Buff-rumped Thornbill

The Buff-rumped Thornbill, Acanthiza reguloides, is a diminutive passerine, a member of the Acanthizidae family. It measures a mere 8–10 cm from beak to tail tip. Its plumage is rather understated, with greenish-brown upperparts and pale-yellow underparts, but it is set apart by a distinctive buff rump. A broad, blackish band adorns the tail, ending in a paler tip. Adult birds boast white irises, contrasting with the dark eyes of their juvenile counterparts.

Identification Tips

To identify the Buff-rumped Thornbill, look for its thin, pointed bill—a hallmark of the Acanthiza genus. Its buff rump is a key distinguishing feature, along with the blackish band on the tail. The bird's small size and the white irises of adults can also aid in identification.

Habitat

This species is well-adapted to dry sclerophyll forests and open eucalypt woodlands, particularly those with an open or sparse understory.

Distribution

The Buff-rumped Thornbill is found primarily in eastern Australia, with its range extending from Chinchilla in Queensland, west to Cobar in New South Wales, and across Victoria to southeastern South Australia.

Behaviour

Buff-rumped Thornbills are gregarious, often seen in small, vocal groups of around 20 individuals. They may form larger flocks during the non-breeding season. Their flight pattern is undulating, and they exhibit remarkable acrobatic skills, including the ability to hang head downward. These birds are known to be territorial and communicate with a rapid "pitta-pitta-pitta-pit" call.

Song & Calls

The vocal repertoire of the Buff-rumped Thornbill includes a distinctive and rapid "pitta-pitta-pitta-pit" call, which they emit frequently as they forage.

Breeding

The breeding behavior of the Buff-rumped Thornbill involves cooperative groups, typically one female and three males. They construct large, dome-shaped nests of bark strips, dried grass, and moss, lined with fur or down and bound with spider web. The nests are situated one to two meters above the ground. Females lay clutches of 2-4 eggs in late August, with a 20-day incubation period. Egg hatching is highly synchronous, and the cooperative breeding group collaborates to feed the chicks.

Similar Species

While the Buff-rumped Thornbill shares its genus with 13 other species, each is unique in plumage and distribution. It is not closely related to hummingbirds, despite the shared name "thornbill."

Diet and Feeding

The diet of the Buff-rumped Thornbill is primarily composed of small insects and plant lice, which it gleans from foliage. It may also consume seeds on occasion.

Conservation status

The Buff-rumped Thornbill is classified as Least Concern. Its populations are secure across its Australian range, though urban development and habitat modification have led to localized declines.