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| ==Taxonomy== | ==Taxonomy== | ||
| In the 1960s, the ] were intensively studying Australian raven populations and their relationship to lambing and sheep in southeastern Australia. It became evident that there was a smaller species of raven living alongside the Australian raven. These birds lived in smaller trees, had smaller throat hackles and lacked the bare skin of their larger relative. They were also nomadic and made |
In the 1960s, the ] were intensively studying Australian raven populations and their relationship to lambing and sheep in southeastern Australia. It became evident that there was a smaller species of raven living alongside the Australian raven. These birds lived in smaller trees, had smaller throat hackles and lacked the bare skin of their larger relative. They were also nomadic and made different calls. ] investigated old scientific names assigned to type specimens and concluded that they matched ''Corvus mellori'' as described by ] in 1912.<ref name=rowley1967>{{cite journal |doi=10.1071/MU966191 | title=A fourth species of Australian corvid | author= Rowley, Ian | journal =Emu |volume= 66 |issue=3 |pages= 191–210 |year=1967}}</ref><!-- cites para --> The type specimen was collected from Angas Plains in South Australia in 1901. It disappeared in transit in 1966.<ref name="rowley 1970">{{cite journal|last=Rowley|first=Ian|date=1970|title=The Genus ''Corvus'' (Aves: Corvidae) in Australia|journal=CSIRO Wildlife Research|volume=15|issue=1|pages=27–71|doi=10.1071/CWR9700027}}</ref> | ||
| The little raven is the closest relative of the ] despite the little raven being the smallest raven species in Australia and the Forest raven being the largest. Initial single gene genetic analysis of the genus using mitochondrial DNA showed the three raven species to belong to one lineage and the two crows to another |
The little raven is the closest relative of the ], despite the little raven being the smallest raven species in Australia and the Forest raven being the largest. Initial single gene genetic analysis of the genus using mitochondrial DNA showed the three raven species to belong to one lineage and the two crows to another however, the crow lineage and raven lineage may not be closely related as the only close similarity is the eye colour. It is thought by some that the ravens in Australia may have been closely related to the extinct ] and ]. The genetic separation between the raven species is small and there was a suggestion the little raven may be nested within the Australian raven, though the authors conceded more genetic work was needed. The Little raven is sometimes considered the link between the Australian and Forest raven. <ref name=haring2012>{{Cite journal | last1 = Haring | first1 = Elisabeth | last2 = Däubl |first2=Barbara | last3 = Pinsker| first3 = Wilhelm | last4 = Kryukov | first4 = Alexey |last5=Gamauf | first5 = Anita | title = Genetic divergences and intraspecific variation in corvids of the genus ''Corvus'' (Aves: Passeriformes: Corvidae) – a first survey based on museum specimens | journal = Journal of Zoological Systematics and Evolutionary Research | year = 2012 | doi = 10.1111/j.1439-0469.2012.00664.x | url = http://www.biosoil.ru/files/00010833.pdf | pages=230–46 | volume = 50 | issue = 3}}</ref> Subsequent multigene analysis using nuclear DNA by Jønsson and colleagues in 2012 showed the forest and little raven are each other's closest relatives, with the Australian raven an earlier offshoot.<ref name="jonsson 2012">{{cite journal|author=Jønsson, Knud A.; Fabre, Pierre-Henri; Irestedt, Martin |year=2012|title=Brains, tools, innovation and biogeography in crows and ravens|journal=BMC Evolutionary Biology|volume=12|url=http://www.biomedcentral.com/1471-2148/12/72|doi=10.1186/1471-2148-12-72}}</ref> | ||
| Rowley proposed that the common ancestor of the five species diverged into a tropical crow and temperate raven sometime after entering Australia from the north |
Rowley proposed that the common ancestor of the five species diverged into a tropical crow and temperate raven sometime after entering Australia from the north. The raven diverged into the ancestor of the forest and little ravens in the east and Australian raven in the west. As the climate was cooler and dryer, the aridity of central Australia split them entirely. Furthermore, the eastern diverged into nomadic little ravens as the climate became dryer and, in forested refuges, forest ravens. As the climate eventually became warmer, the western ravens spread eastwards and outcompeted forest ravens on mainland Australia but coexisted with little ravens.<ref name=rowley1973f>{{cite journal |doi=10.1071/CWR9730157 | title=The Comparative Ecology of Australian Corvids. VI. Why five species? | author= | ||
| Rowley, Ian | journal =CSIRO Wildlife Research |volume= 18|issue=1 |pages= 157–69 |year=1973}}</ref><!-- cites para --> | Rowley, Ian | journal =CSIRO Wildlife Research |volume= 18|issue=1 |pages= 157–69 |year=1973}}</ref><!-- cites para --> | ||
| Rowley proposed the name "little raven" for the new species, conceding it was generic but noting it was demonstrative, and that "little crow" had been adopted over "Bennett's crow" for ''Corvus bennettii''.<ref name=rowley1967/> | Rowley proposed the name "little raven" for the new species, conceding it was generic but noting it was demonstrative, and that "little crow" had been adopted over "Bennett's crow" for ''Corvus bennettii''.<ref name=rowley1967/> The term "crow" is colloquially applied to any or all species of Australian corvid.<ref name="rowley 1970"/> | ||
| ==Description== | ==Description== | ||
| Some of the differences between the two species are as follows: the little raven is, at about |
Some of the differences between the two species are as follows: the little raven is, at about 48–50 cm in length on average, somewhat smaller than the Australian raven (though sizes do overlap between both species), the little raven's beak is slightly smaller. The little raven is a somewhat more sociable species than the Australian raven, often forming large flocks that roam freely over wide areas in search of food. | ||
| ] | ] | ||
| Line 37: | Line 38: | ||
| ===Vocalisations=== | ===Vocalisations=== | ||
| Its call is a harsh, guttural ''"kar-kar-kar- |
Its call is a harsh, guttural ''"kar-kar-kar-kar"'' or ''"ark-ark-ark-ark"''. They also do a quick upward flick of both wings with each note. | ||
| ==Distribution and habitat== | ==Distribution and habitat== | ||
| Line 50: | Line 51: | ||
| ===Diet=== | ===Diet=== | ||
| Little ravens eat more insects than ''C. coronoides'' and feed mainly on the ground, but is omnivorous |
Little ravens eat more insects than ''C. coronoides'' and to feed mainly on the ground, but is probably omnivorous to a similar extent to other '']'' species when opportunity arises. Common invertebrates eaten include spiders, millipedes, centipedes (which ravens behead before eating), grasshoppers, cicadas and caterpillars (especially of the family ]), which are important in feeding nestlings.<ref name=rowley1973e>{{cite journal |doi=10.1071/CWR9730131 | title=The Comparative Ecology of Australian Corvids. V. Food | author=Rowley, Ian; Vestjens, W.J.M. | journal =CSIRO Wildlife Research |volume= 18|issue=1 |pages= 131–55 |year=1973}}</ref> | ||
| Little ravens are intelligent birds, and have been recorded using tools as well as having innovative methods of seeking out food.<ref name="jonsson 2012"/> | Little ravens are intelligent birds, and have been recorded using tools as well as having innovative methods of seeking out food.<ref name="jonsson 2012"/> | ||
| ===Nesting=== | ===Nesting=== | ||
| Little ravens |
Little ravens often nest in a loose colony of up to fifteen pairs, with nests few metres apart. They are closer together as the territories are for breeding only and not feeding, which is more communal.<ref name=rowley1973d>{{cite journal |doi=10.1071/CWR9730091 | title=The Comparative Ecology of Australian Corvids. IV. Nesting and the rearing of young to independence | author= Rowley, Ian | journal =CSIRO Wildlife Research |volume= 18|issue=1 |pages= 91–129 |year=1973}}</ref> They have often been recorded as having several nests within the nesting territory of a single Australian raven which, presumably due to different food preferences, does not seem to consider them a threat to its own food resources. | ||
| Cover does not appear to be important as dead trees with bare branches are used.<ref name=rowley1973d/> | Cover does not appear to be important as dead trees with bare branches are used.<ref name=rowley1973d/> | ||
| The nest is a thin cup of sticks with a layer of bark, grass and wool to create a thick mat. Nests are commonly low to the ground (under 10 meters), often in a forked branch in the outer canopy of a tree. Nests |
The nest is a thin cup of sticks with a layer of bark, grass and wool to create a thick mat. Nests are commonly low to the ground (under 10 meters), often in a forked branch in the outer canopy of a tree. Nests on the ground have been reported. Building the nest is often time-consuming initially as the birds try (and often fail) to wedge sticks into the tree fork to make a platform. Thinner sticks and rootlets are used to make the bowl before the bowl is lined with feathers. Both birds build the nest, with the female taking over the lining of the nest while the male brings her material. New nests are built each year generally, as the re-use of old ones might spread disease or parasites—nests become caked with faeces as the nestlings grow and the parents cannot keep up with its removal. Old nests often disintegrate within twelve months anyway due to their exposed locations.<ref name=rowley1973d/> | ||
| A clutch can comprise up to six eggs, though usually four or five are laid, with four being the commonest number.<ref name=rowley1973d/> Eggs are quite variable and cannot be reliably identified as to which Australian corvid laid them.<ref name=rowley1973d/> | A clutch can comprise up to six eggs, though usually four or five are laid, with four being the commonest number.<ref name=rowley1973d/> Eggs are quite variable and cannot be reliably identified as to which Australian corvid laid them.<ref name=rowley1973d/> | ||
Revision as of 13:49, 12 January 2015
For the American Indian chief, see Little Raven (Arapaho leader).
| Little raven | |
|---|---|
| |
| Conservation status | |
 Least Concern (IUCN 3.1) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Corvidae |
| Genus: | Corvus |
| Species: | C. mellori |
| Binomial name | |
| Corvus mellori Mathews, 1912 | |
| |
| Distribution map | |
The little raven (Corvus mellori) is a species of the family Corvidae that is endemic to Australia. It has all-black plumage, beak and legs with a white iris, as do the other members of the genus Corvus in Australia and some species from the islands to the north. Like those of the other two species of raven in Australia, its black feathers have grey bases. Although the little raven was first named by Mathews in 1912, it was only in 1967 that there was consensus to separate it from the Australian raven (C. coronoides) as a distinct species.
Taxonomy
In the 1960s, the CSIRO were intensively studying Australian raven populations and their relationship to lambing and sheep in southeastern Australia. It became evident that there was a smaller species of raven living alongside the Australian raven. These birds lived in smaller trees, had smaller throat hackles and lacked the bare skin of their larger relative. They were also nomadic and made different calls. Ian Rowley investigated old scientific names assigned to type specimens and concluded that they matched Corvus mellori as described by Gregory Mathews in 1912. The type specimen was collected from Angas Plains in South Australia in 1901. It disappeared in transit in 1966.
The little raven is the closest relative of the Forest raven, despite the little raven being the smallest raven species in Australia and the Forest raven being the largest. Initial single gene genetic analysis of the genus using mitochondrial DNA showed the three raven species to belong to one lineage and the two crows to another however, the crow lineage and raven lineage may not be closely related as the only close similarity is the eye colour. It is thought by some that the ravens in Australia may have been closely related to the extinct new Zealand raven and Chatham raven. The genetic separation between the raven species is small and there was a suggestion the little raven may be nested within the Australian raven, though the authors conceded more genetic work was needed. The Little raven is sometimes considered the link between the Australian and Forest raven. Subsequent multigene analysis using nuclear DNA by Jønsson and colleagues in 2012 showed the forest and little raven are each other's closest relatives, with the Australian raven an earlier offshoot.
Rowley proposed that the common ancestor of the five species diverged into a tropical crow and temperate raven sometime after entering Australia from the north. The raven diverged into the ancestor of the forest and little ravens in the east and Australian raven in the west. As the climate was cooler and dryer, the aridity of central Australia split them entirely. Furthermore, the eastern diverged into nomadic little ravens as the climate became dryer and, in forested refuges, forest ravens. As the climate eventually became warmer, the western ravens spread eastwards and outcompeted forest ravens on mainland Australia but coexisted with little ravens.
Rowley proposed the name "little raven" for the new species, conceding it was generic but noting it was demonstrative, and that "little crow" had been adopted over "Bennett's crow" for Corvus bennettii. The term "crow" is colloquially applied to any or all species of Australian corvid.
Description
Some of the differences between the two species are as follows: the little raven is, at about 48–50 cm in length on average, somewhat smaller than the Australian raven (though sizes do overlap between both species), the little raven's beak is slightly smaller. The little raven is a somewhat more sociable species than the Australian raven, often forming large flocks that roam freely over wide areas in search of food.
Eye colour varies with age: nestlings up to three months old have blue-grey eyes, juveniles aged from three to eleven months have brown eyes, and immature birds have hazel eyes with blue eyerings around the pupil until age one year and eleven months.
Vocalisations
Its call is a harsh, guttural "kar-kar-kar-kar" or "ark-ark-ark-ark". They also do a quick upward flick of both wings with each note.
Distribution and habitat
The little raven ranges over southeastern Australia from southern South Australia, Victoria and New South Wales. Also in Kangaroo Island (S.A) and King Island (Bass Strait). Living within scrub, agricultural areas, grazing pasture, woodlands to treeless plains, coasts, and suburbs.
Little ravens are absent from west Gippsland, where the land is dominated by forest ravens
Its large range, abundance and stable population mean it is classified as Least Concern on the IUCN Red List.
Behaviour
Diet
Little ravens eat more insects than C. coronoides and to feed mainly on the ground, but is probably omnivorous to a similar extent to other Corvus species when opportunity arises. Common invertebrates eaten include spiders, millipedes, centipedes (which ravens behead before eating), grasshoppers, cicadas and caterpillars (especially of the family Noctuidae), which are important in feeding nestlings.
Little ravens are intelligent birds, and have been recorded using tools as well as having innovative methods of seeking out food.
Nesting
Little ravens often nest in a loose colony of up to fifteen pairs, with nests few metres apart. They are closer together as the territories are for breeding only and not feeding, which is more communal. They have often been recorded as having several nests within the nesting territory of a single Australian raven which, presumably due to different food preferences, does not seem to consider them a threat to its own food resources.
Cover does not appear to be important as dead trees with bare branches are used.
The nest is a thin cup of sticks with a layer of bark, grass and wool to create a thick mat. Nests are commonly low to the ground (under 10 meters), often in a forked branch in the outer canopy of a tree. Nests on the ground have been reported. Building the nest is often time-consuming initially as the birds try (and often fail) to wedge sticks into the tree fork to make a platform. Thinner sticks and rootlets are used to make the bowl before the bowl is lined with feathers. Both birds build the nest, with the female taking over the lining of the nest while the male brings her material. New nests are built each year generally, as the re-use of old ones might spread disease or parasites—nests become caked with faeces as the nestlings grow and the parents cannot keep up with its removal. Old nests often disintegrate within twelve months anyway due to their exposed locations.
A clutch can comprise up to six eggs, though usually four or five are laid, with four being the commonest number. Eggs are quite variable and cannot be reliably identified as to which Australian corvid laid them.
They leave the nest at 33-41 days of age,
Notes
- Rowley and colleagues recorded iris colour changes of all five Australian corvid species raised in captivity.
References
- ^ Template:IUCN
- ^ Rowley, Ian (1967). "A fourth species of Australian corvid". Emu. 66 (3): 191–210. doi:10.1071/MU966191.
- ^ Rowley, Ian (1970). "The Genus Corvus (Aves: Corvidae) in Australia". CSIRO Wildlife Research. 15 (1): 27–71. doi:10.1071/CWR9700027.
- Haring, Elisabeth; Däubl, Barbara; Pinsker, Wilhelm; Kryukov, Alexey; Gamauf, Anita (2012). "Genetic divergences and intraspecific variation in corvids of the genus Corvus (Aves: Passeriformes: Corvidae) – a first survey based on museum specimens" (PDF). Journal of Zoological Systematics and Evolutionary Research. 50 (3): 230–46. doi:10.1111/j.1439-0469.2012.00664.x.
- ^ Jønsson, Knud A.; Fabre, Pierre-Henri; Irestedt, Martin (2012). "Brains, tools, innovation and biogeography in crows and ravens". BMC Evolutionary Biology. 12. doi:10.1186/1471-2148-12-72.
{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link) - Rowley, Ian (1973). "The Comparative Ecology of Australian Corvids. VI. Why five species?". CSIRO Wildlife Research. 18 (1): 157–69. doi:10.1071/CWR9730157.
- Rowley, Ian; Vestjens, W.J.M. (1973). "The Comparative Ecology of Australian Corvids. V. Food". CSIRO Wildlife Research. 18 (1): 131–55. doi:10.1071/CWR9730131.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Rowley, Ian (1973). "The Comparative Ecology of Australian Corvids. IV. Nesting and the rearing of young to independence". CSIRO Wildlife Research. 18 (1): 91–129. doi:10.1071/CWR9730091.
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