Irruption of Pallas’s Sandgrouse in Beijing

Saturday 12 November 2022 will go down as one of my best ever birding experiences..  and all the better because it was completely unexpected. 
With a backlog of work to do, I had planned to work all day, despite the fantastic weather, with crystal clear blue skies and a fresh northwest wind, following the passage of a cold front the day before. 
However, during the morning I had heard that a few Pallas’s Sandgrouse (Syrrhaptes paradoxus 毛腿沙鸡 Máo tuǐ shā jī – literal translation “hairy-legged sand chicken”) had been seen at DaShiHe, in Fangshan District, southwest Beijing… 
Mid-November is the prime time for arrivals of this enigmatic species, which irrupts into Beijing every few years, and I thought I would take a quick look in the afternoon at a small patch of rough ground near my apartment just to check (thinking the chance of success was about 1%).  In any case, it would be a nice break from work and wouldn’t take very long to cover.  Little did I know that I would stay until dusk having enjoyed the incredible spectacle of seeing thousands of sandgrouse!
Within ten minutes of arriving at the patch of rough ground, as expected, I realised there were no sandgrouse on site and, after enjoying good views of a flock of Lapland Buntings and a small party of Rustic Buntings, I was about to head back home…  Just as I turned to begin the walk back, I heard a whirring of wings and, looking up, a flock of about 15 Pallas’s Sandgrouse flew right over me, followed a few seconds later by another flock of eight.  Wow – what luck!
I wondered to myself whether this was just a fluke or, perhaps, a sign that there was a large movement.  I headed up to a small hill nearby to see if I could observe any more and I was astonished at what unfolded.  The hill was a fantastic vantage point as, in the crystal clear air, I enjoyed a wide field of view, stretching to at least the CBD area of central Beijing to the south and to the mountains of Changping in the north. I estimated I could see about 20km north and a similar distance to the south.
Flock after flock came from the east, all heading between W and SW… some to the north of me, some to the south and some immediately overhead.  It was incredible. 
Fortunately I had my camera with me and I snapped some photos of the flocks as they passed, including some passing Beijing’s tallest building, the CITIC tower (known as China Zun, a 109-storey tower standing 528m tall).  
Flocks of Pallas’s Sandgrouse passing the CITIC tower, Beijing’s tallest building in the Central Business District.
Flock after flock flew past, all heading W-SW.
Some of the flocks passed overhead, providing superb views
This flock banked and, shortly after, landed just a few metres away from me as the light faded.
I began logging each flock, counting individuals if possible or, in the case of the larger flocks or those seen only briefly, estimating the numbers using ‘blocks’ of 10 or 20 birds.  For the next three hours there were flocks passing almost every minute… and in some cases several flocks simultaneously.  It was an exhilarating experience…
Via WeChat, the most popular social media, other birders reported flocks from the DaShi River, Shahe Reservoir and other sites across the city, with some even seeing flocks from their office or residential blocks in the city centre.  
Over the next three hours or so, I counted 7,363 in total (all between 1400-1722), surely a fraction of the total number of birds involved but smashing the previous day-record of 1,050 birds on 14 November 2019 (Wang Xiaobo). 
My hand-written count sheet, showing time and flock size (all heading W-SW unless otherwise stated).
Although my field of view was extensive, I am sure I missed many flocks, particularly those flying low, and of course I would miss all the birds in Yanqing area (the other side of the Badaling mountains) and those in the south of the city, not to mention those that had passed earlier in the day before I began to watch and count.
Around dusk, several flocks flew very low, calling, and appearing to look for somewhere to land.  One flock did land right in front of me for about a minute and fed actively on seed heads before heading off again..  and as the wind dropped at dusk, most of the flocks were then heading north and not W-SW. 
The flock that landed just a few metres away from my position at dusk.
These birds waddled and fed actively on seed heads for a few minutes before lifting and heading north.
After sunset, the flocks seemed to change direction, with all flocks from 1655-1722) heading north or northwest.
These irruptions are not well understood but are likely driven by conditions in their usual range (e.g. snow cover or extreme cold).  Given that there are so few records further south, I speculate that these birds may come south/southeast from their usual range, explore the North China plain and then most head back north when they realise there isn’t much suitable grassland habitat…  but that’s just a hunch.  It will be fascinating to see whether many hang around or whether they disappear as fast as they arrived.
The Pallas’s Sandgrouse has been a dream bird for me ever since reading Arthur Patterson’s accounts of flocks during the invasions of the UK, particularly along the east coast, in the late 1800s. 
Arthur Patterson (1900) in The Zoologist, 4th series, Vol. IV. p. 534, under ‘The Birds of Great Yarmouth’ says: ‘During the invasion of this species in 1863 (when sixty were killed in Norfolk), several were obtained here. The North Denes and sand-hills were most frequented. The first Norfolk bird was found dead in the surf on May 23rd. A gunner named Nudd, on June 6th, shot a male out of a flock of nine. He mistook them for Plover, but described them to me as “running about like Rats.” On May 27th, 1876, a flock was observed on the Winterton sand-hills; and in May, 1888, a second invasion occurred, when over eleven hundred were seen in Norfolk, and one hundred and eighty-six were killed. A male and female were seen on the Denes as late as Dec. 2nd (vide Stevenson’s Birds of Norfolk, vol. i. pp. 376-404 ; also vol. iii. pp. 392-396).
As a boy growing up in Winterton-on-Sea, the thought that the local sand dunes had once hosted flocks of these enigmatic birds was etched in my mind and during my regular birding walks over the dunes, I often quietly said to myself “one day…”
To see thousands in just a few hours in Beijing, albeit not in those beloved dunes at Winterton, was a dream come true.
It is said that, in China during the Tang Dynasty, the appearance of these birds in Beijing was a sign of impending war because it meant the conditions in their usual range were unusually harsh, prompting the nomads to invade southwards. 
Thankfully, today, Pallas’s Sandgrouse receive a much warmer welcome in the capital.