Lemon-bellied flyrobin

John Gould described the species in 1843 from a specimen from Port Essington in the Northern Territory.[2] The species name is from the Latin word flavus meaning 'yellow', and Ancient Greek gaster meaning 'belly'.[3] Four subspecies are recognised: the nominate flavigaster is found across the top of the Northern Territory, subspecies flavissima in Cape York and New Guinea, subspecies laetissima along the central-northern Queensland coast, and subspecies tormenti in the Kimberley of northwestern Australia.[4] The two Queensland subspecies are separated by the Atherton Tableland and Burdekin-Lynd Divide, and are possibly kept apart by a population of the jacky winter (Microeca fascinans) that replaces it in some areas.[5] Genetic analysis shows that the two Queensland subspecies are very closely related, but that there is quite a large separation from subspecies flavigaster. Subspecies tormenti was not sampled in that study.[6]

Subspecies tormenti, known as the Kimberley flyrobin, was considered a separate species for many years. It is unusual in that it lacks the yellow pigmentation of the other subspecies.[4] Les Christidis and Walter Boles reclassified it as a subspecies, since hybrids between subspecies tormenti and flavigaster have been found in the vicinity of Cambridge Gulf—between the ranges of the two subspecies.[7][8]

As well as lemon-bellied flyrobin, the species is also commonly known as lemon-breasted flycatcher (from when belly was thought crude), yellow-bellied flycatcher, yellow-breasted flycatcher, or brown-tailed flycatcher (subspecies tormenti).[3]

The adult lemon-bellied flyrobin is around 11.5 centimetres (4.5 in) long.[9] The sexes have similar plumage. The nominate subspecies flavigaster has lemon yellow underparts, a white throat, grey face with a white eyebrow stripe, and olive-brown upperparts. Subspecies tormenti has white underparts, more greyish upperparts, has a longer bill and tail and is larger overall. Subspecies flavissima resembles flavigaster but has a more obvious yellow tinge to the upperparts, throat, yellow eyebrow and a shorter tail, while laetissima more closely resembles flavigaster, but has a shorter tail and bill and is larger overall.[4]

The species ranges from the Ord River in the west to coastal Queensland, and is found in mangroves, paperbark swamp forests, and woodland.[9]

The lemon-bellied flyrobin is an insectivore, hunting its prey in the foliage or dead branches of trees and shrubs and only rarely on the ground.[10] Fieldwork in Kakadu National Park found that it occasionally caught large insects over 2 centimetres (0.79 in) in length; insects were generally caught by the bird hawking or sallying.[10]

Breeding throughout its range, the lemon-bellied flyrobin breeds from August to February, raising one or two broods a season. The nest is a small dish-shaped structure made of bark and grasses in the fork of a tree. A single egg measuring 19 by 14 millimetres (0.75 by 0.55 in) is laid, pale blue with brownish markings.[11]