Acanthiza

Acanthiza is a genus of passeriform birds, most endemic to Australia, but with two species (A. murina and A. cinerea) restricted to New Guinea. These birds are commonly known as thornbills. They are not closely related to species in the hummingbird genera Chalcostigma and Ramphomicron, which are also called thornbills.

Acanthiza
Striated Thornbill (Acanthiza lineata)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Passeriformes
Family:	Acanthizidae
Genus:	Acanthiza Vigors & Horsfield, 1827
Type species
Motacilla pusilla[1] Shaw, 1790
Species
14, see text.

They are found primarily in Australia and have a thin long beak. Colloquially the thornbill is sometimes referred to as a “tit” by locals, but in reality the Australian continent lacks any true tits, albeit Acanthiza species do show some similarities with tits in their behavior. They have a similar role as small insect-eating birds with titmice and kinglets.^[2] Like tits, Thornbills live in small groups foraging amidst trees and shrubs, and feed in a similar manner. Cooperative breeding is recorded from most species except the brown and Tasmanian thornbills.^[3]

The habitat preferences of the group vary from dense forest to open saltbush and bluebush plains.

Acanthiza follow a very characteristic undulating path when flying. Their diet is formed essentially of little insects and plant lice that these birds glean from foliage. They are also exceptional acrobats that are easily able to stay head downward like tits do.

The nest of the Acanthiza is a large dome-shaped construction, completely enclosed except for a side hole, just like that of the long-tailed tit; however Acanthiza adds to it an additional room whose function is unknown. It is somewhat similar to the Aegithalidae in combining long incubation periods with highly synchronous hatching.^[4] This combination, normally impossible due to intense competition for food,^[5] occurs because parents and (usually) helpers can organise food supply in such a manner that sibling competition for food is virtually absent.^[6]

The number of eggs usually ranges from two to four, and the incubation period is around twenty days with laying intervals of two days. The length of an adult bird is 8 to 10 centimetres (3.1 to 3.9 in).

Species

The genus contains 14 species:^[7]

Image	Common Name	Scientific name	Distribution
	Mountain thornbill	Acanthiza katherina	north-east Queensland, Australia
	Brown thornbill	Acanthiza pusilla	south-eastern Australia, Tasmania
	Inland thornbill	Acanthiza apicalis	Australia, New Guinea
	Tasmanian thornbill	Acanthiza ewingii	Tasmania and the Bass Strait Islands.
	New Guinea thornbill	Acanthiza murina	New Guinea
	Chestnut-rumped thornbill	Acanthiza uropygialis	Australia.
	Buff-rumped thornbill	Acanthiza reguloides	Western Australia.
	Western thornbill	Acanthiza inornata	southwestern Australia.
	Slender-billed thornbill	Acanthiza iredalei	Australia.
	Yellow-rumped thornbill	Acanthiza chrysorrhoa	southern and eastern Australia as well as Tasmania
	Yellow thornbill	Acanthiza nana	eastern coast of Australia.
	Grey thornbill	Acanthiza cinerea	New Guinea
	Striated thornbill	Acanthiza lineata	Australia
	Slaty-backed thornbill	Acanthiza robustirostris	Australia.

References

1. "Acanthizidae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-07-16.
2. Bell, Harry L.; Ford, Hugh A. (1986). "A Comparison of the Social Organization of Three Syntopic Species of Australian Thornbill, Acanthiza". Behavioral Ecology and Sociobiology. 19 (6): 381–92. doi:10.1007/bf00300540. JSTOR 4599974. S2CID 6197201.
3. Higging, P.J. and J.M. Peter; Handbook of Australian, New Zealand and Antarctic Birds, vol. 6: Pardalotes to Shrike-thrushes. ISBN 0-19-553762-9
4. Ricklefs, R.E.; “Sibling competition, hatching asynchrony, incubation period, and lifespan in altricial birds”; in Power, Dennis M. (editor); Current Ornithology. Vol. 11. ISBN 9780306439902
5. Losdat, Sylvain, Helfenstein, Fabrice, Gaude, Benoît and Richner, Heinz; “Effect of sibling competition and male carotenoid supply on offspring condition and oxidative stress”
6. Ricklefs, Robert E.; “SIBLING COMPETITION AND THE EVOLUTION OF BROOD SIZE AND DEVELOPMENT RATE IN BIRDS”
7. Gill, Frank; Donsker, David, eds. (2019). "Bristlebirds, pardalotes, Australasian warblers". World Bird List Version 9.1. International Ornithologists' Union. Retrieved 21 January 2019.

• Del Hoyo, J.; Elliot, A. & Christie D. (editors). (2006). Handbook of the Birds of the World. Volume 12: Picathartes to Tits and Chickadees. Lynx Edicions. ISBN 978-84-96553-42-2

External links

• Acanthiza fotos & videos on the Internet Bird Collection