Grey grasswren

Two subspecies are recognized:[7]

• A. b. barbatus – Favaloro & McEvey, 1968: found in the Bulloo River watershed (south-western Queensland and north-western New South Wales, Australia)
• A. b. diamantina – Schodde & Christidis, 1987: found in the Diamantina River watershed (extreme south-western Queensland and north-eastern South Australia, Australia)

Favaloro and McEvey described the call of the grey grasswren as a soft double-syllable note which the bird tweeted persistently.[3] Joseph also noted that calls were given constantly over several minutes with a series of three or four high pitched metallic notes, sounding like pit-choo.[12] Carpenter described the call as a high pitched sit-sit-sit.[13]

The breeding behaviour of this species has not been extensively documented but it is thought that the species breeds in July/August usually after flooding or heavy rain.[17] However, Hardy recorded breeding during heavy drought conditions with no local surface water in the study area for at least seven years.[11] The semi-domed nest is built in lignum or cane grass,[10] between 30 and 75 cm above ground level. Favaloro and McEvey noted that the nest was a large well camouflaged nest, very loosely constructed from grass with a large opening on the side. Clutch size is thought to be two eggs[4] with an average weight of 2.4 g. Egg color is dull, white speckled all over with nutmeg brown, nutmeg to reddish-brown or cinnamon brown markings. There is considerable colour variation between eggs within the nest and also between nests.[3] The female is solely responsible for the incubation of the eggs which is estimated at 13 to 15 days. Both parents attend to the feeding of the hatchlings and no details are known of its breeding success.[18]

The shape of the beak suggests that the grey grasswren's diet consists mainly of seed and an analysis of the gut content of a specimen confirmed the presence of mainly small seeds of different plants, two small ants and the remains of small Coleoptera.[3] Hower, other researches have noted that insect larvae is the dominant food source supplemented by mature insects and water snails.[19]

Little is known about its life expectancy but research conducted at one of its prime lignum habitats found from capture/re-capture surveys that this bird reached at least three years of age in that study area.[16] The population of the grey grasswren is highly variable and subject to 'boom and bust' conditions, depending on prevailing climate within its range in the arid interior.[16] Based upon the capture/re-capture method undertaken by Hardy in drought conditions, the New South Wales population was estimated at 1600 birds or 0.2 per hectare. Extrapolation of this to reach an estimate of its Australian population should be viewed with caution due to its geographic range, seasonal and habitat variability.

Research on the grey grasswren is limited and there have been few recent studies into the ecology of this elusive bird. As it occupies specific habitats, the major threat is habitat degradation through overgrazing and trampling by cattle, rabbits, and feral pigs, predation by cats and invasive weeds. A dependence on lignum and associated plant groups also makes the species vulnerable to catastrophic events such as drought and fire. The consequences of climate change also need further consideration to ensure that the grey grasswren continues to exist in arid regions of central Australia through the preservation of suitable areas.

In June 2020 the Government of New South Wales acquired 153,415 ha (379,100 acres),[21] or 1,534 km² (592 sq mi)[22] of private land for a new national park, when it purchased Narriearra station in the state's far north-west. The area includes "ephemeral wetlands and landscapes" that had not previously been included in the state's conservation areas. Together with the nearby Sturt National Park, there would be a nearly contiguous conservation area of about 500,000 ha (1,200,000 acres), which is twice the size of the Australian Capital Territory. The new property lies next to the Pindera Downs Aboriginal area, which is rich in cultural artefacts of Aboriginal Australians.[21] It is the largest ever purchase of private land for conservation in the state.[22] The Dingo Fence on the border with Queensland forms the northern boundary of the property. [23]

Nearly 90 percent of the grey grasswren's habitat lies within Narriearra Station, so this is a significant move towards protecting the bird. The Tibooburra Local Aboriginal Land Council has been invited to suggest a name for the new park.[21]