A small forest-dwelling songbird endemic to the South Island of New Zealand. Distinctive yellow head and yellowish to white underparts. Tends to stay high in the canopy, favoring tall native forest. Often encountered moving in small noisy family flocks, uttering loud staccato chattering calls and trills. Male has a musical canary-like song. Female gives a distinctive buzzing call. Adults can be seen feeding far larger Long-tailed Koel chicks, as this species is a favored host of that nest parasite. Easily distinguished from similarly-colored Yellowhammer by very different habitat use: Yellowhammer favors open farmland and scrub rather than mature forest.