Little raven

From Wikipedia, the free encyclopedia
  (Redirected from Little Raven)
Jump to: navigation, search
For the American Indian chief, see Little Raven (Arapaho leader).
Little raven
Corvus mellori.jpg
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Corvidae
Genus: Corvus
Species: C. mellori
Binomial name
Corvus mellori
Mathews, 1912
Corvus mellori map.jpg
Distribution map

The little raven (Corvus mellori) is a species of the crow and raven family Corvidae, that is endemic to Australia. It has all-black plumage, beak and legs with a white iris, as do the other Corvus members in Australia and some species from the islands to the north. 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[edit]

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. He also 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.[2]

Although called a raven, its closest affinities lie with the other four species of Australian corvid, which include the Torresian crow and little crow as well as the forest raven and Australian raven.[3] 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 genetic separation between 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.[4] 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.[5]

Ian 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.[6]

Description[edit]

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 and more curved, its calls are shorter, and its throat bulges out less while calling. 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. The range of the little raven does overlap the range of the Australian raven, but the latter's range extends further.

A juvenile (right) calls to be fed the grub its mother (left) has just caught.

Distribution and habitat[edit]

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

Behaviour[edit]

Diet[edit]

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.[7]

Nesting[edit]

Little ravens often nest in a loose colony of up to fifteen pairs, with nests few meters apart. 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.

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. Juveniles have brown colored eyes until their 3rd year, their eye color changes to white.

Voice[edit]

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.

External Image Links[edit]

References[edit]

  1. ^ BirdLife International (2012). "Corvus mellori". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ Rowley, Ian (1967). "A fourth species of Australian corvid". Emu 66 (3): 191–210. doi:10.1071/MU966191. 
  3. ^ Australian Museum Online. "Crows and Ravens". Archived from the original on 1 September 2007. Retrieved 12 August 2007. 
  4. ^ 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". Journal of Zoological Systematics and Evolutionary Research 50 (3): 230–46. doi:10.1111/j.1439-0469.2012.00664.x. 
  5. ^ 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. 
  6. ^ Rowley, Ian (1973). "The Comparative Ecology of Australian Corvids. VI. Why five species?". CSIRO Wildlife Research 18 (1): 157–69. doi:10.1071/CWR9730157. 
  7. ^ 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.