Food
Cane toads mostly eat insects, but will consume whatever else they can fit into their mouth including spiders, snails, small frogs, other cane toads, reptiles and mammals. Unlike native frogs, toads also eat inanimate items including pet food, cigarette butts and animal excreta.
Distribution and habitat
The natural range of the cane toad includes Brazil, through central America to eastern Mexico and Texas. Feral populations now occur in many countries including other parts of the Americas and many island groups. Toads were introduced into Puerto Rico, Hawaii and the Philippines in the 1920s and 1930s, and to Queensland in 1935 to control insect pests of sugar cane, but there is no evidence that this was effective.
Since their introduction to Australia, toads have proved to be highly invasive and computer modelling indicates that they could spread over most coastal areas of the continent. They are still spreading in eastern and northern Australia, including two off-shore islands in the Northern Territory. They are also spreading west and now occur in the Kimberley district of WA.
Reproduction and longevity
In Australia, cane toads normally breed from June to January although breeding may occur throughout the year. Females produce 8 000-35 000 eggs at a time and can breed at least twice a year. Local conditions greatly influence the number of eggs and tadpoles that survive to become adults. Toads normally lay eggs in slow-moving freshwater streams or dams, but can also use brackish water and temporary pools and puddles. Tadpoles hatch in 48-72 hours and, depending on temperature and food, they can develop into metamorphs in 17-180 days, reaching sexual maturity in approximately 18 months. Toads can live for at least 15 years in captivity and individuals have bred for at least five years in the wild.
Impact
Native animals affected by cane toads in Australia include frogs, reptiles such as large goannas, crocodiles and blue tongue lizards, fish and mammals such as quolls (native cats). They are vulnerable to cane toad toxin (all toad life stages are poisonous) and are often killed when cane toads first arrive in an area, leading to population reductions. Toads also compete with native species for food, consuming large numbers of native invertebrates, and they carry diseases that can spread to native frogs. Although there are some reports of native predators consuming cane toads safely, the longer-term impact of cane toads on native fauna is not yet clear and is the subject of ongoing research.
Toads eat beneficial insects like dung beetles and constitute an economic threat to beekeepers. Cane toad poison is highly toxic to most animals and causes pain if it comes in contact with eyes. Without emergency veterinary care, dogs and cats which mouth or bite cane toads sometimes die.
Management
Biological control may be the only long-term means of reducing the number of cane toads across large areas. Research to date has been unable to find a suitable disease or parasite specific to cane toads that will provide effective control.
Various physical methods for reducing toad numbers including traps, hand removal and fences are being used by government and volunteer groups in an attempt to slow the westward movement of toads. The effectiveness of these techniques is still being investigated.
Anything being moved from toad-infested areas outside or within WA could contain cane toads and this has already occurred. Vigilance is required by freight companies and travellers as toads have been found in pipes, containers and fruit packaging as well as pot plants, shoes and camping gear. Until effective control methods are available, quarantine checks, public awareness and the removal of detected toads will reduce their rate of spread.
