"Gulling" the East

part three

text and photos by ABu

(links to part 1, part 2)

Right then, now to the gulls. We drove up to the small lake called Bulangijn Tsagaan Nuur (nuur = lake), a little northeast of Buir Nuur and when we arrived on 22 May, it became clear that I probably would not be able to catch as many gulls as intended. Thanks to the previous disappointment at the first (former) colony, I had not expected much. Despite this it came quite as shock to see that this colony which we had also found in 2014, when about 250 pairs were breeding on three small islands, was almost completely gone. This lake was nearly dry and two of the islands did not exist anymore because the water level had dropped so much. Although the remaining island was still occupied by Mongolian Gulls, the number of nests was small. It turned out that there were only 30 nests containing eggs. Many of the gulls on the island were non-adults, strongly indicating that the more experienced gulls had left already. But not completely so: one adult Mongolian Gull that bred on the island was already wing-tagged. It had been individually marked as an adult by my team and me in 2004 some 250 km to the north west, hence it was at least 16 years old and hence not a at the beginning of its life as a breeding gull.

Upon arrival, an upcoming thunderstorm gave us the priority to pitching tents and I decided to catch and check the gulls during the next days. I had a lot of time to do the latter as the thunderstorm developed into straight rain that lasted for the next two days, preventing me from any ringing. I spent most of the days inside my tent and watched the gulls from the distance. Every evening between 400 and 500 gulls, mostly immatures, gathered near the island. So I checked them with the aid of my scope and paid particular attention to those not going conform to my idea of a mongolicus. After the rain had weakened and I tried to take record shots of some of the suspicious gulls I had found. It was still rather dark and windy so the long range (!) shots I achieved are of an awful quality and of course, I could not document all of them.

Luckily a gull that had immediately caught my eyes on our first day at the lake was still around: it was an adult large white-headed gull but it was obviously darker than any of the accompanying Mongolian Gulls. Further, it was not in primary moult and also showed very bright lemon yellow legs. This combination ticked my virtual boxes for Heuglin’s Gull. With the aid of my scope I found that it showed some smaller black markings on its 4 outer primary coverts (in the flight picture this black area looks bigger than it actually was because of blurring) but this does not necessarily mean that it wasn’t adult.

In the bag!

Adult Heuglin’s Gull (composite image)

Eastern Mongolia, May 2016, © Andreas Buchheim

Adult Heuglin’s Gull between mostly adult Mongolian Gulls

Eastern Mongolia, May 2016, © Andreas Buchheim

Adult Heuglin’s Gull between mostly immature Mongolian Gulls

Eastern Mongolia, May 2016, © Andreas Buchheim

There were other gulls which did not moult. They not only differed in this from the Mongolian Gulls of the same age. The odd birds fell into two groups: most of them (4 birds) showed rather white heads with a neck stola and many new feathers on the mantle and wing, giving them a rather fresh look. One bird of these four I considered to belong to heuglini not only because it was as dark (only adult like feathers compared, of course) as the adult (seen side by side once). It also showed a bright orangey pinkish bill with a black tip (like the bill of a young Glaucous Gull). Unfortunately I could not take any pictures of it. The others must have come from the breeding grounds along the arctic as well. For the summer time we are still beginning to get ideas about the ID of immature of those taxa breeding along the coasts of the Asian part of the Arctic Ocean (heuglini, taimyrensis, birulai and vegae; listened by the location of their respective breeding ranges from west to east) so I am not sure about their ID. It would be easiest to call all of them heuglini but probably much more honest to leave them unidentified.

Presumed 2cy Heuglin’s Gull landing behind Mongolian Gulls

Eastern Mongolia, May 2016, © Andreas Buchheim

Possible 2cy Heuglin’s Gull (different bird) between Mong.Gulls

Eastern Mongolia, May 2016, © Andreas Buchheim

The other “group” consisted actually of only a single individual. This one showed an almost evenly streaked head and its belly was also streaked just like those Herring Gulls I know from Europe. All newly replaced feathers of its mantle and wings weren’t plain just as I would expect from a vegae. Of this bird I also could not take any pictures so my observation cannot be recognized as a proper record (due to the previously mentioned uncertainties and no proof).

Gulls of these two kinds can be found in almost any larger gathering of immature gulls during spring and summer here and many of them have previously been attributed to heuglini. Based on our current non-knowledge on the variation of immature plumages of the aforementioned taxa (plus barabensis) only the most typical (what is typical in large white-headed gulls?), if any, might be identifiable.

For many years to come all future observers of such gulls are kindly requested to fully document them by means of photographs (preferably showing the bird also in flight from above and below), or ideally, DNA-sampling, as individuals which just have been photographed we might never be able to safely assign the documented gull to one of the taxa in question.

A Relict Gull entertained me and some Kentish Plovers for quite a while although the little plovers didn’t like that as much as I did. After the rain had stopped I could start ringing. In the end I caught 15 gulls which all got their set of wing-tags. Please watch out for them!

Mongolian Gull

Eastern Mongolia, May 2016, © Andreas Buchheim

Relict Gull

Eastern Mongolia, May 2016, © Andreas Buchheim

Relict Gull

Eastern Mongolia, May 2016, © Andreas Buchheim

Relict Gull and Kentish Plovers

Eastern Mongolia, May 2016, © Andreas Buchheim

Relict Gull and Kentish Plovers

Eastern Mongolia, May 2016, © Andreas Buchheim

Relict Gull and Kentish Plover

Eastern Mongolia, May 2016, © Andreas Buchheim

Relict Gull in flight

Eastern Mongolia, May 2016, © Andreas Buchheim

Because I got tired to sit and sit inside my tent I walked around each day just during the very few rain breaks, but mostly without my camera. Although migration was slow I found some more or less noteworthy birds:

On 23 May:
A flyby Eurasian Whimbrel (unclear which subspecies), c. 120 Spotted Redshanks, c. 300 Red-necked Stints, 9 Sanderlings, some of them sporting their sometimes very bright red breeding plumage.

On 24 May:
A nice flock of 6 taivana Yellow Wagtails (Green-crowned/Green-headed Yellow Wagtail), 3 Little Curlews, an Eurasian Bittern and 4 Caspian Terns.

On 25 May:
A male Amur Falcon dashing through the air towards the east, a dark morph Booted Eagle.

Then, on 26 May, we went on to the famous Khalkhgol plantation a little further up the river and shortly before we arrived a group of 7 Siberian Cranes was seen feeding on the banks of the Khalkh river. Here, many waders were busily foraging: among others I saw c. 1,600 Red-necked Stints, 13 Asian Dowitchers and 65 Curlew Sandpipers.

More about the birds that I saw in the plantation will be reported next!

2cy male Mongolian Reed Bunting
("ssp" lydiae of Pallas's Reed Bunting)

Eastern Mongolia, May 2016, © Andreas Buchheim

2cy male Mongolian Reed Bunting
("ssp" lydiae of Pallas's Reed Bunting)

Eastern Mongolia, May 2016, © Andreas Buchheim

Last light Pied Avocet

Eastern Mongolia, May 2016, © Andreas Buchheim

“tripod” Pied Avocet

Eastern Mongolia, May 2016, © Andreas Buchheim

4 of the 7 Siberian Cranes

Eastern Mongolia, May 2016, © Andreas Buchheim