Madagascar’s Biodiversity Threatened by Toxic Toad

An  invasive toxic toad has made its way onto Madagascar and has the potential to devastate local ecosystems and biodiversity.

The Asian Common Toad has recently made its way to Madagascar. This breach jeopardizes the safety of all native island predators that will eat the invasive toad. When the toad feels threatened they secrete a toxic slime that sends the potential predator into cardiac arrest. The toxin in the skin will kill nearly anything that tries to eat the amphibian. For years scientists have been warning of the toad’s danger to the ecosystem, but they have lacked the hard evidence. However, a recent genetic study confirms that most native Malagasy predators are sensitive to the poison and that they will have huge impacts on the ecosystem. Having the Asian Common Toad on one of the world’s most biodiverse places could lead to the extinction of many species.


A Black and White Ruffed Lemur, just one of the many amazing animals found in Madagascar. Credit: Mathias Appel

You may be familiar with another notoriously devastating invasive species called the Cane Toad. This species has altered ecosystems all over Australia, poisoning many native species there and nearly destroying carnivorous reptile populations. The Cane Toad and the Asian Common Toad are close relatives; both secrete a powerful toxin called bufadienolides from their skin glands. In both instances native predators are unfamiliar with these poisons and are especially sensitive. When they make the mistake of eating the foreign toad they are faced with deadly consequences.

The recent study published in the journal Current Biology tested to see if different predators were resistant to the toads’ toxin by using genetic analyses. The results came back and only one of seventy-seven species showed any toxin resistance.  The other seventy-six species vulnerable to the poison include some of Madagascar’s rarest endemic wildlife.


The Fossa is a carnivorous cat-like mammal endemic to Madagascar. This species is also at risk with the introduction of the Asian Common Toad. Credit: Nathan Rupert

The toad probably arrived in Madagascar by stowing away on a ship that came from Asia. They first showed up in an Eastern port City called Toamasina in 2011 and have been spreading along the coastline ever since.  Even with the spread of the invasive toad, Madagascar’s wildlife are not entirely doomed. In Australia, scientists have witnessed behavioral changes in some predatory species like crows that allow them to safely eat the toads. People are also coming up with ways to get wildlife to not eat the toads by doing taste aversion programs that include making Cane Toad sausages. They lace the toad meat with nausea-inducing chemicals that make the animal temporarily sick and feed it to predators likely to eat the toads in the wild. Researchers hope this will help train native wildlife to avoid eating the toxic toads. Hopefully this research will help scientists figure out a way to protect species on Madagascar from the Asian Common Toad and other invasive species that wreak havoc on biodiversity.

Source: How Stuff Works


Featured photo: Baobab trees in Madagascar. Credit: Rafael Medina

About Noelle Duerwald

Noelle is an undergraduate student at the University of California, Santa Cruz studying Ecology and Evolutionary Biology. She fell in love with the ocean when she was a child on her grandpa's sailboat. Ever since she has had a passion for conservation and protecting endangered species. She is thrilled to support Island Conservation in its mission of preventing extinctions as a volunteer for the Communications and Science departments. In her free time Noelle enjoys cooking, hiking, and scuba diving in the kelp forests of Monterey Bay.

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