Australian Creepers (Climacteridae)

(Climacteridae)

Class: Aves

Order: Passeriformes

Suborder: Passeri (Oscines)

Family: Climacteridae

Thumbnail description
Small to medium-sized, brown to blackish streaked birds with long toes and claws and curved bills that climb up tree trunks and branches

Size
5.7–6.9 in (14.5–17.5 cm); 0.75–1.15 oz (21–32 g)

Number of genera, species
2 genera; 7 species

Habitat
Forests, including rainforests, woodlands, and tall shrublands

Conservation status
Near Threatened: 1 subspecies of one species, and two subspecies of another species; remaining subspecies of both are of Least Concern

Distribution
Australia (except treeless regions), mountains of New Guinea, absent from
Tasmania

Evolution and systematics

Australian treecreepers resemble, in appearance and habits, the Northern Hemisphere creepers (Certhiidae) and a few other ecologically similar species elsewhere. However, this resemblance is the result of convergence due to occupying a similar niche. Details of their anatomy and behavior, and especially molecular studies, indicate that they are related to the large group of other Australian passerines. They do not seem to be closely related to any other family, but their nearest relatives are probably the lyrebirds and scrub-birds.

One genus, identified by Sibley and Monroe, consists of a superspecies including the polytypic white-throated tree-creeper (Cormobates leucophaea) and Papuan treecreeper (C. placens), the only species that occurs outside Australia. The other genus, Climacteris, is remarkably homogeneous.

Physical characteristics

Australian treecreepers are sparrow-sized or slightly larger, fairly robust, with a short neck and longish, decurved bills. Although their legs are short, all toes are long with very long and curved claws, which are presumably adaptations to tree climbing.

Their coloration ranges from rufous through brown to almost black. All species are streaked, sometimes boldly underneath, with white, black, and brown. Several have pale or white throats, and all have a pale stripe through the wing, which is prominent in flight. Sexual dimorphism is subdued, with females typically having orange patches on neck, throat, or breast.

Distribution

Treecreepers are found across Australia, but are absent from sandy and stony deserts and grasslands. These treeless areas often separate subspecies or populations of one species. For instance, the Great Sandy Desert in northwestern Australia lies between two subspecies of the black-tailed treecreeper (Climacteris melanura). The Nullarbor Plain lies between the southwestern and Eyre Peninsula populations of the rufous treecreeper (Climacteris rufa), though they maintain contact along a thin strip of wooded country on the edge of the Great Victoria Desert. Tasmania has no treecreepers despite having extensive rainforests, eucalypt forests, and woodlands, possibly because treecreepers are poor fliers and Tasmania had less forest when it became isolated from mainland Australia.

Despite its extensive forests, New Guinea only has tree-creepers in some of its mountains. The Papuan treecreeper has an inexplicable gap in distribution of about 250 mi (400 km) in central New Guinea.

Habitat

Only one species of treecreeper occurs in rainforest in Australia, with most of the other species in eucalypt forest and woodland. Brown (Climacteris picumnus) and rufous treecreepers are also found in mallee, which are low woodland with multi-stemmed eucalypts. However, they generally avoid areas with dense understory. Black-tailed and white-browed treecreepers (Climacteris affinis) are found in acacia woodland in semi-arid regions, with the latter also having a strong affinity with sheoke trees (Casuarina).

Behavior

Treecreepers are solitary or occur as pairs and family groups. Territorial defense may be strong at pair or group boundaries, involving much calling and chasing. They are strongly sedentary with no indication of migration, though young birds may disperse several miles (kilometers).

Most species have whistling or clicking calls. Displays include tail clicking and flicking.

Feeding ecology and diet

Most treecreepers forage by climbing up or along trunks and branches, typically of rough barked trees. Their strong claws allow them to cling upside-down, however, they rarely move down a trunk or branch. They capture insects by gleaning from the surface or probing into fissures in the bark or in peeling bark. Some species display a significant amount of ground foraging. Ants feature prominently in the diet, but they take other insects, especially beetles, larvae, spiders, and nectar and seeds on rare occasions.

Reproductive biology

Although some species breed as pairs, most are cooperative breeders. Helpers consist of young males, rarely females, from earlier years. There is often a close relationship among neighboring groups, with males often only dispersing one or two territories from their homes, and helping may occur among groups. The breeding season ranges from August to January with repeated attempts, and sometimes two broods reared in a year. All species nest in tree hollows, at which females perform an unusual behavior of sweeping snakeskin, insect wings, or even plastic around the entrance. Clutches are usually two or three white to pinkish eggs with brown markings. Incubation takes from 14–24 days, and fledging from 25–27 days.

Conservation status

Clearance and degradation of woodland has led to the decline of several species, at least locally, with three subspecies being regarded as Near Threatened.

Significance to humans

None known.

Species accounts

Resources

Garnett, S.T., and G.M. Crowley. The Action Plan for Australian Birds 2000. Canberra: Environment Australia, 2000.

Higgins, P.J., J.M. Peter, and W.K. Steele, eds. Handbook of Australian, New Zealand and Antarctic Birds. Vol. 5, Tyrant-flycatchers to Chats. Melbourne: Oxford University Press, 2001.

Sibley, C.G. and J.E. Ahlquist. Phylogeny and Classification of Birds: A Study of Molecular Evolution. New Haven: Yale University Press, 1990.

Luck, G., A. Charmantier, and P. Ezanno. "Seasonal and Landscape Differences in the Foraging Behaviour of the Rufous Treecreeper Climacteris rufa." Pacific Conservation Biology 7 (2001): 9–20.

Noske, R. "Co-Existence of Three Species of Treecreepers in North-Eastern New South Wales." Emu 79 (1979): 120–128.

Noske, R.A. "Intersexual Niche Segregation among Three Bark-Foraging Birds of Eucalypt Forests." Australian Journal of Ecology 11 (1986): 255–267.

Noske, R.A. "A Demographic Comparison of Cooperatively Breeding and Non-Cooperative Treecreepers." Emu 93 (1993): 73–86.

Walters, J.R., H.A. Ford, and C.B. Cooper. "The Ecological Basis of Sensitivity of Brown Treecreepers to Habitat Fragmentation: A Preliminary Assessment." Biological Conservation 90 (1999): 13–20.

[Article by: Hugh Alastair Ford, PhD]