SCRUB-BIRDS: Atrichornithidae

PHYSICAL CHARACTERISTICS

Both species of the ancient scrub-bird family, the noisy and the rufous, are 6.5 to 9 inches (16.5 to 23 centimeters) long. Male noisy scrub-birds typically weigh about 1.7 ounces (52 grams), while the smaller male rufous scrub-bird weighs somewhat less. Plainly colored in drab brown with black bars, the birds use their natural camouflage (KAM-uh-flaj) to hide themselves in dense underbrush. The rufous species is reddish brown on top with a buff belly, while the noisy scrub-bird is brown on top and reddish brown on the lower belly, fading to off-white on its breast. Males of both species have distinct black markings on their throats and breasts. Scrub-birds have strong, short legs and rounded, weak wings that render them semi-flightless. Otherwise they are generally stoutly built. Their flat, long foreheads taper to a triangular bill, and they tend to carry their longish tails at an upward angle. Juveniles look similar to adults, but with duller plumage.

GEOGRAPHIC RANGE

Both species of scrub-bird occur only in Australia and only within restricted ranges. The rufous species lives in isolated populations in the Queensland-New South Wales border area. The noisy scrub-bird occupies the far southwestern corner of the country in Two People's Bay Nature Reserve near Albany and, since they were reintroduced there in 1998, the Darling Range of Western Australia, outside the city of Perth.

HABITAT

Scrub-birds require dense, low vegetation in which to hide from predators, animals that hunt them for food, and forage, search, for food. They are adapted to a thick layer of leaf litter and a moist microclimate, a small, uniformly moist area. The rufous scrub-birds prefer temperate rainforest, whereas the noisy scrub-bird occupies semi-arid areas.

DIET

Both the rufous and noisy scrub-birds eat insects that they find by picking through layers of leaves on the forest floor. Noisy scrub-birds occasionally prey on frogs, geckos, and lizards as well.

BEHAVIOR AND REPRODUCTION

Male scrub-birds are famous for their ear-piercing, metallic calls and ability to imitate other birds' songs as they sing to mark and identify their permanent territories. The noisy scrub-bird has two alarm notes and a three-note call, with a loud, variable song of ten to twenty notes, while the rufous scrub-bird employs a loud, repeated chirp and two alarm notes. Females of both species are much less vocal, and often remain silent or make only quiet squeaks and ticking sounds. Although alert and energetic, both species are shy and highly secretive, moving quickly into dense vegetation when disturbed. Due to their underdeveloped wings, which cannot sustain more than a few yards of flight, scrub-birds prefer to run when threatened. During the mating season (spring for the rufous and winter for the noisy), males of both types prance and display with erect tails, much like their close relatives, the lyrebirds. Scrub-birds generally mate for life, and females occupy areas on the outskirts of the males' territories. Territories are usually widely spaced, with males marking and occupying about 2.5 acres (1 hectare) each. Females take sole responsibility for their clutches of one or two eggs, building a domed nest with a side entrance and partially or completely lined with wood and grass pulp. Nestlings take up to one month to fledge, grow the feathers needed for flying.

BE CAREFUL WHAT YOU WISH FOR …

Many bird lovers have traveled to Australia in search of the scrub-bird, whose elusiveness makes a sighting even more attractive. However, some people have reported that when they finally caught a glimpse of the shy creature, the scrub-bird's alarm call was so piercing and loud that it actually hurt their ears!

SCRUB-BIRDS AND PEOPLE

Both species of scrub-bird are so secretive and sedentary, still, that only the most patient of birdwatchers ever gets to see one. Many people have reported sitting silently for hours near a calling male just to get a glimpse of the creature. The scrub-bird has become a rallying point for Australian conservationists as they have labored to raise the birds' numbers over the past several decades.

CONSERVATION STATUS

The rufous scrub-bird remains one of the rarest birds in the world and has the official conservation status of Near Threatened, in danger of becoming threatened with extinction. Both species were thought to be extinct until the early 1960s, but environmentalists have succeeded in increasing populations of the noisy scrub-bird from fewer than 50 breeding territories in 1961 to nearly 750 in 2002. As a result, the noisy species has been downgraded from Endangered, facing a very high risk of extinction, to Vulnerable, facing a high risk of extinction.

RUFOUS SCRUB-BIRD (Atrichornis rufescens): SPECIES ACCOUNT

Physical characteristics: The rufous scrub-bird ranges in size from 6.5 inches (16.5 centimeters) for females to 7.1 inches long (18 centimeters) for males. Adults are a dark, reddish-brown with fine black bars on top and a dun-colored belly. Males have black markings in the center of a whitish throat. Both sexes carry their relatively long tails slightly upright. The rufous scrub-bird is perhaps the only species of bird in the world that does not have a wishbone, part of the breast bone, which is one reason it cannot fly very well.

Geographic range: This species exists solely on the central east coast of Australia, at the border between New South Wales and Queensland states. Their isolated populations are concentrated on the high-rainfall Border and Gibraltar Ranges, specifically along the Main Border Track from Mount Bithongable to Mount Howbee.

Habitat: Rufous scrub-birds require a moist microclimate at ground level, a dense layer of ground cover at least 3 feet (0.9 meters) high, and thick leaf litter in which to forage for food. These birds are almost always found at elevations above 2,000 feet (600 meters), although a sighting at about 790 feet (240 meters) was reported in 2000. Their habitat is usually associated with human-created or natural openings in the forest canopy. Most of the birds (an estimated 65 percent) live in wet eucalyptus (yoo-kah-LIP-tus) forests or Antarctic beech forests that are well buffered from fires in nearby rainforests. Mating pairs' territories are spaced far apart, with a maximum of six pairs per 0.4 square miles (1 square kilometer).

Diet: Rufous scrub-birds use their strong legs and claws to scratch through leaf litter, flushing out invertebrates such as beetles, ants, and spiders.

Behavior and reproduction: Remaining sedentary within well-defined territories for their entire adult lives, rufous scrub-birds dislike disturbance and will run mouse-like into thick foliage at the slightest threat. The species is alert and forages with enthusiasm, but is shy and evasive in general. The female rufous is even more elusive. Because of their underdeveloped wings, rufous scrub-birds run when threatened, instead of flying. During breeding season in September to November (Australia's spring), males use their elevated and fanned tails, lowered wings, and loud, melodious song to woo their partners. They can mimic other birdcalls well, but also use a species-specific "chip" sound. Rufous scrub-birds are typically monogamous (muh-NAH-guh-mus). Females occupy small areas on the outside of their mates' territories. The birds prefer to have widely spaced territories, with males marking and occupying about 2.5 acres (1 hectare) each, ideally. Females take sole responsibility for their clutches of two eggs (one of which is often infertile). They build a domed nest near the ground with a side entrance, completely lining it with a cardboard-like substance made of chewed wood and grass pulp. She attends the chicks for the month it takes them to fledge.

Rufous scrub-birds and people: Avid birdwatchers from all over the world travel to Australia in hopes of seeing one of these rare birds. The species' elusive and secretive nature, in addition to its declining numbers, make it a thrilling experience for many bird lovers.

Conservation status: A 1999 survey of rufous scrub-bird populations suggested an ongoing decline in the bird's presence. Destruction of the species' preferred habitat through logging and burning has caused much of the population decrease, but conservationists are working to educate people, and land clearing no longer appears to be a threat. The rufous scrub-bird, with habitat estimated at only 580 square miles (1,500 square kilometers), has Near Threatened conservation status. ∎

FOR MORE INFORMATION

Books:

Birdlife International. Threatened Birds of the World. Barcelona: Lynx Edicions, 2000.

Ferrier, S. "Habitat Requirements of a Rare Species, the Rufous Scrub-bird." In Birds of Eucalyptus Forests and Woodlands: Ecology, Conservation, and Management. Sydney: Royal Australian Ornithological Society.

Higgins, P. J., et al., eds. Handbook of Australian, New Zealand and Antarctic Birds. Vol. 5, Tyrant-Flycatchers to Chats. Melbourne: Oxford University Press, 2001.

Schodde, R., and I. J. Mason. Australian Birds: Passerines. Collingwood, Australia: CSIRO, 1999.

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

Periodicals:

Chisolm, A. H. "The Story of the Scrub-birds." Emu 51 (1951): 89–112, 285–297.

Web sites:

"Noisy Scrub-bird Reintroduced to Darling Range." The Nature Base. http://www.calm.wa.gov.au/news/news.cgi?item=923494339 (accessed on May 17, 2004).

"Rufous Scrub-bird (Atrichornis rufescens)." Birdlife.net. http://www.birdlife.net/datazone/search/species (accessed on May 17, 2004).

"Rufous Scrub-bird: Lamington National Park." Lamington National Park, Queensland, Australia. http://www.lamington.nrsm.uq.edu.au/Documents/Birds/rufuousscrubbird.htm (accessed on May 17, 2004).

"Scrub-bird." Fact Index. http://www.fact-index.com/s/sc/scrub_bird.html (accessed on May 17, 2004).

"Scrub-birds." Planet Pets. http://www.planet-pets.com/plntsbrd.html (accessed on May 17, 2004).

"Scrub-birds (Atrichornithidae)." CREAGRUS@Monterey Bay. http://www.montereybay.com/creagrus/scrub-birds.html (accessed on May 17, 2004).