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Cane Toad

History

The cane toad (Bufo marinus) is native to South and Central America.  These amphibians were introduced into Puerto Rico, Hawaii, and the Philippines in the 1920’s and 1930’s and into Queensland in 1935.  Cane toads are characterized by their size and large glands behind their heads.  Cane toads can grow up to 24 cm and can weigh up to 1.8 kg (4lbs). 

Why they were introduced

During the beginning of the 20th century Queensland was having problems with beetles destroying their sugar cane.  In 1935 the Australian Bureau of Sugar Experimental Stations introduced cane toads into Australia because they believed that the toads would  get rid of the cane beetles. 

Problems

The cane toads turned out to be worthless at controlling the greybacked cane beetle.  Since there are no natural predators of the cane toad in Australia, they did succeed in reproducing and spreading over large amounts of Australia.  The major problem with having thousands of cane toads hopping around is that they are poisonous.  Cane toads secrete a venom called bufotoxin from the large glands behind their head.  This toxin has caused many problems with the native animals and other introduced species such as dogs.  Dogs and cats that bite these giant toads die within a few minutes.  Another problem with the cane toads is that they are omnivorous and eat whatever they can swallow.  Since they are so big they can swallow quite a bit.  This is bad for the other animals that feed on the same things as the cane toad.

Control

The Federal Government has funded 6 years of research focused on developing methods for the control of cane toads.  This research will be performed by CSIRO (Commonwealth Scientific and Industrial Research Organization).

One method of control that has been implemented is bio-control.  This is the use of viruses to kill the toads.  The virus was effective in killing cane toads but it also killed one species of native Australian frogs and therefore is no longer in use.  Another suggested form of control was to create a physical barrier so that the toads couldn’t spread anymore.  This plan has been abandoned because of the high cost of keeping the barrier intact, and past use of barriers against rabbits and dingoes has proven ineffective.

Status

There is no realistic control plan as of yet.  Scientists are hoping that during their research, they will discover a predator or pathogen that is self-replicating and specific for the toad.  The rate of spread of the cane toads has averaged about 30 km a year.  Until a plan for control is found cane toad populations will continue to grow and spread out across Australia.

(Above): These toads were introduced to help control the cane beetle population.

(Above): Cane toads are omnivorous and eat whatever they can swallow.

Written By:  Laura Rickman

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