The purple-crowned fairy-wren is a large unmistakeable fairy-wren. Males in breeding plumage have a vivid purple crown with a black centre, surrounded by a broad black band through the eyes and around the nape. The wings and back are cinnamon to sandy, the throat and breast are white, shading to rufous-buff on the flanks and belly. The tail is deep blue and all except the central pair of feathers are broadly tipped with white. Females lack the purple crown and black band, but have white eye rings and brow and broad red-brown cheek patches.

The purple-crowned fairy-wren is known from two subspecies, both of which occur in the Northern Territory (NT). The eastern subspecies, M. c. macgillivayi is known from north-western Queensland and the Gulf hinterland in the NT, extending as far west as the upper Roper River. The western Known locations of the western purple-crowned fairy-wren subspecies, M. c. coronatus occurs from the Victoria River catchment west to the north Kimberley,Western Australia (WA). In WA, the species is found along some of the river systems in the Kimberley. Within this range, purple- crowned fairy-wrens are almost entirely restricted to a narrow band around well- vegetated river channels.

Purple-crowned fairy-wrens prefer thick riparian vegetation, typically of canegrass and/or pandanus, but also dense patchy shrubs up to 3 m. Purple-crowned fairy-wrens live in small family groups of 2-6+ birds. They are territorial and sedentary, feeding in loose groups in the undergrowth or on the ground. They remain in contact using a soft chirping.

They feed on a variety of insects and also eat small quantities of seeds. If conditions are suitable they can breed throughout the year. Females typically lay three eggs in a bulky nest in the crown of a pandanus or in thick clumps of canegrass.

The greatest threat to the subspecies is degradation or loss of habitat. Livestock seeking water eat and trample riparian vegetation, and more frequent and/or more intense fires have also been detrimental in some places. Anne- Marie van Doorn (pers.comm.) reports a decrease of 50 per cent in the adult populations at two sites where grazing and trampling was allowed around habitat patches over a two year period. The canegrass in these areas recovered quickly after the area was fenced, but the wren population has not yet recovered. Boekel (1979) described a similar pattern in the Victoria River area in the 1970s, with cattle grazing destroying habitat during bad droughts and exposing wrens to predation by cats, and failure to recolonise once habitat had apparently recovered.

A similar pattern of decline associated with damage to riparian vegetation by livestock was reported for the Kimberley by Smith and Johnstone (1977). Increased flood energy due to rangeland degradation has also destroyed some areas of riparian vegetation. Heavy weed invasion may also have adverse effects now and in the future. Recent studies (by A-M van Doorn) have indicated very low breeding success, largely due to nest predation. This study site is now known to contain the exotic black rat Rattus rattus, a known voracious nest predator.

They like to feed mainly on insects and sometimes seeds. They will eat all types of small invertebrates and are not very picky! It seems that high temperatures can reduce the lifespan and fitness of young chicks growing up since it damaged their DNA. Since climate change means rising temperatures, this is having an effect on their health. These stunning birds are currently listed as endangered due to human actions such as the grazing of livestock, habitat fires and more.