Giant Neotropical Toad
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The cane toad (''Rhinella marina''), also known as the giant neotropical toad or marine toad, is a large, terrestrial true toad native to
South South is one of the cardinal directions or Points of the compass, compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Pro ...
and mainland Central America, but which has been introduced to various islands throughout Oceania and the
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
, as well as Northern Australia. It is a member of the genus ''
Rhinella ''Rhinella'', commonly known as South American toads, beaked toads or Rio Viejo toads, is a genus of true toads native to Neotropical parts of Mexico, Central and South America. Additionally, the cane toad has been introduced to Australia, the Ca ...
'', which includes many true toad species found throughout Central and South America, but it was formerly assigned to the genus '' Bufo''. The cane toad is an old species. A fossil toad (specimen UCMP 41159) from the La Venta fauna of the late Miocene in
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
is indistinguishable from modern cane toads from northern South America. It was discovered in a floodplain deposit, which suggests the ''R. marina'' habitat preferences have long been for open areas. The cane toad is a prolific breeder; females lay single-clump
spawns Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquat ...
with thousands of eggs. Its reproductive success is partly because of opportunistic feeding: it has a diet, unusual among anurans, of both dead and living matter. Adults average in length; the largest recorded specimen had a snout-vent length of . The cane toad has poison
gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...
s, and the tadpoles are highly toxic to most animals if ingested. Its toxic skin can kill many animals, both wild and domesticated, and cane toads are particularly dangerous to dogs. Because of its voracious appetite, the cane toad has been introduced to many regions of the Pacific and the Caribbean islands as a method of agricultural pest control. The common name of the species is derived from its use against the cane beetle (''Dermolepida albohirtum''), which damages sugar cane. The cane toad is now considered a pest and an
invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...
in many of its introduced regions. The 1988 film '' Cane Toads: An Unnatural History'' documented the trials and tribulations of the introduction of cane toads in Australia.


Taxonomy

Historically, the cane toads were used to eradicate pests from
sugarcane Sugarcane or sugar cane is a species of (often hybrid) tall, Perennial plant, perennial grass (in the genus ''Saccharum'', tribe Andropogoneae) that is used for sugar Sugar industry, production. The plants are 2–6 m (6–20 ft) tall with ...
, giving rise to their common name. The cane toad has many other common names, including "giant toad" and "marine toad"; the former refers to its size, and the latter to the
binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
, ''R. marina''. It was one of many species described by Carl Linnaeus in his 18th-century work ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
'' (1758). Linnaeus based the
specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''marina'' on an illustration by Dutch zoologist Albertus Seba, who mistakenly believed the cane toad to inhabit both terrestrial and marine environments. Other common names include "giant neotropical toad", "Dominican toad", "giant marine toad", and "South American cane toad". In Trinidadian English, they are commonly called ''crapaud'', the French word for toad. The genus ''Rhinella'' is considered to constitute a distinct genus of its own, thus changing the
scientific name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
of the cane toad. In this case, the
specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...
''marinus'' (
masculine Masculinity (also called manhood or manliness) is a set of attributes, behaviors, and roles associated with men and boys. Masculinity can be theoretically understood as socially constructed, and there is also evidence that some behaviors con ...
) changes to ''marina'' (feminine) to conform with the rules of gender agreement as set out by the International Code of Zoological Nomenclature, changing the binomial name from ''Bufo marinus'' to ''Rhinella marina''; the binomial ''Rhinella marinus'' was subsequently introduced as a synonym through misspelling by Pramuk, Robertson, Sites, and Noonan (2008). Though controversial (with many traditional herpetologists still using ''Bufo marinus'') the binomial ''Rhinella marina'' is gaining in acceptance with such bodies as the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
, Encyclopaedia of Life, Amphibian Species of the World and increasing numbers of scientific publications adopting its usage. Since 2016, cane toad populations native to Mesoamerica and northwestern South America are sometimes considered to be a separate species, ''
Rhinella horribilis ''Rhinella horribilis'' is the scientific name used for populations of the cane toad or giant toad located in Mesoamerica and north-western South America when they are considered to be a separate species from ''Rhinella marina'', a name which is ...
''. In Australia, the adults may be confused with large native frogs from the genera ''
Limnodynastes ''Limnodynastes'' (commonly known as the Australian swamp frogs) is a genus of frog native to Australia, southern New Guinea and some Torres Strait Islands. They are ground-dwelling frogs, with no toe pads. The size varies from 45 mm to 90&n ...
'', ''
Cyclorana ''Ranoidea'' is a genus of frogs in the subfamily Pelodryadinae. They are found in Australia, New Guinea, and two nearby groups of islands: the Maluku Islands, and the Louisiade Archipelago. The circumscription of this taxon is still controvers ...
'', and '' Mixophyes''. These species can be distinguished from the cane toad by the absence of large parotoid glands behind their eyes and the lack of a ridge between the nostril and the eye. Cane toads have been confused with the
giant burrowing frog The giant burrowing frog or eastern owl frog (''Heleioporus australiacus'') is a large frog species that occurs in coastal south-east New South Wales and Victoria in Australia. It is also known as the owl frog, southern owl frog, spotted owl fr ...
(''Heleioporus australiacus''), because both are large and warty in appearance; however, the latter can be readily distinguished from the former by its vertical pupils and its silver-grey (as opposed to gold) irises. Juvenile cane toads may be confused with species of the genus ''
Uperoleia ''Uperoleia'' is a genus of frog A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura (ανοὐρά, literally ''without tail'' in Ancient Greek). The oldest fossil ...
'', but their adult colleagues can be distinguished by the lack of bright colouring on the groin and thighs. In the United States, the cane toad closely resembles many bufonid species. In particular, it could be confused with the southern toad (''Bufo terrestris''), which can be distinguished by the presence of two bulbs in front of the parotoid glands.


Genetics

The cane toad genome has been sequenced and certain Australian academics believe this will help in understanding how the toad can quickly evolve to adapt to new environments, the workings of its infamous toxin, and hopefully provide new options for halting this species' march across Australia and other places it has spread as an invasive pest.


Description

Considered the largest species in the Bufonidae, the cane toad is very large; the females are significantly longer than males, reaching a typical length of , with a maximum of . Larger toads tend to be found in areas of lower population density. They have a life expectancy of 10 to 15 years in the wild, and can live considerably longer in captivity, with one specimen reportedly surviving for 35 years. The skin of the cane toad is dry and warty. Distinct ridges above the eyes run down the snout. Individual cane toads can be grey, yellowish, red-brown, or olive-brown, with varying patterns. A large parotoid gland lies behind each eye. The ventral surface is cream-coloured and may have blotches in shades of black or brown. The pupils are horizontal and the irises golden. The toes have a fleshy webbing at their base, and the fingers are free of webbing. Typically, juvenile cane toads have smooth, dark skin, although some specimens have a red wash. Juveniles lack the adults' large parotoid glands, so they are usually less poisonous. The tadpoles are small and uniformly black, and are bottom-dwellers, tending to form schools. Tadpoles range from in length.


Ecology, behaviour and life history

The common name "marine toad" and the scientific name ''Rhinella marina'' suggest a link to
marine life Marine life, sea life, or ocean life is the plants, animals and other organisms that live in the salt water of seas or oceans, or the brackish water of coastal estuaries. At a fundamental level, marine life affects the nature of the planet. M ...
, but cane toads do not live in the sea. However, laboratory experiments suggest that tadpoles can tolerate salt concentrations equivalent to 15% of seawater (~5.4‰), and recent field observations found living tadpoles and toadlets at salinities of 27.5‰ on
Coiba Island Coiba is the largest island in Central America, with an area of , off the Pacific coast of the Panamanian province of Chiriquí. It is part of the Tolé District of that province. History Coiba separated from continental Panama about 12,000 to ...
, Panama. The cane toad inhabits open grassland and woodland, and has displayed a "distinct preference" for areas modified by humans, such as gardens and drainage ditches. In their native habitats, the toads can be found in subtropical forests, although dense foliage tends to limit their dispersal. The cane toad begins life as an egg, which is laid as part of long strings of jelly in water. A female lays 8,000–25,000 eggs at once and the strings can stretch up to in length. The black eggs are covered by a membrane and their diameter is about . The rate at which an egg grows into a tadpole increases with temperature. Tadpoles typically hatch within 48 hours, but the period can vary from 14 hours to almost a week. This process usually involves thousands of tadpoles—which are small, black, and have short tails—forming into groups. Between 12 and 60 days are needed for the tadpoles to develop into juveniles, with four weeks being typical. Similarly to their adult counterparts, eggs and tadpoles are toxic to many animals. When they emerge, toadlets typically are about in length, and grow rapidly. While the rate of growth varies by region, time of year, and gender, an average initial growth rate of per day is seen, followed by an average rate of per day. Growth typically slows once the toads reach sexual maturity. This rapid growth is important for their survival; in the period between metamorphosis and subadulthood, the young toads lose the toxicity that protected them as eggs and tadpoles, but have yet to fully develop the parotoid glands that produce bufotoxin. Only an estimated 0.5% of cane toads reach adulthood, in part because they lack this key defense - but also due to tadpole cannibalism. Although cannibalism does occur in the native population in South America, the rapid evolution occurring in the unnaturally large population in Australia has produced tadpoles 30x more likely to be ''interested'' in cannibalising their siblings, and 2.6x more likely to actually ''do so''. They have also evolved to shorten their tadpole phase in response to the presence of older tadpoles. These changes are likely genetic, although no genetic basis has been determined. As with rates of growth, the point at which the toads become sexually mature varies across different regions. In New Guinea, sexual maturity is reached by female toads with a snout–vent length between , while toads in Panama achieve maturity when they are between in length. In tropical regions, such as their native habitats, breeding occurs throughout the year, but in subtropical areas, breeding occurs only during warmer periods that coincide with the onset of the wet season. The cane toad is estimated to have a critical thermal maximum of and a minimum of around . The ranges can change due to adaptation to the local environment. Cane toads from some populations can adjust their thermal tolerance within a few hours of encountering low temperatures. The toad is able to rapidly acclimate to the cold using physiological plasticity, though there is also evidence that more northerly populations of cane toads in the United States are better cold-adapted than more southerly populations. These adaptations have allowed the cane toad to establish invasive populations across the world. The toad’s ability to rapidly acclimate to thermal changes suggests that current models may underestimate the potential range of habitats that the toad can populate. The cane toad has a high tolerance to water loss; some can withstand a 52.6% loss of body water, allowing them to survive outside tropical environments.


Diet

Most frogs identify prey by movement, and vision appears to be the primary method by which the cane toad detects prey; however, it can also locate food using its sense of smell. They eat a wide range of material; in addition to the normal prey of small rodents, other small
mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s,
reptile Reptiles, as most commonly defined are the animals in the class Reptilia ( ), a paraphyletic grouping comprising all sauropsids except birds. Living reptiles comprise turtles, crocodilians, squamates (lizards and snakes) and rhynchocephalians ( ...
s, other
amphibian Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
s, birds, and even bats and a range of invertebrates (such as ants, beetles, earwigs, dragonflies,
grasshopper Grasshoppers are a group of insects belonging to the suborder Caelifera. They are among what is possibly the most ancient living group of chewing herbivorous insects, dating back to the early Triassic around 250 million years ago. Grasshopp ...
s, true bugs, crustaceans, and
gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...
s), they also eat plants, dog food, cat food, feces, and household refuse.


Defences

The skin of the adult cane toad is toxic, as well as the enlarged parotoid glands behind the eyes, and other glands across its back. When the toad is threatened, its glands secrete a milky-white fluid known as bufotoxin. Components of bufotoxin are toxic to many animals; even human deaths have been recorded due to the consumption of cane toads. Dogs are especially prone to be poisoned by licking or biting toads. Pets showing excessive drooling, extremely red gums, head-shaking, crying, loss of coordination, and/or convulsions require immediate veterinary attention. Bufotenin, one of the chemicals excreted by the cane toad, is classified as a schedule 9 drug under Australian law, alongside
heroin Heroin, also known as diacetylmorphine and diamorphine among other names, is a potent opioid mainly used as a recreational drug for its euphoric effects. Medical grade diamorphine is used as a pure hydrochloride salt. Various white and brow ...
and LSD. The effects of bufotenin are thought to be similar to those of mild poisoning; the stimulation, which includes mild hallucinations, lasts less than an hour. As the cane toad excretes bufotenin in small amounts, and other toxins in relatively large quantities, toad licking could result in serious illness or death. In addition to releasing toxin, the cane toad is capable of inflating its lungs, puffing up, and lifting its body off the ground to appear taller and larger to a potential predator. Since 2011, experimenters in the Kimberley region of Western Australia have used poisonous sausages containing toad meat in an attempt to protect native animals from cane toads' deadly impact. The Western Australian Department of Environment and Conservation, along with the University of Sydney, developed these sausage-shaped baits as a tool in order to train native animals not to eat the toads. By blending bits of toad with a nausea-inducing chemical, the baits train the animals to stay away from the amphibians.


Predators

Many species prey on the cane toad and its tadpoles in its native habitat, including the
broad-snouted caiman The broad-snouted caiman (''Caiman latirostris'') is a crocodilian in the family Alligatoridae found in eastern and central South America, including southeastern Brazil, northern Argentina, Uruguay, Paraguay, and Bolivia. It is found mostly in fr ...
(''Caiman latirostris''), the
banded cat-eyed snake The banded cat-eyed snake (''Leptodeira annulata'') is a species of mildly venomous, rear-fanged, colubrid snake, endemic to the New World.ITIS (Integrated Taxonomic Information System). Itis.gov. Common names Additional common names include: ca ...
(''Leptodeira annulata''), eels (family Anguillidae), various species of killifish, the rock flagtail (''
Kuhlia The flagtails (' or ' in the Hawaiian language) are a family (Kuhliidae) of perciform fish of the Indo-Pacific area. The family consists of several species in one genus, ''Kuhlia''. Most are euryhaline and often found in brackish water, but th ...
rupestris''), some species of catfish (order Siluriformes), some species of ibis (subfamily Threskiornithinae), and '' Paraponera clavata'' (bullet ants). Predators outside the cane toad's native range include the whistling kite (''Haliastur sphenurus''), the rakali (''Hydromys chrysogaster''), the
black rat The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...
(''Rattus rattus'') and the water monitor (''Varanus salvator''). The tawny frogmouth (''Podargus strigoides'') and the
Papuan frogmouth The Papuan frogmouth (''Podargus papuensis'') is a species of bird in the family Podargidae. Taxonomy The species was originally described by zoologist Jean René Constant Quoy and naturalist Joseph Paul Gaimard in 1830. The three subspeci ...
(''Podargus papuensis'') have been reported as feeding on cane toads; some Australian crows ('' Corvus'' spp.) have also learned strategies allowing them to feed on cane toads, such as using their beak to flip toads onto their backs. Opossums of the genus '' Didelphis'' likely can eat cane toads with impunity.
Meat ant The meat ant (''Iridomyrmex purpureus''), also known as the gravel ant or southern meat ant, is a species of ant endemic to Australia. A member of the genus ''Iridomyrmex'' in the subfamily Dolichoderinae, it was described by British entomolo ...
s are unaffected by the cane toads' toxins, so are able to kill them. The cane toad's normal response to attack is to stand still and let its toxin kill the attacker, which allows the ants to attack and eat the toad. Saw-shelled turtles have also been seen successfully and safely eating cane toads.


Distribution

The cane toad is native to the Americas, and its range stretches from the Rio Grande Valley in
South Texas South Texas is a region of the U.S. state of Texas that lies roughly south of—and includes—San Antonio. The southern and western boundary is the Rio Grande, and to the east it is the Gulf of Mexico. The population of this region is about 4.96 ...
to the central Amazon and southeastern Peru, and some of the continental islands near Venezuela (such as Trinidad and Tobago). This area encompasses both tropical and semiarid environments. The density of the cane toad is significantly lower within its native distribution than in places where it has been introduced. In South America, the density was recorded to be 20 adults per 100 m (109 yd) of shoreline, 1 to 2% of the density in Australia.


As an introduced species

The cane toad has been introduced to many regions of the world—particularly the Pacific—for the biological control of agricultural pests. These introductions have generally been well documented, and the cane toad may be one of the most studied of any introduced species. Before the early 1840s, the cane toad had been introduced into Martinique and Barbados, from French Guiana and
Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...
. An introduction to Jamaica was made in 1844 in an attempt to reduce the rat population. Despite its failure to control the rodents, the cane toad was introduced to Puerto Rico in the early 20th century in the hope that it would counter a beetle infestation ravaging the sugarcane plantations. The Puerto Rican scheme was successful and halted the economic damage caused by the beetles, prompting scientists in the 1930s to promote it as an ideal solution to agricultural pests. As a result, many countries in the Pacific region emulated the lead of Puerto Rico and introduced the toad in the 1930s. Introduced populations are in
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, Florida, Papua New Guinea, the Philippines, the Ogasawara, Ishigaki Island and the Daitō Islands of Japan, , Taiwan Nantou
Caotun Caotun Township, formerly transliterated as Tsaotun Township, is an urban Township (Taiwan), township in the northwest of Nantou County, Taiwan. It is the largest township in Taiwan by population. History The area was historically known as ''Chh ...
, most Caribbean islands,
Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...
and many other Pacific islands, including Hawaii. Since then, the cane toad has become a pest in many host countries, and poses a serious threat to native animals.


Australia

Following the apparent success of the cane toad in eating the beetles threatening the sugarcane plantations of Puerto Rico, and the fruitful introductions into Hawaii and the Philippines, a strong push was made for the cane toad to be released in Australia to negate the pests ravaging the Queensland cane fields. As a result, 102 toads were collected from Hawaii and brought to Australia. Queensland's sugar scientists released the toad into cane fields in August 1935. After this initial release, the Commonwealth Department of Health decided to ban future introductions until a study was conducted into the feeding habits of the toad. The study was completed in 1936 and the ban lifted, when large-scale releases were undertaken; by March 1937, 62,000 toadlets had been released into the wild. The toads became firmly established in Queensland, increasing exponentially in number and extending their range into the Northern Territory and New South Wales. In 2010, one was found on the far western coast in
Broome, Western Australia Broome, also known as Rubibi by the Yawuru people, is a coastal pearling and tourist town in the Kimberley region of Western Australia, north of Perth. In the the population was recorded as 14,660. It is the largest town in the Kimberley reg ...
. However, the toad was generally unsuccessful in reducing the targeted grey-backed cane beetles (''
Dermolepida albohirtum ''Dermolepida albohirtum'', the cane beetle, is a native Australian beetle and a parasite of sugarcane. Adult beetles eat the leaves of sugarcane, but greater damage is done by their larvae hatching underground and eating the roots, which eithe ...
''), in part because the cane fields provided insufficient shelter for the predators during the day, and in part because the beetles live at the tops of sugar cane—and cane toads are not good climbers. Since its original introduction, the cane toad has had a particularly marked effect on Australian biodiversity. The population of a number of native predatory reptiles has declined, such as the
varanid The Varanidae are a family of lizards in the superfamily Varanoidea within the Anguimorpha group. The family, a group of carnivorous and frugivorous lizards, includes the living genus '' Varanus'' and a number of extinct genera more closely relat ...
lizards ''
Varanus mertensi Mertens' water monitor (''Varanus mertensi''), also called commonly Mertens's water monitor, and often misspelled Mertin's water monitor, is a species of lizard in the family Varanidae. The species is endemic to northern Australia, and is a wide ...
'', '' V. mitchelli'', and '' V. panoptes'', the land snakes ''
Pseudechis australis The king brown snake (''Pseudechis australis'') is a species of highly venomous snake of the family Elapidae, native to northern, western, and Central Australia. Despite its common name, it is a member of the genus ''Pseudechis'' (black snakes) ...
'' and '' Acanthophis antarcticus'', and the crocodile species ''
Crocodylus johnstoni The freshwater crocodile (''Crocodylus johnstoni''), also known as the Australian freshwater crocodile, Johnstone's crocodile or the freshie, is a species of crocodile endemic to the northern regions of Australia. Unlike their much larger Aus ...
''; in contrast, the population of the agamid lizard ''
Amphibolurus gilberti ''Amphibolurus'' is a genus of lizards in the family Agamidae. The genus is endemic to Australia. Description Characteristics of the genus ''Amphibolurus'' include: * Moderate size nout–vent length * Long limbs and long tail * One to five cr ...
''—known to be a prey item of ''V. panoptes''—has increased.. On snake populations see .
Meat ant The meat ant (''Iridomyrmex purpureus''), also known as the gravel ant or southern meat ant, is a species of ant endemic to Australia. A member of the genus ''Iridomyrmex'' in the subfamily Dolichoderinae, it was described by British entomolo ...
s, however, are able to kill cane toads.''Meat Ant.''
Australian Environmental Pest Managers Association (AEPMA) (accessed July 2022)


Caribbean

The cane toad was introduced to various Caribbean islands to counter a number of pests infesting local crops. While it was able to establish itself on some islands, such as Barbados, Jamaica, and Puerto Rico, other introductions, such as in Cuba before 1900 and in 1946, and on the islands of
Dominica Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Dominica, is an island country in the Caribbean. The capital, Roseau, is located on the western side of the island. It is geographically ...
and Grand Cayman, were unsuccessful. The earliest recorded introductions were to Barbados and Martinique. The Barbados introductions were focused on the biological control of pests damaging the sugarcane crops, and while the toads became abundant, they have done even less to control the pests than in Australia.Kennedy, Anthony quoted in The toad was introduced to Martinique from French Guiana before 1944 and became established. Today, they reduce the mosquito and mole cricket populations. A third introduction to the region occurred in 1884, when toads appeared in Jamaica, reportedly imported from Barbados to help control the rodent population. While they had no significant effect on the rats, they nevertheless became well established. Other introductions include the release on
Antigua Antigua ( ), also known as Waladli or Wadadli by the native population, is an island in the Lesser Antilles. It is one of the Leeward Islands in the Caribbean region and the main island of the country of Antigua and Barbuda. Antigua and Bar ...
—possibly before 1916, although this initial population may have died out by 1934 and been reintroduced at a later date— and
Montserrat Montserrat ( ) is a British Overseas Territories, British Overseas Territory in the Caribbean. It is part of the Leeward Islands, the northern portion of the Lesser Antilles chain of the West Indies. Montserrat is about long and wide, with r ...
, which had an introduction before 1879 that led to the establishment of a solid population, which was apparently sufficient to survive the Soufrière Hills volcano eruption in 1995. In 1920, the cane toad was introduced into Puerto Rico to control the populations of white grub (''Phyllophaga'' spp.), a sugarcane pest. Before this, the pests were manually collected by humans, so the introduction of the toad eliminated labor costs. A second group of toads was imported in 1923, and by 1932, the cane toad was well established.. "After a completely successful method of killing white grubs by chemical means was found, the only opportunities for its use in Puerto Rico have been limited to small areas in pineapple plantations at elevations where the toad is even yet not present in sufficient abundance." The population of white grubs dramatically decreased, and this was attributed to the cane toad at the annual meeting of the International Sugar Cane Technologists in Puerto Rico. However, there may have been other factors. The six-year period after 1931—when the cane toad was most prolific, and the white grub had a dramatic decline—had the highest-ever rainfall for Puerto Rico. Nevertheless, the cane toad was assumed to have controlled the white grub; this view was reinforced by a '' Nature'' article titled "Toads save sugar crop", and this led to large-scale introductions throughout many parts of the Pacific. The cane toad has been spotted in Carriacou and
Dominica Dominica ( or ; Kalinago: ; french: Dominique; Dominican Creole French: ), officially the Commonwealth of Dominica, is an island country in the Caribbean. The capital, Roseau, is located on the western side of the island. It is geographically ...
, the latter appearance occurring in spite of the failure of the earlier introductions. On September 8, 2013, the cane toad was also discovered on the island of
New Providence New Providence is the most populous island in the Bahamas, containing more than 70% of the total population. It is the location of the national capital city of Nassau, whose boundaries are coincident with the island; it had a population of 246 ...
in the Bahamas.


The Philippines

The cane toad was first introduced deliberately into the Philippines in 1930 as a biological control agent of pests in sugarcane plantations, after the success of the experimental introductions into Puerto Rico. It subsequently became the most ubiquitous amphibian in the islands. It still retains the common name of ''bakî'' or ''kamprag'' in the Visayan languages, a
corruption Corruption is a form of dishonesty or a criminal offense which is undertaken by a person or an organization which is entrusted in a position of authority, in order to acquire illicit benefits or abuse power for one's personal gain. Corruption m ...
of 'American frog', referring to its origins. It is also commonly known as "bullfrog" in Philippine English.


Fiji

The cane toad was introduced into
Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...
to combat insects that infested sugarcane plantations. The introduction of the cane toad to the region was first suggested in 1933, following the successes in Puerto Rico and Hawaii. After considering the possible side effects, the national government of Fiji decided to release the toad in 1953, and 67 specimens were subsequently imported from Hawaii. Once the toads were established, a 1963 study concluded, as the toad's diet included both harmful and beneficial invertebrates, it was considered "economically neutral". Today, the cane toad can be found on all major islands in Fiji, although they tend to be smaller than their counterparts in other regions.


New Guinea

The cane toad was introduced into New Guinea to control the hawk moth larvae eating
sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant that belongs to the Convolvulus, bindweed or morning glory family (biology), family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a r ...
crops. The first release occurred in 1937 using toads imported from Hawaii, with a second release the same year using specimens from the Australian mainland. Evidence suggests a third release in 1938, consisting of toads being used for human pregnancy tests—many species of toad were found to be effective for this task, and were employed for about 20 years after the discovery was announced in 1948. Initial reports argued the toads were effective in reducing the levels of cutworms and sweet potato yields were thought to be improving. As a result, these first releases were followed by further distributions across much of the region, although their effectiveness on other crops, such as cabbages, has been questioned; when the toads were released at Wau, the cabbages provided insufficient shelter and the toads rapidly left the immediate area for the superior shelter offered by the forest. A similar situation had previously arisen in the Australian cane fields, but this experience was either unknown or ignored in New Guinea. The cane toad has since become abundant in rural and urban areas.


United States

The cane toad naturally exists in
South Texas South Texas is a region of the U.S. state of Texas that lies roughly south of—and includes—San Antonio. The southern and western boundary is the Rio Grande, and to the east it is the Gulf of Mexico. The population of this region is about 4.96 ...
, but attempts (both deliberate and accidental) have been made to introduce the species to other parts of the country. These include introductions to Florida and to the islands of Hawaii, as well as largely unsuccessful introductions to Louisiana. Initial releases into Florida failed. Attempted introductions before 1936 and 1944, intended to control sugarcane pests, were unsuccessful as the toads failed to proliferate. Later attempts failed in the same way. However, the toad gained a foothold in the state after an accidental release by an importer at Miami International Airport in 1957, and deliberate releases by animal dealers in 1963 and 1964 established the toad in other parts of Florida. Today, the cane toad is well established in the state, from the
Keys Key or The Key may refer to: Common meanings * Key (cryptography), a piece of information that controls the operation of a cryptography algorithm * Key (lock), device used to control access to places or facilities restricted by a lock * Key (map ...
to north of
Tampa Tampa () is a city on the Gulf Coast of the U.S. state of Florida. The city's borders include the north shore of Tampa Bay and the east shore of Old Tampa Bay. Tampa is the largest city in the Tampa Bay area and the seat of Hillsborough County ...
, and they are gradually extending further northward. In Florida, the toad is a regarded as a threat to native species and pets; so much so, the Florida Fish and Wildlife Conservation Commission recommends residents to kill them. Around 150 cane toads were introduced to Oahu in Hawaii in 1932, and the population swelled to 105,517 after 17 months. The toads were sent to the other islands, and more than 100,000 toads were distributed by July 1934; eventually over 600,000 were transported.


Uses

Other than the use as a biological control for pests, the cane toad has been employed in a number of commercial and noncommercial applications. Traditionally, within the toad's natural range in South America, the Embera-Wounaan would "milk" the toads for their toxin, which was then employed as an arrow poison. The toxins may have been used as an entheogen by the Olmec people. The toad has been hunted as a food source in parts of Peru, and eaten after the careful removal of the skin and parotoid glands. When properly prepared, the meat of the toad is considered healthy and as a source of omega-3 fatty acids. More recently, the toad's toxins have been used in a number of new ways: bufotenin has been used in Japan as an aphrodisiac and a hair restorer, and in cardiac surgery in China to lower the heart rates of patients. New research has suggested that the cane toad's poison may have some applications in treating
prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...
. Other modern applications of the cane toad include pregnancy testing, as pets, laboratory research, and the production of leather goods. Pregnancy testing was conducted in the mid-20th century by injecting urine from a woman into a male toad's
lymph sacs Lymph sacs are a part of the development of the lymphatic system, known as lymphangiogenesis. The lymph sacs are precursors of the lymph vessels. These sacs develop through the processes of vasculogenesis and angiogenesis. However, there i ...
, and if spermatozoa appeared in the toad's urine, the patient was deemed to be pregnant. The tests using toads were faster than those employing mammals; the toads were easier to raise, and, although the initial 1948 discovery employed ''
Bufo arenarum ''Rhinella arenarum'' is a species of toad in the family Bufonidae that is found in southern Brazil and Uruguay; can also occur in Paraguay. It is also found in Argentina from the Chubut Province northward, Bolivia , image_flag ...
'' for the tests, it soon became clear that a variety of anuran species were suitable, including the cane toad. As a result, toads were employed in this task for around 20 years. As a laboratory animal, the cane toad has numerous advantages: they are plentiful, and easy and inexpensive to maintain and handle. The use of the cane toad in experiments started in the 1950s, and by the end of the 1960s, large numbers were being collected and exported to high schools and universities. Since then, a number of Australian states have introduced or tightened importation regulations. There are several commercial uses for dead cane toads. Cane toad skin is made into leather and novelty items. Stuffed cane toads, posed and accessorised, are merchandised at souvenir shops for tourists. Attempts have been made to produce fertiliser from toad carcasses.


Invasive species

Cane toads pose a serious threat to native species when introduced to a new ecosystem. Classified as an invasive species in over 20 countries, multiple reports exist of the cane toad moving into a new area to be followed by a decline in the biodiversity in that region. The most documented region of the cane toad's invasion and subsequent effect on native species is
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, where multiple surveys and observations of the toad's conquest have been completed. The best way to illustrate this effect is through the plight of the northern quoll, as well as Mertens' water monitor, a large lizard native to South and Southeast Asia. Two sites were chosen to study the effects of cane toads on the northern quoll, one of which was at Mary River ranger station, which is located in the southern region of Kakadu National Park. The other site was located at the north end of the park. In addition to these two sites, a third site was located at the East Alligator ranger station, and this site was used as a control site, where the cane toads would not interact with the northern quoll population. Monitoring of the quoll population began at the Mary River ranger station using radio tracking in 2002, months before the first cane toads arrived at the site. After the arrival of the cane toads, the population of northern quolls in the Mary River site plummeted between October and December 2002, and by March 2003, the northern quoll appeared to be extinct in this section of the park, as no northern quolls were caught in the trapping trips in the following two months. In contrast, the population of northern quolls in the control site at the East Alligator ranger station remained relatively constant, not showing any symptoms of declining. The evidence from the Kakadu National Park is compelling not only because of the timing of the population of northern quolls plummeting just months after the arrival of the cane toad, but also because in the Mary River region 31% of mortalities within the quoll population were attributed to lethal toxic ingestion, as no signs of disease, parasite infestation, or any other obvious changes at the site were found that could have caused such a rapid decline. The most obvious evidence that supports the hypothesis that the invasion of the cane toads caused the
local extinction Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...
of the northern quoll is that the closely monitored population of the control group, in the absence of cane toads, showed no signs of decline. In the case of Mertens' water monitor, only one region was monitored, but over the course of 18 months. This region is located 70 km south of
Darwin Darwin may refer to: Common meanings * Charles Darwin (1809–1882), English naturalist and writer, best known as the originator of the theory of biological evolution by natural selection * Darwin, Northern Territory, a territorial capital city i ...
, at the Manton Dam Recreation Area. Within the Manton Dam Recreation Area, 14 sites were set up to survey the population of water monitors, measuring abundance and site occupancy at each one. Seven surveys were conducted, each of which ran for 4 weeks and included 16 site visits, where each site was sampled twice per day for 2 consecutive days throughout the 4 weeks. Each site visit occurred between 7:30 and 10:30 am, and 4:00–7:00 pm, when ''Varanus mertensi'' can be viewed sunbathing on the shore or wrapped around a tree branch close to shore. The whole project lasted from December 2004 to May 2006, and had a total of 194 sightings of ''Varanus mertensi'' in 1568 site visits. Of the seven surveys, abundance was highest during the second survey, which took place in February 2005, 2 months into the project. Following this measurement, the abundance declined in the next four surveys, before declining sharply after the second to last survey in February 2006. In the final survey taken in May 2006, only two ''V. mertensi'' lizards were observed. Cane toads were first recorded in the region of study during the second survey during February 2005, also when the water monitor abundance was at its highest over the course of the study. Numbers of the cane toad population stayed low for the next year after introduction, and then skyrocketed to its peak in the last survey during May 2006. When compared, the two populations side by side clearly show that the onset of the cane toads had an immediate negative impact on the monitors, as their population began to drop in February 2005, which was when the first cane toads entered the Manton Dam Recreation Area. At the end of the study, some scattered populations of water monitors remained in the upper sites of the Manton Dam, which suggests that local extinctions occurred at certain shoreline sites within Manton Dam, but a complete extinction of the population did not occur.


References

Notes Bibliography * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *


External links


Species Profile – Cane Toad (''Rhinella marina'')
National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for cane toad. {{Taxonbar , from=Q321087 Rhinella Amphibians described in 1758 Taxa named by Carl Linnaeus Agricultural pests Amphibians of South America Amphibians of Central America Fauna of the Rio Grande valleys Vertebrates of Brazil Vertebrates of Guyana Amphibians of Trinidad and Tobago Amphibians of the Dominican Republic Fauna of Barbados Amphibians of Queensland Amphibians of New South Wales Amphibians of the Northern Territory Amphibians of Japan Frogs of Australia Amphibians of Mauritius