Grey-crowned Warbler

The grey-crowned warbler (Phylloscopus tephrocephalus) is a species of Old World warbler in the family Phylloscopidae. It is found in Bangladesh, China, India, Laos, Myanmar, Thailand and Vietnam. Its natural habitats are temperate forests, subtropical or tropical moist lowland forest, and subtropical or tropical moist montane forest. The grey-crowned warbler was previously placed in the genus Seicercus. However, a molecular phylogenetic study published in 2018 found that neither Phylloscopus nor Seicercus were monophyletic. (Wikipedia, general species account).

In the subsequent reorganization, the two genera were merged into Phylloscopus, which has priority under the rules of the International Commission on Zoological Nomenclature. The accessible general account establishes the species identity, distribution and the natural-history points stated above. Behaviour, diet and breeding can vary geographically, and the available source does not support adding precise Vietnam-specific measurements or nesting dates. This profile therefore retains only species-wide information that can be stated defensibly, rather than filling gaps with unsupported local claims (Wikipedia, general species account).