Limestone leaf warbler

The limestone leaf warbler (Phylloscopus calciatilis) is a species of warbler in the family Phylloscopidae. When this species was first seen, beginning in 1994, it was mistaken for the similar sulphur-breasted warbler. It is smaller than the sulphur-breasted warbler, and has more rounded wings. The plumage is almost identical, with comparisons showing only a slightly colder yellow below and a greyer tinge above. Although smaller, the bill is proportionally larger than that of the sulphur-breasted warbler. Accurate measurements are not available; the holotype has a wing length of 5.2 cm (2.0 in); the paratype a tail length of 3.7 cm (1.5 in) and a bill length of 1.39 cm (0.55 in). The species is known to occur in northern Vietnam and Laos, and potentially also occurs in southern China as well. The species name, calciatilis, means "dwelling on limestone", which along with its common name is a reference to its natural habitat, which is broadleaved evergreen and semi-evergreen forest growing around limestone karst mountains. The bare-faced bulbul, described in 2009, was found in the karst of the same region.