Birds
Superb Fairywren
Malurus cyaneus · also called superb fairywren, superb fairy-wren, blue wren
The superb fairywren is one of Australia’s most familiar garden birds: a tiny, long-tailed sprite that bounces through the undergrowth in noisy family parties, the breeding male dressed in electric blue. It is also a favourite of behavioural scientists, because behind the charm is a bird that stays paired for life while conducting, on both sides, one of the most thoroughly documented double lives in the animal world.
Overview
Superb fairywrens live across southeastern Australia, including Tasmania, anywhere with low dense shrubs for cover — forest, heath, farmland, parks, and suburban gardens. They are about 14 cm long including the tail and weigh just 8–13 g. Breeding males have an iridescent blue crown, cheeks, and back with a black mask; females and non-breeding males are plain grey-brown with a reddish bill and eye-ring.
Family groups
A territory is usually held by a dominant pair plus one or more helpers — typically their own grown sons — that feed nestlings, mob predators, and defend the boundary. Young are raised by a small team, which is why fairywrens travel in little parties.
A double life
Pairs stay together year-round and often for life, yet genetic studies show about three-quarters of broods contain at least one chick fathered from outside the pair. Paired males make pre-dawn raids into neighbouring territories, and females deliberately seek out males they rate more highly. Both sexes pursue it.
Petals and deception
Males carry bright flower petals, usually yellow, as courtship props — rare among birds. They also give false hawk alarms to make a rival freeze or a female stay put, a behaviour researchers describe as tactical deception.
Status
The superb fairywren is Least Concern, abundant, and thoroughly at home in gardens and parks.
Superb Fairywren: common questions
Why is the superb fairywren called unfaithful when pairs stay together for life?
Because social life and reproduction are separated in this species. A male and female hold a territory together all year, cooperate to raise young, and often remain paired until one dies, which is social monogamy. But DNA testing of the chicks tells a different story about who the parents actually are. In most nests, some or all of the young were fathered not by the resident male but by other males from nearby territories. Around three-quarters of broods contain at least one such chick. Both sexes pursue this — paired males leave at dawn to seek matings elsewhere, and females deliberately seek out and visit males they rate more highly than their own partner.
How do you tell male and female superb fairywrens apart?
In the breeding season it is easy. Adult males moult into a striking plumage with an electric-blue crown, blue ear tufts, and a blue upper back, set off by a black mask, bill, and collar. Females, immatures, and males outside the breeding season are much plainer, mostly soft grey-brown above and paler below, and the quickest way to pick a female or young bird is the warm reddish-orange colour of the bill and the bare skin around the eye, which the black-billed breeding male lacks. All of them share the small size, upright stance, and long tail usually held cocked.
What are the helper birds at a fairywren nest?
Superb fairywrens are cooperative breeders. A territory is typically held by one dominant breeding pair, but they are often accompanied by one to several additional adult birds, usually sons from previous years that have stayed on rather than dispersed. These helpers do not normally breed themselves. Instead they carry food to the nestlings, help feed the incubating female, mob predators, and join in territorial disputes with neighbours. Having helpers can raise the number of young a group fledges and gives the helpers experience and a chance to inherit the territory, and it is why fairywrens move around in little parties rather than as lone pairs.
Do superb fairywrens really carry flower petals?
Yes. Males have been seen to pick brightly coloured petals, most often yellow ones that contrast with their blue plumage, and hold them in the bill while displaying to a female, sometimes one in their own territory and sometimes one they are visiting elsewhere. The petal seems to serve no purpose except as a visual prop in courtship, which is unusual, since most birds that use objects in display, such as bowerbirds, build or decorate a structure rather than carry a single item around. It is one of several behaviours that have made this small, common bird a favourite subject for behavioural research.