Invasive Species: the Cane Toad

The Cane Toad, also known by its scientific name Bufo Marinus, is the largest toad in the world ranging from two to nine inches long and can weigh in at over four and a half pounds. They have tough, warty skin, and come in numerous shades of brown and dark yellow. Females tend to have smoother skin and grow to be bigger than their male counterparts (The Animal Files). The Cane Toad has a large head with large bony ridges coming out above their eyes. Behind these eyes adult Cane Toads have large, easily visible parotoid glands that, when they are in danger, produce a milky looking poison known as bufotoxin. The Cane Toad also have a lot of smaller glands covering the rest of their body that produce this venom as well. The poison that the toad emmits is made up of a complex mixture of 14 different chemicals that could kill an animal in only 15 minutes if swallowed (The Animal Files).

Cane toads hunt at night in a multitude of different habitats. The toad primarily eats earth bound and water bound insects and snails. They will even take food that has been left out for pets. Cane toads need constant moisture to survive, they obtain this by using the skin on their stomach to absorb water (The cane toad). Cane toads can can actually absorb too much water and die if they are confined to a flooded area. They can also die from extremely dry conditions that cause too much loss of water. These toads can breed during any time of year but usually prefer to do so with the start of the wet season. They will lay their eggs in still or slow-moving waters, as most toads do . Female Cane Toads can lay anywhere from 8,000 to 30,000 eggs at one time. While most native frogs typically only lay 1,000 to 2,000 eggs per year (The cane toad).

Cane Toads’ native environment is in Central and South America, but they have been introduced into Australia, some South Pacific islands, and Florida. They prefer to live in flattened areas because it is easier for them to move around; however, Cane Toads are very versatile and can live in almost any type of habitat (2017). They have thrived in the areas that they were introduced to because those places happen to have similar climates to that whence they came but lack the predators who are immune to their poison. They were once thought to be seaside animals, hence they are also called marine toads or giant toads. In the jungles of Suriname and Costa Rica, they inhabit open areas at the edges of ­thicker vegetation (Frazier, 2017).

The Cane Toad was introduced to Australia sometime around 1935 because they are fierce predators of insects and it was thought that they would get rid of the beetle population in the sugar cane industry, thus the name “cane”(The cane toad). They were later introduced to Florida in 1955 when a pet dealer accidentally released 100 specimen at Miami airport, and by following releases during the 1960s (Giant Toad).

The cane toad defends itself using poison and is poisonous during all of its life stages. As mentioned earlier Cane Toads have deadly poison glands behind their eyes and even though some native predators, such as different types of birds, have learned to avoid the poison glands on the adult toads, other predators are not as lucky and die soon after ingesting a toad (Giant Toad). The arrival of cane toads to Kakadu National Park in Australia was linked to a significant decrease in some of the native predators within the park, mostly northern quolls and large goannas (The cane toad). However, based on current evidence it seems that some of these predator species that were negatively impacted when toads arrived have been making rapid adaptations making it possible for population recovery in the long term (The cane toad). Adult cane toads tend to compete with Australia's native animals, in particular for shelter. A 2004 study revealed that cane toads had ruined one-third of the nest attempts of rainbow bee-eaters by taking hold of their nest burrows and eating their eggs and young nestlings (The cane toad).

The Cane toad seems to be displacing the Southern toad and other amphibians in Florida and Australia and the predators in the ecosystems that might eat them and die they may be a potentially serious problem in the wild environments (Frazier, 2017). In Australia dogs have become addicted to mouthing the toads and getting high off the venom, along with some humans who have boiled the toads and drank the broth for psychedelic effects.

It is possible to control or even eliminate the Cane toad population in a small area, like a local pond. This method is to collect the cane toad eggs that clump into long strings from the water. This approach to cane toad control means continued monitoring of the pond. Fine-mesh fencing may also help keep cane toads from ponds that need protection from them. Another method is by freezing the adult toads and some people even shoot them with air rifles, but this can have a negative environmental impact if people are not taking precautions so as to not shoot another toad species that is indigenous. There will probably never be a broadscale method that can be used to control cane toads across Australia and Florida. Protecting the vulnerable native species on the local scale is the main focus of the planning around cane toads currently being discussed.

While the Cane Toad does pose a threat to the ecosystems they have invaded, they are not a great enough threat as to prompt immediate and potentially costly action because it seems as if the native amphibians of the regions have started to adapt to the presence of the cane toads. They however do still pose a threat to other types of animals and should be kept under control using the methods previously mentioned, but they do not need to be eradicated. The benefits of removing the cane toad do not outweigh the potential costs of trying to do so.

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