Male adult birds with small tails are all black with purple metallic flashes; The forehead feather at the base of the mouth is a tufted black feather, which extends forward on the peak of the mouth and is covered with tufted feathers except the tip; Forehead, eyes, cheeks and ears are black; The head and neck have scaly metallic luster; The back, shoulders, waist and tail are covered with black feathers with purple-blue luster; The wings and feathers are dark brown, and the headland is shiny and metallic; The tail feathers are dark brown, and the headland has a metallic luster. The outermost pair of tail feathers are extremely slender, and their stems are partially exposed. The inner and outer headlands at the end are symmetrical with each other, showing a "disc-tail shape", and other inner tail feathers are normal, only about 1/3 of the length of the outermost pair of tail feathers. The lower body is black, and the edges of throat and chest feathers are decorated with scaly metal blue-green luster; Smoke is gray; The abdomen and tail are covered with gray-black feathers with a slight luster; The alar feather and axillary feather are dark brown, with gray spots at the tip.
Female adult birds are like male birds, but the metal flash is not obvious; The outermost tail feather is slightly shorter than that of the male. The tufted forehead feathers of young birds are underdeveloped; Body feathers shine slightly; The alar feather and axillary feather are dark brown, and the white spot at the tip of the feather is large and obvious; Under normal circumstances, the tail feathers are deeply forked, the outermost pair of tail feathers are not very extended, the stems are not exposed, and there is no extended "disc tail".
Iris reddish brown; The mouth, tarsus, toes and claws are all black.
Size measurement: weight ♂42-48g, ♀ 40-47g; Body length (including extended tail feathers) ♂476-580mm, ♀ 447-541mm; Mouth peak ♂2 1-22mm, ♀ 22-26mm; Wing ♂ 132- 138mm, ♀130-138mm; Tail ♂359-439mm, ♀ 320-409 mm; Tatar ♂ 19-20mm, ♀20-22mm. (Note: ♂ male; ♀ Female)
(Note: Website of Small End Atlas)