Snakes and the Cane Toad
…The Cane Toad has few predators…in Australia. Or, more correctly, there are few predators that live after ingesting it. In this lies the secret to its successful spread…The Cane Toad is a hopping cocktail of cardio-active substances…
(Ingram, 1988).
Cane Toad
Cane Toads in a well
Death Adder killed by Cane Toad
Keelback killed attempting to eat a mature Cane Toad
The Cane Toad, Bufo marinus, is not a native Australian amphibian. It was brought here in 1935 in the hope that it would spread in sugar cane growing areas and, by consuming cane beetles, help control these costly pests. Spread, the Cane Toad did. Control beetle pests of sugar cane, it did not. Affect native animals it did, although exactly to what extent is far from clear.
Many of Australia’s snakes feed on frogs. To these species a Cane Toad looks like a frog, but doesn’t taste like a frog and, for most snakes, the 'cardio-active substances' in the Cane Toad are lethal. Even mouthing a Cane Toad when capturing it spells doom for many snakes.
Specimens of the following snakes have been found dead with Cane Toads in either their mouths or guts:
(Covacevich & Archer, 1975; Ingram & Covacevich, 1990; Covacevich & Couper, 1992)
Only one of these is known to be able to use the Cane Toad, under certain circumstances, as a food source.. The Common Keelback is one of a handful of native Australian animals that can prey successfully on Cane Toads. It can consume large numbers of eggs, tadpoles and newly–metamorphosed young of the Cane Toad safely. However, a freshly dead specimen of the Common Keelback with a young adult Cane Toad partly ingested was found near Cairns in 1976. In their report of this, Ingram & Covacevich (1990) concluded:
…The discovery of this single known unsuccessful encounter between T. mairii and B. marinus is not conclusive evidence that larger B. marinus are invariably toxic to T. mairii, but this species is apparently more susceptible to B. marinus toxins than was supposed, particularly because…the snake had begun to ingest the toad from the rear, thus avoiding toxin concentrations in the parotid glands immediately behind the head.