The chestnut-rumped thornbill (Acanthiza uropygialis) is a small passerine bird in the Acanthizidae family, endemic to Australia. Specially named for its pale-chestnut rump from mediaeval Latin uropygium, the rump.Its other names include chestnut-tailed or chestnut-backed thornbill, tit or tit-warbler, chestnut-rumped tit or tit-warbler.A plain, pale thornbill, with pale eyes, it is widespread throughout inland Australia, West of the Great Dividing Range to the West Australian coast but is absent in the far north and humid southwestern WA. It is a cooperative breeder like some of the other thornbills