The striated grasswren (Amytornis striatus) is a small, cryptically coloured ground-dwelling species of wren-like bird in the family Maluridae, endemic to Australia. It occupies a large discontinuous range across arid and semi-arid areas of western, central and southern Australia where it is associated with spinifex (Triodia) grass.
Description
The striated grasswren is one of 13 species in the genus Amytornis, commonly known as the grasswrens, found only in arid and semi-arid areas of Australia. All are small cryptic birds with long, usually cocked-tails, characterised by diagnostic distinctive interscapular gap in the feathering, an enlarged auditory bulla (tympanic chambers) and ten rectrices. The striated grasswren is a slim, long-tailed grasswren with a slender pointed bill. The plumage is highly variable across its range, suited to local soil and rock colour; birds are slightly sexually dimorphic; females have a brighter rufous flank-patch. All populations are soft red-brown above, streaked white; an orange-buff eyebrow and fore-supercilium; white throat; bold black submostachial stripe; and buffish underbody. Like other grasswrens they have short rounded wings and are unable to undertake long flights, typically flitting or hopping from perch to perch within vegetation, and run or hop when on the ground in a series of fast jerky movements. While closely related to the familiar fairy-wrens (Malurinae) striated grasswrens are larger (17-20g c.f. 6-16g), and more sombrely coloured, with varyingly prominent white streaking on varying shades of brown, rufous and black plumage. Striated grasswrens are usually seen as pairs, but sometimes as individuals, and often in small groups of up to five birds, which are unobtrusive, shy, and typically difficult to approach, often first detected by their calls. When breeding, birds may be inquisitive of intruders of their territory.
Ecology and behavior
Distribution and habitat
Striated grasswrens are the most widespread of the grasswrens, with a range which extends from through northern South Australia, across central and southwestern New South Wales, northwest Victoria and into southern and eastern South Australia. Populations of striated grasswren are strongly associated with sandplains, dunes and stony hills dominated by spinifex (Triodia) grass, with or without an overstorey of shrubs such as grevillea, Hakea, acacia, banksia or mallee eucalypts. Spinifex provides critical habitat for foraging and protective nesting and cover for this species, and also for most other species of grasswren. Striated grasswrens have been shown to have a preference for areas with large hummocks of spinifex, 25–40 years post-fire, though birds have been found to occupy some areas 6 to 8 years after fire.
Behaviour
Striated grasswrens may be active throughout the day, and in warm temperatures (over 35 °C) may be observed thermoregulating by holding wings partly open, but are generally more active in the early morning and late afternoon. Like other grasswrens, striated grasswrens mainly forage on the ground, sifting through leaf-litter beneath shrubs and surrounding spinifex Triodia tussocks, never far from cover. While foraging, birds move mainly by hopping, with tail held almost vertical; when moving through shrubs and dense vegetation, the tail is held horizontal. When disturbed in the open, they move with great speed and agility from cover-to-cover with a half-bounding half-flying action reminiscent of a bouncing ball.
Diet
Striated grasswrens are insectivorous and granivorous, foraging on the ground amongst leaf-litter and open areas, and gleaning from the foliage of herbs, forbs and low shrubs for primarily beetles and ants, and seeds of spinifex (Triodia) and other plants. Striated grasswrens have been often observed to form foraging associations with other bird species including rufous-crowned emu-wren (Stipiturus ruficeps), willie wagtail (Rhipidura leucophyrus) and variegated fairy-wren (Malurus lamberti).