The mountain chiffchaff or eastern chiffchaff (Phylloscopus sindianus) is a species of leaf warbler found in the Caucasus (P. s. lorenzii) and Himalayas (P. s. sindianus), and is an altitudinal migrant, moving to lower levels in winter. The nominate subspecies is similar to the Siberian chiffchaff, but with a finer darker bill, browner upperparts and buff flanks; its song is almost identical to the common chiffchaff, but the call is a weak psew. P. s.