It has dark grey plumage and paler underparts, highlighted by yellow wing-patches and a broad, black crescent, outlined in white, down the sides of its breast.

The crescent honeyeater is found in areas of dense vegetation including sclerophyll forest and alpine habitats, as well as heathland, and parks and gardens, where its diet is made up of nectar and invertebrates.

[2] It was later named Certhia australasiana by George Shaw in 1812,[3] Melithreptus melanoleucus by Louis Pierre Vieillot in 1817,[4] and Meliphaga inornata by John Gould in 1838.

[5] The generic term comes from the French phylidonyre, which combines the names for a honeyeater and a sunbird (previously thought to belong to the same family).

[11] DNA analysis has shown honeyeaters to be related to the Pardalotidae (pardalotes), Acanthizidae (Australian warblers, scrubwrens, thornbills, etc.

[12] "Crescent honeyeater" has been designated as the official common name for the species by the International Ornithologists' Union (IOC).

[8] Both sexes have dark grey legs and feet, deep ruby eyes and a long, downcurved black bill.

[6] Young birds are similar to the adults, though not as strongly marked,[8] and have dark grey bills, duller brown eyes, and yellow gapes.

[17] Moulting patterns of the species are poorly known; crescent honeyeaters appear to replace their primary flight feathers between October and January.

It is restricted to sclerophyll forest in eastern South Australia,[23] where isolated populations have been recorded in the Mount Lofty Ranges and on Kangaroo Island.

[6] It has been frequently recorded in wet sclerophyll forest dominated by eucalypts and with a thick mid-story and understory of shrubs such as blackwood, silver wattle, Cassinia, Prostanthera, and Correa.

There is widespread evidence of seasonal migration to lower altitudes in cooler months, yet a proportion of the population remains sedentary.

During courtship the male performs song flights, soaring with quivering wings and continuously calling with a high piping note.

[17] Parent birds have been observed using a range of anti-predator strategies: the female staying on the nest until almost touched; one or other of the pair performing distraction displays, fluttering wings and moving across the ground; the female flying rapidly at the intruder; and both birds giving harsh scolding calls when a kookaburra, tiger snake or currawong approached.

One study found that only 42% of the nestlings were sired by the male partner at the nest, despite paternity guards such as pairing and territorial defence.

[26] The crescent honeyeater is arboreal,[6] foraging mainly among the foliage and flowers in the understory and tree canopy on nectar, fruits and small insects.

[6] A study in forest near Hobart in Tasmania found that the crescent honeyeater's diet was wholly composed of insects during the breeding season, while nectar was a significant component during winter.

It fed on nectar as plants came into flower in the autumn and winter, and then foraged in Tasmanian blue gum (Eucalyptus globulus) during the breeding season in spring.

[27] In Bondi State Forest it was also recorded feeding at cluster-flower geebung (Persoonia confertiflora), native holly (Lomatia ilicifolia), tall shaggy-pea (Oxylobium arborescens), silver wattle (Acacia dealbata) and blackthorn (Bursaria spinosa).

[6] The threats to the crescent honeyeater include habitat destruction, as the alpine forests in which it breeds are being reduced by weed infestations, severe bushfires, drought and land-clearing.