Pallas's Leaf Warbler - Taxonomy

Taxonomy

Pallas's Leaf Warbler is named after the German zoologist Peter Simon Pallas, who discovered it on the Ingoda River in Siberia in 1811; the species name proregulus derives from its similar size to the Goldcrest Regulus regulus. In the past, it was treated as a complex of several subspecies; apart from the nominate subspecies breeding in northern Asia, two to four other subspecies were accepted, breeding much further south at high altitudes in the Sino-Himalayan mountain system from the western Himalaya east to western China (Yunnan north to Gansu and Hebei). Even though they differ only slightly in plumage, they are very distinct vocally with both song and calls differing. Genetic analysis has also shown them to be distinct, and they are now treated as separate species:

• Lemon-rumped Warbler Phylloscopus chloronotus. Himalaya, SW China. Three subspecies, P. c. chloronotus, P. c. forresti, P. c. simlaensis.
• Gansu Leaf Warbler Phylloscopus kansuensis. Central western China. Monotypic.
• Chinese Leaf Warbler Phylloscopus yunnanensis (syn. P. sichuanensis). Western China. Monotypic.

Of these, Phylloscopus chloronotus forresti is possibly also a separate species, but further analysis is required to confirm this. Gansu Leaf Warbler and Chinese Leaf Warbler overlap in breeding range in southern Gansu, but are separated ecologically, with Gansu Leaf Warbler using taller forest habitats and Chinese Leaf Warbler in lower, often scrubby habitats.