I got no proper experience of Yellow-bellied Bush Warbler. The books are quite confusing except for the call/song, which is very distinctive, at least in summer. It is interesting to compare this bird to that of Peter's. On Peter's bird, the chestnut on the crown is very clear. I think that is good for strong-footed (or Mountain) Bush Warbler. The bird on this post is really interesting. The call is very unlike any strong-footed Bush Warbler that I know of. I think there is a real chance that this is actual a Yellow-bellied Bush Warbler.
HF Cheung
