BIRDING MONGOLIA: arthropods

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September 29, 2016

Tuul Gol, August, 30th 2016

text & photos by ABu

Northern slope of Bogd Khan Uul, UB, August 2016

Decades of relentless trampling by livestock has caused the parallel lines across the slope; but obviously, higher vegetation is now slowly coming back; this is because of encroachment and the subsequent fencing off of almost the complete bottom of the slope; of course, all of the encroachment here, in Mongolia’s first National Park, established as protected area as early as 1778 (!), is illegal!

As regular readers of BirdingMongolia probably know, I do bird walks along the Tuul Gol (gol = river) that flows through the south of Ulaanbaatar (see label “Ulaanbaatar observations” at the sidebar). My chosen stretch lies east of the Marshall Bridge and covers the northern bank upstream for about 5 to 7 km. In summer it is not easy or even impossible to cross the river as it is untamed and quite deep, but during the winter time I also try to count the birds on the southern bank, simply because there are much fewer birds to count in total.

Over the past years, I witnessed a slight change in the vegetation along “my” stretch. Grazing (and browsing) has come almost to a complete halt. Consequently, the bushes returned and meanwhile, many formerly open areas are overgrown and all the bushes have now grown very dense. Though it is actually very good to see the recovering of the riparian woodland, at least at this small part of the river, while the rest of the country is still severely suffering from overgrazing, the bird watching got increasingly difficult. No more I just have to follow the paths trampled by the live stock, I now have to navigate through the shrubs and bushes by finding a way through the thick undergrowth. Stalking a bird has become now almost impossible, but sometimes I catch the unwary one.

After a few very cold nights—yes, autumn is approaching—with the lowest temperature of -4°C (24.8°F) two nights before, I was keen to see what birds were on stopover. So I set out for a patrol at 09:00h at a still quite cold 5°C (41°F). By noon the temperature had risen to 22°C (71.6°F) which is much more comfortable, but the wind had picked up and had driven more clouds in.

As usual I tried to avoid double counts but this is very hard to achieve, so please treat the numbers given in the list below just as very rough “best guesses” rather than most accurate count data! In total, I spent 5 hours in the thickets.

Most birds gave me a wide berth hence I could only get two species of bird photographed: Siberian Rubythroat and "Stoliczka’s" White-crowned Penduline Tit Remiz coronatus stoliczkae. Concerning the latter my ID is not fully sure.

"Stoliczka’s" White-crowned Penduline Tit (hereafter SWCPT) is the eastern subspecies of White-crowned PT and breeds along many Mongolian rivers where it is not rare. Even birds breeding along the Kherlen Gol in Choibalsan, that is in the east of Mongolia, belong to this taxon (Harrap & Quinn 1996, and pers. obs.). Whether or whether not birds breeding along the Khalkh Gol (in the Far East of the country) also represent this taxon remains unclear. Despite several visits to that region we never came across any Chinese Penduline Tit (hereafter CPT) Remiz consobrinus but most if not all birds were heard only and not seen, let alone being photographed or even mist-netted. So there is still something to be discovered in the east and not only there, indeed.

Although there are officially no other penduline tits than SWCPT on the Mongolian Bird List, CPT once has been claimed for the country (in June 2004 along the Kherlen Gol few km north of Choibalsan). Unfortunately this record was not backed up by any means of evidence so the taxon remains off the country list. The species could, however, straggle to Mongolia and why not during its fall migration? But is it possible to identify CPT in autumn here in Ulaanbaatar? I have absolutely no idea!

The only paper dealing with this subject is that by Bot et al. 2011. Unfortunately, is does not at all deal with the ID of fall migrants. In fact the authors only focus on face mask differences. Either there are no other features in which the taxa differ, but this is not mentioned, or it simply did not matter to the authors. They visited the breeding grounds and did never face such a non-breeding season ID-challenge.

A quick check of photos of both taxa in question, assuming, all birds had been correctly identified, available on the much recommended Oriental Bird Club’s bird image database Oriental Bird Images did not reveal any certain criteria. Only there is tendency for a slight difference in the pattern of the greater coverts. These are less rufous in CPT and the pale tips eat along the outer fringe much more in CPT than in SWCPT. Most of the pictures had not been taken in autumn though and some did show only a frontal view of the bird which is of no help in regards of finding differences on the wings and upper side. The degree of variation, be it individual, seasonal or sex related, is another still unclear point that needs urgent treatment by birdwatchers. It seems quite likely that there is a huge overlap in the coloration and pattern of the greater coverts of the two species.

After their breeding season PT form flocks and these flocks could potentially come from far away so the chance of finding a CPT within Mongolia during migration should not be dismissed.

Several questions remain unanswered and bird watchers could contribute to solve this ID problem by scrutinizing all PT they come across. For the time being it seems reasonable to treat all PT in this post as SWCPT.

As always, comments of the ID of the birds (any objections about the SWCPT?), plants (here: On which bush are the two PT in picture 2 foraging? Myricaria longifolia? Or is it belonging to the true tamarisks?) and other wildlife shown on this blog, are most welcome. All pictures shown here had been taken with a handheld digital camera.