Australia and its offshore islands and territories have 898 recorded bird species as of 2014. Of the recorded birds, 165 are considered vagrant or accidental visitors, of the remainder over 45% are classified as Australian endemics: found nowhere else on earth. It has been suggested that up to 10% of Australian bird species may go extinct by the year 2100 as a result of climate change.
Australian species range from the tiny 8 cm weebill to the huge, flightless emu. Many species of Australian birds will immediately seem familiar to visitors from the Northern Hemisphere - Australian wrens look and act much like northern wrens and Australian robins seem to be close relatives of the northern robins, but in fact the majority of Australian passerines are descended from the ancestors of the crow family, and the close resemblance is misleading: the cause is not genetic relatedness but convergent evolution.
For example, almost any land habitat offers a nice home for a small bird that specialises in finding small insects: the form best fitted to that task is one with long legs for agility and obstacle clearance, moderately-sized wings optimised for quick, short flights, and a large, upright tail for rapid changes of direction. In consequence, the unrelated birds that fill that role in the Americas and in Australia look and act as though they are close relatives.
Australian birds which show convergent evolution with Northern Hemisphere species:
honeyeaters (resemble sunbirds)
sittellas (resemble nuthatches)
Australasian babblers (resemble scimitar babblers)
Australian robins (resemble Old World chats)
Scrub robins (resemble thrushes)
Australian birds can be classified into six categories:
Old endemics: long-established non-passerines of ultimately Gondwanan origin, notably emus, cassowaries and the huge parrot group
Corvid radiation: Passerines peculiar to Australasia, descended from the crow family, and now occupying a vast range of roles and sizes; examples include wrens, robins, magpies, thornbills, pardalotes, the huge honeyeater family, treecreepers, lyrebirds, birds-of-paradise and bowerbirds
Eurasian colonists: later colonists from Eurasia, including plovers, swallows, larks, thrushes, cisticolas, sunbirds and some raptors
Recent introductions: birds recently introduced by humans; some, such as the European goldfinch and greenfinch, appear to coexist with native fauna; others, such as the common starling, blackbird, house and tree sparrows, and the common myna, are more destructive
Migratory shorebirds: a suite of waders in the Scolopacidae and Charadriidae families which breed in northern Asia and Alaska and spend the non-breeding season in Australasia
Seabirds: a large and cosmopolitan group of petrels, albatrosses, sulids, gulls, terns and cormorants, many of which either breed on islands within Australian territory or frequent its coast and territorial waters
For comprehensive regional lists, see:
List of birds of Australia, covering Australia and its territories
List of birds of Australia, New Zealand and Antarctica, the HANZAB list for Australia, New Zealand, Antarctica and the surrounding ocean and subantarctic islands.
For Australia's endemic species, see:
List of endemic birds of Australia
Other regional, state and island bird lists:
Victoria
New South Wales & Lord Howe Island
Queensland
Western Australia
Tasmania
Northern Territory
South Australia
Ashmore Reef
Boigu, Saibai and Dauan Islands
Christmas Island
Cocos (Keeling) Islands
Heard Island
Kangaroo Island
Macquarie Island
Houtman Abrolhos
National organizations
BirdLife Australia (previously known as Birds Australia) is the leading Australian NGO for birds, birding, ornithology and conservation, formed by a merger of the Royal Australasian Ornithologists Union and Bird Observation & Conservation Australia
Australian Bird Study Association, for banders and other field ornithologists
Birding-Aus - an Internet mailing list about Australian birds
Australian regional and state organisations
Australian Capital Territory
Birds Australia Southern NSW & ACT
Canberra Ornithologists Group
New South Wales
NSW Bird Atlassers Inc.
Birding NSW
Birds Australia Northern NSW
Birds Australia Southern NSW & ACT
Cumberland Bird Observers Club
Blue Mountains Bird Observers Inc.
Queensland
Birds Australia Capricornia
Birds Australia North Queensland
Birds Australia Southern Queensland
Birds Queensland
South Australia
Birds SA
Tasmania
Birds Tasmania
Victoria
Birds Australia - Victoria
Western Australia
Birds Australia Western Australia
