The red-billed leiothrix (Leiothrix lutea) is a member of the family Leiothrichidae, native to southern China and the Himalayas. Adults have bright red bills and a dull yellow ring around their eyes. Their backs are dull olive green, and they have a bright yellow-orange throat with a yellow chin; females are somewhat duller than males, and juveniles have black bills. It has also been introduced in various parts of the world, with small populations of escapees having existed in Japan since the 1980s. It has become a common cagebird and amongst aviculturists it goes by various names: Pekin robin, Pekin nightingale, Japanese nightingale, and Japanese (hill) robin, the last two being misnomers as it is not native to Japan (although it has been introduced and naturalised there).
The leiothrix is about six inches in length, generally olive green, and has a yellow throat with orange shading on the breast. It also has a dull yellowish ring around the eye that extends to the beak. The edges of the wing feathers are brightly coloured with yellow, orange, red and black and the forked tail is olive brown and blackish at the tip. The cheeks and side of the neck are a bluish grey colour. The female is a lot paler than the male and lacks the red patch on the wings. It doesn't fly frequently, except in open habitats. This bird is very active and an excellent singer but very secretive and difficult to see.