Family PETROICIDAE Mathews, 1920

Museums

Regional Maps

• Petroicidae Mathews, G.M. 1920. Birds of Australia. London : Witherby & Co. Vol. 8 xiv + 316 pp.

  Type genus:

   Petroica Swainson, 1830.

Introduction

The Petroicidae, the Australasian robins, are a large polytypic group of small insectivorous birds. They are colourful, the males varying from blue-grey or grey to black with shadings of red or pink in some genera (e.g. Petroica) while their females lack these bright colours and instead are adorned by greys or browns. Both sexes often have white patches on the forehead and as a distinct wing barring. In other genera (e.g. Eopsaltria) males and females share the plumage colouration and, with their yellow and grey plumage, are visually indistinguishable. The young again have brown or greyish body plumage, heavily streaked with fine paler lines. All are accomplished songsters.

The family's centre of diversity is Australia and New Guinea, but extending into New Zealand and the south-west Pacific island chains, including Norfolk Island (Schodde & Mason 1999; Dickinson 2003). Australia has eight genera - 62% of the known 12 genera - and 22 (49%) of the world's 45 species. There are about 39 recognised ultrataxa in Australia and its territories. Only one Australian genus is endemic: Melanodryas is widespread across the mainland (M. cucullata) and in Tasmania (M. vittata).

Australasian robins are terrestrial, scansorial and arboreal in habit, feeding through perch and pounce actions. They are gregarious or to be found in small groups and pairs and breed by constructing cupped nests. Nesting sites vary considerably depending on the genus. Nests can be placed in trunk cavities, or on horizontal vines or branchlets, or in open forks of trees or shrubs, and on the ground near a tree base. Most nests are constructed of vegetable matter and are decorated externally with vertically hanging bark or even lichen; the nests have an internal lining of finer tendrils and feathers. Normal egg clutch numbers vary from two to four, averaging two or three, although one species, Drymodes brunneopygia (Southern Scrub-robin), produces a single-egged clutch. Egg colouration varies from having base colours of pale greyish white to pale or brownish olive. Each egg contains greyish-brown or reddish brown spots or dots. Such markings may be concentrated as capped or wreathed designs.

Australasian robins have adapted to occupy all major habitats that occur within their distribution, including alpine meadows, scrublands, woodlands, forests, human habitation, heaths, mallee, mangroves, mulga and rainforests. A number are altitudinal migrants. They migrate from their summer and breeding haunts in the highlands to lower regions during winter. Mass migration involves both day and night movement. Some Tasmanian species migrate across Bass Strait. Other species are either sedentary or locally nomadic. Movement is difficult to follow as often moving birds are replaced by others coming in from other regions giving an incorrect impression that they are present throughout the year. Eight species are shared with New Guinea.

Diagnosis

'The fossa at the head of the humerus is pachycephaloid in form, single and trabeculated, and the horns of the vomer are articulated and dorsoventrally flattened in one plane to protrude forward of the apically inflated maxillo-palatine processes. Robins also differ from other families of this Australasian corvoid assemblage in the openly aperturate narial and orbital cavities, much reduced temporal fossae with short post-orbital and zygomatic processes, and small, almost unwinged ectethmoid plate that tapers towards the jugular without reaching it; free lachrymals are missing.'

Diagnosis References

Schodde, R. & Mason, I.J. 1999. The Directory of Australian Birds : Passerines. A Taxonomic and Zoogeographic Atlas of the Biodiversity of Birds in Australia and its Territories. Collingwood, Australia : CSIRO Publishing x 851 pp.

History of changes