The yellow thornbill (Acanthiza nana), formerly known as the little thornbill, is a tiny passerine bird endemic to the eastern coast of Australia. While currently listed as Least Concern by the IUCN, the general consensus is that the population is decreasing. Taxonomy Acanthiza nana was named by Irish zoologist N. A. Vigors and American naturalist Dr Thomas Horsfield in 1827, with the bird noted in the Sydney Cove area. However, the earliest field notes with type description record the yellow thornbill in 1803, with records sent at the time to the Linnean Society of London. The generic name Acanthiza derives from Ancient Greek akantheōn 'thorn-brake' and zaō 'live, inhabit'. The specific epithet nana is Latin for a 'female dwarf'. The yellow thornbill is one of 13 currently recognised species of thornbill within the genus Acanthiza. There are five species groups recognised within this genus, with the yellow thornbill (Acanthiza nana) most closely related to the striated thornbill (Acanthiza lineata). The only Acanthiza species which occurs outside Australia, the New Guinea thornbill (Acanthiza murina), also bears close molecular similarities to both the yellow and striated thornbills. Description Although similar to the striated thornbill and brown thornbill in both size and shape, the yellow colour of the yellow thornbill is more prominent. There is no sexual dimorphism, so that males and females look alike. They are around in length, with an average wing span of , and weighing between . Adults The back feathers are greenish, the primary and secondary wing coverts are olive-brown with a paler edge on the primaries that contrast with the alula. Upper- and under-tail are more dull than the rest of the body, and the same colour as the wings except for a dark brown-black subterminal band. Their throat and chin is a pale buff-orange that blends into the soft, creamy-yellow of the breast. Legs, toes, and bill are all black. Their eyes are dark brown with a grey outer-ring, although in some individuals the outer ring of the iris is almost white or pale brown. The eye-ring is narrow and cream in colour. The lores are also cream, with a slight grey tone. Belly Juveniles Juveniles appear similar to adults, though feathers are "softer" looking and duller by comparison . When recently fledged, their gape is still yellow. The yellow feathers on their belly are more subdued, and back and head feathers are more brown than