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

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