Toxicity of a tropical Australian frog, Litoria dahlii, to sympatric snakes

Abstract

Although Litoria dahlii is one of the most abundant frog species of floodplain habitats in tropical Australia, it is rarely eaten by snakes. Force-feeding trials showed that L. dahlii is highly toxic to snakes: ingestion of even a single large frog was potentially fatal for pythons (Liasis childreni and Liasis fuscus), colubrids (Dendrelaphispunctulatus and Stegonotus cucullatus) and elapids (Acanthophis praelongus and Demansia atra). Only one species, the keelback, Tropidonophis mairii (Colubridae), could consume these frogs without ill effects. Keelbacks were also the only snakes recorded to eat these frogs in the wild. The fact that these abundant tropical frogs are highly toxic to most snakes, and generally not eaten by them, suggests that the anurophagous snakes of the Australian tropics assess amphibian chemical defences before consuming their prey. Thus, these snakes may be better-able to deal with the invasion of cane toads, Bufo marinus, than has been generally supposed.