Eastern Crowned Warbler Phylloscopus coronatus photos Sid Francis
A species on the western edge of its range, not commonly reported on Sichuan lists - we have found breeding in NE Sichuan, and there are reports from throughout Sichuan Province. A large warbler with very chunky bill with large yellow under mandible, a very strongly defined supercilium and thin single wingbar that almost gives it appearance of a "no-wingbar" species - but not a very distinctive bird if it's not singing. We have found it breeding in low plantation dominated forest woodland below the 1,000m mark but other records from the rest of China are from 2,000m. This suggests potentially wide altitude range.and it could be a much under recorded species. It will also be a passage bird. Photos can really help identification - to compare bills with other crown-stripe warblers, especially kloss's and claudia's but also the faint lemon vent, clearly seen in above photo (click to enlarge), can show up far better in photography than in field views.
Similar species - Kloss's and Claudia's both with crown stripes and noticble yellow on bills are the two obvious species that could create confusion, but the far more local Emei is also a candidate. Single thin, almost invisible, wingbar of Eastern crowned combined with that that super chunky bill are its best visual field identification pointers - and of course you have very different songs with these three species.
Habitat - distribution of this species is centred in Eastern Asia - NE China being its Chinese stronghold. Recent extensive reforestation projects have used tree species, especially pines, that are native to eastern regions and the type of tree found in core breeding range, theoretically creating more attractive habit. Other northeastern species, like Zappey's Flycatcher and Grey-faced Buzzard, seem to have made a southwestern spread with this type of tree planting - maybe Eastern Crowned is following the same trend? Lower plantation type habitat is among habitat not well visited by birders, again suggesting this bird could be more widespread and plentiful.
Vocalizations - a high ptched repeated phrase of SeeHurrZiiiiii, where Ziiiiii is a kind of buzzing trill - we've found it not that strident or noticeble but very distinct when heard. Call is an indistinctive repetition of chip notes
Song here Sid Francis iNaturalist