Tui have almost-black heads, underparts, wings and tails that have an iridescent blue and green sheen, especially on the head and wings. The upper back and flanks are dark reddish brown with a bronze sheen, the nape and sides of the neck have filamentous white feathers, and there are two unusual curled white feather tufts on the throat (poi). Small white shoulder patches on the upperwing show prominently in flight, but are usually concealed when perched. The bill and feet are black, and the eye dark brown. The sexes are alike, but the male is larger. Adults have a notch on the 8th primary, and this feather quivers from the narrow part creating the whirring sound in flight. At first, juveniles have a browner body and lack the throat tuft, but after a few months they are only distinguishable in the hand from the lack of notch on the 8th primary.

Voice: a loud and complicated mix of tuneful notes interspersed with coughs, grunts and wheezes. In flight, tui maintain contact and harass raptors with a repetitive scream.

Similar species: male blackbirds are uniformly black, lack throat tufts, and have an orange bill. Bellbirds have very similar song, but this is more fluid, and lacks the loud coughs, grunts and wheezes of tui.

Tui in flaxbush