Slender-billed Thornbill

The Slender-billed Thornbill, Acanthiza iredalei, is a diminutive avian species endemic to Australia. This bird is characterized by its modest size, measuring between 9 to 10 centimeters in length. It boasts an olive-grey to olive-brown back, with the base of its tail displaying an olive-yellow hue. The underbelly is a smooth cream, and it is distinguished by its dark bill and pale eyes.

Identification Tips

When attempting to identify the Slender-billed Thornbill, look for its small stature and the distinctive coloration of its plumage. The olive-yellow base of the tail is a key feature, as is the contrast between the bird's cream underbelly and its darker upper parts. The dark bill and pale eyes are also notable identifiers.

Habitat

The Slender-billed Thornbill is typically found in shrublands and salt marshes, particularly those surrounding salt lakes or situated on low heath on sand plains.

Distribution

This species includes three subspecies with distinct distributions. The A. i. iredalei subspecies inhabits six isolated populations in Western Australia and a significant population in the Carnarvon bioregion. The A. i. hedleyi subspecies is located in southeastern South Australia and western Victoria, while the A. i. rosinae subspecies is most commonly found in the Gulf St Vincent region of South Australia.

Behaviour

The Slender-billed Thornbill is a sociable bird, rarely observed alone. It is usually seen in flocks of around eight or in pairs. It prefers to feed at higher elevations in shrubs and trees, seldom descending to the ground.

Breeding

Nests of the Slender-billed Thornbill are small and constructed within low shrubs. They are made from grass, bark, cobwebs, and other debris found in their shrubland habitat. Females lay up to three eggs during the breeding season, which spans from July to November.

Diet and Feeding

The diet of the Slender-billed Thornbill consists mostly of insects and spiders, which it captures in the shrubs of its habitat.

Conservation status

The conservation status of the Slender-billed Thornbill varies by subspecies. The A. i. rosinae is considered vulnerable, while the A. i. hedleyi is near threatened. The A. i. iredalei subspecies is also deemed vulnerable. Notably, the A. i. iredalei subspecies is extinct in northern Australia, marking it as the only indigenous species to have become extinct in that region since European settlement. In Victoria, the A. i. hedleyi is listed as threatened under the Victorian Flora and Fauna Guarantee Act 1988, though an Action Statement for its recovery has not been prepared.