Superb Fairywren

Appearance

The Superb Fairywren is 14 cm long and weighs 8–13 g, with males on average slightly larger than females.

The average tail length is 5.9 cm, among the shortest in the genus. Averaging 9 mm in subspecies "cyaneus" and 8 mm in subspecies "cyanochlamys", the bill is relatively long, narrow and pointed and wider at the base.
Wider than it is deep, the bill is similar in shape to those of other birds that feed by probing for or picking insects off their environs.

Like other fairywrens, the Superb Fairywren is notable for its marked sexual dimorphism, males adopting a highly visible breeding plumage of brilliant iridescent blue contrasting with black and grey-brown. The brightly coloured crown and ear tufts are prominently featured in breeding displays.

The breeding male has a bright-blue forehead, ear coverts, mantle and tail, brown wings, and black throat, eye band, breast and bill.

Females, immatures, and non-breeding males are a plain fawn colour with a lighter underbelly and a fawn or dull greyish blue tail. The bill is brown in females and juveniles and black in males after their first winter.

Immature males moult into breeding plumage the first breeding season after hatching, though incomplete moulting sometimes leaves residual brownish plumage that takes another year or two to perfect.

Both sexes moult in autumn after breeding, with males assuming an eclipse non-breeding plumage. They moult again into nuptial plumage in winter or spring. Breeding males' blue plumage, particularly the ear-coverts, is highly iridescent because of 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 this part of the spectrum.

Naming

Two subspecies groups are recognized, though future DNA studies may prompt reclassification.

⤷ "M. c. cyaneus", the nominate subspecies described in 1782, is found throughout Tasmania and on the Bass Strait Islands. Birds are larger and darker than the mainland subspecies, with males having a deeper azure blue coloration. Those of King Island were first described as a separate species "elizabethae" by A.J. Campbell in 1901, with a deeper blue colour still. Birds of Flinders Island are of intermediate colour between the King Island and Tasmanian forms. Schodde in his 1982 review reclassified "elizabethae" under "cyaneus".

⤷ "M. c. cyanochlamys", described by Richard Sharpe in 1881, is found on mainland Australia; in general, birds are smaller and paler than those of Tasmania, with Queensland male birds bearing a pale silvery blue crown, ear tufts and mantle.

Distribution

The Superb Fairywren is common throughout most of the relatively wet and fertile south-eastern corner of the continent, from the south-east of South Australia and the tip of the Eyre Peninsula, through all of Victoria, Tasmania, coastal and sub-coastal New South Wales and Queensland, through the Brisbane area and extending inland – north to the Dawson River and west to Blackall.

Behavior

Like all fairywrens, the Superb 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, with its balance assisted by a proportionally 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.

The Superb Fairywren is a cooperative breeding species, with pairs or groups of 3–5 birds maintaining and defending small territories year-round. The group consists of a social pair with one or more male or female helper birds that were hatched in the territory, though they may not necessarily be the offspring of the main pair. These 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 engaging in mutual preening.

Habitat

It is a common bird in the suburbs of Sydney, Melbourne and Canberra. It is found in wooded areas, generally with plenty of undergrowth, and has also adapted to urban existence and can be found in gardens and urban parks as long as there is an undergrowth of native plants nearby.

Reproduction

Breeding occurs from spring through to late summer; the nest is a round or domed structure made of loosely woven grasses and spider webs, with an entrance in one side generally close to the ground, under 1 m, and in thick vegetation.

Two or more broods may be laid in an extended breeding season. A clutch of three or four matte white eggs with reddish-brown splotches and spots, measuring 12 x 16 mm. The eggs are incubated for 14 days, after which they hatch within 24 hours.

Newborn chicks are blind, red and featherless, though quickly darken as feathers grow. Their eyes open by day five or six and are fully feathered by day 10. All group members feed and remove fecal sacs for 10–14 days.

Fledglings are able to feed themselves by day 40 but remain in the family group as helpers for a year or more before moving to another group or assuming a dominant position in the original group. In this role they feed and care for subsequent broods and repel cuckoos or predators.

Food

Superb Fairywrens are predominantly insectivorous. They eat a wide range of small creatures as well as small quantities of seeds, flowers, and fruit. Their foraging, termed 'hop-searching', occurs on the ground or in shrubs that are less than two metres high. Because this foraging practice renders them vulnerable to predators, birds tend to stick fairly close to cover and forage in groups. During winter, when food may be scarce, ants are an important 'last resort' food, constituting a much higher proportion of the diet. Nestlings, in contrast to adult birds, are fed a diet of larger items such as caterpillars and grasshoppers.

Predators

Major nest predators include Australian Magpies, butcherbirds, Laughing Kookaburra, currawongs, crows and ravens, shrike-thrushes as well as introduced mammals such as the Red Fox, cat and Black Rat.

Defense

Superb Fairywrens may utilise a 'Rodent-run' display to distract predators from nests with young birds. The head, neck and tail are lowered, wings held out and feathers fluffed as the bird runs rapidly and voices a continuous alarm call.

Evolution

In his 1982 monograph, ornithologist Richard Schodde proposed a southern origin for the common ancestor of the Superb and Splendid Fairywrens. At some time in the past it was split into southwestern and southeastern enclaves. As the southwest was dryer than the southeast, once conditions were more favourable, the Splendid forms were more able to spread into inland areas. In the east, the Superb Fairywren spread into Tasmania during a glacial period when the sea level was low and the island was connected with the rest of the continent via a land bridge. What gave rise to subspecies "cyaneus" became isolated as the sea levels rose. The Bass Strait forms were isolated from Tasmania but more recently and so their subspecific status was not maintained. Further molecular studies may result in this hypothesis being modified.

Cultural

The Superb Fairywren is used as an emblem by the Bird Observation & Conservation Australia. On 12 August 1999, a Superb Fairywren was mistakenly illustrated for an Australia Post 45c pre-stamped envelope meant to depict a Splendid Fairywren. Called the Blue Wren as it was then known, it had previously featured on a 2s.5d. stamp, released in 1964, which was discontinued with the advent of decimal currency.