"Ah … ahh … aaaaah."
No outback scene seems complete without a corvid's cry.
Corvids are birds that belong to the family Corvidae and in Australia are crows and ravens.
Their cry is as much a soundtrack of regional Australia as the relentless drone of a billion insects.
However, the owner of this mournful caw is often mistakenly identified.
It is the voice, not of a crow, but of the Australian raven. And they are not the same.
Telling the difference
Australia has five native corvids, according to Birdlife Australia's Sean Dooley.
Three are ravens; two are crows. They are very closely related and difficult to tell apart just by appearance.
Mr Dooley says the size of a bird, its subtle vocal cues and geography are used to distinguish crows from ravens.
"Location, location, location" is the most helpful clue.
"Each capital city has a different dominant species, so if you're in Perth, Sydney or Canberra, the main corvid you will see is the Australian raven," he said.
"In fact, in Perth, it's the only one you'll see."
The little raven is dominant in Melbourne and Adelaide; the forest raven in Hobart; and the Torresian crow in Brisbane and Darwin.
Mr Dooley said subtle visual cues could also help.
"Ravens are generally considered to be larger, for example.
"The only [reliable] difference really comes down to the colour of the down at the base of the feathers: in crows it's white, in ravens it tends to be browner.
"That is a feature you only see if you either catch a raven and blow on its feathers or if you're up close on a really windy day.
"There are differences in body shape, and with a few feathers around the head and neck as well, but the easiest difference between the five Australian species of crow and raven is geographic range."
Distinctive calls
While it's hard to identify the birds by sight, listening to their idiosyncratic calls is a comparatively reliable way to tell them apart.
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While all five species have a tuneless, guttural tone that will never win a bird singing contest, each has a distinctive variation.
"The typical Australian raven call is the most distinctive, with those three or four notes, a rising inflection and then a downward inflection at the end," Mr Dooley said.
"It's the sound you most think of as an Australian crow caw.
"By comparison, the Torresian crow's standard call has a duck-like quacking quality to it.
"The little crow is a lot like Torresian crow but sounds nasal and flat. Somebody once described it as sounding like it has an American accent.
"The little raven has a bit more variation but it's more a single note repeated, and it's a bit deeper than the Australian raven.
"The forest raven is quite distinctive because it has the deepest call to the point that it's very growly."
A bad rap
Few Australian animals are better equipped to survive Australia's hospitable landscape.
Corvids are competent and efficient flyers that can travel considerable distances without burning up much energy.
Even the conspicuous "basic black" shared by all Australian corvids serves a cooling purpose. The outer feathers absorb heat and are insulated from the birds' skin.
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Corvids' intelligence is at the highest level of the bird kingdom, on par or even surpassing parrots and cockatoos.
"I wouldn't like to anthropomorphise birds or any other animal too much because it's different, but you can compare the density of bird brains," Mr Dooley said.
"A lot of research on bird intelligence has focused on various species of crows, particularly the New Caledonian crow (Corvus moneduloides), which is renown for its tool-making ability.
"They can make tools to help make other tools, which is next level in terms of puzzle-solving ability.
"Some have put crow intelligence at the equivalent of a seven-year-old child when it comes to cognitive problem solving.
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"They can work through more than 14 steps to solve a puzzle, and research shows they have an astonishing long-term memory and what we call a working memory.
"There's also tests that show corvids can count up to at least 16 or 17."
For all their comparative genius and complex behaviours, corvids are not widely loved. Mr Dooley said their grim characterisation as harbingers of doom was unfair.
"It just seems us humans have an antipathy towards other animals which are successful. It's like we resent any other animal dominating," he said.
"They have a reputation of lamb-killers but when the researchers have done the scientific study, it's found they are just taking advantage of an animal that is already dead or dying."
Australian crows and ravens (Family: Corvidae)
Australia's five species of crows and ravens can be very difficult to distinguish from each other, especially where their territories overlap.
Peter Rowland, author of A Naturalists Guide to the Birds of Australia, offers these spotting notes:
Australian raven (Corvus coronoides)
Feathers have an obvious purple-blue or greenish glossy sheen. Hackles are long, lance-shaped, and form a floppy "beard". Adults have a patch of bare black skin (pink in juveniles) at the base of the lower mandible and sides of the chin.
Widespread throughout central and eastern Australia, but also in southern South Australia and south-eastern Western Australia.
Little raven (Corvus mellori)
Hackles are shorter, bifurcated (forked), and appear spiky when calling. Found across south-eastern Australia, from northern NSW, through Victoria to central and northern South Australia, and is the "default" corvid in Melbourne and Adelaide.
Forest raven (Corvus tasmanicus)
Largest species, and looks heavily built with a slow, heavy flight. The only species in Tasmania (also occurs in southern Victoria, south-eastern South Australia, and north-eastern NSW), and is the "default" corvid in Hobart.
Torresian crow (Corvus orru)
Larger than the little crow, with conspicuous throat hackles, leading to confusion with ravens. Feathers have a noticeable iridescent sheen, but more subtle than that of the Australian raven. Widespread through the northern two-thirds of Australia and into New Guinea. The "default" corvid in Brisbane, Darwin and Cairns.
Little crow (Corvus bennetti)
Smallest of the corvid species. Relatively short bill, and small throat hackles. Widespread throughout the drier parts of mainland Australia, but not the "default" corvid in any capital city.
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