Sustainable harvest of magpie geese (Anseranas semipalmata) is critical to both the long-term viability of geese populations and to the continued customs of Aboriginal Australians. Once prevalent across southern and south-eastern Australia, magpie geese are now restricted to the tropical north as a result of wetland habitat loss, over-exploitation and drought. Aboriginal and recreational harvest of geese continues across northern Australia, but is reliant on the conservation of sub-coastal wetland systems that support the birds through provision of foodplants and nesting sites. Already degraded by feral ungulates and introduced grasses, wetlands are now further threatened by saline water intrusion through sea level rise and increased temperatures. We model these threats using a stage-structured spatially-explicit model, and further incorporate epizootics as catastrophes. We test the additive and synergistic effects of these threats and continued harvest on bird long-term survival.
Results/Conclusions
We find that geese are only likely to persist under global change if Aboriginal and recreational harvest is seriously restricted. Further we find that an increase in either the frequency or severity of disease outbreaks (while harvest continues) will result in localised extinction of the goose metapopulation. We recommend that sustained harvest can continue if key wetland habitats are carefully managed for the benefit of geese (and other waterfowl). We also recommend more rigorous monitoring of unregulated Aboriginal harvest.
