This report finds that in Western Australia, the potential habitat zone of starlings is around 1 million sq km, and under full infestation and with a conservatively estimated prevalence rate of 12.5 starlings per sq km, this would mean that the Western Australian habitat zone could support at least 12.5 million starlings.
Such a population of starlings could consume in excess of 110,000 tonnes of food in a year, of which two-thirds would come from commercially valuable sources such as horticulture and grains. Starlings would account for a loss of 0.5 per cent of the Western Australian grains crop, and 3 per cent of the State?s horticultural crop (grapes, apples, pears, etc.). The annual damage caused on this basis has been valued at $21.2 million. The plausibility of these estimates has been corroborated using existing evidence on bird damage to crops.
A range of other costs, including management of urban roost situations, damage to property, clean-up costs, weed control, and the likely cost of recovery plans for displaced native birds, takes the estimate of annual damage done by starlings under a full infestation to at least $30.0 million per year. This estimate does not include less easily verifiable costs such as threatened existence values that the community might place on native birds.
Using a range of starling population growth scenarios, we find that given the current body of evidence it is reasonable to assume that the population of starlings in Western Australia will increase to 12.5 million over the next 25 to 30 years if the infestation is not controlled. Under the worst case scenario, however, such a population could establish within 10 years from now.
|Author||ACIL Tasman Pty Ltd|
|Secondary title||Assessing the likely cost of an incursion|
|Publisher||Prepared for the Invasive Animals CRC|
|Institution||ACIL Tasman Pty Ltd|
|Documents||Starlings in Western Australia