Cane toad (Bufo marinus)
The cane toad is native to South America but has been introduced to many countries in the vain attempt to control some insect pests. It was introduced to Australia in 1935 from Hawaii and released into canefields of far north Queensland to try to (unsuccessfully) control greyback cane beetles, a major pest of sugar cane.
Soon after their introduction, cane toads spread rapidly and now occur through northern NSW and most of the eastern and northern parts of Queensland, including urban areas. Recently they have colonised the Northern Territory and they are predicted to move into the northern parts of Western Australia. Their rate of spread into the Northern Territory has been estimated to be approximately 30-50 kilometres per year. Where they occur, cane toads are very common, only localised high altitude and corresponding low temperatures seem to limit their distribution.
Cane toads are relatively long-lived with specimens being recorded of 16 years. Females can weigh up to 2.5 kg. They are active mostly at night and eat mostly ants, termites and beetles but have been known to take a wide variety of insects, frogs, small reptiles and even some small mammals. Under ideal conditions, they can reach adult size within 12 months. Cane toads can lay up to 35,000 small, black eggs at a time and form long, sticky strings attached to water plants or snags in slow moving water.
Cane toads are regarded as a major nuisance by the public and are believed to have a serious impact on native wildlife although there have been few studies aimed at quantifying the damage that they cause.
In the wild, cane toads are believed to compete for food, shelter and breeding sites with native frogs. Also they are extremely toxic to many other animals such as native quolls and goannas. The parotoid glands of the cane toad release toxin when the animal is provoked or squeezed as happens in the mouth of a predator. They can cause extreme irritation to humans if incorrectly handled.
Currently there are no management strategies that are specific to cane toads. Actions have included detection and surveillance programs at the boundaries of their current distribution in an attempt to prevent their further spread. Agencies have investigated the potential for using parasites and diseases for their control but this work is in its infancy and would need extensive studies including an assessment of the potential impact of the control agent on native wildlife, particularly native frogs, before they could be used extensively.