Crescent honeyeater

Appearance

The crescent honeyeater measures 14–17 centimetres, in length, with a wingspan of 16–23 centimetres, and weighs about 16 grams. It is sexually dimorphic, with the female a paler version of the male.

The male is dark grey with clear yellow wing-patches with a broad, black crescent, outlined in white, down the sides of its breast, and a white streak above his eye. The top of the tail is black, with yellow edges to the feathers forming distinctive yellow panels on the sides of the tail. White tips on the undertail are usually only visible in flight. The underparts are pale brownish-grey fading to white.

The female is duller, olive brown with faded yellow wing patches with similar, though less clear, crescentic markings. Both sexes have dark grey legs and feet, deep ruby eyes and a long, downcurved black bill. The gape is also black. Young birds are similar to the adults, though not as strongly marked, and have dark grey bills, duller brown eyes and yellow gapes. Male nestlings can be distinguished by their more extensive yellow wing patches from seven days old. Moulting patterns of the species are poorly known; crescent honeyeaters appear to replace their primary flight feathers between October and January.

While both subspecies have the same general appearance, the female of ''halmaturinus'' has paler plumage than the nominate race, and both male and female have a smaller wing and tail and longer bill. The ''halmaturinus'' population on Kangaroo Island has a significantly shorter wing and longer bill than the Mount Lofty population, although this size variation of an insular form is at odds with Allen's and Bergmann's rules.

Distribution

There are records of scattered populations of the crescent honeyeater on the Central Tablelands, the Mid North Coast, and in the Hunter Region of New South Wales, and it is widespread in the areas of New South Wales south of Dharug National Park and east of Bathurst. In Victoria it is widespread across an area from the NSW border south west to Wallan with scattered populations recorded further west. It is widespread in Tasmania, except in the north-east part of the state where it is more sparsely distributed. It is restricted to sclerophyll forest in eastern South Australia, where isolated populations have been recorded in the Mount Lofty Ranges and on Kangaroo Island. Local influxes have occurred outside its normal range in response to changes in habitat. Recorded population densities range from 0.3 birds per hectare near Orbost, to 8.7 pairs per hectare in Boola Boola State Forest, also in Victoria.

Status

While the population numbers and distribution are sufficient for the crescent honeyeater to be listed as of ''Least Concern'' for conservation, numbers have fluctuated significantly over the past twenty-five years and currently seem to be in decline.

Habitat

While the crescent honeyeater occupies a wide variety of habitats including coastal heath, rainforest, wet sclerophyll forest, mountain forest, alpine woodland, damp gullies and thick tea-tree scrub, they all demonstrate its preference for dense vegetation.

Reproduction

Crescent honeyeaters occupy territories during the breeding season of July to March, with pairs often staying on in the territory at the end of the season and committing to one breeding site for several years. Banding studies have recaptured birds within metres of the nest in which they were raised, and one female was re-trapped at the banding place almost ten years later. The pairs nest solitarily, or in loose colonies with nests around 10 metres apart. The male defends the territory, which is used both for foraging and breeding, though during the breeding season he is more active in protecting the area, and therefore much more vocal. During courtship the male performs song flights, soaring with quivering wings and continuously calling with a high piping note.

The female builds the nest close to the boundary of the territory, usually near water, low in the shrubs. It is a deep, cup-shaped, bulky nest of cobweb, bark, grass, twigs, roots and other plant materials, lined with grass, down, moss and fur. The long strips of bark from stringybark or messmate trees are often used.

The clutch size is 2 or 3, occasionally 4. Measuring 19 millimetres by 15 millimetres, the eggs are pale pink, sometimes buff-tinged, with lavender and chestnut splotches. The base colour is darker at the larger end. The female incubates and broods the eggs, but both sexes feed the nestlings and remove fecal sacs, although the female does the majority of caring for the young. The young birds are fed insects, with flies making up much of the regurgitated material according to one study. The incubation period is 13 days, followed by a fledging period of 13 days. The parent birds feed the fledglings for around two weeks after they leave the nest, but the young do not remain long in the parents' territory. The young are independent within 40 days of egg-laying.

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. The nests of the crescent honeyeater are usually low in the shrubs, which makes the birds and their young vulnerable to predation by birds and snakes; however, domestic and feral cats are the most likely predators to hunt this species.

Crescent honeyeaters pair in long-term relationships that often last for the whole year; however, while they are socially monogamous they appear to be sexually promiscuous. 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. The crescent honeyeaters observed exhibited a number of characteristics consistent with genetic promiscuity: sexual dimorphism, with sex-specific plumages identifiable at nestling stage; reduced male contribution to feeding and caring for the young; vigorous defence of the territory by the male; and frequent intrusions into other territories by females which were tolerated by the males holding those territories.

Food

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