Papamoscas de Zappey Cyanoptila cumatilis

Very similar to Blue-and-white Flycatcher (breeding grounds do not overlap). Females and juveniles are essentially unidentifiable while on migration unless seen with an adult male, which is radiant, electric blue above and white below, lacking the contrasting black throat and breast of Blue-and-white, instead transitioning more smoothly from blue to white. Pale gray smudging on the flanks, while more difficult to see, can also serve to differentiate the two. Song is a thrush-like series of bright, slightly slurred warbles and whistles. Breeds in submontane mixed forests in northern China; wintering grounds little-known, but presumably at a similar altitudinal range in evergreen forests.