Red-backed Fairywren Malurus melanocephalus Scientific name definitions

A diminutive but charismatic savanna bird, the Red-backed Fairywren is endemic to northern and eastern Australia. It is a member of the genus Malurus, a diverse group of fairywrens known for cooperative breeding, high rates of extra-pair mating, and intense sexual selection. An insectivore with a relatively broad diet, its dispersal is limited and the species does not migrate. It is fairly tolerant of human activity and habitat disturbance, and thus quite common throughout its range, occurring in backyard gardens and along roadsides. There is significant geographic variation within the species, with two described subspecies that primarily differ in the male's plumage coloration.

A prototypical sexually dimorphic species, older males are mostly jet black with a brilliantly contrasting red or orange back and scapulars. Females and juveniles are predominantly pale brown, blending in well with their grassland habitat. Young males can vary from female-like brown plumage to the more common red- or orange-and-black plumage, with associated behavioral differences. Individuals appear somewhat compact and rotund in the field, with stubby wings, pointed bills, relatively long legs, and long tails often held upright. Rarely venturing up to the canopy or undertaking long-distance flights, the Red-backed Fairywren navigates its environment chiefly by hops and short flights through grass and low shrubs. Despite its relatively poor flying capabilities, the species is agile when moving through grass, owing to its light weight, long legs, and stabilizing tail.

Both males and females produce a relatively long, high-pitched, squeaky song, and pairs often duet. The song varies in subtle ways geographically, particularly between the two subspecies, with males of each subspecies being most responsive to their local song types. When not singing, individuals give frequent contact calls while foraging in dense vegetation.

The Red-backed Fairywren is a cooperative breeder, but it does not occur in the large groups typical of some of its congeners. Pairs frequently breed without helpers, and cooperative groups rarely exceed one helper: usually a non-dispersing male offspring from the previous year. Females build domed nests woven neatly into low grass, and are exclusively responsible for incubating the eggs, as well as providing most of the parental care. Nests are parasitized by several species of cuckoo.

Pairs are socially monogamous, but extra-pair mating is rampant. It is not uncommon for a brood to have two or three different sires. As a result of strong sexual selection, most males invest heavily in testes and sperm, and foray onto neighboring territories where they court potential extra-pair mates by puffing up their back feathers and presenting females with colorful flower petals.

As with the genus as a whole, the Red-backed Fairywren has been the focus of significant research efforts. Detailed studies have focused on its habitat use and fire ecology, mating system dynamics, alternative male mating strategies, sperm competition, as well as the costs and benefits of cooperative breeding, the hormonal basis of plumage color, the form and function of song, and hybrid zone dynamics.