The great toad war

Nobody knows for sure how or when they first arrived, but for the last few years, millions of toxic toads have plagued eastern Madagascar.

The Asian toads (Duttaphrynus melanostictus) first appeared between 2007 and 2010, most likely in shipping containers, and have rapidly increased in number to about four million.

The toads are threatening much of Madagascar's unique wildlife in the area, including hundreds of its endemic frog species.

They also pose a threat to humans. If anyone eats the toads, their toxins could kill.

A new report is calling for action to prevent an "environmental catastrophe". It states that the priority is to control the toads' population growth while eradicating those that remain.

Separated from mainland Africa, Madagascar is home to a range of creatures found nowhere else in the world.

These include the 106 species of lemur, many of which are already dangerously rare. It is also home to hundreds of unique plants.

As the toad population continues to spread, much of Madagascar's biodiversity could be affected.

"It could disrupt food chains and cause native predators, prey, and competitors to decline or even go extinct," says report co-author Christian Randrianantoandro of Madagasikara Voakajy, a Malagasy biodiversity organisation.

Predators that feed on amphibians could be poisoned by eating the toads. These include snakes, hawks and fossa, a cat-like predator also unique to Madagascar.

"We expect population clashes. It pretty much disrupts everything," says Christopher Raxworthy of the American Museum of Natural History, another co-author of the report. "It's got the capacity to ultimately occupy most areas of Madagascar. It's a very serious threat."

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