Aug

23

2021

piersmai Red Knot migration in the EAAF

The migration of Red Knots Calidris canutus piersmai, from Roebuck Bay and 80 Mile Beach has been a long term study. In recent years the establishment of a regular monitoring programme at the Luannan Coast, Bohai Bay, China by GFN and Beijing Normal and Forestry universities has shed some light on the northward migration. Then after many attempts with geolocators and satellite transmitters GFN published a paper with the work led by Eva Kok, Ginny Chan and Theunis Piersma.

And, now Eva has produced this beautiful visual depiction of Red Knots migrating north and south.

This graphic was produced using the R package moveVis (Schwalb-Willmann et al. 2020).

Schwalb-Willmann, J.; Remelgado, R.; Safi, K.; Wegmann, M. (2020). moveVis: Animating movement trajectories in synchronicity with static or temporally dynamic environmental data in R. Methods Ecol Evol. 2020; 11: 664–669. https://doi.org/10.1111/2041-210X.13374

One aspect of the Red Knot migration, that we are certain is vital to the current populations and their migration strategies, is the distribution of the small bivalve Potamocorbula laevis. See the latest Bohai Northward Migration report recently posted and the paper led by Hebo Peng on the this topic Homogenizing effect of aquaculture on mudflat biodiversity China-Peng et al.

Aug

22

2021

The Clive Minton Discovery Centre

Please see the attached news item about some very exciting news for Broome Bird Observatory.

Aug

16

2021

Bohai Report 2021

Please find the GFN Bohai Report 2021 at the download button below. Of particular interest is the positive advancements with the establishment of the Wetland Park see page 27 and 28 for that. And I hope there will be much more to interest you throughout the report. Thank you to all the authors and particularly to Katherine Leung, Rainy Cai and Tong Mu for completing the field work component of the project.

Jun

16

2021

Bohai 2021 – Update 4

Update 4 – Farewell Knots!

Bohai spring season 2021 concluded on 7 June with the season ending “typically” like previous years. At the end, we have a number of days with higher count of over 5000 Red Knots, but did not encountered any large number over 10 thousand. We finished the season with 411 sightings of 208 North-west Australia colour banded Red Knot individuals.

The missing birds

Since late May our team has tried to contact birders along China coast (via the China Coastal Waterbird Census network https://www.eaaflyway.net/ccwc-2012-2019-report/)  to see if anyone saw any large flock of Red Knots. Unfortunately, we did not find much clue except knowing that Red Knot numbers have increased slightly at 2 sites in Jiangsu compare to same period in 2020, and that no big flock has been seen along Bohai coast this year. Table below shows the daily number of Red Knot presented at our study sites during our last twelve days in the field compare to the past 2 years:

Table 1: Daily count of Red Knot from late May to early June

Date 2019 2020 2021
27-May   10,000 7,000
28-May   6,000 2,500
29-May 27,500 5,000 1,932
30-May   4,000 6,404
31-May 16,000 4,000 5,450
1-Jun 10,000 500 3,500
2-Jun 8,370 2,500 1,224
3-Jun 6,550 2,500 1,200
4-Jun 4,720 1,500 1,494
5-Jun 4,213 1,500 2,307
6-Jun 1,765 751 763
7-Jun   490 700
Season peak count: 47,537 (22-May) 20,000 (24-May) 9,000 (12-May)

We had our best colour band resighting day on 27-May with 29 Red Knot individuals plus one Great Knot individual. Then scanning become increasingly difficult on the Nanpu mudflat with birds foraging far along tide line, heat haze as tide falling later each day and some extreme weather (see next section).

Red Knot flock feeding right at the tide line as the tide recede (photo by Katherine on 28-May)

As per previous year experience, we know that Red Knots tend to rely on brine shrimp eggs in the salt ponds when they are about to depart in late May/early June, thus we focus our effort in the salt pond in our last week. What’s different from previous years was that regardless of suitable water levels at several places, there wasn’t many ponds that the Red Knots were using. This was probably because of the small number of birds presented. Even so, we had some luck resighting the “usual” late arriving individuals at the ponds for a couple of days, which gave us the clue that migration season was getting close to the end.

   Left: Brine shrimp and eggs under microscope (photo by Zhang Wei).
Tong and Rainy scanning at the salt pond in strong wind (photo by Katherine).

Crazy weather

If you are a fan of extreme weather, Nanpu is obviously an interesting place to visit. Earlier in April, I have been running on the street in the middle of a dust storm followed by heavy rain and thunder. In the last 12 days in the field, we had experienced super strong wind, misty and hazy mornings and thunder storm with hail in size of marbles. All these added on to the difficulties in scanning and finding Red Knots, and may have pushed some of the birds to move on earlier. 

Left:

Scanning in super strong wind and dust can only be carried out inside our car
(photo by Tong on 29-May)
Feeding Red Knots in Tong’s telescope during dust storm (photo by Tong on 29-May)
Katherine and roosting Red Knot flock on salt pond bund in morning mist and haze
(photo by Zhang Wei on 3 June).

Lightening hit the Nanpu mudflat photographed from salt pond (photo by Tong on 7 June).

Food supply

For a few days we had a film crew with us which was appointed by the National Forestry and Grassland Administration to produce a series of documentary on China’s natural environment to be broadcast on China Central Television, including 10 minutes featuring Red Knot as an “international bird” in the wetland episode. Other than filming us scanning and doing interviews, they were also interested to complete their story with what Red Knots feed on at Nanpu. Thus, we took the chance to demonstrate mud sampling and explained Red Knot’s reliance on Potamocorbula laevis.

We had already heard from our colleague Hebo that P. laevis density was low at Nanpu this year along his long-term monitoring transect. Tong and Rainy, who had carried out sampling at Nanpu in 2017-2019, agreed with Hebo’s finding. Very few P. laevis were found in a standard sample about 50m away from the seawall. We found slightly more but still low number of P. laevis close to the seawall, where birds were less likely to feed to avoid disturbance. Maybe this explains why we seldom saw Red Knot spreading along the 7km long mudflat to feed this year.

Left: Director Zhang filming closely how mud sampling was carried our
(photo by Katherine).

Small number of P. laevis collected from a “standard” sample, comparing to >200 individuals in past years (photo by Zhang Wei).

All these clues seem to suggest that maybe the Red Knots choose to spread out more widely along China coast this year and did not concentrate at “traditional” sites in Bohai (?). I can’t wait to find out what they will do next Spring already!

Last but not least, some positive news

After our field work ended, on 8-10 June, I attended a workshop organised by WWF-China in Luannan Town, which brought together stakeholders of the newly established Luannan Nanpu Zuidong Provincial Wetland Park. The meeting was very fruitful and I found it great to be able to listen to the local people from Beipu village (shellfish harvesting on mudflat) and from the salt pond (salt, brine shrimp and salt pond shrimp production) about their work routine and local knowledge, which help us better understand Red Knot movement around the site. More importantly, we explored possibility to further improve the shellfish, salt and shrimp production in a bird-friendly and sustainable way. As such, aqua products from the Wetland Park could be sold at the market at higher price with accreditation in future. This would be a win-win situation for both the local communities and the birds. More details of this workshop will be included in the 2021 final report.

Young village head from Beipu village (2nd person at the back row) explaining their harvesting routine and expectation to keep harvesting at the Nanpu mudflat, which is now part of the Wetland Park (photo by WWF-China Shanghai Office).

Imagine you can choose to buy “Nanpu Wetland Park Red Knot friendly shellfish” in the market in future? (photo by Katherine)

That’s all for 2021 updates, please don’t miss our final report with all the results from this year field work.

Katherine Leung 15-Jun-2021

Jun

16

2021

Bohai 2021 – Update 4

Please click here for the PDF version of the update.

Jun

15

2021

Zipping from Broome to Taiwan UPDATE

Zipping from Broome to Taiwan

Do you remember this story?

You can click on the title above to remind yourselves or the short version is;

I saw a bird then Weiting Liu saw the same bird in Taiwan (not unusual with the great array of skilled observers spread throughout the EAAF.)

The story finished with ‘So, a minimum of 4,720 km in a maximum of 89 hours. Minimum speed of 53 km/hr. Nothing out of the ordinary for a migratory shorebird.

Will our luck continue and will the bird be seen again on its 2021 northward migration? Well it has been recorded in Nanpu, Bohai Bay, China in 2011, 2014, 2015, 2016, 2017, 2018, 2019 and 2020.

So, over to you Katherine and the Bohai Team 2021.’

Did they see it?

Of course they did!

24-04-2021 Tzu-Hu, Chin-Men County (24.47, 118.32) Taiwan. Weiting Liu, Image

27-05-2021 NAN PU OIL RIG SITE (39.06, 118.22) China. Cai Shang Xiao (Rainy) GFN Team 2021

30-05-2021 NAN PU OIL RIG SITE (39.06, 118.22) China. Katherine Leung GFN Team 2021

31-05-2021 NAN PU OIL RIG SITE (39.06, 118.22) China. Katherine Leung GFN Team 2021

That’s only a 1,620 km flight in a direct line, just 30 hours of flying for a Red Knot so it probably stopped elsewhere between Kinmen and Nanpu as there is a months’ time gap.

Great work GFN Team 2021.

A full report detailing the northward migration field work season in Bohai Bay 2021 will be out soon.

May

31

2021

Update 3 – Ups and downs with the tides

Since the previous update in early May, another fortnight has gone and we are now in the final week of May when we expect 20,000 or more Red Knots. But this has been an unusual season. Here in Bohai, we are constantly asking: “Where are the birds?” and “Has migration season ended?”

The frustrations

“Frustrating is the life of a scanner” (C. Hassell, 2021). Maybe Chris has made this statement a couple of decades ago since his life as a scanner is obviously much longer than mine. In the past 2.5 week our team has been busy running around Nanpu, Beipu and Hangu searching for Red Knots, sometimes we found 6,000, sometimes we found less than 1,000.

According to GFN counts in recent years, low counts of Red Knot were recorded in 2016 (20,000), 2017 (17,000) and 2020 (20,000).  So far this year, even if we are adding up the numbers at all 3 sites, Red Knot number is certainly not getting up to 10,000 yet. Besides, colour band and flag records suggested that these birds are moving around these 3 sites. Also, unlike 2020, our colleague Hebo didn’t find large number of Red Knots in Cangzhou (southern Bohai) this week. So, where are the birds?

On “the other half” of the world, at Roebuck Bay, NW Australia, Chris saw record late departure of 34 Red Knots in a flock on 19-May. Maybe the birds are still staging somewhere in Southern China? Maybe they will be here soon? We can’t stop wondering how this field season will turn out to be. Will these late birds arrive and move on quickly? Or will they come and stay later than usual? Or are they not going to stop at Bohai at all? We do hope to find out in 2 weeks’ time.

Just to give a sense of the difference in Red Knot densities: Red Knot flock on 26-May-2020 (top), Red Knot flock on 26-May-2021 (bottom) (photo by Katherine).

The joys

Even though we have hard time searching for Red Knots and sometimes their uncooperative behaviours, such as leaving the mudflat well before the tide coming in, have been giving us some frustrations, we are still enjoying much of our scanning life here.

Xiao Liu, our driver and a full scanning team member this year, recalls the excitement we had scanning at Hangu near the wind farm on 12-May: ‘that was the best scanning session in my life! Birds were so close to the seawall and my telescope was filled up with Red Knots and Curlew Sandpipers, so many of them have flags or colour bands. But I don’t have time to look at Curlew Sandpiper flags at all, I have to concentrate on the Red Knots so that we can record them within the last hour of sunlight. That was so wonderful and I hope to have such once in a life time experience again!

Red Knots, Curlew Sandpipers, Asian Dowitchers and other shorebirds lining up near the seawall for us to scan on 12-May evening at Hangu.  (Photo by Katherine)

Indeed, regardless of the low number of Red Knots around, we are gradually seeing more colour banded individuals. Quite often we are surprised by the number of colour bands and flags we recorded together as a team each day. After we return from the field and enter all of our data on the excel file, the numbers usually turned out to be beyond what we felt like in the field.   

Various “scanning posture” you can find in our team: Xiao Liu, Katherine, Tong and Rainy (photo by Rainy, Tong and Zhang Wei).

Other birds

Another question we are constantly asking here is: “Has migration season ended?” This is mainly to do with the scattered number of terrestrial migrants we have seen so far. Many of the “Nanpu regulars” seemed to be showing up quickly and gone even quicker! Several species of Flycatchers, Thrushes and Robins were only seen briefly for one or two days despite we kept checking our woodland birding sites every few days. 

Very brief excitement for us finding a Blue Whistling-thrush at Hangu Coast Trees on 23-May, new species for the GFN Bohai Bird List, but very common bird in Southern China for me, Rainy and Tong! (Photo by Tong).

On the other hand, we are watching shorebird departures as well. Great Knot, Dunlin, Marsh Sandpiper and Black-tailed Godwit bohaii ssp. are gone. Asian Dowitcher, Curlew Sandpiper and Sharp-tailed Sandpiper numbers are gradually going down. On 25-May, we witness departure of a small flock of Grey Plover and Ruddy Turnstone from the Hangu mudflat.  

Flock of Grey Plover with abdominal profile score 5 (scores range from AP 1-thin to AP 5-obese) migrated a few seconds after the top photo was taken. Red Knot with abdominal profile score 3, looks like it is going to stay for at least a week or so to fatten up. (Photo by Katherine)

Thanks very much for reading!

Don’t miss the final update of the season in a couple of week time to find out how this unusual season finishes!

Katherine Leung 26-May-2021

May

27

2021

Red Knot migration, north west Australia to New Siberian Islands

May

27

2021

Bohai 2021 update – 3


May

10

2021

Bohai 2021 – Update 2