Brown Treecreeper

The brown treecreeper (Climacteris picumnus), the largest of the Australasian treecreepers, is a bird of subtle charm and quiet demeanor. Its plumage is a harmonious blend of light grey-brown above, with a lighter grey face and neck. The crown is a darker grey, and the ear-coverts match this shade. A prominent, pale supercilium graces the adult, while the juvenile's is grey and less distinct. The throat is a creamy white, transitioning to a pale brown on the breast, which is finely streaked with black-grey and white. In flight, one can observe a dark wing-bar. This species exhibits sexual dimorphism: males have black and white streaking on the uppermost breast, while females display rufous and white streaking.

Identification Tips

When observing the brown treecreeper, look for the bird's size, approximately 16.5 centimeters in length with a wingspan of 26 centimeters, and an average weight of around 31.5 grams. The distinct streaking on the upper breast can help differentiate between the sexes. Juveniles can be identified by their darker hind-neck, nape, crown, and forehead compared to adult males.

Habitat

The brown treecreeper is found in a variety of habitats, from coastal forests to mallee shrublands, but shows a preference for eucalypt-dominated woodlands up to 1,000 meters in elevation. It tends to avoid areas with dense, shrubby undergrowth.

Distribution

Endemic to eastern Australia, the brown treecreeper's range extends from Cape York, Queensland, through New South Wales and Victoria, to Port Augusta and the Flinders Ranges in South Australia. The population has seen a contraction from the edges of its pre-European range.

Behaviour

This gregarious bird exhibits a complex social structure, maintaining territories that sometimes overlap with other groups of its kind. Typically seen in pairs or small groups, the brown treecreeper is known to forage on the ground and tree surfaces, feeding on ants, beetles, and insect larvae. It roosts solitarily and nocturnally.

Song & Calls

The brown treecreeper's call is a distinctive "spink spink," which can be heard echoing through its woodland habitat.

Breeding

Breeding pairs are socially monogamous and may breed cooperatively. The breeding season spans from July to February, with most eggs laid from September to late October. The female alone incubates the eggs, which are slightly glossy and speckled in shades of pink, reddish-brown, or purplish-red.

Similar Species

The brown treecreeper is closely related to the rufous treecreeper (Climacteris rufus) and the black-tailed treecreeper (C. melanurus), which share similar habitats and have sexually dimorphic markings.

Diet and Feeding

Primarily insectivorous, the brown treecreeper's diet consists of ants, beetles, and their larvae. It forages by probing tree fissures and hopping along logs, spending more time on the ground in arid regions.

Conservation status

The IUCN lists the brown treecreeper as "Least Concern," though the subspecies victoriae is considered "Vulnerable" under the Threatened Species Conservation Act in New South Wales and by the Department of Climate Change, Energy, the Environment and Water at the national level.

Threats to the species include habitat loss and fragmentation due to land clearing, competition for nesting hollows with invasive species, and changes in fire regimes affecting their foraging substrates.