Mountain chiffchaff Caucasus, but interbreeding occurs rarely, if ever. The mountain chiffchaff differs from "tristis" in vocalisations, external morphology and mtDNA sequences. Its two subspecies appear to be distinct vocally, and also show some difference in mtDNA sequences. Mountain chiffchaff 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
Hawking (birds) nighthawk does not). When different kinds of birds have the same adaptations, such similarities are not necessaily indicative of any familial relationship between bird species. Rather, they are the result of convergent evolution. Consider, for example, the marked resemblance in body size, shape, and coloration between flycatchers of several families, though these species are not closely related: the Asian brown flycatcher (of the Muscicapidae or Old World flycatcher family), Acadian flycatcher (of the Tyrannidae or tyrant flycatcher family) of the New World, and slaty monarch (of the Monarchidae or monarch flycatcher family), endemic to Fiji. All three use flycatching to