Birds Australia Conservation Statement No. 1 NATIVE GRASSLANDS AND THE PLAINS- WANDERER by David Baker-Gabb SUMMARY: Lowland native grasslands are among the most depleted ecosystems in south-eastern Australia, and contain a dispro- portionately large number of threatened plant species. Threatened grassland fauna such as the Plains-wanderer have suffered a similar decline. Plains-wanderers are permanent residents in their favoured patches of sparse native grassland. However, they cannot survive where these grasslands are converted to crops or dense introduced pasture, or are overgrazed by stock. In the five years since the publication of the first RAOU Plains-wanderer Conser- vation Statement in 1993, considerable effort has been expended in surveying and studying the temperate native grasslands of South Australia, Victoria and New South Wales. This work has revealed that the status of the Plains-wanderer is worse than previously thought. A very significant new threat has emerged from an expanding rice industry in the Plains-wanderer’s stronghold, the Riverina of New South Wales. The situation for Plains- wanderers in Queensland remains unclear, but there is no reason to suspect that it is improving given the expansion of the cotton industry and conversion of native grasslands to introduced pasture there. On the positive side, recent studies have provided refined information on managing native grasslands to maintain their biodiversity, and they provide some clear targets for urgent conservation action. High quality native grassland with sparse open structure, NSW Riverina – typically favoured Plains- wanderer habitat. Photo by Marianne Porteners/ Royal Botanic Gardens Sydney Female Plains-wanderer. Photo by Tom Wheller Supplement to Wingspan, vol. 8, no. 1, March 1998 ii Birds Australia Conservation Statement 24 WINGSPAN / December 1997 THE DESTRUCTION OF LOWLAND NATIVE GRASSLANDS is not unique to temperate south-eastern Australia. The pampas of Argentina, the prairies of North America and the chalk grasslands of Europe have all been drastically altered and depleted, owing to their suitability for – and sensitivity to – agriculture. As their habitats have been changed or lost, threatened grassland fauna such as the Plains- wanderer Pedionomus torquatus have declined as well. The Plains-wanderer is a small ground-dwelling bird of sparse native grasslands.1 It is an inland shorebird that superficially resembles button-quail (Turnix spp.). Both the male and female have cryptic plumage, with the female being larger and more brightly coloured than the male.2 The Plains-wanderer is of great scientific interest, being the sole member of a family of birds found only in south-eastern Australia, the Pedionomidae. It may be an ancient member of Australia’s avifauna, and its closest relatives are seedsnipe (Thinocorus spp.), which are South American inland shorebirds.3, 4 The first RAOU Conservation Statement on Plains-wanderers and native grasslands5 was published in 1993. This revised Plan, appearing only five years later, has been necessary because this period has seen the development of significant new findings and threats to the species. Plains-wanderers’ The many achievements of those working for the PLAINS-WANDERER BIOLOGY nesting site: there is a conservation of Plains-wanderers over the past five well-camouflaged nest years include four outstanding results: Population status and distribution (inset) in the centre of the picture. Note the structure (i) identification of, and the stimulus to purchase, The Plains-wanderer has declined greatly in numbers 6, 7, 8 of the vegetation and the the last remaining area of significant native and distribution since European settlement. amount of bare ground in grassland in north-central Victoria, adjacent to Areas where the species was formerly common and is this sparse native grassland Terrick Terrick State Park; now effectively extinct include south-western on a Riverina grazing (ii) provision of an excellent regional conservation Victoria, south-eastern South Australia and eastern property. Plains-wanderers 7, 9, 10 can co-exist with domestic planning tool for south-west New South Wales New South Wales. Its current stronghold is the 1, 7 stock in such paddocks, grasslands through the identification and Riverina of south-western New South Wales. Areas providing grazing pressure mapping of much of the Plains-wanderer of secondary importance include north-central is not too high. If habitat there; Victoria and central-western Queensland.1, 7 overgrazing occurs during (iii) provision of information that assisted in the A viable Plains-wanderer population is not known drought, then Plains- wanderers are eliminated decision to purchase Astrebla National Park in to occur in any reserve. However, the reserve most from such areas. central-western Queensland; and likely to contain a viable population is the 200,000 ha Photos by Tom Wheller (iv) a significant increase in awareness of the value of Astrebla National Park, about 200 km west of native grasslands among land owners, wildlife Windorah, in central-western Queensland. Over 20 agencies, politicians and community groups. Plains-wanderers were located in this former section of Native Grasslands and the Plains-wanderer iii December 1997 / WINGSPAN 25 Davenport Downs Station11 before it was purchased Victoria, with about 25 per cent of these birds on for a reserve in 1996. Plains-wanderers have also been just one property.14 In south-western Victoria and recorded on the 500,000 ha Diamantina Lakes south-eastern South Australia there are no viable National Park, immediately to the north of Astrebla populations, with the plains south and east of the National Park. About 120 Plains-wanderers occur, and Flinders Ranges containing just a few birds.10 some breed, on the 1400 ha native grassland While there have been no surveys for Plains- purchased in late 1997 which is adjacent to (and now wanderers in south-west and central Queensland in part of) the Terrick Terrick State Park in north-central the past decade, past surveys and records are Victoria, 60 km north of Bendigo. insufficient for optimism.11 Nevertheless, these Surveys conducted over the past 15 years have records indicate that inland Queensland is now shown that numbers of Plains-wanderers on the second only to the Riverina in importance for the Riverine Plain can vary by a factor of 10 (one bird conservation of the Plains-wanderer. per 2.2–20 km), depending on seasonal conditions, An accurate total estimate of Plains-wanderer Male Plains-wanderer. stocking rates and the time of year when the survey numbers is difficult to obtain for the whole of Males are smaller and more 12 cryptically coloured than was conducted. Suitable habitat comprises about south-eastern Australia. Nevertheless, recent surveys females, so much so that 5 per cent of 37 large grazing properties surveyed in show that previous estimates, though possibly the sexes were originally the Riverina, covering over 0.5 million hectares.12 accurate when they were made over a decade ago, are described by John Gould in However, the amount of suitable habitat drops to now too optimistic. Habitat destruction has 1840 as two species. Males around 1–2 per cent in very wet or dry years, when continued apace,9, 10 and the total number of birds do most of the incubation and all of the chick-rearing, the grasslands become too dense or are grazed too must be revised down by 30 per cent to a maximum leaving the female free to bare for Plains-wanderers. of about 8000 after several good seasons, and a find a second mate. minimum of 2500 in very dry or wet years. Photo by Tom Wheller Recent intensive ground surveys indicate that earlier estimates of 5500 Plains-wanderers in the The new IUCN criteria indicate that the Plains- Riverina1 represent the maximum number after wanderer is currently vulnerable nationally,13 but several years of ideal conditions. In very wet or dry recent evidence suggests that it could quickly years, when most birds disperse or perish, the become nationally endangered if appropriate action number in the Riverina could drop below 1000 is not taken soon, particularly in New South Wales. mature individuals. The new IUCN criteria13 determine that the species’ status in New South Habitat requirements Wales is vulnerable, but it will not need to decline Areas favoured by Plains-wanderers are hard, red- much further to become endangered there. brown earths with a sparse covering of native herbs Victoria and South Australia contained perhaps and grasses. Such areas contain about 50 per cent the greatest numbers of Plains-wanderers at the time bare ground, with fallen litter making up a further of European settlement,7, 14 but nearly all native 10 per cent.16, 17 The more robust plants in the flora grasslands in these States have been converted to are generally spaced 10–20 cm apart and rarely dense introduced pasture or croplands. Recent exceed 30 cm in height. The bulk (94 per cent) of comprehensive surveys show that the species is now the vegetation is less than 5 cm, but the small endangered in both these States.9, 10, 14, 15 There are proportion above this height is important for fewer than 500 Plains-wanderers in north-central concealment from predators. iv Birds Australia Conservation Statement 24 WINGSPAN / December 1997 In the Riverina, pairs of Plains-wanderers They may also leave when unusually heavy winter occupy home ranges averaging 18 ha.1 Several pairs rains promote dense growth of introduced and may be found