By Matt Walker
Editor, Earth News
Cane toads, one of the world's most destructive invasive species, have started killing native wildlife outside of Australia.
Cane toads are poisonous, secreting a toxin that kills predators not adapted to eat them, and as a result the toads have caused a decline in native Australian reptiles and marsupials.
Now scientists have discovered that the toads are also killing boa snakes in the West Indies, suggesting that other predators in the Caribbean and elsewhere may also be at risk.
The cane toad is a large toad species, which secretes a powerful bufogenin toxin.
Its native range extends from northern South America through Central America and into the southern United States.
In the early to mid 19th Century, the toad was intentionally introduced to islands in the Caribbean, including Jamaica in 1844, and then through the South Pacific.
The toad was introduced to eat and control pests of sugar cane, including rats and beetles.
However, the toad has had a destructive impact in many places where it has spread, out-competing native species.
More recently, the toad has devastated populations of amphibian predators, including large lizards, snakes and marsupials, in Australia.
Jamacian boas are falling victim
The threat there continues to grow as the toads spread west across the country from Queensland into New South Wales and the Northern Territory.
Cane toads are so prevalent in Australia that people in the Australian state of Queensland have even taken part in a mass capture of the poisonous amphibians, as part of a collective effort at pest control.
Now scientists have documented the cane toad killing rare native fauna in the Carribean.
Dr Byron Wilson, at the University of West Indies in Jamaica, and his colleagues there and in the US have found numerous examples of cane toads poisoning Jamaican boas (Epicrates subflavus), large predatory snakes that are endemic to the island of Jamaica.
The boa, also known as the yellow snake, is Jamaica's top native terrestrial predator.
Already rare, the snake is threatened by habitat destruction and introduced dogs and pigs.
"To our knowledge, this is the first report of cane toads causing mortality in naturally occurring predators outside of Australia," say the authors in the journal Biological Invasions.
"Although cane toads have been present on Jamaica for more than 160 years, it is clear from our observations that Jamaican boas have not yet learnt to avoid this toxic prey species."
The researchers now fear that the toads could pose a threat to the snake across its island range.
They also worry that other species in Jamaica and on other Caribbean islands are at risk from bufotoxin poisoning.