The Cane Toad: An Invasive Species
The cane toad, scientifically known as the Rhinella marina, is a terrestrial toad originating from South and Central America, which was initially introduced in Australia in 1935 in an effort to help combat cane beetles that were damaging sugar cane crops. Their physique and insatiable appetite, initially an appealing quality to farmers, led them to become prolific invaders. Unfortunately, the toads ultimately failed at regulating the cane beetles and instead started praying on other native insects. Since the first release of 3,000 toads, the cane toad populations in Australia number in the billions, and their range continues to expand, threatening the continent's endangered lizards and mammals. In addition to Australia, they are found in South Florida, throughout the Caribbean, and in other tropical and subtropical locales.
The main concern with Cane toads is that they are poisonous at all stages of their life cycle, including eggs, tadpoles, toadlets, and adults, and even their ingestion can kill native predators. They are responsible for the decline and extinction of several native predator species in the Northern Territory and Queensland, including the northern quoll. This species releases a toxic substance from a parotoid gland behind its ears, which is strong enough to kill cats or dogs that munch on the toads and cause burning eyes or skin irritation in humans who handle the critters. Because their toxin is strong enough to kill most native animals that generally eat frogs or frog eggs, including birds, amphibians, reptiles, and mammals, they pose a risk to native animals and pets.
Furthermore, cane toads have an insatiable appetite, causing them to eat various foods, including household scraps, meat, and pet food, depleting other animals' food sources. While their primary diet is insects, including beetles, bugs, honey bees, ants, winged termites, and crickets, they will also eat larger animals, including native frogs, smaller toads, small mammals, and snakes. Hence it is no revelation that cane toads, being robust and adaptive, can thrive in urban and disturbed areas. They breed quickly, which allows them to colonize and dominate an area rapidly. Lastly, Cane toads compete with native species for not only food but also habitats. This causes the Native frogs to become especially vulnerable to the threat of cane toads in terms of a food source for the toad and as a competitor for other food sources.
Because they are toxic, predatory, adaptive, and competitive, cane toads threaten biodiversity. Hence, control methods have been sought out and implemented. Currently, manual removal is the primary management strategy for cane toads. Although toads can be removed as adults, it is easiest to collect the jelly-like strings of cane toad eggs from local creeks or ponds. Additionally, mesh fencing can stop the spread of the cane toad, but native animals can also get trapped in the nets. However, according to a study by the University of Sydney, "refrigeration followed by freezing is the most efficient, effective, and humane method of cane toad euthanasia" (Cane). There is a widespread education campaign in Australia to warn people about the dangers of cane toads and invasive species.
“Cane Toads.” NSW Environment, Energy and Science, 28 July 2018, www.environment.nsw.gov.au/topics/animals-and-plants/pest-animals-and-weeds/pest-animals/cane-toads.
Daley, Jason. “Thousands of Invasive Cane Toads Overtake Florida Community.” Smithsonian.com, Smithsonian Institution, 26 Mar. 2019, www.smithsonianmag.com/smart-news/plague-invasive-cane-toads-overruns-florida-community-180971797/.
Israel, Brett. “Cane Toads Invade, Conquer Australia.” LiveScience, Purch, 24 June 2010, www.livescience.com/29560-cane-toad-conquest-invades-australia.html. ▲ Go to link