Brown songlark: Difference between revisions
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* [http://photogallery.canberrabirds.org.au/old_world_warblers.htm Old World Warbler photos] |
* [http://photogallery.canberrabirds.org.au/old_world_warblers.htm Old World Warbler photos] |
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[[Category:Birds of Australia]] |
[[Category:Birds of Australia]] |
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[[Category:Cincloramphus]] |
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Revision as of 10:18, 3 June 2007
| Brown Songlark | |
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| Species: | C. cruralis
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| Binomial name | |
| Cincloramphus cruralis Vigors & Horsfield, 1827
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The Brown Songlark (Cincloramphus cruralis), also Australian Songlark, is a small passerine bird found throughout much of Australia. The species is notable for sexual size dimorphism, amongst the most pronounced in any bird.[2] Males are 23-25 cm long versus 18-19 cm for females, and may weigh 2.3 times as much.[3] In general, the birds have a dusky brown plummage tapering to brownish-white underparts, although breeding males may display a cinnamon-colour. Its eyes and bill are black.
The bird ranges throughout all of Australia, except parts of the far north, with particularly dense populations in the south. It prefers pastures and grassy scrub, and feeds on seeds and insects. The species is highly nomadic and will often flee from drought affected areas.[4]
Nesting occurs from August to December. Clutches range in size from 2 to 5 eggs, and are generally well concealed in shrubbery. Females provide most of the parenting. Foxes and snakes prey upon nests.[3]
Sexual dimorphism
The sexual dimorphism of the species has been the subject of study. Males are highly polygynous and compete directly for mates, giving rise to the pronounced size differential. Preferring open terrain, there is significant habitat heterogeneity (sameness) and excellent visibility across Brown Songlark territories. This allows males to defend large territories and support multiple nesting females.[3]
Research has shown an interesting corollary to the dimorphism of the species: though males are larger than females, females hatch from larger eggs and are initially heavier than their brothers. This may provide them an early competitive advantage. Particularly, in periods of low food availability, the greater nutrient reserves of female hatchlings may skew the sex-ratio toward "cheaper" daughters. Whether it is advantageous for mothers to favour the smaller or larger sex in size dimorphic species remains ambiguous.[2]
Taxonomy and status
The Brown Songlark is species of Sylviidae, the Old World Warblers, a successful passerine family. It shares the genus Cincloramphus with the Rufous Songlark, another species endemic to much of Australia.
The Brown Songlark has a large range, between 1,000,000 and 10,000,000 km; while population size has not been quantified the bird is reported to be common. The IUCN thus lists it as a species of "least concern."[1]
References
- ^ a b Template:IUCN2006 Database entry includes justification for why this species is of least concern.
- ^ a b Magrath, Michael J. L. (2003). "Egg size and laying order in relation to offspring sex in the extreme sexually size dimorphic brown songlark". Behavioral Ecology and Sociobiology. 54 (3): 240–248. doi:10.1007/s00265-003-0627-y. Retrieved 2007-06-02.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ a b c Magrath, Michael J. L. (2003). "Breeding behaviour and ecology of the sexually size-dimorphic brown songlark, Cinclorhamphus cruralis". Australian journal of zoology. 51 (5): 429–441. Retrieved 2007-06-01.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Brown Songlark". Birds in Backyards. Australian Museum. Retrieved 2007-06-01.