Recent invasions of World Heritage rainforests in north-east New South Wales by the cane toad Bufo marinus

The cane toad Bufo marinus is well recognised as a threat to biodiversity in northern Australia. Concern about this impact has grown in recent years as the species spreads geographically. Previous estimates of the potential distributional limits of B. marinus have excluded high elevation rainforest, largely based on thermal tolerances and known habitat preferences. This paper reports on the detection of B. marinus over a five-year study in the Border Ranges National Park in northern NSW. More than 400 toads were detected in rainforests at elevations between 810 m and 1130 m, with all captures being made along an isolated section of road within the reserve. No breeding was observed, all captures were of adults and nearly all appeared to be female. The indications are that toads migrated through heavily forested steep escarpment to the east, rather than along the road network and thus represent a significant emerging threat to the entire reserve. Models predicting the distributional limits of B. marinus will need to consider a broader range of elevations, habitat types and thermal tolerances than has been previously considered. Further research is urgently required to understand the threat this invasion may pose to the unique biodiversity of this World Heritage Area and attempt to mitigate the threat.