Variegated fairywren

Appearance

The variegated fairywren is 14–15 cm long and weighs 6–11 g. Like other fairywrens, it is notable for its marked sexual dimorphism, males adopting a highly visible breeding plumage of brilliant iridescent blue and chestnut contrasting with black and grey-brown.

The brightly coloured crown and ear tufts are prominently featured in breeding displays. The male in breeding plumage has striking bright blue ear coverts, with the crown often slightly darker, a black throat and nape, a royal blue upper back, chestnut shoulders and a bluish-grey tail. The wings are grey-brown and the belly creamy white. Non-breeding males, females and juveniles are predominantly grey-brown in colour; all males have a black bill and lores , while females have a red-brown bill and bright rufous lores.

Immature males will develop black bills by six months of age and moult into breeding plumage the first breeding season after hatching, though this may be incomplete with residual brownish plumage and may take another year or two to perfect. Both sexes moult in autumn after breeding, with males assuming an eclipse non-breeding plumage. They will moult again into nuptial plumage in winter or spring. The blue coloured plumage, particularly the ear-coverts, of the breeding males is highly iridescent due to the flattened and twisted surface of the barbules. The blue plumage also reflects ultraviolet light strongly, and so may be even more prominent to other fairywrens, whose colour vision extends into that part of the spectrum.

Naming

Four subspecies are recognised; there are zones with intermediate forms between the ranges of each subspecies, contrasting with the well-defined borders between ''M. lamberti'' and the other chestnut-shouldered wrens. However, molecular analysis may shed more light on relationships and the current taxonomic treatment may change. The purple-backed- and lavender-flanked fairywrens were considered distinct species in the past.

⤷  ''M. l. lamberti'' is the nominate subspecies from coastal eastern Australia and the original form described by Vigors and Horsfield in 1827. Unlike other subspecies, the head of a male in breeding plumage is a more uniform blue, with the crown azure and ear coverts lighter. It also has a blue rather than purple back.
⤷  ''M. l. assimilis'', commonly known as purple-backed fairywren, occurs across central Australia, from Queensland and western New South Wales to coastal Western Australia. It was initially described in 1901 by Australian ornithologist Alfred John North and called the purple-backed superb warbler. Breeding males of this and the other two northern subspecies differ from subspecies ''lamberti'' in having a darker violet blue crown and a purple back. Females are identical, however. There is a broad area where intermediate forms between this and subspecies ''lamberti'' live that is bordered by Goondiwindi, Wide Bay, Rockhampton and Emerald in southern Queensland.
⤷  ''M. l. dulcis'', commonly known as lavender-flanked fairywren, is found in Arnhem Land. It was described in 1908 by amateur ornithologist Gregory Mathews, though this and subspecies ''rogersi'' were long considered forms of the lovely fairywren until integrades were noted over a wide area of northern Australia with subspecies ''assimilis''. Like subspecies ''rogersi'', females are predominantly blue-grey rather than grey-brown and have white lores and eye rings rather than the rufous coloration of the other subspecies.
⤷  ''M. l. rogersi'' occurs in the Kimberleys and was originally named by Mathews in 1912. It was also known as the lavender-flanked fairywren and considered as the same taxon. Though the males are similar to the widely occurring inland subspecies ''assimilis'', the females are predominantly blue-grey rather than grey-brown. A broad hybrid zone with females of both subspecies has been recorded from northeastern Western Australia and the northwestern Northern Territory.

Distribution

Distributed over 90% of the Australian continent, the variegated fairywren is found in scrubland with plenty of vegetation providing dense cover. It prefers rocky outcrops and patches of ''Acacia'', ''Eremophila'' or lignum in inland and northern Australia. They have been reported to shelter in mammal burrows to avoid extreme heat. In urban situations such as suburban Sydney, these wrens have been said prefer areas with more cover than the related superb fairywren, though a 2007 survey in Sydney's northern suburbs has proposed that variegated fairywrens may prefer areas of higher plant diversity rather than denser cover as such. Forestry plantations of pine and eucalypts are generally unsuitable as they lack undergrowth.

Behavior

Like all fairywrens, the variegated fairywren is an active and restless feeder, particularly on open ground near shelter, but also through the lower foliage. Movement is a series of jaunty hops and bounces, its balance assisted by a relatively large tail, which is usually held upright, and rarely still. The short, rounded wings provide good initial lift and are useful for short flights, though not for extended jaunts. During spring and summer, birds are active in bursts through the day and accompany their foraging with song. Insects are numerous and easy to catch, which allows the birds to rest between forays. The group often shelters and rests together during the heat of the day. Food is harder to find during winter and they are required to spend the day foraging continuously.

Like other fairywrens, male variegated fairywrens have been observed carrying brightly coloured petals to display to females as part of a courtship ritual. In this species, the petals that have been recorded have been yellow. Petals are displayed and presented to a female in the male fairywren's own or another territory.

The variegated fairywren is a cooperative breeding species, with pairs or small groups of birds maintaining and defending small territories year-round. Though less studied than the superb- and splendid fairywrens, it is presumably socially monogamous and sexually promiscuous, with each partner mating with other individuals. Females and males feed young equally, while helper birds assist in defending the territory and feeding and rearing the young. Birds in a group roost side-by-side in dense cover as well as engage in mutual preening. Occasionally larger groups of around 10 birds have been recorded, though it is unclear whether this was incidental or a defined flock.

Major nest predators include Australian magpies , butcherbirds , laughing kookaburra , currawongs , crows and ravens , and shrike-thrushes , as well as introduced mammals such as the red fox , feral cats and black rat . The variegated fairywren readily adopts a 'rodent-run' display to distract predators from nests with young birds. The head, neck and tail are lowered, the wings are held out and the feathers are fluffed as the bird runs rapidly and voices a continuous alarm call.

Reproduction

Breeding occurs from spring through to late summer; the nest is generally situated in thick vegetation and less than 1 m above the ground. It is a round or domed structure made of loosely woven grasses and spider webs, with an entrance in one side. Two or more broods may be laid in an extended breeding season. A clutch consists of three or four matte white eggs with reddish-brown splotches and spots, measuring 12 mm × 16 mm. The female incubates the eggs for 14 to 16 days, after which newly hatched nestlings are fed and their fecal sacs removed by all group members for 10–12 days, by which time they are fledged. Parents and helper birds will feed them for around one month. Young birds often remain in the family group as helpers for a year or more before moving to another group, though some move on and breed in the first year. Variegated fairywrens commonly play host to the brood parasite Horsfield's bronze cuckoo and, less commonly, the brush cuckoo and fan-tailed cuckoo .

Food

The variegated fairywren consumes a wide range of small creatures, mostly insects, including ants, grasshoppers, bugs, flies, weevils and various larvae. Unlike the more ground-foraging superb fairywrens, they mostly forage deep inside shrubby vegetation, which is less than 2 m above the ground.