yet to come, probably in December or January.

10 Northern Shovelers was a new high count for Po Toi and the Eurasian Wigeon was even the first record.

And I’m sure there will still be a lot to discover in the next surveys. To be continued…

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20 to 23 November

I was planning a second survey for November and the weather looked okay on the above days. Not just only for another cold front, but certainly as much for the expectation of cloudy skies, which would produce more favorable lighting conditions.

The cold front looked very similar as before, and coincidentally on exact the same days of the week, with the front arriving on Monday (but during the day, rather than during the night before):

temperatures.jpg (95.49 KB)

25/11/2021 09:52

I also decided to try to get more out of the Saturday and took the earliest ferry, which was packed with people and left early, as a second ferry would bring even more people to Po Toi. I was told 700 on Saturday and 1,000 on Sunday. But we’re there for the birds.

So, on 20 November, I started at 11h15 and seawatched until 16h45. It was sunny, alas, but with some cloudy periods in the afternoon. Winds came from the east, with force 5 decreasing to 4. It was not a bad day.

Ducks:
1 Northern Shoveler

Gulls:
1 large white-headed gull spec.
2 Black-headed Gulls
2 Mongolian Gulls

Terns:
59 Caspian Terns

Also 2 gulls/terns spec.

A big surprise was two males Chinese Grosbeaks flying north. Here’s the checklist: https://ebird.org/checklist/S97808589

21 November was the day before the cold front. I watched from 06h45 until 16h30. It was mostly cloudy and overcast, with just some sunny periods in the afternoon, and a bit misty. Winds came from the northeast, force 4 decreasing to 3.

Ducks:
2 female/1st year Red-breasted Mergansers
2 Northern Pintails

Terns:
1 Caspian Tern

Beside these birds turning-up in the morning 07h00-11h00), it was an extremely boring rest of the day as there were hardly any birds. Here’s the checklist: https://ebird.org/checklist/S97862890

22 November was the day of the cold front, although it didn’t yet feel very cold in the morning. It was overcast with some light rain in the earliest hour, and a but misty far out. Some heat haze on the horizon as well. Winds now came from the north. In Hong Kong waters they blew with only force 3, but far out, on the South China Sea it was more like force 6. I watched from 06h45 to 11h00 and from 12h30 to 16h45.

The reason for the break was a search for Red-breasted Mergansers in the bays around Nam Kok Tsui, but there were none (see remarks). Not that many birds, but nevertheless a better day than the previous one.

Seabirds:
2 adult light morph Pomarine Jaegers

Egrets:
7 Little Egrets
3 Eastern Cattle Egrets

Ducks:
1 female/1st year Red-breasted Merganser

Waders:
1 Northern Lapwing

Gulls:
1 Heuglin’s Gull

Terns:
19 Caspian Terns

Also 30 Barns Swallows, which was the highest count for this autumn by far (see remarks) and two Oriental Turtle Doves flying in from the sea. Here’s the checklist: https://ebird.org/checklist/S97917245

And lastly, 23 November, the day after the cold front. Birded from 07h00 to 14h15. It was overcast, with heat haze and some mist far out, the latter especially during the first hour and a half. Winds came from the north with force 4 to 5.

It was an abnormal day, as there were no birds until 08h21 and then there were only Streaked Shearwaters and nothing else. Only in the last 15 minutes all the gulls and terns were suddenly seen. I was lucky, as I was about to pack at 14h00 but then saw a long stretch of more than 130 Black-headed Gulls.

Seabirds:
10-20 Streaked Shearwaters

Egrets and herons:
12 white egrets spec.
9 Grey Herons
1 Little Egret

Ducks:
12 ducks spec.

Gulls:
135 Black-headed Gulls
1 Black-tailed Gull

Terns:
1 Caspian Tern
1 Common Tern

Also 1 House Swift. Here’s the checklist: https://ebird.org/checklist/S97994627

Remarks:

The Red-breasted Mergansers flew rather close, the pair to the northwest and the single one to the north. It looked as they were hanging around in the area, as I’ve seen other (migrating) ducks far out and all flying to the west.

The high count of the 30 Barn Swallows might have been the only indication of a cold front, but even that is not certain as it was not noted during the previous survey.

Anyway, I’ve made a small table again, and added Barn Swallow:

cold front.jpg (66.52 KB)

25/11/2021 09:52

I can’t see a clear trend in most species or families. The only noticeable thing is a peak of both egrets and herons, and Black-headed Gulls the day after the cold front. With Streaked Shearwaters and Caspian Terns, the high/low numbers are opposite in the two surveys. It can all be just random as well.

The Northern Lapwing was only the second record for Po Toi, the previous one was two individuals on 3 December 2017 (thanks to Geoff Welch for providing this information).

The total count for the Streaked Shearwaters was 33, but 20 flew west, 11 northeast and 2 were present. The largest groups were 7 (to NE) and 6 (to W). So, the real number of individuals may differ from the count and it might be safer to put the number at "approximately 10 to 20". In the overview table below, I’ve put the number at the middle of 10 to 20 (15). I saw one shearwater turning around (= from northeast to west and then back to northeast), and others sometimes interrupted their flight to feed. They didn’t behave as migrants. Remember I saw possible Streaked Shearwaters on 6 November, but very far out. They most probably were indeed this species and perhaps they are present in the area, east-southeast off Po Toi. We’ll certainly pay special attention to them in future surveys. By the way, our observations on 23 November represent another new late date for the species in Hong Kong.

The Common Tern, a 1st year bird, is a new late date for Hong Kong (23 November). By quite a large margin, as the previous late date was 26 October.

Not only raptors, but also other birds, like swallows, swifts, passerines, doves, etc. come from the direction of Dangan Island and fly north to the direction of Po Toi.

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November 2021

Let’s wrap-up November. There were two surveys, with seven observation days: two full days, two full days with a noon break, and three half days.

November is not particularly birdy. The main migrants – those with the largest numbers – were egrets, herons, ducks, Black-headed Gulls and Caspian Terns. But we managed to record seabirds without typhoons, namely the Streaked Shearwaters and the 2 Pomarine Jaegers.

It was not clear whether the cold fronts had an impact on species and numbers, but much more research is necessary (e.g. also on the same days but without cold fronts in future years).

But interestingly in November were the relatively large numbers of migrant Black-headed Gulls (total of 618) and Caspian Terns (total of 197), which was previously unknown. Also, there were no November records in Hong Kong of Streaked Shearwater, and the fact we saw roughly 18 to 28 birds is noteworthy. The Red-breasted Mergansers appeared relatively early. And there were some new late dates and some new high counts during November as well. And a Po Toi rarity, Northern Lapwing.

[ Last edited by badesc at 26/12/2021 17:32 ]

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Summary of autumn 2021

This is an overview of all seabirds (including Red-necked Phalaropes and Red-breasted Mergansers), and terns and gulls seen during the autumn (i.e. September, October and November) of 2021. Below are the totals for the whole season. I’ve made two tables, as one was too broad. I also have not included wind directions and force, like I did for the summer overview, as there doesn’t seem to be ‘golden rules’ or anything weather-wise that guarantees the passage of a certain species of seabirds. Being there is the most important thing, no matter what kind of wind is blowing, it seems. Strong onshore winds (southeast) should bring more seabirds to Po Toi, but this wind direction is rare and was even absent during any of our autumn surveys. We mainly encountered east or northeast winds.

SummarySeabirds.jpg (125.12 KB)

25/11/2021 10:00

SummaryGullsTerns.jpg (184.55 KB)

25/11/2021 10:00

There were 23 survey-days, but many of them only half days. Three surveys in September, two in October and two in November.

No typhoons were encountered, as we missed the two in October.

But autumn is damn good, on Nam Kok Tsui. Especially September, with thousands upon thousands of terns. Let’s jump to some of the most interesting sightings and good counts of certain species that we saw off Po Toi:

c23 Streaked Shearwaters
2 Bulwer’s Petrels
1 Swinhoe’s Storm Petrel
1 Red-footed Booby
2-3 Red-breasted Mergansers
13 jaegers spec.
3 Parasitic Jaegers
2 Pomarine Jaegers
1 Long-tailed Jaeger
651 Black-headed Gulls
9,420 terns spec.
634 Greater Crested Terns
256 Caspian Terns
200 Common Terns
And 10,672 terns in total

Adding to my previous post on thoughts of Swinhoe’s Storm Petrel, the table has now been updated. Some changes have been made. I’ve written the probable or uncertain ones in italics. And the one on 29 August was seen outside HK Southern Waters (both the bird and the observers were clearly and without doubt outside Hong Kong territory). Also in italics is the storm petrel found on Shek O beach; it was (and I presume still is) not certainly a Swinhoe’s. And so are the 7 dark-rumped storm petrels off Cap D’Aquilar on 13 October. If any incorrect information is presented here, do not hesitate to correct me, please.

Swinhoe's.jpg (91.56 KB)

25/11/2021 10:00

From this data since 2000, autumn clearly has the most sightings, from mid-August to mid-October. Most sightings were when there was no typhoon. But when one does occur (as on 13/10/2021) it brings in more storm petrels.

Additionally, we now have three sightings of sure (but yet to be accepted by the Records Committee!) Bulwer’s Petrels in Hong Kong this year, plus two probable/likely ones.

All these sightings indicate that both species are indeed pseudo-vagrants and actually scarce or rare passage migrants or visitors. And also, that autumn seems to be better than spring. More boat trips and seawatching from land in autumn, and not only in spring, might confirm this presumption.