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Black Grasswrens are medium-size, black/rufous birds with long tails. Their cryptic plumage is dimorphic, i.e. males and females are slightly different. Both sexes have a dark-brown head and neck, finely streaked with silver/white. The back is rufous/chestnut, with downward-dimishing streaking. The rump is rufous/chestnut, tail and upperwings are dark-brown, the latter with coverts that have rufous fringes. The difference between the sexes is that males have a dark-brown to black chest and belly, while females have a chestnut/rufous chest and belly. Both sexes have brown irises. The bill, legs and feet are dark-grey. Juveniles are similar to females, with a pale gape, duller colours, and a much shorter tail. Also their streaking is less conspicuous than in adults.

The overall distribution of this species can be assessed, and specific locations where birds have been spotted can be found, based on individual sighting reports submitted by birdwatchers to ebird.org .

The overall distribution of the Black Grasswren is available HERE .

Black Grasswrens are endemic to Western Australia (WA). As is the case with all species of grasswrens, their overall distribution is complex, patchy and highly irregular. Some races also have very restricted ranges. This is mainly caused by the fact that grasswrens are rather poor fliers and individual populations, once separated, will not merge again, leading to a separation of the gene pools.The range of the Black Grasswren is restricted to an area in the northern Kimberley, WA, extending from near the Walcott Inlet, Ex Charnley River, in the West to the Mitchell Plateau, Lawley River NP, in the East. The majority of sightings is reported from the Mitchell Falls and Mertens Falls area.

Black Grasswrens have a strong preference for remote rocky environments, such as escarpments or boulders along creeks and rivers, especially around rapids and falls, with an abundance of crevices in which they forage.

M. Eaton and M. Seve report finding Black Grasswrens at Big Mertens Falls, Mitchell River NP, WA, in June 2026. All sighting, photographic and audio information presented on this page has been kindly contributed by M. Eaton and M. Seve.