The White-gaped Honeyeater - Lichenostomus unicolor - (18 to 20 centimetres) is a mainly grey bird; upper parts are plain grey-brown, under parts a dull grey. Eye is grey to grey-brown. Legs and feet are grey. Head is grey, there is a dark-grey to black patch between eye and bill and a characteristic small white triangle at the base of the beak.
Male and female similar. Immature birds are similar to adults with a yellow wash on grey under parts and the triangle at the base of the bill is yellow.
Usually lives near water in streamside thickets, mangroves, swamp and riverine woodlands across northern Australia from the Kimberley to the Queensland east coast as far south as about Mackay/Broad Sound. Locally common except in the eastern part of the range where the Yellow Honeyeater occupies the same habitat. Established pairs and small groups appear to remain in the same foraging area all year. This area is defended with active chasing and loud singing, often in duet, from within shrubbery. White-gaped Honeyeaters feed under shrubs and in tree canopies hopping actively and picking up fruit, insects and spiders. Flight between shrubs is low and erratic.
Breeds from September to March, sometimes later. The nest is cup-shaped, made of bark strips (particularly Melaleuca inner bark), grasses, rootlets and bound with cobweb; lined with fine grass. Usually suspended by the rim in the fork of a small tree, often over water. Two eggs, smooth, slightly lustrous, white to pale flesh colour with freckles of red and purple, particularly at the large end, oval, about 22 mm by 17 mm.
Both parents feed the young. When the male has food for the young he calls loudly before approaching the nest; the female replies and leaves the nest. Parents swallow the faecal sacs of newly hatched young but later carry them away.