SummaryIn this paper on the Swift Parrot.Lathamus discolor, we have endeavoured to give a comprehensive survey of the habits, breeding range, and distribution generally, of the species in eastern and southern Australia and Tasmania.The possibility that breeding takes place only in Tasmania is examined in the light of positive records. In addition, reference is made to nesting reports from mainland Australia.The known migration range of the Swift Parrot extends north from the island of Tasmania to central coastal Queensland and west into southeastern South Australia (See Fig. 1). While migration routes, if such really exist, have not yet been clearly defined, it seems fairly evident that the species leaves Tasmania entirely after the close of the breeding season and crosses Bass Strait to disperse throughout south-eastern Australia, returning to Tasmania the following spring.A feature of the movements of the species is the occurrence of large numbers of birds in areas from which they may have been absent for years; these irruptions, while unpredictable, appear to be influenced by the presence of a plentiful supply of suitable food such as nectar, lerps and other insects, and seeds.