More than 70 and probably over 100 species of birds have been introduced to Australia (Long, 1981). At present, at least 22 species of birds of foreign origin are established (Table 25.1), at least half of which originated in the Mediterranean Basin. Four previously established species now appear to have become extinct and seven species are tenuously established in very restricted ranges. Two species are classed as ‘feral’ birds and at least 13 native species of birds have been translocated or reintroduced within Australia.

The majority of the species which were introduced and became established in Australia were deliberate releases by acclimatisation societies. Balmford (1978) discussed the events leading up to the establishment in 1861 of the first of these societies in Australia: namely, the Acclimatization Society of Victoria. Fortunately for Australia, the efforts made by these societies were less successful than their founders probably anticipated. Other successful species are the results of accidental arrivals, aviary escapes and releases from captivity and also from colonisation.

Generally, those taxa which have become at all widespread in Australia are those which have wide ecological niches in their region of origin. For birds, as for plants, there is a tendency for the more evolutionarily advanced taxa to be more successful than primitive ones (Sibley & Ahlquist, 1986).