The mountain chiffchaff or eastern chiffchaff (''Phylloscopus sindianus'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

leaf warbler Leaf warblers are small insectivorous passerine birds belonging to the genus ''Phylloscopus''. Leaf warblers were formerly included in the Old World warbler family but are now considered to belong to the family Phylloscopidae, introduced in 2006 ...

found in the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

(''P. s. lorenzii'') and

Tian Shan The Tian Shan, also known as the Tengri Tagh or Tengir-Too, meaning the "Mountains of God/Heaven", is a large system of mountain ranges in Central Asia. The highest peak is Jengish Chokusu at high and located in Kyrgyzstan. Its lowest point is ...

(''P. s. sindianus''). It is an altitudinal migrant, moving to lower levels in winter. The nominate subspecies is similar to the

Siberian chiffchaff Siberian chiffchaff (''Phylloscopus collybita tristis'') is a leaf-warbler which is usually considered a subspecies of the common chiffchaff, but may be a species in its own right. Range Siberian chiffchaff breeds in Siberia east of the Pechor ...

, but with a finer darker bill, browner upperparts and buff flanks; its song is almost identical to the

common chiffchaff The common chiffchaff (''Phylloscopus collybita''), or simply the chiffchaff, is a common and widespread leaf warbler which breeds in open woodlands throughout northern and temperate Europe and the Palearctic. It is a bird migration, migratory ...

, but the call is a weak ''psew''. ''P. s. lorenzii'' is warmer and darker brown than the nominate race; it is

sympatric In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...

with common chiffchaff in a small area in the Western Caucasus, but interbreeding occurs rarely, if ever. The mountain chiffchaff differs from ''tristis'' in vocalisations, external morphology and

mtDNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the DNA contained in ...

sequences. Its two subspecies appear to be distinct vocally, and also show some difference in mtDNA sequences.

References

*(German) Martens, Jochen (1982): Ringförmige Arealüberschneidung und Artbildung beim Zilpzalp, Phylloscopus collybita. Das lorenzii-Problem. Zeitschrift für Zoologische Systematik und Evolutionsforschung 20: 82–100. *German) Martens, Jochen; Hänel, Sabine (1981): Gesangformen und Verwandtschaft der asiatischen Zilpzalpe Phylloscopus collybita abietinus und Ph. c. sindianus. Journal für Ornithologie 122 (4): 403–427. ith English abstractdoi:10.1007/BF01652928 *Sangster, George; Knox, Alan G.; Helbig, Andreas J.; Parkin, David T. (2002). "Taxonomic recommendations for European birds". Ibis 144 (1): 153–159. doi:10.1046/j.0019-1019.2001.00026.x. https://doi.org/10.1046/j.0019-1019.2001.00026.x *Helbig, Andreas J.; Martens, Jochen; Seibold, I.; Henning, F.; Schottler, B; Wink, Michael (1996). "Phylogeny and species limits in the Palearctic Chiffchaff Phylloscopus collybita complex: mitochondrial genetic differentiation and bioacoustic evidence". Ibis 138 (4): 650–666. https://www.uni-heidelberg.de/institute/fak14/ipmb/phazb/pubwink/1996/13_1996.pdf. mountain chiffchaff Alpide belt endemic bird species mountain chiffchaff {{Phylloscopidae-stub