Threatened Species of the Northern Territory

HORSFIELD’S BUSHLARK(Tiwi Islands subsp.)SINGING BUSHLARK Mirafra javanica melvillensis

Description

The Singing Bushlark is a small short squat lark with a short robust bill and a rounded head. The top of the head and neck appear black, streaked with rufous and there is a distinct pale-buff eyebrow. The upperparts are mottled brownish-grey with rufous edging to the feathers, and a strongly rufous wing. The underparts are pale cream-rufous with strong dark streaking on the breast. The legs are short. Birds can raise a short crest, but this is not usually visible.Distribution

Singing Bushlarks are found throughout South-East Asia, the Philippines and Australia, as well as across northern sub-Saharan Africa, the Arabian Peninsula and southern Asia. They are widespread in Australia and occur in all mainland Australian states and territories. As a species, it is probably one of the most numerous birds in the Northern Territory (NT), with estimates

of 6 million birds. Most records come from the savanna belt, including the Victoria River District and the Barkly Region, but there are also records from the Darwin-Daly Region, Arnhem Land, Alice Springs Region and the eastern Simpson Desert.

Known locations of the Tiwi Singing Bushlark

There are eight recognised subspecies of Singing Bushlarks, four of which occur in the NT. One of these, M. j. melvillensis is endemic to the Tiwi

For more information visit www.denr.nt.gov.au

Conservation statusAustralia: Critically EndangeredNorthern Territory: Vulnerable

Photo: BirdLife Australia*

Islands, and all records so far have come from Melville Island. This subspecies is the focus of this listing. It is the only subspecies of Singing Bushlark that occurs on the island. Conservation reserves where reported: None.

Ecology

Bushlarks generally are grassland birds, particularly occupying perennial tussock grasslands with rank cover. They tend to be less numerous as tree-cover increases. The Tiwi Singing Bushlark is largely confined to treeless plains dotted within the tropical forest and woodland matrix that dominates the islands. These treeless plains consist of Acacia open shrublands with Sorghum grassland understorey. Singing Bushlarks forage entirely on the ground, feeding on seeds and invertebrates. They make a nest on the ground, under cover, and lay three to four eggs per clutch. In the NT, most breeding occurs in November-early April. Conservation assessment

There are few records of the Tiwi Singing Bushlark and in 2000-2001, the most intensive fauna survey of the islands by Woinarski et al. (2003) recorded them in only two sites from a total of 351 survey sites and 400 person-days of opportunistic surveys across the range of terrestrial habitats on the islands. They appear confined to areas of treeless plains which cover only 191 km2 on the islands, and not all of this is likely to be suitable habitat. The status of the Tiwi Singing (Horsfield’s) Bushlark was assessed in 2010 by Garnett et al. (2011). They estimate the population to be less than 1 000 individuals, and classify the species as Vulnerable. This species qualifies as Vulnerable in the NT (under criterion D1), based on:

An very small total population size (<1 000).

Threatening processes

The area of treeless plains habitat of the Tiwi Singing Bushlark was reduced last century by replacement by plantations of exotic Caribbean pines. Such replacement is unlikely to occur in the future. More recent commercial plantations on Melville Island with non-native Acacia mangium have replaced eucalypt forests and woodlands, not treeless plains. It is not known whether this clearance of native forest for plantations will be beneficial or detrimental for this subspecies. Fire regimes on the Tiwi Islands have changed significantly and are now characterised by larger, hotter and more frequent fires in accessible areas and less frequent fires in more remote areas (Garnett et al. 2011). The spread of weeds, both grassy weeds and feral plantation species, into treeless plains is likely to alter their vegetation composition and structure, as well as fuel loads. Grazing and disturbance by feral water buffalo, pigs and horses may also degrade treeless plain habitats, though they may also reduce grass density, which may be beneficial. Consequently, threats to Tiwi Singing Bushlarks are not clearly defined at present, and the subspecies may have always been in low numbers.Conservation objectives and management

The primary conservation objectives are to maintain and enhance the condition of treeless plain areas on the Tiwi Islands, and to retain a stable population of Tiwi Singing Bushlarks. Management objectives include developing and implementing a monitoring program for the subspecies. Compiled by

Simon Ward [updated December 2012][EPBC update July 2015]

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References*BirdLife Australia www.birdlife.org.au

Garnett, S.T., Szabo, J.K., and Dutson, G. (2011). The action plan for Australian Birds 2010. (CSIRO Publishing/Birds Australia, Melbourne.)

Higgins, P.J., Peter, J.M. and Steele, W.K. (eds)(2001). Handbook of Australian, New Zealand and Antarctic Birds. Volume 5: Tyrant flycatchers to chats. (Oxford Univ. Press, Melbourne.)

Woinarski, J., Brennan, K., Hempel, C., Armstrong, M., Milne, D., and Chatto, R. (2003). Biodiversity conservation on the Tiwi islands, Northern Territory. Part 2. Fauna. 127 pp. (Department of Infrastructure Planning and Environment: Darwin.)

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