The splendid fairywren is found across much of the Australian continent from central-western New South Wales and southwestern Queensland over to coastal Western Australia.

Exhibiting a high degree of sexual dimorphism, the male in breeding plumage is a small, long-tailed bird of predominantly bright blue and black colouration.

[3] The habitat of the splendid fairywren ranges from forest to dry scrub, generally with ample vegetation for shelter.

Unlike the eastern superb fairywren, it has not adapted well to human occupation of the landscape and has disappeared from some urbanised areas.

[5] Specimens were initially collected at King George Sound, and the splendid fairywren then described as Saxicola splendens by the French naturalists Jean René Constant Quoy and Joseph Paul Gaimard in 1830,[6] three years before John Gould gave it the scientific name of Malurus pectoralis and vernacular name of banded superb-warbler.

There are four subspecies currently recognized:[15] In his 1982 monograph, ornithologist Richard Schodde proposed a southern origin for the common ancestor of the superb and splendid fairywrens.

These split into at least three enclaves which subsequently evolved in isolation in the following drier glacial periods until the current more favourable climate saw them expand once again and interbreed where they overlap.

[20] A 2017 genetic study using both mitochondrial and nuclear DNA found the ancestors of the superb and splendid fairywrens diverged from each other around 4 million years ago, and their common ancestor diverged around 7 million years ago from a lineage that gave rise to the white-shouldered, white-winged and red-backed fairywrens.

Exhibiting a high degree of sexual dimorphism, the breeding male is distinctive with a bright blue forehead and ear coverts, a violet throat and deeper rich blue back wings, chest and tail with a black bill, eye band and chest band.

[25] Breeding males' blue plumage, particularly the ear-coverts, is highly iridescent due to the flattened and twisted surface of the barbules.

[26] 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.

Habitat is typically dry and shrubby; mulga and mallee in drier parts of the country and forested areas in the southwest.

Movement is a series of jaunty hops and bounces,[33] with its balance assisted by a proportionally large tail, which is usually held upright and rarely still.

Splendid fairywrens are sexually promiscuous, each partner mating with other individuals and even assisting in raising the young from such trysts.

[35] Major nest predators include Australian magpies (Gymnorhina tibicen), butcherbirds (Cracticus spp.

[40] Several courtship displays by splendid fairywren males have been recorded; the 'sea horse flight,' so named for the similarity of movements to those by a seahorse, is an exaggerated undulating flight where the male, with his neck extended and his head feathers erect, flies and tilts his body from horizontal to vertical and by rapidly beating wings is able to descend slowly and spring upwards after alighting on the ground.

[43] It is notable that fairywrens are socially monogamous and sexually promiscuous: pairs will bond for life,[44] but regularly mate with other individuals; a proportion of young will have been fathered by males from outside the group.

The nest is built by the female; it is a round or domed structure made of loosely woven grasses and spider webs, with an entrance in one side close to the ground and well-concealed in thick and often thorny vegetation, such as Acacia pulchella or a species of Hakea.

[52] The splendid fairywren is predominantly insectivorous; its diet includes a wide range of small creatures, mostly arthropods such as ants, grasshoppers, crickets, spiders and bugs.

Food can be scarce in winter and ants are an important 'last resort' option, constituting a much higher proportion of the diet.

[54] Adult fairywrens feed their young a different diet, conveying larger items such as caterpillars and grasshoppers to nestlings.