Striated grasswren

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.[3][4][7] 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.[8][3] Spinifex provides critical habitat for foraging and protective nesting and cover for this species, and also for most other species of grasswren.[8][9][3] 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.[10][11]

Striated grasswren, Gluepot Reserve, South Australia

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.[6] 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.[3] While foraging, birds move mainly by hopping, with tail held almost vertical; when moving through shrubs and dense vegetation, the tail is held horizontal.[3] 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.[3]

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.[3] 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).[6]

Striated grasswrens are most often recorded in pairs, and sometimes in groups of 3 and up to 10 birds, it is believed that pairs or family congregations may be more common outside of breeding season, and may range more widely over suitable areas of habitat.[6][3][12] The cooperative breeding seen in other Maluridae has not been recorded in the wild in striated grasswrens.[3][12] In captivity, members of family groups have been observed to allopreen and sunbathe together on branches, bathe in dry soil and fine water mists, and chase one-another around.[13] Breeding is typically between July and November,[4][3] but breeding outside of the usual period is likely to occur in response to sufficient rainfall, particularly in central and northern Australia.[14][12][3] Nest is a bulky domed structure of spinifex spines, lined with bark strips, grass, plant down and feathers, close to the ground and well concealed, usually in a spinifex tussock.[4][5][3] Eggs are rounded oval, white to pinkish white, finely textured and sparsely marked with purplish-red spots and blotches, mainly at the larger end.[4][5][3] A clutch of 2, rarely 3 eggs is incubated by the female for 13–14 days.[5][3] Upon hatching, both parents observed to be equally active in the feeding of chicks, and removal of faecal sacs.[3][13] Chicks fledge at 12–14 days, and remain hidden in dense cover close to the nest for 3–4 days, not gaining full independence for a further 3 to 4 weeks.[3][13] Striated grasswren nests are known to be parasitized by Horsfield's bronze cuckoo (Chrysococcyx basalis), black-eared cuckoo (Chrysococcyx osculans) and fan-tailed cuckoo (Cacomantis flabelliformis).[15]

Striated grasswren calling at Scotia Station, New South Wales. Source: Dan Eyles

Striated grasswrens are recognised as having three calls: a contact call, song and an alarm call.[6] The contact call has been described as a regularly uttered high pitched seep, see-see or tseee-tseet, which is very soft and may be inaudible in moderate winds.[3][6] The song is diagnostic and much louder than contact calls, and may be audible for up to 40 m.[6] It is described as a sweet, rippling wren-like reel, lasting up to 10 seconds, varying in pitch and consisting of whistles, buzzes, twangs and staccato notes, is uttered far less frequently, and has been observed singing from an exposed branch with its open bill pointing skywards.[3][6] The alarm call is described as a series of short, loud, harsh single notes, transliterated as jit-jit or tchiritt, given when birds are flushed from cover.[3][6]

Clearing of large areas for agriculture in the southeast of this species range have caused the direct loss of some populations and fragmentation of remnant areas of habitat, reducing the size of these populations rendering them more vulnerable to genetic effects and change events such as fire and drought.[9][11] Striated grasswrens are vulnerable to large wildfires which cause direct mortalities of these weak flying species, and remove critical habitat and protection from predators, birds show 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.[10][9][11] Grazing by introduced herbivores affects habitat structure and is likely to contribute to population declines.[9][11][18] Predation from introduced foxes and cats, particularly where populations have already declined, or are exposed by small areas of habitat following land clearance or fire.[9][11]

The striated grasswren is listed as near threatened nationally under the Environment Protection and Biodiversity Conservation Act and within Victoria under the DELP Advisory List; and vulnerable in NSW under the Threatened Species Conservation Act and South Australia under the National Parks and Wildlife Act.

The management of fire to reduce the incidence of large wildfires removing vast areas of habitat, through prescribed burning and avoidance of anthropogenic fire is critical to the maintenance of areas of suitable habitat.[9][11] Reduced stocking rates of introduced herbivores, particularly goats, and exclusion of these from some areas, to allow adequate regeneration of vegetation.[9][11] Control of exotic pest species such as cats, foxes and rabbits reduces the threat of predation, and competition for resources.