Rediscovery of Sillem’s Mountain Finch
The email i received from Krys was reading : “I was processing and uploading your pics when I arrived at your mystery bird. Rather worryingly, it looks rather like the long lost Sillem’s Mountain Finch (Leucostcite sillemi) .”
It was a bit of a shock, albeit a pleasant one, not the least because of the circumstances in which the picture was taken, and the unlikelihood that it would possibly end up in the sighting, and photograph, of a bird that had not been seen since 2 specimens were collected in 1929 by a dutch expedition in the Karakoram range, over 1500 km to the west of where i got the picture.
I did not venture into the upper reaches of Yenigou Valley, a remote area of western Qinghai, China, with any scientific goal, and it was not a birdwatching nor a photography expedition either, even though i was carrying a DSLR camera and a 400mm, just in case. It was just a trek with 2 friends, that was about to fail since Bertrand and myself were struggling hard with a food poisoning. Bertrand had already pulled out when we reached the location, elevation just below 5000m, after 2 days of a strenuous hike, at least for me. I told Paljor, my tibetan friend who by contrast never feels better than when trekking through the wilderness, that i’d rather stop for a full day hoping for some improvement in my condition. After setting up camp, there was still time to explore the surroundings and that’s when i had the first sighting, and photography, of a finch that i had not seen before. It was sitting quietly among a loose flock of what i identified as being female Tibetan Rosefinches (Kozlowia roborowski), a bird that i had not seen before either, but that was on my short list of “birds to look for” during the trek. The next day, we came across roborowski several times again, mostly females, and also 2 stunning males, which mostly crimson plumage looks out of place in the midst of the barren and rocky landscape. Other birds in the area included Brandt’s Mountain Finch (Leucosticte brandti) and Horned Larks (Eremophila alpestris). In the afternoon i met the “mystery” finch again, almost same location, and it flew after a pair of shots. I did not think much of it at the time, just took a few notes back to the tent, leaving a proper identification for later. I had been to Qinghai a couple of times before, seen a number of birds that occur in the area, but certainly not all of them, and i knew those high elevation finches can be tricky to ID. The next morning i did not feel significantly better, and to add insult to injury, the camera was out of order due to the frost. Hopefully, the pictures on the card were safe. So we turned back and retraced to the starting point, aborting a trek that was supposed to last over 3 weeks and take us to the borders of Xinjiang, and that i had spent months preparing.
I left the pictures sleeping on my hard disk a few weeks and only in August after coming back from Europe i looked at them again, and made some Identification work on the finch. i could not succeed as none of the finches occurring in the area were a match to the bird. I quickly went over the Sillem’s Mountain finch, which is described in the Mac Kinnon’s “Birds of China” guide book, but as the presumed location was so far off i did not pursue. I was rather convinced that i had simply overlooked a more common bird, maybe an immature form.
As a next step i sent the pictures of birds i took during the trip, including the finch that i labelled “mystery bird”, to Krys Kazmierczak. Krys manages the Oriental Bird Images database (http://orientalbirdimages.org) for the Oriental Bird Club (see the Conservation page), which is a great tool for birdwatchers and also bird illustrators and even biologists, as a repository of over 60000 pictures of almost 3000 birds of the oriental region. Over the years, Krys has developed a network of birdwatchers and photographers that provide him with their images, and he spends a good amount of his time processing those images and putting them online for the benefit of all. I was glad to join that network a couple of years ago, sending some of my images of birds where few pictures were available, and also getting Krys’ expert opinion when struggling with an identification.
So when he replied after reviewing my pictures, i knew it was serious, as he would not put forward the name of a very rare bird without a good amount of certainty. The next few weeks was a captivating process of procuring more information about Sillem’s Mountain Finch, gathering other experts’ opinions, and examining more attentively all the pictures that were taken on the location. The conclusions so far are :
- The picture of the bird fits the description of the male Sillem’s Mountain Finch, according to all experts contacted, including C.S. Roselaar whose taxonomic work on the specimen collected by the Dutch expedition led to the recognition of L. sillemi as a distinct species in an article published in the 1992 Bulletin of the British Ornithologist’s Club (112 /225-231). In addition to plumage, important structural features include a very high wing to tail length ratio (higher than K. roborowski, itself higher than L. brandti, who are seemingly the closest related finches to sillemi), with the wing tip very close to the tail tip, and a short beak compared to roborowskii. Those features are obvious in the pictures shown below.
- In addition, further examinations of the pictures of the female rosefinches showed that in fact 2 distinct species might have been observed : Tibetan Rosefinch, and a paler bird, with streaks on the underparts limited to the breast, a shorter beak, and longer wings compared to the tail. As the “structural” differences are similar to those between male Tibetan Rosefinch and Sillem’s Mountain Finch, it is natural to believe that the “pale form” is actually a female Sillem’s Mountain Finch. Females of L. brandti are similar to males and considered indistinguishable in the field.
- This would also be consistent with the observations made by C. S. Roselaar in his 1992 paper on Sillemi : “The adult female [of L. sillemi] is as yet unknown, but the fact that the juvenile of this species is far more heavily streaked than the adult male, unlike other Leucosticte, may indicate that the female is streaked too, and thus not similar to the adult male. If this assumption is valid, then L. sillemi perhaps is better included in Kozlowia, showing the same adaptations to high-mountain life, with very long wing and short tail and leg.”
- In terms of habitat, Sillem’s mountain finch appears to be a very high altitude specialist, possibly sympatric with brandti (the 2 specimens collected by Sillem were part of a flock of brandti) and roborowski (in the Eastern part to its range, as roborowski is not known to occur West of Qinghai). The fact that its wings are longer than brandti and roborowski suggests that its degree of specialization to high altitudes is even superior.
- Location wise, this possible sighting is situated at the same latitude as the type location, but over 1500km to the East. However, climatic conditions are believed to be similar, and in between those 2 places lies the Kunlun range with elevations permanently above 4000m, and exceeding 7000m at the highest point, therefore providing a continuous stretch of suitable habitat for Sillem’s Mountain Finch.
All this however needs confirmation, from further sightings and photographs, and also possibly the procurement of blood sample of the bird for DNA analysis. The location of the sighting is fairly remote, as it takes a 2 days trek to reach the place, but birdwatchers are encouraged to look for the bird at more accessible locations along the Golmud-Lhasa highway, and in particular around and above the Kunlun pass (4760m, 160km South of Golmud) and the Tanggula pass (5230m, around 200km further south).
For more on Sillem’s Mountain FInch :
- http://www.sillem-family.com/sillems-finch.html (for the illustration, i am not vetting the text)