Swift Parrot

Genetic evidence has shown that the swift parrot is a single, genetically mixed and nomadic population that moves around the landscape each year. Because they are nomadic, swift parrots can occur across a very large potential area, but settlement at a given location depends on the local availability of food. However, in the Tasmanian breeding range, swift parrots need both food and suitable nesting sites to occur in close proximity in order to nest at a given site. The swift parrot migrates each year across Bass Strait between Tasmania and the mainland of Australia. They arrive in Tasmania during September and return to south-eastern Australia during March and April. They can be found as far north as south-eastern Queensland and as far west as Adelaide in South Australia, although recent sightings have been restricted to the south-eastern part of the state. Because swift parrots are nomadic migrants, their occurrence at any one location are difficult to predict. Although they will repeatedly return to the same locations, local occurrence may only happen intermittently depending on whether or not food (flowering trees) is available in a given year.

Modelling of demographic data predicted that the swift parrot is Critically Endangered. Further modelling showed that other aspects of their life history (sex ratio bias and shared paternity) makes their population declines worse than originally predicted. Genetic evidence showed there is only one swift parrot population, so threats at different times and places can potentially act on the entire population. Although expert opinion has estimated the species population size as approximately 2,000 individuals, recent genetic evidence suggests this is overly optimistic, and that the (minimum) census size of the population may be lower than 300 individuals. Severe deforestation of their breeding range has been long recognised as the principal threat to the species. Logging has already had severe impacts on habitat availability in recent decades and there is evidence that up to 23% of swift parrot breeding habitat has been logged just in the Southern Forests region of Tasmania over the last 20 years. Deforestation also affects the rate of predation by sugar gliders – where mature forest cover is diminished, parrots suffer worse predation rates. Given the severity of deforestation across the breeding range, and the relationship between deforestation and sugar glider predation intensity, habitat loss in critical breeding areas of Tasmania may be the species most severe threat. Unfortunately, there is evidence that weak and ineffective policy for protection of threatened species in Tasmania's logged forests is likely to continue to threaten the swift parrot into the future.