Thursday 30 September 2010, 11:30 AM (AAD Theatrette)

Ben Raymond

Australian Antarctic Data Centre

Qualitative modelling of invasive species eradication on subantarctic Macquarie Island

Invaded ecosystems present complex management issues. This problem is exacerbated in many situations by lack of knowledge about the ecosystem. However, delaying conservation action to collect further data and so reduce such uncertainty is often either impractical or inadvisable. The Macquarie Island Pest Eradication Project is attempting to eradicate rabbits, rats, and mice from the island. We undertook qualitative modelling of this project, examining a range of likely outcomes and their possible ecological consequences. Results were aggregated across a large number of possible models, in order to account for uncertainty concerning interactions within the ecosystem. Results strongly support current actions of simultaneous eradication of all three pest species, as simulated eradications of only one or two generally led to continued impacts on the island's native biota. The results also provided support for the anticipated positive outcomes of the project, with predicted recoveries of tall tussock vegetation, and burrow- and surface-nesting seabirds. However, the model predictions also highlighted potential risks: the eradication of mice from the island may not succeed, due in part to the structural position of this species within the ecosystem. Successful eradication of all three target species could potentially release the self-introduced, non-native redpolls and starlings, allowing expansion of their populations, with possible impacts on macro-invertebrates and vegetation. These results demonstrate that qualitative modelling approaches can in some cases deliver consistent results, despite high levels of uncertainty regarding interactions within the underlying ecosystem. Such outcomes can provide assistance in the development of strategic contingency plans and ongoing future management action.