Rediscovery of Sillem's Mountain Finch
Sillem's Mountain Finch Leucosticte sillemi is a species known
only from two specimens collected by Dutch explorer Jérôme Alexander
Sillem during the Netherlands Karakoram Expedition in 1929 from Kushku
Maidan, a barren plateau in the Xinjiang Autonomous Region in western
China, at an altitude of 5125m. One bird is a worn adult male, and the
other a juvenile male with wings not yet fully grown (implying that the
species bred in the area).
Both specimens languished in a mixed drawer of Leucosticte and
Montifringilla finches in the collection of the Zoological Museum
of Amsterdam, labelled as Brandt's Mountain Finch L. brandti,
until Dutch ornithologist C. S. Roselaar noticed in 1991 that they did not match the
other specimens in the drawer. A comparison with 400 specimens of
L. brandti established that the birds represented a new species;
in particular, the grey-fringed flight feathers, tawny-cinnamon head and
neck, and an absence of black on the lores and forehead all serve to
separate it from Brandt's Mountain Finch. In addition, the juvenile is
heavily streaked above, unlike any juvenile Brandt's. He named the new
species L. sillemi in a paper in the Bulletin of the British
Ornithologists' Club in 1992.
OrientalBirdImages.org has
photographs of the type specimens,
kindly contributed by Dr. Roselaar.
Rediscovery in Qinghai in 2012
In early June 2012, Yann Muzika photographed many finches during a
difficult trek in Yeniugou Valley in western Qinghai, China (1500km east
of Kushku Maidan), including one he could not identify. In August, he
sent a batch of photographs to Krys Kazmierczak, the maintainer of
OrientalBirdImages.org, who immediately identified the mystery bird as
the long-lost Sillem's Mountain Finch. The identity of the birds has
been confirmed by various experts, including Dr. Roselaar. Upon
studying the remaining photographs, some images of what appear to be the
female (hitherto unknown) were also found.
A presumed female Sillem's Mountain Finch. The female was
hitherto unknown.
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Dr. Roselaar's paper describing the species speculates that, unlike
other Leucosticte finches (in which the sexes are identical), the
heavy streaking on the juvenile suggests that the adult female Sillem's
Mountain Finch may look different from the male (which calls its
taxonomy into question). Yann's photographs confirm this guess.
Click the photographs above for larger versions, or visit
Yann's blog
for an account of the rediscovery and more photographs (including some
comparisons with Kozlowia roborowskii and Leucosticte brandti).
Further research is needed, which may include trapping the bird for
measurements and close-up examination, as well as possibly procuring a
blood sample for DNA analysis. The decision to make this news public at
this stage was taken in order to encourage visitors to the remoter areas
of the Tibetan plateau to look out for the species, so that we may learn
more about its distribution and habitat requirements and endeavour to
ensure that it continues to survive.
References
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