Himalayan Prinia

It was formerly lumped with the striped prinia as the striated prinia, and populations in Myanmar, most of China and Taiwan are now considered P. striata after a 2019 study (Wikipedia, general species account).

The tail is long and broad and cold-toned dark, and there is significant sexual dimorphism in size and colour. In the breeding season males have a blackish crown, paler around the edges in many individuals, while in the non-breeding season both sexes have streaking on the upperparts and mottling on the sides of the face and breast, and breeding females are lighter with less streaking (Wikipedia, general species account).