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| Cane Toad (Rhinella marina) Taveuni, Fiji |
The infamous Cane Toad (Rhinella marina) naturally occurs in tropical South America, east of the Andes. (There is a sister species which occurs west of the Andes and north into Central and North America). However, it is most famous for the fact that it now occurs all over the world due to its introduction to try and control pest insect species. It is now found on islands in the tropical Pacific (including Hawaii, Fiji, the Cook Islands, Marianas Islands, and many others), New Guinea, Australia, the Philippines, many Caribbean and Antillean Islands, Florida, Bermuda, Japan, Taiwan and there are likely other areas still waiting to be documented*.
Once they get established, their generalist habits make them easily adapt to the new environment. These Cane Toad tadpoles were photographed in a stream right next to the ocean away from the tourist areas on the relatively isolated island of Taveuni, Fiji.
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| Cane Toad tadpoles Taveuni, Fiji |
The problem is that although the species was introduced as a pest control method, they have become pests themselves in many of these areas. It is a large toad with a large appetite and will eat anything it can swallow. It has significantly impacted the local amphibian populations in some areas simply by eating and outcompeting the native frogs and toads.
Furthermore, for larger animals it presents a problem because it is highly toxic. It's skin, particularly its massive parotoid glands behind the eye and on the shoulder, produce a toxic sticky secretion. In some areas where it is introduced (e.g. Australia), there are no native toad species so native animals have no experience with or resistance to their poisonous skin secretions and eat the toads and die.
They have also killed a few domestic pets through poisoning. However, this propensity to kill dogs is greatly exaggerated on the internet. Several studies have shown that most dogs that get intoxicated by attacking Cane Toads simply salivate a bit extra and occasionally vomit. Most dogs never require medical attention after attacking Cane Toads. And of the very small percentage that are brought to the vet, over 95% of those dogs recover fully. So only a fraction of a percent of dogs that attack Cane Toads die, and those were shown to have a couple of characteristics in common. They were small breeds of famously stubborn/aggressive toad attackers (small terriers). Most more intelligent dogs and larger dogs learned from the negative taste of the toxin to leave the toad alone and recovered without medical care.
This species does have a place in the world. In its native range there are controls to its population that have evolved along with it. It isn't the Cane Toad's fault it is a problem, it is the fault of the humans who transported it from its native range.
The call of the Cane Toad is actually what you would expect for a huge toad. Toads generally have trilled calls. Smaller toads have faster, high-pitched trills and big toads have slower, low-pitched trills. The bigger the toad the lower pitched the trill.
Here's a call from an individual the Daintree National Park in northern Queensland, Australia.
Cane Toad call from Daintree National Park, Australia
© Chris Harrison 2014
* one of the difficulties presented by the new split of the Cane Toad (R. marina) from the Giant Toad (R. horribilis) will be sorting out exactly which species is introduced around the world. At the moment, the data suggest all the introduced "Cane" Toads are Rhinella marina.
However, a recent analysis of Rhinella toads in the area of Hillsborough, Florida has shown that it is R. horribilis that is invasive in that area. So the details of which invasive species you have still needs to be worked out.
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