Introduction
This is a review of the year 2021 in which regular seawatching surveys were done from Nam Kok Tsui on Po Toi Island.
The surveys started in March, by Sam. We did two sessions together at the end of April, and I continued on my own from there until the end of the year.
Some important points to start with. Firstly, some records still need to pass the Hong Kong Records Committee. And secondly, the list which follows below is a review, but the ‘official’ records will later be published in the Hong Kong Bird Report 2021. Of course, they should be the same, but one should refer to the Bird Report. The review on this site is kind of provisory.
Although there have been several new findings, there is still much work to be done to get a more complete picture of migrants off Po Toi. A ton of pioneering work has been done mainly by Geoff Welch from 2006 until (the spring of) 2013, although the focus was then not exclusively on seawatching, but on landbirding as well (with extraordinary sightings). In 2021, I focused almost entirely on seawatching, and from July onwards also spending all available time doing just that on almost all survey-days.
So, please keep in mind that this review is just about 2021 and that we started from the end of March, so data of the two first months and most of March is lacking. The list below is of seabirds and coastal migrants, mostly species for which Po Toi is a specifically good spot in Hong Kong. Also note that it is based on a few surveys per month, so the gaps on the graphs (from Trektellen.nl –
https://trektellen.nl/site/info/3323) are mostly because we weren’t there. Hence this overview does not intent to draw a full picture, just some snapshots that we try to connect.
General
Let’s look at some general items first.
• We seawatched for a total of 492 hours and 25 minutes.
• We watched the most hours in July, followed by September and August.
• Record non-stop hours seawatching were 12 hours and 15 minutes on 16 August and 12 hours on 7 July. We also watched for 10 to 11 hours non-stop on several other days.
• The most birdy month by far was September, with 11,101 migrant birds counted. August is next, but with ‘only’ 3,236 birds counted. June was the quietest month, with just 115 birds counted.
• As we did not do any full-time surveys in spring, southbound migration numbers (birds flying past Po Toi to the west) were much higher than northbound ones (birds flying past Po Toi to the northeast). Southbound: 18,766, northbound: 3,458. But it might also be that autumn is just busier than spring, especially for terns.
• We counted a total of 22,224 migrating birds*. Not bad, but note that nobody was seawatching during most of the time in 2021 and that I was mostly alone when I did seawatch and must have missed some birds. I leave it up to your imagination how many birds pass Po Toi every year, but I’d say: a lot!
• We identified 69 migrating species during the year. A 70th species, Common Swift on 22 December, is still under consideration and has been submitted to the Records Committee.
*
This is based on Trektellen, but “gull/tern spec.” cannot be reported on the site. It involves 130 individuals, which does bring the total count of all migrating birds to 22,354. Indeed all migrant birds, so besides the below list also raptors, passerines, swifts, swallows, etc.
Here is the chart from Trektellen with all the numbers:
For reports on every survey, please consult these posts:
Spring -
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1
Summer -
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1
Autumn -
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1
Winter -
http://www.hkbws.org.hk/BBS/view ... &extra=page%3D1
Rarities
You don’t hear me complaining, for sure, but I just believe that we did not encounter any true rare vagrant seabirds off Po Toi in 2021. No rare shearwater, no storm petrel that wasn’t Swinhoe’s, no Pterodroma petrel, no tropicbird, no rare frigatebird, no noddy, no rare tern.
I did submit eight Unusual Record Forms (URF) of seabirds to the Hong Kong Records Committee, but all involved more than one individual of the following species: Bulwer’s Petrel (2 individuals), Swinhoe’s Storm Petrel (2 individuals), Brown Booby (3 individuals) and Red-footed Booby (2 individuals). Brown Booby has recently been removed from the rarities list, no longer requiring observers to submit a URF.
Weather
I will not go in much detail on the complex and comprehensive subject of weather, but just shed some light on the most obvious elements. After all, when it comes to seawatching, everybody keeps an eye on the weather and wind direction.
I used both the websites and apps from the Hong Kong Bird Observatory (
https://www.hko.gov.hk/en/index.html) and Windy (
https://www.windy.com/) for predictions and actual weather conditions, while Ventusky has been particularly useful to dive into the history of wind and weather patterns (
https://www.ventusky.com/).
Winds and typhoons
To start with typhoons, we encountered only one typhoon, Cempaka, when it was relatively close to Hong Kong on 20 July (see:
http://www.hkbws.org.hk/BBS/view ... amp;page=1#pid86932). That day produced more than a dozen tubenoses: 9 Streaked Shearwaters, 3 Short-tailed Shearwaters, 1 possible Wedge-tailed Shearwater and 1 very likely Bulwer's Petrel (and by the way, almost nothing else).
But the main point I want to draw attention to, is that good species or good numbers of birds were seen on days with no typhoons at all. That is actually excellent news: we don’t necessarily need a typhoon to see Swinhoe’ Storm Petrels, Bulwer’s Petrels, boobies, thousands of terns or record numbers of Streaked Shearwaters. Typhoons can produce excellent birds as well, of course, and maybe more and better ones than during other types of weather. And it is possible that after the typhoon has already passed, interesting stuff can still be seen. So, I don’t downplay the positive effect that a typhoon can have, but just want to emphasize that you can see great stuff without one as well.
I’m hesitant to express any strong opinion on wind direction and birds off Po Toi. I’ve watched with strong onshore winds (southeasterly force 5 to 6) and seen nothing. I’ve watched with offshore winds (northeasterly or westerly), strong or light, and seen Bulwer’s Petrel and Swinhoe’s Storm Petrel.
The message is similar as with typhoons. Yes, strong onshore winds can bring in more seabirds, but one shouldn’t be reluctant to go out seawatching on po Toi in any other wind condition. As Geoff often says: “With seabirds, you never know for sure”. I couldn’t say it any better. The best approach is to take the weather as it is, although I must admit that strong onshore winds or foggy circumstances do look more attractive.
Cold fronts
I did a few ‘tests’ with cold fronts, but don’t believe any clear and meaningful conclusion can be drawn from it. Maybe our data are not yet sufficient enough and we might perhaps get a clearer picture in the future. It’s a complex matter as well, and might not only be about temperatures dropping, but the weather system that comes with it.
Map area
This is the map of the area:
Po Toi is circled in black and the blue ‘line’ is the flyway of most migrating seabirds and coastal migrants; northbound from west to northeast and southbound from northeast to west. Raptors and passerines seem to have a very different flyway. In spring they come from the south, but in autumn as well. In the latter case, they have most probably chosen a route over the sea (from Taiwan?) and then make a northwestwardly bend to continue their southbound migration over land. Hence, on Po Toi we see them coming from the sea.
The Lema Channel, also called the Dangan Passage, is the waterway to the south of Hong Kong. And to the south of the Lema Channel is a part of the Wanshan Archipelago, more specifically the Dangan Islands. The closest island of the archipelago is Dangan Island, about 11,3 km. off Po Toi.
Apart from that, there is one red lightboat in the area.
The fixed location of this lightboat, which is clearly visible from Po Toi, is 22°07′36″.3N,114°13′32″.2E. This information is based on the Notices of Mariners published by The Maritime Safety Administration of the People′s Republic of China and kindly provided by the Hydrographic Office of the Marine Department of Hong Kong.
In other words, the lightboat is positioned about 4.4 km to the southwest of Hong Kong, in Chinese territorial waters. I haven’t seen any bird flying behind that lightboat. This is most likely due to heat haze or distant fog, but even on clear days I was unable to see birds behind it. In theory, one should be able to see larger birds, like shearwaters or large gulls and terns, flying at that distance. Then the obvious questions come to mind: what else passes through the Lema Channel, further out, that we are unable to see? Or do most migrants follow the blue line as depicted on our map? Why don’t we see any migrants flying southwest or coming from that direction? Are there higher numbers of birds migrating closer to the Dangan Islands? And what about seabirds on the other (south)side of the Dangan Islands? Indeed, many questions remain unanswered (at least to my knowledge).
Method
A few words on how I seawatched at Nam Kok Tsui.
I go to any of these watchpoints on the peninsula, depending on the season and the direction and strength of the wind. We’ve now found five suitable points on the rocks. Plus, an option for the lighthouse area in case of a strong typhoon.
Looking from the southwest, these are the 5 points and the 6th, being the lighthouse, in the back.
Looking from the southeast, these are the 5 points on the rocks.
Let’s go into more detail.
Watchpoint 1
This is the most westerly positioned point, excellent in spring, but not ideal in autumn. As there is a high rock formation to the east of this point, the entrance of the Lema Channel, to the southeast of Nam Kok Tsui, is not visible. It is well shielded from south to easterly winds, up to force 6. But strong(er) winds, certainly from the south, could splash seawater on the rocks, though. So, it’s not ideal in all circumstances.
Watchpoint 2
Perfect if winds are blowing from any northerly direction. This is the southernmost watchpoint with a very good – if not to say: the best – panoramic view and it is relatively high positioned, so suitable when there are high waves. You can view the northeast and also most of Hong Kong southern waters. Alas, not shielded from onshore winds, coming from the southeast. Northeast winds are okay.
Watchpoint 3
This is the watchpoint that Geoff used. Well-located and easy to reach, but on days with ferries, you won’t be alone there nowadays. So, personally, I choose another watchpoint, where I can sit quietly on my own (of course, I wouldn’t mind the presence of other seabirders!).
Watchpoint 4
Down from watchpoint 3, this is the most ‘private’ of all the watchpoints. Hardly anybody will come down here, for the simple reason that it requires a short but steep and a bit risky climb to reach it. I’ve been sitting there for several surveys, but have changed this difficult-to-get-to-point for watchpoint 5, which is a lot safer to reach and is at the same height. Both points 4 and 5 are ideal for observing southbound migration. In spring, I would choose points 1 or 2.
Watchpoint 5
Is very easy to reach and positioned more to the northeast than the other ones. Like watchpoint 4, it also has plenty of space and plateaus of slightly different heights. Not shielded from onshore (south-easterly) winds, though. But in (late) autumn, I’ve not experienced any onshore winds here, but mostly north-easterly winds. And then this watch point is fine.
Watchpoint 6
The lighthouse. I’ve never watched from there but it might be the only point that’ll be suitable in case of a strong typhoon (force 7 and higher), as the rocks will then be partly flooded and being splashed with seawater. The lighthouse has a few disadvantages, namely that it is very high up and there is at least 60 meters of land on the southeast side and even 330 meters to the southwest side, making it far from ideally positioned. And it remains to be seen how well you’d be shielded from typhoon winds up there.
To conclude: I use watch point 1 in spring/summer and during strong southerly or south-easterly winds. I use watchpoint 2 at any season if winds are not strong onshore. And I use point 5 in autumn and winter.
I mainly use a telescope (30x-70x), which I usually put at a fixed point. But it can be rewarding to scan the area from time to time. I sometimes scan with binoculars (12x). As a lone observer, I’m sure I miss birds that fly somewhere else than were I’m watching and I also miss birds that fly very close (below my scope view) or high (above my scope view).
My strategy is to spend as much time as available at the watchpoint and don’t limit seawatching to only the morning hours. So, full-time seawatching. It’s simple: sit on your ass, watch and wait for it. Yes, the early morning hours were usually the best, but I’ve seen both continuing migration or the appearance of rare/scarce (sea)birds during the rest of the day. I’m of the opinion that it is definitely worth to spend the whole time seawatching, as it greatly increases your chances of seeing more birds.
I record all my observations on a voice recorder. On busy days, this has the advantage of not having to interrupt the seawatch to write down the counts. A description of a bird can also be made in real-time by speaking and watching.
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Last edited by badesc at 28/01/2022 15:53 ]
