The family Pachycephalidae, collectively the whistlers, includes the whistlers, shrikethrushes, shriketits, pitohuis and crested bellbird, and is part of the ancient Australo-Papuan radiation of songbirds. Its members range from small to medium in size, and occupy most of Australasia. Australia and New Guinea are the centre of their diversity, and in the case of the whistlers, the South Pacific islands as far as Tonga and Samoa and parts of Asia as far as India. The exact delimitation of boundaries of the family are uncertain.
The whistlers are birds of forests and wooded areas. Most species inhabit rainforest, particularly in the Asian and Papuan parts of their range, but Australian species inhabit a wider range of habitats including woodlands, arid scrubland and mangrove forests. Some species are restricted to a particular ecosystem, whereas others are more catholic and will inhabit a range of habitat types.
The whistlers are stout birds with strong bills, and the group was once known as the thickheads due to the large rounded heads of many species. Their plumage is rufous, brown, or grey in the majority of species. Nevertheless, a few species, particularly the golden whistler and its close relatives, have bright plumage. One of the more unusual traits of this family is found in the feathers of some of the pitohuis, which have toxins. These toxins are probably a deterrent to parasites and may also serve to dissuade predators from taking the birds.
They are insectivorous, picking insects off leaves, branches, or leaf litter. While insects make up the majority of the diet they will also feed on spiders, worms, centipedes, snails, and small crabs; larger species will also tackle small vertebrates such as frogs, geckos and baby birds. They are generally sedate foragers and do not engage in hawking to obtain prey, instead being gleaners and probers. Only a few species migrate, most remaining resident in their tropical environment.
Little is known about the breeding biology of most of the family; what is known generally comes from a small number of Australian species and the three New Zealand Mohoua species. They are monogamous and generally nest as simple pairs, although breeding groups have been recorded in some species.
Several species belonging to this family are outstanding songsters: the whistlers produce an astonishing volume for their size, and the lyrebirds aside, the grey shrikethrush is often regarded as the finest, most inventive songbird of them all.
- Subfamily: Falcunculinae
- Subfamily: Pachycephalinae
*Although traditionally included in this family, recent genetic evidence suggests that the yellow-flanked whistler, also known as the olive-flanked whistler, actually should be placed in a monotypic subfamily of the family Bombycillidae. Comparably, the genus Mohoua, which includes three species from New Zealand, has often been placed in Pachycephalidae, but they are better placed in their own family, Mohouidae.
- Dumbacher JP, Beehler BM, Spande TF, Garraffo HM, Daly JW (1992). "Homobatrachotoxin in the genus Pitohui: chemical defense in birds?". Science 258 (5083): 799–801. doi:10.1126/science.1439786. PMID 1439786.
- Garnett, Stephen (1991). Forshaw, Joseph, ed. Encyclopaedia of Animals: Birds. London: Merehurst Press. p. 201. ISBN 1-85391-186-0.
- Spellman, G. M., A. Cibois, R. G. Moyle, K. Winker, and F. K. Barker. 2008. Clarifying the systematics of an enigmatic avian lineage: What is a Bombycillid? Molecular Phylogenetics and Evolution. 49(3): 1036-1040
- Zachary Aidala et al. Phylogenetic relationships of the genus Mohoua, endemic hosts of New Zealand’s obligate brood parasitic Long-tailed Cuckoo (Eudynamys taitensis). Journal of Ornithology, published online June, 2013; doi: 10.1007/s10336-013-0978-8
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