IUCN Endangered (EN)
King Island Brown Thornbill
Acanthiza pusilla magnirostris
Last updated: December 2025
The King Island Brown Thornbill is a subspecies of the Brown Thornbill and is found only on King Island, an island in Bass Strait between Victoria and mainland Tasmania. Listed as Endangered (EPBC Act 1999), habitat destruction has driven its decline, and it is estimated there are only 50-100 individuals left.
The King Island Brown Thornbill is a small (~10cm) bird with an olive brown back, rufous-brown forehead and rump, pale-yellow belly, and off-white chin, neck and breast with fine black streaks. Adults have a dark red iris, while the iris of juveniles is dull red.
The King Island Brown Thornbill has a noticeably longer bill than the Brown Thornbill on mainland Tasmania.
The King Island Brown Thornbill has a pretty, melodious rippling sequence of warbling notes, rendered as too-weet-et-wrrrrt.
The King Island Brown Thornbill is usually found in wet Eucalyptus brookeriana forests and forests including Eucalyptus globulus, Melaleuca ericifolia swamp forest, Acacia melanoxylon swamp forest and hardwood plantations (Pegarah State Forest). It has also been found in King Island eucalypt woodland and Scrub complex on King Island.
Distribution map
Brown Thornbills usually forage in pairs, though sometimes alone or in small flocks (often with other species), high in the canopy. They also forage in low vegetation in the understory and on the ground.
Brown Thornbills feed on insects and other invertebrates, and occasionally eat seeds, fruit and nectar.
Little is known about the breeding behaviour of King Island Brown Thornbills. Brown Thornbills are thought to breed from around June to March and build a domed nest close to the ground.
Species considered to be facing a very high risk of extinction in the wild.
IUCN status reflects the conservation status of this species globally.
Climate change
Domestic animals
Habitat destruction
Invasive species
Loss of genetic diversity
King Island Brown Thornbills were thought to be widespread across King Island before European settlement in the late 1800s. Since then, over 70% on native vegetation on the island has been cleared, and unlawful clearing continues to threaten the little habitat which remains.
Most recent sightings of King Island Brown Thornbills have been from in and around Pegarah State Forest, a site which is zoned for timber production. In addition to extensive habitat loss, other threats to King Island Brown Thornbills are:
BirdLife Australia is working with the King Island Birds Recovery Team and others to coordinate the recovery of five threatened birds endemic to King Island, including the King Island Brown Thornbill. More information.
