Adults: Above, plain mid grey-brown. Rump, rich russet. Wings, dusky brown. Tail, dusky with narrow white tips to inner webs of all but central pair of feathers. Forehead feathers scalloped white on brown-black. Face, mottled brown and white. Below, from chin to undertail, off-white, washed greyer from sides of neck to flanks. Eye, white. Bill, dusky. Feet, dusky. Southern birds are slightly darker than those from the north.
Semi-arid and arid zones of southern Australia; absent from tropical northern and from eastern seaboard.
 
Central-western Australia to the southern part of the Northern Territory and south to about Esperance, WA. South Australia, Victoria, western New South Wales and south-western Queensland.
 
Rarity Status
Currently this species is not classified as a rarity in this country OR information has not been updated.
Population
Estimated population is unknown (2010).
Food
Insects, larvae, spiders and some seeds and vegetable mater. They feed at all levels of the vegatation, from leafy tree tops to the ground. Often joins Brown Thornbill (Acanthiza pusilla), Slaty-backed Thornbill (Acanthiza robustirostris), Yellow Thornbill (Acanthiza nana) and Yellow-rumped Thornbill (Acanthiza chrysorrhoa) in mixed feeding parties.
Voice
Call: Quiet, constant twitter of single and run-together 'chips' from feeding flocks, Also soft, carrying, plaintive whistles 'pseee, pseee' in contact. Churring buzzing 'chips' in alarm. Song: Prolonged chirping twittering, throughout the year but mostly during breeding. Also mimics others.
Chestnut-rumped Thornbill (Acanthiza uropygialis) [XC605834]
by Peter Boesman from Campbell Swamp, Australia (uncertain)
Chestnut-rumped Thornbill (Acanthiza uropygialis) [XC263832]
by nick talbot from Brookfield Conservation Park, SA, Australia (call)
Breeding Season (Guide)
July - December, but not during drought.
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Nest
Domed, with a side-entrance, composed of bark and grass, bound with cobweb, lined with feathers. Usually placed in a hollow in a dead tree-trunk, behind loose bark, or in similar situations, including buildings.
Eggs (Guide)
3; pale pinkish-white, minutely freckled all over with red-brown, particularly in a zone at the larger end; oblong-oval; about 16 x 12 mm.
Young
Altricial, nidicolous. Fledge in about 14 - 21 days. Fed by both parents.
Subspecies
No subspecies.
Recent analysis of mitochondrial DNA suggests that this species may be close to Slender-billed Thornbill (Acanthiza iredalei). Variation is clinal, plumage becoming darker from northern and west to southern and east, and palest inland. Naming of geographical subspecies moora (in south-western Australia) and augusta (arid interior of south, east to Flinders Ranges, in South Australia) considered unwarranted.
The Field Guide to the Birds of Australia Pizzey, G., and Knight, E., 1997, Angus & Robertson, Sydney ISBN 0 207 19691 5
Field Guide to Australian Birds Morecombe, M., 2000, Steve Parish Publishing Pty Ltd. ISBN 1 876282 10 X
Field Guide to the Birds of Australia Simpson, K., and Day, N., 1999, 6th Edition, Viking ISBN 0 670 87918 5
Reader's Digest Complete Book of Australian Birds 1988, 2nd Edition, Reader's Digest ISBN 0 949819 99 9
What Bird is That? 1984, Revised Edition, Angus & Robertson, Sydney ISBN 0 207 14846 5
Handbook of Australian, New Zealand & Antarctic Birds 1990 - , Oxford University Press, Melbourne ISBN 0 19 553244 9