Summary

In Australia, the common myna, Acridotheres tristis, is a feral bird that reduces biodiversity through predation and aggressive competition with native wildlife, particularly hollow-nesting birds and mammals. Mynas also reduce public amenity through noise at communal roosts, and fouling, with attendant risk for human and domestic animal health. Canberra was myna-free until 1968, when about 100 birds were released, mostly in Forrest. Mynas now occupy all Canberra suburbs; in many areas there are more than 100 birds to the square kilometre. Numbers still appear to be rising, with escalating spillover effects into adjoining lands, much of which is anthropogenically modified woodland, the myna’s preferred habitat. Many nature reserves have been invaded by mynas. Feral myna populations are similarly expanding in most parts of eastern Australia and many other parts of the world, notably the Pacific islands, where several endemic birds have become seriously threatened as a consequence. In 2000, the Common Myna became the most common feral bird in Canberra and the World Conservation Union (IUCN) declared A. tristis among “100 of the World’s Worst Invasive Species”. Clearly, reduction of myna numbers is desirable, but is it practicable? Poisoning, habitat modification and fertility control have all been considered as possibilities for controlling mynas. Poisoning is clearly undesirable because it is non-specific, habitat modification because it would require lopping or removal of roosting trees of a huge range of species. Fertility control seems impractical, at least at the present time.

The objective of the Minimising Mynas Project Phase 1 was to determine if myna numbers could be reduced by trapping in a way that was selective, safe for humans and the environment, and its humaneness was acceptable to a majority of the community. A multi-catch trap, that is selective for mynas and starlings (another feral species) and a euthanasia system that is considered to be humane by animal welfare authorities, have both been developed. Pilot trials have been conducted to evaluate the selectivity, effectiveness over long time scales and public acceptability of the prototype traps. Four such traps were constructed and operated in Canberra backyards from August 2001 – October 2002. The system was considered to be humane by an overwhelming majority of observers (many hundreds), and, given deployment of enough traps, appears to have the potential to substantially reduce myna numbers on a broader scale. Commercial manufacture of the traps has been organised to enable testing and refinement of the system on a broader scale. Plans are being finalised for an expanded trial in collaboration with Environment ACT and Canberra Ornithologists Group. Trials to reduce myna numbers are also being planned in other areas of Australia, in concert with local government and nongovernment organisations.