Cane toad

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Cane toad
An adult cane toad, brown in colour, displaying the unwebbed front feet, webbing on the back feet, and large parotoid glands on the side of the head.
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Bufonidae
Genus: Bufo
Species: B. marinus
Binomial name
Bufo marinus
(Linnaeus, 1758)

Distribution of the cane toad. Native distribution in blue, introduced in red.
Synonyms

Rhinella marinus[2]
Chaunus marinus[2]

The cane toad (Bufo marinus), also known as the Giant Neotropical Toad or Marine Toad, is a large, terrestrial true toad native to Central and South America. It is a member of the subgenus Chaunus of the genus Bufo, which includes many different true toad species throughout Central and South America. The cane toad is a prolific breeder; females lay single-clump spawns with large numbers 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 10 to 15 centimetres (4–6 in) in length; the largest recorded specimen weighed 2.65 kilograms (5.8 lb) with a length of 38 centimetres (15 in) from snout to vent.

The cane toad has poison glands, and the tadpoles are highly toxic to most animals if ingested. 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, notably failing in the case of Australia in 1935, and derives its common name from its use against the greyback cane beetle pests. The cane toad is now considered a pest and invasive species in many of its introduced regions because its toxic skin kills many native predators when ingested. It has many negative effects on farmers because of pets and animals eating the creatures.

Contents

[edit] Taxonomy

The common name is derived from the original purpose of using it to eradicate pests in sugar cane crops. The cane toad has many other common names, including "Giant Toad" and "Marine Toad"; the former refers to their size, and the latter to the binomial name, Bufo marinus. It was one of the many species originally described by Linnaeus in his 18th-century work Systema Naturae.[3] Linnaeus based the specific epithet, marinus, on an illustration by Dutch zoologist Albertus Seba, who mistakenly believed the cane toad to inhabit both terrestrial and marine environments.[4] Other common names include "Giant Neotropical Toad",[5] "Dominican Toad",[6] "Giant Marine Toad",[7] and "South American Cane Toad".[8] In Trinidadian English they are commonly called "Crapaud".[9]

A large, adult cane toad, showing the light colouration that is present in some specimens of the species.
A lightly coloured cane toad

In Australia, the adults may be confused with native species such as Limnodynastes, Cyclorana and Mixophyes. These species can be distinguished from the cane toad by the lack of large parotoid glands behind their eyes and by the lack of a ridge between the nostril and the eye.[10] Cane toads have been confused with the Giant Burrowing Frog (Heleioporus australiacus), because both are large and warty in appearance; however, the Giant Burrowing Frog can be readily distinguished from the cane toad by the frog's vertical pupils and its silver-grey (as opposed to gold) iris.[11] Juvenile cane toads may be confused with species of the Uperoleia genus, but the cane toad can be distinguished from these species by the lack of bright colouring on the groin and thighs.[12]

In the United States, the cane toad closely resembles many Bufonid species. In particular, it could be confused with the Southern toad (Bufo terrestris). The Southern Toad can be distinguished by the presence of two bulbs in front of the parotoid glands.[13]

[edit] Description

A juvenile cane toad, showing many of the features of the adult toads, but without the large parotoid glands.
A young cane toad (Bufo marinus)

The cane toad is very large;[14] the females significantly exceed males in length,[15] reaching an average length of 10–15 centimetres (4–6 in).[14] "Prinsen", a toad kept as a pet in Sweden, is listed by the Guinness Book of Records as the largest recorded specimen. It reportedly weighed 2.65 kilograms (5.84 lb) and measured 38 centimetres (15 in) from snout to vent, or 54 centimetres (21 in) when fully extended.[16] As a general rule, the larger toads tend to be found in areas of lower population density.[17] They have a life expectancy of 10 to 15 years in the wild,[18] and can live considerably longer in captivity, with one specimen reportedly surviving for 35 years.[19]

The skin of the cane toad is dry and warty.[14] It has distinct ridges above the eyes which run down the snout.[10] Individual cane toads can be grey, yellowish, red-brown or olive-brown in colour, with varying patterns.[20] A large parotoid gland lies behind each eye.[14] The ventral surface is cream and may have blotches in shades of black or brown. The pupils are horizontal and the irises golden.[11] The toes have a fleshy webbing at their base,[14] and the fingers are free of webbing.[20]

The juvenile cane toad is much smaller than the adult cane toad – only 5 to 10 centimetres (2–4 in) long. Typically, they have smooth, dark skin, although some specimens have a red wash. Juveniles lack the adults' large parotoid glands, so they are usually less poisonous.[17] The tadpoles are small and uniformly black, and are bottom-dwellers, tending to congregate to form schools.[21] Tadpoles range from 10 to 25 millimetres (0.4–1.0 in) in length.[22]

[edit] Ecology, behaviour and life history

The common name of "Marine Toad" and the scientific name Bufo marinus suggest a link to marine life; there is no such relationship.[23] The adult cane toad is entirely terrestrial, only venturing to fresh water to breed, and tadpoles have been found to tolerate salt concentrations equivalent at most 15% that of sea water.[24] The cane toad inhabits open grassland and woodland, and has displayed a "distinct preference" for areas that have been modified by humans, such as gardens and drainage ditches.[25] In their native habitats, the toads can be found in subtropical forests,[22] although dense foliage tends to limit their dispersal.[26]

The cane toad begins life as eggs, which are laid in long strings of jelly in water. The strings can stretch up to 20 metres (65 ft) in length.[23] The black eggs are covered by a membrane and their diameter is in the range 1.7–2.0 millimetres (0.07–0.08 in). A female lays 8,000–25,000 eggs at once.[23] The rate at which an egg evolves into a tadpole is dependent on the temperature: the speed increases as the temperature rises. Tadpoles typically hatch within 48 hours, but the period can vary from 14 hours up to almost a week.[23] This usually involves thousands of tadpoles – which are small, black and have short tails – forming into groups. It takes between 12 to 60 days for the tadpoles to develop into toadlets, with four weeks being a typical period.[23] Just as with adult toads, both eggs and tadpoles are toxic to many animals.[14]

When they emerge, toadlets typically are about 10–11 millimetres (0.39–0.43 in) in length, and grow rapidly – while the rate of growth varies based on the region, time of year and sex of the toad, Zug and Zug found an average initial growth rate of 0.647 millimetres (0.025 in) per day, followed by an average daily rate of 0.373 millimetres (0.015 in). Growth typically slows once the toads have reach sexual maturity.[27] This rapid growth is important for their survival – in the period between metamorphosis and sub–adulthood, the young toads have lost the toxicity that protected them as eggs and tadpoles, but have yet to fully develop the parotoid glands that produce bufotoxin.[28] Because they lack this key defence, it is estimated that only 0.5% of metamorph cane toads reach adulthood.[17][29]

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 of between 70 and 80 millimetres (2.76–3.15 in), while toads in Panama achieve maturity when they are between 90 and 100 millimetres (3.54–3.94 in) in length.[30] In tropical regions, such as their native habitats, breeding occurs throughout the year, but in subtropical areas breeding occurs only during warmer periods with the onset of the wet season.[31]

The cane toad is estimated to have a critical thermal maximum of 40–42 degrees Celsius (104–107.6 °F) and a minimum of around 10–15 degrees (50–59 °F).[32] The ranges can change due to adaptation to the local environment.[33] The cane toad also has a high tolerance to water loss. One study showed that individuals can withstand a 52.6% loss of body water, which allows them to survive outside tropical environments.[33]

[edit] Diet

Most frogs identify prey by their movements, and vision appears to be the primary method by which the cane toad detects prey; however, the cane toad can also locate food using their sense of smell.[34] As a result, they will also eat plants, dog food and household refuse in addition to the normal prey of small rodents, reptiles, other amphibians, birds and a range of invertebrates. They eat a wide range of material and have a habit of swallowing their prey.[35]

An adult cane toad with dark colouration, as found in El Salvador. The parotoid gland is prominatly displayed on the side of the head.
A specimen of Bufo marinus from El Salvador. The large parotoid glands are visible behind the eyes.

[edit] Defences

The adult cane toad possess enlarged parotoid glands behind the eyes and other glands across the back. When threatened, their glands secrete a milky-white fluid known as bufotoxin.[36] Bufotoxin contains components that are toxic to many animals. There are many reported deaths of animals,[37] and even humans who have consumed cane toads.[22]

Bufotenin, one of the chemicals excreted by the cane toad, is classified as a Class 1 drug under Australian drug laws. This places it in the same category as heroin and marijuana. It is thought that the effects of bufotenin are similar to that of mild poisoning; the stimulating effect, which includes mild hallucinations, lasts for less than an hour.[38] As the cane toad excretes bufotenin in small amounts, and other toxins in relatively large amounts, toad licking could result in serious illness or death.[39]

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.[36]

[edit] Predators

Many species prey on the cane toad in its native distribution. These include the Broad-snouted Caiman (Caiman latirostris), the Banded Cat-eyed Snake (Leptodeira annulata), the eel (family: Anguillidae), various species of killifish,[40] the Rock flagtail (Kuhlia rupestris), some species of catfish (order: Siluriformes) and some species of ibis (subfamily: Threskiornithinae).[40] Predators outside the cane toad's native range include the Whistling Kite (Haliastur sphenurus), the Rakali (Hydromys chrysogaster), the Black Rat (Rattus rattus) and the Water Monitor (Varanus salvator). Occasional cases of the Tawny Frogmouth (Podargus strigoides) and the Papuan Frogmouth (Podargus papuensis)[41] feeding on cane toads have been reported.

[edit] Distribution

The cane toad is native to the Americas, from the Rio Grande Valley in southern Texas to central Amazon and south-eastern Peru.[42][43] This range includes both tropical and semi-arid environments. The density of the cane toad within its native distribution is significantly lower than that of its introduced distribution. In South America, it is recorded at densities of 20 adults per 100 metres (109 yards) of shoreline, but in Australia the density reaches 1,000–2,000 adults over the same area.[44]

[edit] Introductions

The cane toad has been introduced to many regions of the world – particularly the Pacific – for the biological control of agricultural pests.[42] These extensive introductions have, on the main, been well documented, the cane toad may be one of the most studied of any introduced species.[45]

Before the early 1840s, the cane toad had been introduced into Martinique and Barbados, using toads imported from French Guiana and Guyana.[46] A further introduction was made to Jamaica in 1844 in an attempt to reduce the rat population.[47] Although the toad was unsuccessful in controlling the rodents, it was introduced to Puerto Rico in the early 20th century in the hope that it would be more effective against a beetle infestation that was ravaging the sugar cane plantations. It was, and following the economic success of the toad in negating the beetles, scientists in the 1930s praised it as an agricultural solution.[48]

As a result, many countries in the Pacific region emulated the lead of Puerto Rico and introduced the toad in the 1930s.[49] There are introduced populations in Australia, Florida,[50] Papua New Guinea,[51] the Philippines,[52] the Ogasawara and Ryukyu Islands of Japan,[53] most Caribbean islands,[49] and many Pacific islands,[49] including Hawaii[54] and Fiji.[55] Since then, the cane toad has become a pest in many host countries, and poses a serious threat to native animals.[56]

[edit] Australia

Main article: Cane toads in Australia
A map of Australia with the cane toad's distribution highlighted. The area follows the north-eastern coast of Australia, ranging from the Northern Territory through to the top end of New South Wales.
Distribution of the cane toad in Australia

Following the apparent success of the cane toad in reducing the white grub that was threatening the sugar cane plantations in Puerto Rico, and the successful introductions of the toad into Hawaii and the Philippines, there was a strong push for the cane toad to be released in Australia in order to assist with pest reduction in the Queensland cane fields.[57] Subsequently 102 toads were collected from Hawaii, consisting of an equal number of male and female specimens, and brought back to Australia.[58] After an initial release in August 1935, the Commonwealth Department of Health decided to ban future releases until a study could be conducted into the feeding habits of the toad. The study was completed in 1936 and the ban lifted, at which point large scale releases were undertaken – by March, 1937, 62,000 toadlets had been released into the wild.[57][58] The toads became firmly established in Queensland, increasing in number exponentially and extending their range into the Northern Territory and New South Wales.[20][58]

Tyler argues that the toad was unsuccessful in reducing the targeted beetles, in part because the cane fields provided insufficient shelter for the toads during the day.[59] Instead, 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, like the varanid lizards Varanus mertensi, V. mitchelli and V. panoptes, as well as the crocodile species Crocodylus johnstoni; in contrast, the population of the agamid lizard Amphibolurus gilberti – known to be a prey item of V. ponaptes – has increased.[60]

[edit] Caribbean

The cane toad was introduced to islands in the Caribbean in a number of attempts to control pests infesting local crops.[61] While it was able to establish itself in some regions, such as Barbados and Jamaica, other introductions, such as in Cuba before 1900 and in 1946, and on the islands of Dominica and Grand Cayman, were unsuccessful.[62]

The earliest recorded introductions were to Barbados and Martinique. The Barbados introductions were focused on the biological control of pests that were damaging the sugar cane crops,[63] and while the toads are abundant on the island, they have not been as successful in controlling the pests as in Australia.[64] In Martinique, the toad was introduced from French Guiana before 1944 and became established. Today, they reduce the mosquito and mole cricket populations.[65] A third introduction to the region occurred in 1884, with the toads appearing on the island of 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 in the area.[66] Other introductions include those released on Antigua, possibly before 1916, although there are suggestions that this initial population may have died out by 1934 and been reintroduced at a later date;[67] and Montserrat, which saw an introduction before 1879 that led to the establishment of a solid population, apparently sufficient to survive the Soufrière Hills volcano eruption in 1995.[68]

In 1920, the cane toad was introduced into Puerto Rico to control the populations of white-grub (Phyllophaga spp.), a sugar cane pest.[69] Before this, the pests were manually collected by humans. The introduction of the toad eliminated labor costs.[69] A second group of toads was imported in 1923, and by 1932 the cane toad was well established on the island.[70] The population of white-grubs dramatically decreased,[69] and at the annual meeting of the International Sugar Cane Technologists in Puerto Rico, the decrease in the white-grub population was attributed to the cane toad.[56] However, there may have been other factors.[56] The six-year period after 1931 (when the cane toad was most prolific, and the white-grub saw dramatic decline) recorded the highest ever rainfall for Puerto Rico.[71] Nevertheless, the assumption was that the cane toad controlled the white-grub; this view was reinforced by a Nature article titled "Toads save sugar crop",[56] and this led to large-scale introductions throughout many parts of the Pacific.[72]

More recently, the cane toad has been spotted in Carriacou and Dominica, the latter appearance occurring in spite of the failure of the earlier introductions.[73]

[edit] Fiji

The cane toad was introduced into Fiji to combat insects that infest sugar cane 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 impact, the national government of Fiji decided to release the toad in 1953, and 67 specimens were subsequently imported from Hawaii.[74] Once the toads were established, a 1963 study concluded as since the toad's diet included both harmful and beneficial invertebrates, it was considered "economically neutral".[55] 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.[75]

[edit] New Guinea

The cane toad was successfully introduced into New Guinea to control hawk moth larvae that were eating sweet potato crops.[51] The first release occurred in 1937 using toads imported from Hawaii, with a second release the same year using toads from the Australian mainland. Evidence suggests there was a third release in 1938, consisting of toads that were being used for human pregnancy tests (as many species of toad were found to be effective for this task, and were employed for aproximately 20 years after the discovery was announced in 1948).[76][77] Initial reports argued that the toads were effective in reducing the incidence of cutworm and it was suggested that sweet potato yields were improving.[78] Thus these first releases were followed by further distributions across much of the region,[78] 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 improved shelter offered by the forest.[79] (A similar situation occurred in the Australian cane fields before this date, but Tyler suggests this experience was either ignored in New Guinea or was not sufficiently publicized in the region).[79] The cane toad has since become abundant in rural and urban areas.[80]

[edit] United States

The cane toad naturally occurs in southern Texas, but attempts (both deliberate and accidental) have been made to introduce the species to other parts of the country. These include introductions to the mainland state of Florida and to the islands of Hawaii, as well as largely unsuccessful introductions to Louisiana.[81]

Initial releases into Florida failed. Attempted introductions before 1936 and 1944 to control sugar cane pests, along with subsequent attempts to introduce the species to the region, were unsuccessful as the toads failed to proliferate.[82][83] However, the toad gained a foothold in the state after an accidental release by an importer at the Miami International Airport in 1957, and deliberate releases by animal dealers in 1963 and 1964 established the toad in other parts of Florida.[83][84] Today, the cane toad is well established in Florida from the Florida Keys to north of Tampa, and they are gradually extending further northward.[85] Generally, while many may regard the toad as a nuisance, their presence does not seem to have adversely affected the native wildlife.[86]

A selection of cane toad merchandise, including key rings made from their legs, a coin purse made from the head, front limbs and body of a toad, and a stuffed cane toad.
Cane toad merchandise

Around 150 cane toads were introduced to Oahu in Hawaii in 1932, and the population swelled to 105,517 after 17 months.[49] The toads were sent to the other islands, and more than 100,000 toads were distributed by July 1934;[87] eventually over 600,000 were transported.[88]

[edit] Uses

Other than the previously mentioned use as a biological control for pests, the cane toad has been employed in a number of commercial and non-commercial applications. Traditionally, within the toad's natural range in South America, the native population would "milk" the toads for their toxin, which was then reportedly employed on hunting arrows. There are also suggestions that the toxins may have been used as a narcotic by the Olmec people. The toad has been hunted as a food source in parts of Peru, and eaten after the removal of the skin and parotoid glands.[89] More recently, the toad's toxins have been used in a number of new ways: bufotenine has been used in Japan as both an aphrodisiac and as a hair restorer, while it has been employed in cardiac surgery in China to lower the heart rates of patients.[22]

Other modern applications of the cane toad include pregnancy testing,[89] as pets,[90] laboratory research,[91] 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, and if spermatozoa appeared in the toad's urine, the patient was deemed to be pregnant.[89] The tests using toads were faster than those employing mammals, toads were easier to raise, and, although the initial 1948 discovery employed Bufo arenarum for the tests, it soon became clear that a variety of anuran species were suitible – including the cane toad. Thus for approximatly 20 years toads were employed in this task.[77] As a laboratory animal the cane toad is regarded as ideal; they are plentiful, and easy and inexpensive to maintain and handle. They use of the cane toad in experiments started in 1950s, and by the end of 1960s large numbers were being collected and exported to high schools and universities.[91] Since then, a number of Australian states have introduced or tightened importation regulations.[92] Even dead toads have value. Cane toad skin has been made into leather and novelty items;[93][94] stuffed cane toads, posed and accessorised, have found a home in the tourist market;[95] and attempts have been made to produce fertilizer from their bodies.[96]

[edit] Citations

  1. ^ Solis et al. 2008. Database entry includes a range map and justification for this species is of least concern.
  2. ^ a b Crossland, Alford & Shine 2009, p. 626
  3. ^ Linnaeus 1758, p. 824
  4. ^ Beltz 2007
  5. ^ Easteal et al. 1985, p. 185
  6. ^ "Cane Toad (Bufo marinus)". National Invasive Species Information Center. United States Department of Agriculture. June 15, 2009. http://www.invasivespeciesinfo.gov/animals/canetoad.shtml. Retrieved on June 17, 2009. 
  7. ^ Caughley & Gunn 1996, p. 140
  8. ^ Australian State of the Environment Committee 2002, p. 107
  9. ^ Kenny 2008, p. 35
  10. ^ a b Vanderduys & Wilson 2000, p. 1
  11. ^ a b "Giant Burrowing Frog". Wildlife of Sydney. Australian Museum. April 15, 2009. http://australianmuseum.net.au/Giant-Burrowing-Frog. Retrieved on June 17, 2009. 
  12. ^ Barker, Grigg & Tyler 1995, p. 381
  13. ^ Brandt & Mazzotti 2005, p. 3
  14. ^ a b c d e f Robinson 1998
  15. ^ Lee 2001, p. 928
  16. ^ Wyse 1997, p. 249
  17. ^ a b c Tyler 1989, p. 117
  18. ^ Tyler 1989, pp. 117-118
  19. ^ Grenard 2007, p. 55
  20. ^ a b c Cameron 2009
  21. ^ Tyler 1976, p. 81
  22. ^ a b c d Invasive Species Specialist Group 2006
  23. ^ a b c d e Tyler 1989, p. 116
  24. ^ Ely 1944, p. 256
  25. ^ Lever 2001, p. 3
  26. ^ Barker, Grigg & Tyler 1995, p. 380
  27. ^ Zug & Zug 1979, pp. 14–15
  28. ^ Zug & Zug 1979, p. 15
  29. ^ Anstis 2002, p. 274
  30. ^ Zug & Zug 1979, p. 8
  31. ^ Lever 2001, p. 6
  32. ^ Tyler 1989, p. 118
  33. ^ a b Tyler 1989, p. 119
  34. ^ Lever 2001, p. 10
  35. ^ Tyler 1989, pp. 130–132
  36. ^ a b Tyler 1989, p. 134
  37. ^ Tyler 1989, pp. 134–136
  38. ^ Fawcett 2004, p. 9
  39. ^ Weil & Davis 1994, pp. 1–8
  40. ^ a b Tyler 1989, p. 138–139
  41. ^ Angus 1994, pp. 10–11
  42. ^ a b Tyler 1989, p. 111
  43. ^ Zug & Zug 1979, pp. 1–2
  44. ^ Lampo & De Leo 1998, p. 392
  45. ^ Easteal 1981, p. 94
  46. ^ Easteal 1981, p. 96
  47. ^ Lannoo 2005, p. 417
  48. ^ Tyler 1989, pp. 112–113
  49. ^ a b c d Tyler 1989, pp. 113–114
  50. ^ Smith 2005, pp. 433–441
  51. ^ a b Zug, Lindgrem & Pippet 1975, pp. 31–50
  52. ^ Alcala 1957, pp. 90–96
  53. ^ Kidera et al. 2008, pp. 423–440
  54. ^ Oliver & Shaw 1953, pp. 65–95
  55. ^ a b Hinckley 1963, pp. 253–259
  56. ^ a b c d Tyler 1989, p. 113
  57. ^ a b Tyler 1976, p. 77
  58. ^ a b c Easteal 1981, p. 104
  59. ^ Tyler 1976, p. 83
  60. ^ Doody et al. 2009, pp. 46–53
  61. ^ Lever 2001, p. 67
  62. ^ Lever 2001, pp. 73–74
  63. ^ Lever 2001, p. 71
  64. ^ Kennedy, Anthony quoted in Lever 2001, p. 72
  65. ^ Lever 2001, p. 81
  66. ^ Lever 2001, pp. 78–79
  67. ^ Easteal 1981, p. 98
  68. ^ Lever 2001, pp. 81–82
  69. ^ a b c Tyler 1989, p. 112
  70. ^ Van Volkenberg 1935, pp. 278–279. "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."
  71. ^ Freeland 1985, pp. 211–215
  72. ^ Tyler 1989, pp. 113–115
  73. ^ Lever 2001, pp. 72–73
  74. ^ Lever 2001, pp. 128–129
  75. ^ Lever 2001, pp. 130–131
  76. ^ Easteal 1981, p. 103
  77. ^ a b Tyler, Wassersug & Smith 2007, pp. 6–7
  78. ^ a b Lever 2001, p. 118
  79. ^ a b Tyler 1976, pp. 83–84
  80. ^ Lever 2001, p. 119
  81. ^ Easteal 1981, pp. 100–102
  82. ^ Lever 2001, p. 57
  83. ^ a b Easteal 1981, p. 100
  84. ^ Lever 2001, p. 58
  85. ^ Lever 2001, p. 59
  86. ^ Lever 2001, p. 61
  87. ^ Lever 2001, p. 64
  88. ^ Easteal 1981, p. 101
  89. ^ a b c Lever 2001, p. 32
  90. ^ Mattison 1987, p. 145
  91. ^ a b Tyler 1976, p. 85
  92. ^ Tyler 1976, pp. 88–89
  93. ^ McCarin 2008, p. 8
  94. ^ Hardie 2001, p. 3
  95. ^ Bateman 2008, p. 48
  96. ^ Australian Associated Press 2006

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