Australian warblers

(Acanthizidae)

Class Aves

Order Passeriformes

Suborder Passeri (Oscines)

Family Acanthizidae

Thumbnail description
Tiny to medium-sized, generally dull brown birds with fine bills, inhabiting canopy down to ground

Size
3.5–10 in (9–27 cm); 0.25–2.5 oz (7–70 g)

Number of genera, species
14–16 genera; 63–68 species

Habitat
Rainforests, eucalypt forests and woodlands, heathland and semi-arid woodland and scrub

Conservation status
Extinct: 1 species; Endangered: 2 species; Vulnerable: 6 species

Distribution
New Zealand, Australia, New Guinea, Southeast Asia to Philippines, Vietnam, and Thailand

Evolution and systematics

The Australian warblers resemble in appearance and ecology the Old World warblers (Sylviidae). However, molecular studies show that they are more closely related to honeyeaters (Meliphagidae) and fairy-wrens (Maluridae) and are consequently part of the large Australian adaptive radiation of passerines. The pardalotes (Pardalotus) are closely related to the Acanthizidae and may be included in this family. The bristlebirds are sometimes placed in a separate subfamily (Dasyornithinae), but the pilotbird (Pycnoptilus floccosus) is intermediate between them and the other genera. The Mohuinae are a New Zealand group of uncertain affinities that are usually placed in the Acanthizidae. The most successful genera are the thornbills (Acanthiza) with about 12 species, and the gerygones (Gerygone) with about 20 species, though species limits are unclear due to many distinctive isolated forms. Sericornis also has many species, and at times has been expanded to include members of up to five other genera. Information from molecular biology and osteology, however, suggest the retention of a large number of genera with only one or two species.

Physical characteristics

Most species of acanthizids are tiny olive-green birds of the canopy or small brown birds of the understory. However, most have distinctive markings on the head or face, including light eyebrows and streaks or spots, and some species have contrasting yellow or reddish rumps. Some of the thornbills and gerygones have yellow underparts while the pilotbird and rockwarbler (Origma solitaria) are reddish brown below. Most have slender bills, typical of small insectivores, while the wee-bill (Smicrornis brevirostris) has a short deep bill for prying off lerps (scales of psyllid insects). Whitefaces (Aphelocephala) also have deep bills, and the large-billed scrub-wren (Sericornis magnirostris) has a long pointed bill. All, except for the long-tailed bristlebirds (Dasyornis), have shortish tails. Bristlebirds have prominent rictal bristles.

Distribution

Australia has 43–45 species, with more than one species occurring at any point and five or more in many coastal regions. Thornbills tend to predominate in temperate regions and gerygones in the tropics, whereas scrubwrens occupy wetter areas. Twenty species are found in New Guinea, most of which are scrubwrens or gerygones. The gerygones alone have reached New Zealand, including the Chatham Islands, as well as Indonesia and South East Asia.

Habitat

Acanthizids occur in all habitats in Australia, including mangroves (the key habitat for three gerygones), rainforests

(where most of the scrubwrens are found), eucalypt forests and woodlands (weebill, several of the thornbills). The bristlebirds are found in dense coastal and upland heaths, whereas the rockwarbler, heathwrens (Hylacola), and field-wrens (Calamanthus) also occur in habitats with heathy shrubs. The whitefaces and the redthroat (Pyrrholaemus brunneus) may be found in arid shrublands and deserts.

Behavior

The Australian warblers are almost always active, typically hopping on the ground or among the foliage of trees or bushes. Some species, especially the bristlebirds, can be quite cryptic. Breeding pairs are territorial in the breeding season, with many species joining flocks outside the breeding season. Thornbills, scrubwrens and gerygones are often nuclear species of mixed species feeding flocks in a wide range of habitats. Almost all species are sedentary or at most show very local movements, whereas the white-throated gerygone (Gerygone olivacea) migrates into southeastern Australia in spring. All species, except the gerygones, are rather weak fliers. A few species cock their tails. Many species have twittering calls and songs, though the wavering, downward warbles of the gerygones have earned them the name of bush canaries. The heathwrens and fieldwrens are also noted songsters and several species include mimicry in their calls.

Feeding ecology and diet

Most of the acanthizids are gleaners, taking small invertebrates from the foliage, from twigs, branches and trunks, or from the ground. Weebills and the gerygones include more active modes, such as snatching and hovering. Occasionally, insects are held under the feet. Within a habitat, different species often use different microhabitats. For instance, striated thornbills (Acanthiza lineata) glean from foliage in the canopy and subcanopy, while brown thornbills (A. pusilla) forage among shrubs and buff-rumped thornbills (A. reguloides) feed from the ground or bark. Although the food of most species is predominantly invertebrates, seeds and fruits are occasionally eaten. Whitefaces consume large quantities of seeds.

Reproductive biology

Cooperative breeding is common in the family, and has been studied in several thornbills and scrubwrens. Mostly, though, acanthizids breed as pairs with some being assisted by a third or fourth bird. The breeding season is typically late winter to early summer and several attempts are made each season. Nests are domed, often with a clear hood above the entrance, and those of gerygones are pendant, attached to foliage. Although usually placed in trees or shrubs, crannies and hollows are also used and some species nest on the ground. The most common clutch is two eggs, though up to five eggs have been recorded. Egg color ranges from white in the rock-warbler, and white with sparse spotting in Acanthiza and Gery-gone, to cream or buff with heavier spotting in many genera to plain chocolate in redthroat and speckled warblers (Chthonicola sagittatus). Eggs are laid at 48-hour intervals and are incubated by the female alone. Incubation periods and dependency of the fledglings are long. Both parents, and sometimes helpers, feed the young. Many nests are lost to predators, especially larger birds, and others are parasitized

by bronze-cuckoos (Chrysococcyx). Annual adult survival is 80% or more for some species; high for such small birds.

Conservation status

The species of gerygone on Lord Howe Island (G. insularis) is Extinct, that on Biak (G. hypoxantha) is Endangered, and the one on Norfolk Island (G. modesta) is Vulnerable. These island forms have suffered from major habitat loss as well as from introduced mammalian predators. The yellowhead (Mohua ochrocephala) of New Zealand is also Vulnerable. The 2000 Action Plan for Australian Birds lists a large number of acanthizids as threatened or nearly so. The bristlebirds have suffered from habitat loss, increased fire frequency, grazing by introduced mammals, and predation by mammalian carnivores. The western subspecies of rufous bristlebird (Dasyornis broadbenti) is Extinct, both sub-species of eastern bristlebird (D. brachypterus) are Endangered, one critically, whereas the western bristlebird (D. longirostris) is regarded as Vulnerable. Only the Coorong subspecies of rufous bristlebird is currently secure. Several isolated subspecies are threatened—with brown thornbills and scrubtits (Acanthornis magnus) on King Island being Critically Endangered. The chestnut-breasted whiteface (Aphelocephala pectoralis) and speckled warbler were considered Near Threatened throughout their range. Loss and degradation of habitat by agriculture and grazing are the main causes.

Significance to humans

As small, dull-colored and sometimes cryptic birds, acanthizids are generally not noticed much by people. Many are loosely called tits by country people, due to their superficial resemblance to members of the Paridae. The songs of bush canaries are well known, though the gerygones that produce the songs are less familiar to most people. Thornbills, scrub-wrens and gerygones can provide a challenge to bird watchers, especially where there are local, indistinct species (e.g. Tasmanian thornbill [Acanthiza ewingi], Atherton scrubwren [Sericornis keri]), and the vocal but well-hidden bristlebirds can prove frustrating.

Species accounts

List of Species

Eastern bristlebird

Dasyornis brachypterus

subfamily

Acanthizinae

taxonomy

Turdus brachypterus Latham, 1801, Sydney, New South Wales, Australia. Two subspecies.

other common names

English: Bristle bird; French: Dasyorne brun; German: Braunkopf-Lackvogel; Spanish: Pájaro Cerdoso Común.

physical characteristics

8.5 in (22 cm); 1.5 oz (c. 42 g). A gray-brown bird with small wing and sturdy legs and feet.

distribution

Eastern coastal Australia, with two isolated subspecies.

habitat

Dense, coastal and montane scrub, especially with grass tussocks.

behavior

Solitary, shy and cryptic, mostly hidden in dense vegetation. May cock or fan tail. Sedentary, weak flier. Song is loud "it-wood-weet-sip" and harsh, abrupt call "zeip".

feeding ecology and diet

Gleans on ground, especially among leaf litter, taking insects and other arthropods, as well as seeds.

reproductive biology

Breeds August to December. Domed nest is made of grass and plant tendrils and placed in a clump of grass. Two eggs, white

to pale brown with gray and brown spots. Rarely more than one young raised.

conservation status

Northern subspecies is Critically Endangered, with only a few dozen individuals. Southern subspecies is Endangered, with a populations of about 1,500 adults. Although most populations occur in national parks, frequent fires may kill the bird and render its habitat unsuitable for many years. Conversely, habitat that has not been burnt for a long time becomes unsuitable.

significance to humans

None known.

White-browed scrubwren

Sericornis frontalis

subfamily

Acanthizinae

taxonomy

Saxicola longirostris Quoy and Gaimard, 1830, Western Port, Victoria, Australia. Up to 12 subspecies.

other common names

English: Buff-breasted scrubwren, cartwheel bird; French: Séricorne à sourcils blancs; German: Weissbrauen-Sericornis; Spanish: Sericornis de Cejas Blancas.

physical characteristics

4.5 in (120 cm); 0.4–0.5 oz (11–15 g). A relatively small bird with a distinctive white brow above the eyes, white chest, and brown back.

distribution

Coastal southwestern, southern, and southeastern Australia, including Kangaroo Island. Birds north and west of Adelaide have been regarded as a separate species (S. maculatus—spotted scrubwren). There is also physical variation on the east coast with northern birds being brighter and as many as 12 sub-species have been recognized.

habitat

Coastal heathlands and swamps, eucalypt forest with dense understory, rainforests. Occasionally in parks, gardens, and exotic pine plantations.

behavior

An active ground and shrub dweller, which can sometimes be hidden but at other times quite visible and confiding. Typically in family groups, often with other scrubwrens and small birds. Quite sweet and complex, but rather erratic song. Harsh, scolding calls. Sedentary.

feeding ecology and diet

Mostly gleans from ground, including amongst leaf litter, and from shrubs. May forage in association with scrub-turkeys (Alectura lathami) who rake leaf litter into their mounds. Takes insects and other invertebrates, and some seeds.

reproductive biology

Long breeding season from July to February. Rather large domed nest placed in low shrub or on the ground, and made of grass, bark, roots, and feather lining. Typically three, occasionally one, two or four eggs, which are pale blue, with brown freckles. May lay up to six clutches in a season. Some pairs have helpers. Incubation period is 17–22 days, fledging period is 12–18 days. Young are dependent on parents for a further six to seven weeks. Adults may live up to 17 years.

conservation status

Not threatened.

significance to humans

None known.

Mangrove gerygone

Gerygone levigaster

subfamily

Acanthizinae

taxonomy

Gerygone levigaster Gould, 1843, Port Essington, Northern Territory, Australia.

other common names

English: Mangrove warbler, buff-breasted warbler; French: Gérygone des mangroves; German: Mangrove-Gerygone; Spanish: Ratona Hada de los Mangles.

physical characteristics

4 in (10–11 cm); 0.25 oz (7 g). A tiny bird with a brown back, white underparts, and a white brow.

distribution

Coasts of northern and eastern Australia south to Newcastle. Also small area in southeastern New Guinea.

habitat

Mangroves and neighboring vegetation, sometimes rainforests and gardens.

behavior

Active and fairly tame. May be migratory at southern part of range. Attractive, whistling song and soft chattering notes.

feeding ecology and diet

Gleans, snatches, and hovers at outer foliage of mangroves and other trees for insects.

reproductive biology

Breeds from September to April. Oval nest is suspended from foliage of mangroves and has a hooded side entrance. Two or three pinkish, speckled eggs.

conservation status

Not threatened.

significance to humans

None known.

Yellow-rumped thornbill

Acanthiza chrysorrhoa

subfamily

Acanthizinae

taxonomy

Acanthiza chrysorrhoa Quoy and Gaimard, 1830, New South Wales, Australia.

other common names

English: Yellow-tailed thornbill, tom-tit; French: Acanthize à croupion jaune; German: Gelbbürzel-Dornschnabel; Spanish: Acanzisa de Cola Amarillo.

physical characteristics

4 in (10 cm); 0.32 oz (9 g). Characterized by a bright yellow rump, black crown spotted white, and white brow.

distribution

Southern and central Australia, including Tasmania.

habitat

Open woodland and edges, farmland and grassland with scattered trees or bushes, parks and gardens.

behavior

Typically in family groups or small flocks, often with other thornbills. Active and noisy, with twittering songs and calls. Yellow rump very conspicuous in flight so that bird almost disappears when it lands. Sedentary or local movements only.

feeding ecology and diet

Primarily ground feeding, taking insects, other arthropods and sometimes seeds. Occasionally forages on shrubs and low trees.

reproductive biology

Breeds from July to December, occasionally later. Domed nest is placed in a bush or sapling. Typically made of grass, lichen, and other plant fibers. The true entrance is at the side, and concealed by a hood, but there is a false cup-shaped nest placed on the top, possibly to confuse predators or cuckoos. Two to four pink eggs, lightly speckled. Both parents build nest, but only female incubates. Incubation period of 18–20 days, fledging period of 17–19 days. Parents are often assisted by helpers. Many nests fail due to predation or are parasitized by bronze-cuckoos.

conservation status

Not threatened.

significance to humans

A well-known bird to many country dwellers.

Rockwarbler

Origma solitaria

subfamily

Acanthizinae

taxonomy

Sylvia solitaria Lewin, 1808, Parramatta, New South Wales, Australia.

other common names

English: Origma, rock robin, cave-bird; French: Origma des rochers; German: Steinhuscher; Spanish: Origma Piedra.

physical characteristics

5.5 in (14 cm); c. 0.4 oz (12 g). Brown back with reddish brown underparts.

distribution

Very restricted range in sandstone and limestone country around Sydney, New South Wales.

habitat

Scrubby forest and heathland, especially near bare rock faces and cliffs.

behavior

Solitary, but easily seen. Song is described as repeated "good-bye," also penetrating, rasping and twittering calls. Sedentary.

feeding ecology and diet

Typically feeds on rock surfaces or bare ground, including parking areas, etc. Gleans insects, and other arthropods, and occasionally seeds. Sometimes takes insects from bark or captures them in flight.

reproductive biology

Breeds August to December. Nest is placed in a cave, or cleft in the rock, but also in man-made structures such as mine-shafts. It is made of rootlets, bark, grass and moss and is spherical with a side entrance. Three or four white eggs.

conservation status

Not threatened.

significance to humans

The only bird endemic to the state of New South Wales.

Southern whiteface

Aphelocephala leucopsis

subfamily

Acanthizinae

taxonomy

Xerophila leucopsis Gould, 1841, Adelaide, South Australia.

other common names

English: Chestnut-bellied whiteface, white-faced titmouse, eastern whiteface, tomtit; French: Gérygone blanchâtre; German: Fahlrücken-Weisstirnchen; Spanish: Ratona Blanca.

physical characteristics

4.5 in (11 cm); 0.4 oz (11 g). Gray-brown upperparts and whitish underneath. Forehead is white with black edge extending to eye. Dark tail tipped white. Stubby, finch-like bill.

distribution

Southern and central Australia, though generally avoiding coastal areas.

habitat

Open eucalypt and acacia woodland, grassland and farmland with scattered trees.

behavior

Typically in small to sometimes large groups, often with finches or small insectivores. Actively hops on ground, reminiscent of a sparrow. Song consists of musical, bell-like notes and twittering calls. Sedentary.

feeding ecology and diet

Mostly forages on the ground for small invertebrates and seeds, but also takes insects from shrubs and bark of trees.

reproductive biology

Breeds from June to November. Nests are typically in shrubs or small trees but may be placed in hollows or even buildings. Two to five dull white eggs, with sparse brown or red speckles.

conservation status

Not threatened.

significance to humans

Fairly familiar to many people in drier farming areas.

Bicolored mouse-warbler

Crateroscelis nigrorufa

subfamily

Acanthizinae

taxonomy

Sericornis nigro-rufa Salvadori, 1894, Moroka, New Guinea.

other common names

English: Black-backed mouse-warbler, mid-mountain mouse-babbler; French: Séricorne noir et roux; German: Schwarzrücken-Waldhuscher; Spanish: Ratona Semi Montañes.

physical characteristics

5 in (12–13 cm); c. 0.35 oz (10 g). Rufous underparts from chin to lower breast. Abdomen rufous or black, depending on subspecies. Upperparts are black, flanks brown.

distribution

Scattered through central mountains of New Guinea.

habitat

Rainforest at mid-altitudes.

behavior

Solitary, in pairs or small groups. Active, rapidly moving through an area, on the ground or in shrubs. When disturbed, bounces to and fro. Three-note whistling calls, and scolding alarms.

feeding ecology and diet

Forages on the ground, and in low shrubs.

reproductive biology

Not well-known. Domed nest is placed in a bush, and is made of rootlets, moss, grass and feathers. Two white, lightly marked eggs.

conservation status

Not threatened.

significance to humans

None known.

Yellowhead

Mohua ochrocephala

subfamily

Mohuinae

taxonomy

Mohua ochrocephala Gmelin, 1798, Queen Charlotte Sound, New Zealand.

other common names

English: Mohua, bush canary; French: Mohoua à tête jaune; German: Weissköpfchen; Spanish: Cabeza Amarilla.

physical characteristics

6 in (15 cm); c. 0.7 oz (20 g). Brownish olive upperparts with bright yellow head and yellow breast.

distribution

South Island of New Zealand, including Marlborough, Nelson, Westland, western Otago, Southland and near Dunedin.

habitat

Forest, especially dominated by beech (Nothofagus).

behavior

Pairs and trios occupy large home ranges in breeding season. Several families form larger flocks in nonbreeding season, which are joined by other bird species. Varied, mechanical call of six to eight notes rapidly repeated.

feeding ecology and diet

Spend most of the day foraging, in shaded canopy or upper subcanopy. Glean from foliage, branches and trunks and sometimes

rip into dead wood. Mostly insectivorous, especially taking larvae, but occasionally eat fruit, flowers and fungi.

reproductive biology

Facultatively cooperative or possibly polygamous. Breeds October to February. Cup-shaped nests placed in holes. Three to four pinkish eggs, blotched with reddish brown. Incubated by female for 18–21 days, young fledge at 21 days and are fed by two or three adults up to 55 more days.

conservation status

Declared Vulnerable, due to extensive decline as a result of forest loss. Also avoids edges, stunted and regrowth forests. Less vulnerable to nest predators than many New Zealand birds, due to hole nesting, but recently fledged young may be at risk.

significance to humans

None known.

Resources

Books

Coates, B. J. The Birds of Papua New Guinea, Including the Bismarck Archipelago and Bougainville. Brisbane: Dove, 1990.

Garnett, S. T., and G. M. Crowley. The Action Plan for Australian Birds 2000. Canberra: Environment Australia, 2001.

Serventy, V. N., A. R. McGill, J. D. Pringle, and T. R. Lindsey. The Wrens and Warblers of Australia. Sydney: Angus and Robertson, 1982.

Schodde, R., and I. Mason. The Directory of Australian Birds: Passerines. Melbourne: CSIRO, 1999.

Periodicals

Magrath, R., et al. "Life in the slow lane: Reproductive life history of the white-browed scrubwren, an Australian endemic." Auk 117 (2000): 479–489.

Noske, R.A. "Nesting biology of the mangrove gerygone (Gerygone levigaster) in the monsoonal tropics." Emu 102 (in press).

Organizations

Birds Australia. 415 Riversdale Road, Hawthorn East, Victoria

3123 Australia. Phone: +61 3 9882 2622. Fax: +61 3 98822677. E-mail: [email protected] Web site: <http://www.birdsaustralia.com.au>

Hugh Alastair Ford, PhD