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).
Taxonomy
The red-billed leiothrix was formally described in 1786 by the Austrian naturalist Giovanni Antonio Scopoli under the binomial name Sylvia lutea. Scopoli based his account on "La mésange de Nanguin" that had been described and illustrated in 1782 by the French naturalist Pierre Sonnerat in the second volume of his book Voyage aux Indes orientales et à la Chine. The species is now placed together with the silver-eared mesia in the genus Leiothrix that was introduced in 1832 by the English naturalist William Swainson. The genus name combines the Ancient Greek leios meaning "smooth" and thrix meaning "hair". The specific epithet lutea is from Latin luteus meaning "saffron-yellow". Scopoli specified the type location as China but this was subsequently restricted to the mountainous regions of the Chinese province of Anhui.
Five subspecies are recognised: The female is a lot paler than the male and lacks the red patch on the wings.
Distribution and habitat
The leiothrix is usually found in India, Bhutan, Nepal, Burma and parts of Tibet. This species is a bird of the hill forests, found in every type of jungle though it prefers pine forests with bushes. It has also been found at elevations ranging from near sea level to about . In Japan it prefers forests of Abies and Tsuga with a dense understorey of bamboo. The leiothrix was released in Western Australia but it failed to become established. This species was also introduced in Great Britain but permanent establishment was thought to be unsuccessful, although a cluster of sightings in 2020–2022 in southern England suggests that some colonies may have been established. It was introduced to France, where it is now established in several areas, Spain where it is increasing and spreading from the Collserola Park, and Portugal. In Japan, naturalised populations of what is probably the nominate subspecies of this species have been recorded since the 1980s and it has become established in central and southwestern Japan. It is also established on the Mascarene island of Réunion. The species has also been introduced in Italy where three major populations can be identified (Tuscany and Liguria, Latium, Colli Euganei) and there are several areas at high risk of invasion.
Behaviour and ecology
The presence of the avian malaria parasite has been found in the blood of this species. The nests of the red-billed leiothrix are composed of dry leaves, moss and lichen; however, they are not well hidden because concealment isn't really a primary factor when determining a nest site.