Torresian Crow call is nasal, high-pitched cawing uk-uk-uk-uk-uk-uk or ok-ok-ok-ok-ok-ok-ok. The notes are short and clipped, in contact and advertisement, from perch or in-flight; never an aaa sound as in Australian Raven. Torresian Crow is sporadically more long-drawn caws, similar to those of Little Crow. Western birds give long garbled yodeling caw in flight, possibly as a territory marker.
Torresian Crow, Papuan Crow, or Australian Crow (Corvus orru) occupies much the same ecological niche as the Australian Raven in the south. Where they meet through inland northeastern Australia, both defend territories against one another and others of their own species. Conflict is only reduced where the crow breeds a month or two later than the raven and nests in less particular sites.
Like the ravens, Torresian Crows are sedentary and live territorially in a premium habitat that provides all their needs for food, roosting, and nesting. It is a mixture of pasture, field, and treed woodland or open forest around the coast and eucalypt-lined watercourses and hill valleys in the drier inland. Although roaming flocks of 50-60 form in autumn and winter-mostly of immature and non-breeding adults-established pairs hold a permanent territory.
Territories commonly cover 1 00-200 hectares. Torresian Crows feed mainly on the ground, walking about or hopping one foot in front of the other to move faster or before taking flight. Like other Australian corvids, they are omnivorous and will scavenge almost anything anywhere. They visit refuse dumps and slaughter yards, pick at carcasses of road-killed animals, and land on crops to pick grain. Maize and sorghum are attacked in this way, and the birds also take other seeds and fruit on the ground.
Their diet, overall, comprises about 26 percent carrion, 43 percent insects, and 31 percent plant materials. When traveling, the crows fly easily through and over treetops with shallow loping wing beats, much as do Little Crows. They call often, in rather staccato caws, both on the wing and from perches to advertise territory and to maintain contact among pairs and groups.
In-flight, calling birds often undulate steeply, wings to the body, like cuckoos; on perches, they stand with head thrown forward and wings jerking up and tail down as each note is uttered. As is usual in corvids, only the female incubates but both adults feed the young. Nests are often parasitized by Channel-billed Cuckoos, a fate unknown in any other Australian crow or raven.
Fledged young remain with their parents for several months before being driven out and dispersed. Until about 20 years ago it was thought that this species, the Little Crow and the Australian Raven were the only corvids in Australia. Now it is known that there are five. Their similarity to one another and their white eyes-which are unique among the world’s crows-suggest that they all evolved from a common ancestor that arrived fairly recently, in geological terms, in Australia.
How they split off from one another makes for fascinating conjecture. The first split probably developed between the crows in the northern Torresian forests and the ravens in the Bassian south. Not only do both crows have pure white feather bases but they also often undulate like cuckoos when calling in flight. None of the ravens seem to have these traits.
The evolution of species within the crows and the ravens might then be explained most simply by sequences of east-west invasions north and south of a central desert region. In the north, past changes in climate broke up habitat and separated ancestral crows into two populations, one in the east, the other in the west or center.
The one in the west then evolved in isolation into the Little Crow and the one in the east into the Australian Crow. When climate later ameliorated and allowed the birds and their habitat to spread and overlap once more, the two crows kept apart, perhaps no longer able to interbreed. The sequence in the south was more complicated because three species of the raven are involved. What could have happened is that ancestral ravens across southern Australia were first split into progenitors of the Forest Raven in the east and the Little Raven in the west.
Then the climate changed, allowing ancestral Little Ravens to colonies in the east, only to change again and cut them of£ The eastern isolate became the Little Raven as we now know it; the remnant in the west developed into the Australian Raven which has since spread east once more. Torresian Crow is also called, Australian Crow, Crow, Kelly, Large-billed Crow, or Papuan Crow.
Torresian Crow is about 480-540 mm in length. ADULTS: Sexes similar. The plumage is wholly black, with green and purple gloss; under-down pure white, clearly demarcated. Throat hackles short and inconspicuous. Eyes are white, with a blue inner ring, and bill and feet are black. IMMATURES: As adults but breast and belly sooty brown; Underdown greyish white; eye brown. The eye does not whiten until the third year, as in other Australian corvids.
Torresian Crow Breeds August-October in the south; farther north eggs are still laid in February. Nest of finer twigs than in other crow nests; scantily lined; usually placed in the tree canopy, presumably for shade; 4-9 m above ground. Eggs: usually five to six; pale green, lightly or boldly marked with dark and olive-brown spots and blotches according to race; oblong-oval, about 44 x 30 mm. Incubation by female bird.
Torresian Crow is a common bird and widespread across the tropical Australian woodlands. Northern population extends west to Kimberleys, southwest to central Australian ranges, and southeast to coastal New South Wales (Port Stephens). Isolated by Great Sandy and Simpson Deserts, the western population ranges from Pilbara south to beyond Kalgoorlie. Also Moluccas, New Guinea, New Britain, and Tanimbar. Four or five races; probably two in Australia.