Brown treecreeper

Appearance

Adult birds are around 16.5 centimetres long, with a wingspan of 26 centimetres, and weigh on average around 31.5 grams.

Adult plumage is light grey-brown above with light grey face and neck, darker grey on the crown with dark ear-coverts. The supercilium is prominent and pale on adults, while grey and indistinct on juveniles. The throat is cream to white and pale brown on the breast. The lower breast is streaked with fine black-grey and white. In flight a dark wing-bar is visible. Sexes of the species differ in plumage, with the uppermost breast of the male streaked black and white, while the female has rufous and white streaking. Juvenile plumage is different from that on the adult with the hind-neck, nape, crown and forehead darker than that of adult males.

Naming

Threats to the species include land clearing and the resultant habitat loss and fragmentation, the impacts of which are thought to disrupt dispersal and therefore recruitment. The removal of fallen timber and other woody debris, and competition with exotic species such as the common starling for nesting hollows are also threats to the species.

Subspecies "melanotus" has declined from eastern parts of its range in Cape York Peninsula, thought to be due to more extensive and frequent fire regime, which has affected fallen tree trunks and logs.

Status

The conservation status of the brown treecreeper is considered of "least concern" by the IUCN, while the subspecies "victoriae", is listed in New South Wales as Vulnerable under Schedule 2 of the Threatened Species Conservation Act. Subspecies "victoriae" is listed by the Department of Sustainability and Environment, Victoria, as Near-threatened on the Advisory List of Threatened Vertebrate Fauna though this listing does not infer any statutory protection.

Reproduction

The breeding female usually lays a clutch-size usually of three smooth, slightly glossy, fine-grained, slightly pink or rose, reddish-brown or red and purplish-red speckled eggs measuring 22.6 by 17.9 mm. Intervals between egg-laying is most likely 24 hours, with re-laying occurring in the event of failure. Females are able to raise two broods in a season but more often raise one brood. Hatchlings emerge with grey down on their head and back fourteen to sixteen days after incubation.

For a few days after hatching, the female is fed by the primary male. The young are fed by the breeding female who is passed food by the primary male. Faecal sacs are removed from the nest by all members of the group though most often it is the males who do so. Helpers, usually young males related to the breeding male, service their territorial nest and often will service other nests in 2–3 other territories. A variety of insects are fed to the young, with lepidopteran larvae forming the bulk of their diet. Adults avoid feeding the young ants, likely due to the ant's formic acid content. The contribution of helpers to feeding the young is generally equal to the efforts of the breeding pair. Records exist of a single helper servicing the nests of five different territories. Records indicate that in nests attended by helpers, breeding success is four times more likely and significantly more offspring are produced.

Food

Roosting nocturnally and solitarily, the brown treecreeper forages during the day on the ground and on tree surfaces in small groups or pairs, feeding mainly on ants, beetles and insect larvae. While occasionally feeding on nectar, the brown treecreeper more often probes fissures, cracks and hollows of trees, gleaning and probing as it hops along logs or spirals up rough barked trees, spending more time foraging on the ground if a resident of an arid territory.

Predators

Threats to the species include land clearing and the resultant habitat loss and fragmentation, the impacts of which are thought to disrupt dispersal and therefore recruitment. The removal of fallen timber and other woody debris, and competition with exotic species such as the common starling for nesting hollows are also threats to the species.

Subspecies "melanotus" has declined from eastern parts of its range in Cape York Peninsula, thought to be due to more extensive and frequent fire regime, which has affected fallen tree trunks and logs.