AUSTRALIAN CREEPERS: Climacteridae

PHYSICAL CHARACTERISTICS

Australian creepers, or treecreepers, tend to be small birds about the same size as sparrows. They average in length from 5.7 to 6.9 inches (14.5 to 17.5 centimeters), with an average weight of 0.75 to 1.15 ounces (21 to 32 grams). Their legs are short, with long toes that have claws that are curved and long. They have short necks, and long decurved, downward curved, bills. Their color varies from a reddish brown, to brown, to almost black. Each species displays a streak, either white, black, or brown, on their undersides, and display an off-white to rufous, red, bar across their flight feathers that are noticeable when they are in flight. Some species have white throats, for instance, the white-throated treecreeper. Brows range in color from a pale buff, as in the case of the brown treecreeper; to red, in the red-browed treecreeper; to white, as shown in the white-browed treecreeper. The difference between males and females is slight. Orange patches on the neck, throat, or breast usually distinguishes the female from the male.

GEOGRAPHIC RANGE

Australian treecreepers are distributed throughout Australia, except in the sandy and stony deserts, or grasslands. One of the eight species, the Papuan treecreeper, is native to New Guinea, where it is found in some of the mountains. However they are unexplainably absent from an area of approximately 250 miles (400 kilometers) in central New Guinea. The island of Tasmania, off the southeastern coast of Australia, has no treecreepers despite the fact that it has a natural environment suitable to the birds—rainforests, eucalyptus forests, and woodlands. The explanation that has been suggested for this is that Tasmania did not have the extensive forest before it became isolated from the mainland, and treecreepers are poor fliers, so have not colonized Tasmania since then.

HABITAT

Australian treecreepers live in various environments throughout the continent, preferring eucalyptus forest, dry savanna, or semi-arid mulga, an evergreen shrub, that inhabits Australia's interior. Brown treecreepers and rufous treecreepers can also be found in mallee—low woodland with eucalyptus (yoo-kah-LIP-tus) that are multi-stemmed. As a rule, these treecreepers do not inhabit areas that have a dense understory, vegetation under the forest canopy.

DIET

Australian treecreepers are primarily insectivores, insect eaters, with ants composing the biggest portion of their diet. They forage, search for food, for ants and other insects along the trunks and branches of trees they have climbed, especially trees that have rough bark. Treecreepers are known to peel bark, or dig into fissures, cracks, in order to find their prey. Their long claws make it possible for them to hang onto a trunk or branch in an upside down position, but they seldom move downward on a tree. The other insects they eat include beetles, larvae, and spiders. Rarely, a treecreeper might take nectar or seeds in addition to insects.

GREAT AUSTRALASIAN RADIATION

The Great Australasian Radiation refers to the period of time when many different birds evolved across Australia and Asia—the birds evolved in isolation for eons. Australian treecreepers are part of that radiation. Data has indicated that they are related to lyrebirds, scrub-birds, and bowerbirds. The birds' behavior had originally placed them near the northern treecreepers, spotted creepers of Africa and India, and Philippine creepers. But they are not related to any of these birds. Their tree-climbing is an example of convergent evolution, where species develop similar characteristics although they are not related.

BEHAVIOR AND REPRODUCTION

Australian treecreepers are usually found in pairs, family groups, or alone. When they are found in pairs, or family groups, territorial defenses are more obvious, such as chasing and calling. Otherwise, the birds tend to be sedentary, stay in one place. Only in some young birds does any migration, travel, occur, and then it is only within several miles or kilometers.

Most species have a voice that consists of shrill, high-pitched whistles. Their display includes tail clicking and flicking.

Some species breed in pairs. Those include the white-throated treecreeper in Australia and New Guinea. Most are cooperative breeders, where young males from previous breedings help care for and protect the current chicks. Those species that breed cooperatively include the red-browed treecreeper, the black-tailed treecreeper, the brown treecreeper, and the rufous treecreeper. Neighboring groups of treecreepers often have close relationships with each other, with males going only one or two territories away from their homes to live. The breeding season is from August to January, with many attempts to breed. It is not uncommon for Australian treecreepers to have two broods a year. The nests are built deep into tree hollows, or sometimes in a hollow log or other cavity. Nests are made of grasses, plant down, soft bark, and animal fur. The female is known to sweep snakeskin, insect wings, and even plastic around the entrance to the nest. One or more males assist the female in incubation, the process of sitting on eggs to provide warmth for development. Eggs are found in clutches of two or three and are white to pinkish in color with brown markings. The incubation takes place over fourteen to twenty-four days, with fledging at twenty-five to twenty-seven days.

AUSTRALIAN CREEPERS AND PEOPLE

There is no special significance between Australian treecreepers and people.

CONSERVATION STATUS

Due to the clearing and breakdown of woodland, some species have declined in numbers. Three subspecies have been categorized as Near Threatened, in danger of becoming threatened with extinction.

RUFOUS TREECREEPER (Climacteris rufa): SPECIES ACCOUNT

Physical characteristics: Rufous treecreepers have faces that are cinnamon-rufous, reddish brown, with rufous brows, and cheeks that have a black eye stripe. Their undersides are rufous with white streaks for the female, and black with white streaks on the male. Their upperparts are gray-brown. Their length averages 6.7 inches (17 centimeters). These birds weigh between 1.1 and 1.2 ounces (30 and 33 grams).

Geographic range: Rufous treecreepers can be found throughout southwestern Australia and on the Eyre Peninsula of South Australia.

Habitat: Australian treecreepers live in eucalyptus forest and accompanying woodland, and in the mallee, dense thickets formed by various shrubby species of Australian eucalyptus.

Diet: Rufous treecreepers, like other species of Australian treecreepers forage for their food along the trunks and lower branches of eucalyptus and casuarinas, and on the ground. They are primarily insectivores, with ants as their preference; but also eat centipedes, snails, small reptiles, and seeds.

Behavior and reproduction: The rufous treecreeper lives in family groups that are made up of the breeding pair and its offspring from previous breedings. They tend to be sedentary, and make peeping and churring calls at their predators. Their voice is like the brown treecreeper with short, staccato notes and harsh rattles, with chuckling songs, but they are higher in pitch.

This bird has a breeding season from August to January. Their nests, like those of other Australian treecreepers, are built deep into the hollows of tree branches, stumps, and fallen logs. A clutch has one to three eggs that the female incubates for seventeen days. The young are fed by both parents, and by helpers, usually the young of previous breedings. At twenty-six days they fledge with a great success rate—one study in western Australia showed that 78 percent of attempts succeeded.

Rufous treecreepers and people: There is no known significance between rufous treecreepers and people.

Conservation status: As a species, the rufous treecreeper is not threatened. Populations have declined, with extinction in some local areas of the wheat growing region of western Australia where the land has been cleared extensively. ∎

FOR MORE INFORMATION

Books:

Campbell, Bruce, and Elizabeth Lack, eds. A Dictionary of Birds. Vermillion, SD: Buteo Books, 1985.

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

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

Sibley, C. G. Birds of the World. On diskette, Windows version 2.0. Santa Rosa, CA: Charles G. Sibley, 1996.

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

Simpson, Ken, and Nicolas Day. The Birds of Australia. Dover, NH: Tanager Books, 1984.

Periodicals:

"The Demography and Cooperative Breeding Behaviour of the Rufous Treecreeper, Climacteris rufa." Australian Journal of Zoology (December 2001): 515–537.

Web sites:

"Austral-Papuan Tree-creepers." Treecreepers, Lyrebirds, Bowerbirds and Fairy Wrens of the World. http://camacdonald.com/birding/Sampler6_TreecreepersLyrebirdsBowerbirdsFairyWrens.htm#Treecreepers (accessed on June 18, 2004).

"Australian Treecreepers, Climacteridae." Bird Families of the World. http://www.montereybay.com/creagrus/treecreepers.html (accessed on June 18, 2004).

"Australian Treecreepers." Birds of the World. http://www.eeb.cornell.edu/winkler/botw/climacteridae.html (accessed on June 18, 2004).

"Rainforest understory." Rainforest Education. http://www.rainforesteducation.com (accessed on June 18, 2004).