Behavioural responses of native predators to an invasive toxic prey species

One important impact of invasive species may be to modify the behaviour of native taxa. For example, the invasion of highly toxic cane toads (Bufo marinus) kills many anurophagous native predators, but other predators learn to recognize and avoid the toxic invader. We exposed native fish (northern trout gudgeons, Mogurnda mogurnda) and Dahl's aquatic frogs (Litoria dahlii) to cane toad tadpoles, then monitored the predator's responses during subsequent trials. Both the frogs and fish initially attacked toad tadpoles, but rapidly learned not to do so. Fish and adult frogs retained their aversion for at least a week, whereas recently metamorphosed frogs did not. Clearly, the spread of cane toads through tropical Australia can modify feeding responses of native aquatic predators. For predators capable of rapid avoidance learning, the primary impact of cane toads may be on foraging behaviour rather than mortality.