Taxonomic name: Rhinella marina (Linnaeus, 1758)
Synonyms: Bufo agua Clark 1916, Bufo marinis [sic] Barbour 1916, Bufo marinus marinus Mertens 1972, Bufo marinus Mertens 1969, Bufo marinus Schneider 1799, Bufo strumosus Court 1858, Chaunus marinus Frost et al. 2006
Common names: Aga-Kröte (German), bufo toad, bullfrog, cane toad (English), crapaud (Caribbean), giant American toad (English), giant toad (English), kwapp (Caribbean), macao (Dominican Republic), maco pempen (Dominican Republic), Maco toro (Dominican Republic), marine Toad, Suriname toad
Organism type: amphibian
Cane toads were introduced to many countries as biological control agents for various insect pests of sugarcane and other crops. The cane toads have proved to be pests themselves. They will feed on almost any terrestrial animal and compete with native amphibians for food and breeding habitats. Their toxic secretions are known to cause illness and death in domestic animals that come into contact with them, such as dogs and cats, and wildlife, such as snakes and lizards. Human fatalities have been recorded following ingestion of the eggs or adults.
Cane toads are heavily built with short legs. They can sometimes grow up to 30cm long, with 20cm not uncommon for females and and average of 12-15cm in many regions. Males are slightly smaller. Fingers lack webbing, but the toes are heavily webbed. Adults have a rough, warty skin, coloured tan, brown or dark brown, dull green or black. The tympanum is distinct, about one half to two thirds the size of the eye. Venom glands are aggregated together to form large and distinctive parotoid glands, found above each shoulder. These glands are able to ooze venom. (Gautherot, 2000)
agricultural areas, lakes, natural forests, riparian zones, ruderal/disturbed, urban areas, water courses, wetlands
Cane toads' original habitat, before their dispersal by humans, was seasonal Amazonian savanna, with small fresh water lakes. Cane toads are found in rain forests, both in their native range and introduced range, such as in Hawai'i and New Guinea, though not at high densities (Fred Kraus pers.comm). However, they can now be found in many places, such as man-made ponds, gardens, drain pipes, debris, under cement piles and beneath houses. Cane toads will usually stay on dry land and reproduce in any shallow water near its surroundings. Toads and tadpoles are able to tolerate very high levels of salinity. Tadpoles have been observed in water, metres from the open ocean.
Cane toads will eat “almost any terrestrial animal”, although they are more likely to consume those active at ground level during the night (Hinkley 1962). Covacevich and Archer, (1975) in their paper on the effects of the cane toad on indigenous verteberates in Australia, state that snakes, such as the carpet python, the black headed python, death adder and some other snakes have been found dead with the cane toad in their mouths or guts. Studies in Australia where the range of the cane toad is ever expanding have shown that the cane toad plays an important role in structuring native anuran communities (Crossland, 2000) via direct and indirect mechanisms and is thus a threat to the survival of native Australian fauna ( Catling,P.C et al.2003).
Toads have been implicated in the decline of populations of monitor lizards in Guam (Jackson 1962, Dryden 1965). Pernetta and Watling (1978) consider that the toads do not interact with native frogs because they use different habitats; the frogs are either along stream banks or in the foliage of dense forest. Villadolid (1956) found rats and mice in stomachs of toads in the Philippine Islands. Hinkley concluded that this toad is “economically neutral” because it consumes both “harmful” and “beneficial” invertebrates.
Secretions from the parotoid glands are produced when the toad is provoked or localised pressure is applied, such as a predator grasping the toad in its mouth (NRM, 2001). The toxic secretions are known to cause illness and death in both domestic and wild animals that come into contact with toads, such as dogs, cats, snakes and lizards. The toxin causes extreme pain if rubbed into the eyes (NRM, 2001). Human fatalities have been reported, but are probably confined to people who deliberately concentrate the toxin and then ingest it.
Overall, the major impacts are on predatory species that attempt to eat toads and then die; in particular, species that normally specialise amphibians, such as Mertens water monitor in northern Australia.
Bufotenine toxin produced by the cane toad is used as an aphrodisiac and hair-restorer in Japan. In mainland China it is used to lower the heart rate of patients undergoing cardiac surgery (Musgrave, 1996). The toxin is used by South American Indians on hunting arrows. The toxin is sometimes used as a narcotic by some people (Lever, 2001).
Cane toads were used for pregnancy testing in humans. A woman's urine was injected subcutaneously into the lymph glands of a male toad, resulting in spermatazoa becoming present in the toad's urine if the woman was pregnant (Berra, 1998 in Lever, 2001).
Native range: Cane toads are indigenous to northern South America (Argentina, Bolivia, Brazil, Ecuador, Colombia, Paraguay, Venezuela, the Guianas, Peru, Trinidad and Tobago), Central America, and Mexico northward to extreme southern Texas.
Known introduced range: Most introductions were made as early attempts to use biological control against various beetle pests of sugar cane, banana and other cash crops (Hinkley 1962). Introduced to: Hawai'i, Puerto Rico, U.S. Virgin Islands, Guam and Northern Mariana Islands, American Samoa and the Republic of Palau: found in much of the Caribbean, including Antigua, Barbados, Bermuda, Cuba, Dominica, Grenada and Carriacou Island, Guadeloupe, Grand Cayman Island, Haiti, Dominican Republic, Jamaica (including Cabarita Island), Martinique, Montserrat, Nevis, St. Kitts, St. Lucia and St. Vincent. In the Pacific, Australia, Japan, Papua New Guinea, Philippines, Cook Islands, Micronesia, Fiji Islands, Kiribati, Republic of the Marshall Islands, the Solomon Islands and Tuvalu (USGS). Other worldwide introductions include Egypt, Mauritius and Diego Garcia of the Chagos Archipelago (Easteal, 1981, 1986; Lever, 2001).
Introduction pathways to new locations
Acclimatisation societies: Cane toads have been introduced to many locations around the world as a biological control agent for crop pests (NRM, 2001).
Natural dispersal: Cane toads have spread over large areas of Australia under their own power (Lever, 2001). In the north of their Australian range, dispersal is primarily effected by adults hopping large distances (up to about 55km per year), in relatively straight lines. Cane toads in northern Australia are thus the fastest moving anurans yet recorded. This remarkable dispersal ability appears to be the result of strong selection operating on toads over the last seventy years (Philips et al. 2006).
Road vehicles (long distance): Cane toads have been transported in Australia by large freight trucks or 'road trains' (Sydney Morning Herald, 2002).
Seafreight (container/bulk): Cane toads have been found on Norfolk Islands
Local dispersal methods
Natural dispersal (local): Cane toads have spread over large areas of Australia under their own power (Lever, 2001). In the north of their Australian range (on the invasion front), dispersal is primarily effected by adults hopping large distances (up to about 55km per year), in relatively straight lines. Cane toads in northern Australia are thus the fastest moving anurans yet recorded.
This remarkable dispersal ability appears to be the result of strong selection operating on toads in the invasion front over the last seventy years (Philips et al. 2006).
Road vehicles: Cane toads have been transported in Australia by large freight trucks or 'road trains' (Sydney Morning Herald, 2002).
Water currents: Free-swimming cane toad tadpoles are liable to be swept away during flash floods.
Preventative measures: The main controls on the spread of cane toads in southern Australia are quarantine checks and public awareness and response. One publicity campaign on the north coast of New South Wales resulted in 100 people collecting more than 900 cane toads.
Physical: Cane toads can be excluded from garden ponds and dams by a 50cm high barrier, such as a thick hedge or a wire mesh fence. Toads may be killed humanely by putting them inside a plastic bag or container and placing them in a freezer (Brandt and Mazzotti, 1990).
Biological: In 1994, the CSIRO Division of Wildlife and Ecology (Australia) was assessing the pathogenicity and specificity of viruses against cane toads. Scientists at the CSIRO Animal Health Laboratory in Victoria have been searching for biological controls of cane toads and in 2001 they began investigating gene technology as a mechanism of control. Environment Australia have launched a project for the development of a cane toad biological control. The aim is to develop a self disseminating viral vector to disrupt the development of the toad. Scientists at the University of Adelaide (Australia) have isolated a sex pheromone in a native Australian frog; they hope that a similar pheromone will be found in cane toads that could be used to disrupt the breeding cycle. These are long term solutions.
Scientists at Sydney University have identified a parasitic worm that attacks the cane toads' lungs, stunting their growth and, in most cases, killing them. They believe the parasite has the potential to reduce toad populations dramatically.
Cane toads eat “almost any terrestrial animal”, although they are more likely to consume animals active at ground level during the night. The major diet items are insects, including grass-hoppers, caterpillars and ants, together with millipedes and land snails (Hinkley, 1962 in SPREP, 2000).
The cane toad is opportunistic in its feeding habits and will consume almost anything that it is able to catch (Zug and Zug, 1979 in Lever, 2001). Terrestrial arthropods make up the bulk of the diet, but snails, crabs, small vertebrates (mammals, birds, lizards and frogs), pet food and human faeces may also be consumed (Lever, 2001). Cane toads will gorge themselves if food is in abundance. Unusual items that cane toads have been observed eating include rotting garbage, a coral snake (Micrurus circinalis), fledgling birds and a lit cigarette butt (Lever, 2001).
Cane toads breed between the months of April and September in the Northern Hemisphere and they can be heard calling their mates, beginning in late March. In the Southern Hemisphere, in Australia, it has been noticed that the male cane toad calls in any month of the year, peaking during the wet season. Every year the female cane toad produces two clutches of about 8,000 to 35,000 eggs. The eggs are externally fertilised by the male's sperm. The eggs can be found floating on the surface of water in a jelly-like string or wrapped around vegetation and other debris in the water. The age and size of the female will determine how many eggs the toad will produce (Honolulu Zoo).
Cane toad eggs hatch within 24 to 72 hours of laying into tiny, shiny black tadpoles. Tadpoles metamorphose after two to seven weeks (Alford et al. 1995), becoming very small (10-12mm) terrestrial juveniles. These small juveniles experience very high mortality, and unlike adults or larger juveniles they tend to be diurnal.
It has been estimated that less 0.5 percent of cane toads toad eggs survive to maturity. It takes a year for the toads to reach maturity, when they will be about 75mm long. Cane toads survival in the wild is unknown, but unlikely to be more than 5 years. Animals kept in captivity are estimated to live 10-40 years (Honolulu Zoo).
This species has been nominated as among 100 of the "World's Worst" invaders
Principal sources: Lever, C. 2001. The Cane Toad: the history and ecology of a successful colonist. Westbury Publishing, West Yorkshire. 230pp.
Gautherot, J., 2000. Bufo marinus. 2001 James Cook University.
Compiled by: IUCN SSC Invasive Species Specialist Group
Updates with support from the Overseas Territories Environmental Programme (OTEP) project XOT603, a joint project with the Cayman Islands Government - Department of Environment
Last Modified: Wednesday, 26 May 2010