Overview

Brief Summary

Biology

The green and golden bell frog is unusual in that it is often also active during the day. They breed in the warmer months from October to March (4). During the breeding season, males tend to call whilst partially submerged in the water (4) and females lay 3,000 to 10,000 eggs in gelatinous masses that initially float, but sink up to 12 hours after laying. Two days later the tadpoles hatch out and on average they will have fully metamorphosed into young froglets after a further two months (3), although the development period depends on the temperature (2). The voracious adults have a very broad diet, including insects and other frogs, even of the same species (4). The tadpoles feed on detritus, algae and bacteria (3). Natural predators include wading birds and snakes, and the tadpoles are taken by tortoises, eels and other fish (2) as well as a range of invertebrate predators (7).
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Description

The green and golden bell frog belongs to the tree frog family (Hylidae) (4) and was once one of the most common frogs in south-east Australia (5). Unfortunately it has undergone a major decline, and is now classified as globally Vulnerable by the IUCN Red List of Threatened Species (1). It is a large, stout-looking frog, with bright pea-green upperparts blotched with metallic brassy-brown or golden markings (2). A creamy-white stripe bordered below with black and above with gold extends from behind the eye to the groin. The belly is cream or white in colour, and has a granular texture (3). The legs are green and gold and the inside thigh and groin are electric-blue (2). Males are smaller than females and develop a yellowish throat when mature (2). When in breeding condition, males have swollen thumbs as they develop 'nuptial pads', used to grip females during mating (3). The large tadpoles have deep bodies and high tail fins (3). Just before their limbs form, they begin to develop the greenish colouration of the adults (2). This frog produces a deep, growling call which has been described as a four-part 'craw-awk, crawk, crok crok' (4) that has been likened to the sound of a motorbike changing gears (5).
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Comprehensive Description

Description

Green above with irregular bronze colored blotches, although there is variation in hues and the degree of blotching. Dorso-lateral skin fold is creamy, running from eye to groin though sometimes discontinuous. It is paralleled by a black canthal stripe that begins at the nostril and extends over the conspicuous tympanum to the groin. A white glandular stripe extends from the mouth to the base of the forearm. Flanks are brown with cream spots, and limbs are bronze to brown in color. Hind-side of thighs and groin are bright blue, and the belly is whitish. The skin is relatively smooth above, and it is granular below. Fingers lack webbing, while toes are almost fully webbed, and discs are conspicuous on both. Between the internal nasal openings (choanae), vomerine teeth are distinct. A pectoral fold is present (Cogger 1996).

Reproductively mature males have thumbs that are swollen through the development of nuptial pads (Pyke 1999). Males range from 57 to 69 mm, while females range from 65 to 108 mm in length. Larvae are large at metamorphosis, with a high tail fin and heavy pigmentation, typical of Litoria (Barker et al. 1995).

Featured in Amazing Amphibians on 2 December 2013

  • Barker, J., Grigg, G. C., and Tyler, M. J. (1995). A Field Guide to Australian Frogs. Surrey Beatty and Sons, New South Wales.
  • Morgan, L. A., and Buttemer, W. A. (1996). ''Predation by the non-native fish Gambusia holbrooki on small Litoria aurea and L. dentata tadpoles.'' Australian Zoologist, 30(2), 143-149.
  • Cogger, H. G. (1996). Reptiles and Amphibians of Australia. Reed Books Australia, Port Melbourne.
  • Medway, L. and Marshall, A. G. (1975). ''Terrestrial vertebrates of the New Hebrides: origin and distribution.'' Philosphical Transactions of the Royal Society of London. Series B., 272, 423-65.
  • Pyke, G. H. (1999). ''Green and Golden Bell Frog.'' Nature Australia, 26(4), 50-59.
  • Pyke, G. H. and White, A. W. (1996). ''Habitat requirements for the Green and Golden Bell Frog Litoria aurea (Anura: Hylidae).'' Australian Zoologist, 30(2), 224-232.
  • Van De Mortel, T. F., and Buttemer, W. A. (1996). ''Are Litoria aurea eggs more sensitive to ultraviolet-B radiation than eggs of sympatric L. peronii or L. dentata?'' Australian Zoologist, 30(2), 150-157.
  • White, A. W. and Pyke, G. H. (1996). ''Distribution and conservation status of the Green and Golden Bell Frog Litoria aurea in New South Wales.'' Australian Zoologist, 30(2), 177-189.
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Distribution

Range Description

This Australian species has been recorded along the south-east coast from East Gippsland in Victoria, north to approximately Byron Bay in north-east New South Wales (Gillespie 1996; White and Pyke 1996). Most records are from elevations below 100m asl. North of Sydney, there were a few high-elevation records of the species and almost all records were east of the Great Divide (the only discrepant records are from Armidale and Ebor) (White and Pyke 1996). On the Southern Tablelands, the species does not appear to occur above 800m asl (Osborne, Littlejohn and Thomson 1996) and in Victoria the species does not appear to occur above about 670m asl (Gillespie 1996). Populations occur on two offshore islands in New South Wales, Bowen Island in Jervis Bay (Osborne and McElhinney 1996) and Broughton Island north of Port Stephens (New South Wales NPWS Atlas 1998). It remains unknown whether or not these populations are relictual or the result of assisted translocation (Mahony 1999). It has been introduced to New Zealand and is widespread across northern North Island, and pet traders have moved it between the North and South Islands. It is also introduced to New Caledonia and New Hebrides (Tyler 1979).
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Distribution and Habitat

Found primarily at lower altitudes in eastern and southeastern New South Wales, Australia, as well as far eastern Victoria. It has been introduced to New Zealand and a number of other Pacific Islands where it is locally abundant (Medway and Marshall 1975).

Prefers freshwater habitat, where the water bodies are still, shallow, unshaded, ephemeral, and unpolluted (Pyke and White 1996). Inhabited water bodies are generally isolated and free of native fish species. Individuals disperse and forage over large areas, and diverse terrestrial habitats. Emergent aquatic vegetation, such as reeds and rushes, furnish foraging and basking habitat, and nearby grassy areas provide the principal feeding ground (Pyke 1999).

  • Barker, J., Grigg, G. C., and Tyler, M. J. (1995). A Field Guide to Australian Frogs. Surrey Beatty and Sons, New South Wales.
  • Morgan, L. A., and Buttemer, W. A. (1996). ''Predation by the non-native fish Gambusia holbrooki on small Litoria aurea and L. dentata tadpoles.'' Australian Zoologist, 30(2), 143-149.
  • Cogger, H. G. (1996). Reptiles and Amphibians of Australia. Reed Books Australia, Port Melbourne.
  • Medway, L. and Marshall, A. G. (1975). ''Terrestrial vertebrates of the New Hebrides: origin and distribution.'' Philosphical Transactions of the Royal Society of London. Series B., 272, 423-65.
  • Pyke, G. H. (1999). ''Green and Golden Bell Frog.'' Nature Australia, 26(4), 50-59.
  • Pyke, G. H. and White, A. W. (1996). ''Habitat requirements for the Green and Golden Bell Frog Litoria aurea (Anura: Hylidae).'' Australian Zoologist, 30(2), 224-232.
  • Van De Mortel, T. F., and Buttemer, W. A. (1996). ''Are Litoria aurea eggs more sensitive to ultraviolet-B radiation than eggs of sympatric L. peronii or L. dentata?'' Australian Zoologist, 30(2), 150-157.
  • White, A. W. and Pyke, G. H. (1996). ''Distribution and conservation status of the Green and Golden Bell Frog Litoria aurea in New South Wales.'' Australian Zoologist, 30(2), 177-189.
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Range

This species is found in eastern and south-eastern New South Wales, the Australian Capital Territory and eastern Victoria, Australia (3). In New South Wales and Victoria this species has undergone a severe decline in terms of both range and abundance since the 1960s (1). It has disappeared from all highland areas over 250m except for the population in the Australian Capital Territory, and coastal populations have become small and highly isolated. A study of subpopulations throughout the region has shown that many are worryingly small (less than 20 adults) (1). This frog still survives in some areas of Sydney, one of which was the proposed site for the tennis courts for the 2000 Sydney Olympics. After the frog was discovered on the site, the courts were built elsewhere, and the species has been monitored at the site ever since (5). This frog has been introduced to New Zealand and some Pacific Islands (3).
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Physical Description

Type Information

Holotype for Litoria aurea
Catalog Number: USNM 15478
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Amphibians & Reptiles
Preparation: Ethanol
Year Collected: 1840
Locality: Wollongong, Illawara, New South Wales, Australia
  • Holotype: Girard, C. 1853. Proc. Acad. Nat. Sci. Philadelphia. 6 (11): 422.
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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
The natural habitat requirements of the species have proved difficult to define because it has been associated with almost every type of water body except fast-flowing streams (Pyke and White 1996). There also appears to be some confusion over whether or not forested habitats are utilized by the species (Lemckert 1996; Gillespie 1996). Pyke and White (1996) examined sites where L. aurea is known to have been present, and compared the habitat at sites where breeding was identified with that at locations where breeding was not identified, in New South Wales. Sites which supported breeding populations were found to contain waterbodies which are still, shallow, ephemeral, unpolluted, unshaded, with aquatic plants and generally free of Gambusia and other predatory fish (but not always); adjacent terrestrial habitats consisted of grassy areas and vegetation no higher than woodlands, and a range of diurnal shelter sites. Breeding occurred in a significantly higher proportion of sites with ephemeral ponds rather than sites with fluctuating or permanent ponds, and where predatory fish were absent. Mahony (1999) commented on the limitations of the study and suggested that the results do not necessarily identify the requirements of the species prior to declines. It is worthy to note that the use of ephemeral breeding sites was not a feature associated with members of the bell frog group in earlier habitat descriptions (Mahony 1999). Pyke and White (1996) suggest that the habitat requirements of L. aurea in New South Wales and Victoria differ. In New South Wales the species occupies disturbed habitats and breeding largely occurs in ephemeral ponds (Pyke and White 1996). However, in Victoria it occupies habitats with little human disturbance and commonly breeds in permanent ponds as well as ephemeral ponds (Pyke and White 1996). Goldingay (1996) argued that this is because most natural habitats are degraded or lost in New South Wales. In Victoria the species is predominantly found on the coastal plains and low foothills of the hinterland where it has been recorded in a range of lentic and terrestrial habitats (Gillespie 1996). Breeding has been documented from dams in both forested and cleared areas, swamps in farmland, gravel pits, billabongs, marshes, coastal lagoon wetlands, wet swale herb lands and isolated stream-side pools (Gillespie 1996). These habitats are mostly permanent, but include some ephemeral waterbodies (Gillespie 1996). All habitats are characterized by stationary water (Gillespie 1996). Virtually all isolated waterbodies are free of native fish species and typically have dense emergent vegetation (Gillespie 1996). It can be found in a variety of terrestrial habitats including lowland forest, banksia woodland, wet heath land, riparian scrub complex, riparian shrubland, riparian forest, damp forest, shrubby dry forest and cleared pastoral lands (Gillespie 1996). It is seasonally active and has been observed from September to early May (Daly 1995). Males call between September and March. Spawn is laid amongst aquatic vegetation and has been observed in December, January and February (Daly 1995). Counts of eight egg masses ranged from 2,463-11,682 eggs (van de Mortel and Goldingay 1998). Eggs hatch within three days and metamorphosis can take from 2-11 months (Daly 1995); however, six weeks appears to be an average duration for the field (R. Goldingay pers. comm.).

Systems
  • Terrestrial
  • Freshwater
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Although a member of the tree frog family, this species tends to spend most of its time on the ground or in water (4). Its habitat requirements have been difficult to pin-point, as it has been found in a huge range of water bodies except fast-flowing streams (1). It is most typically found in short-lived freshwater ponds that are still, shallow and unpolluted, and it tends to avoid waters supporting native fish (3). Foraging and basking habitats are characterised by the presence of dense vegetation that protrudes out of the water; furthermore, grassy habitats are usually close at hand to provide suitable terrestrial feeding grounds (3).
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
VU
Vulnerable

Red List Criteria
A2ace

Version
3.1

Year Assessed
2004

Assessor/s
Jean-Marc Hero, Graeme Gillespie, Harold Cogger, Frank Lemckert, Peter Robertson

Reviewer/s
Global Amphibian Assessment Coordinating Team (Simon Stuart, Janice Chanson and Neil Cox)

Contributor/s

Justification
Listed as Vulnerable because of a population decline, estimated to be more than 30% over the last ten years, based on an observed reduction in the number of mature individuals, Area of Occupamcy, number of locations, the extent and quality of its habitats, and the effects of chytridiomycosis and introduced predators.

History
  • 2002
    Vulnerable
  • 1994
    Insufficiently Known
    (Groombridge 1994)
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Status

Classified as Vulnerable (VU A2abce) by the IUCN Red List (1) and listed on Schedule 1 of the New South Wales Threatened Species Conservation Act 1995 (3). Listed as near threatened under the Victorian Flora and Fauna Guarantee Act (1998) (6).
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Population

Population
This species was formerly considered to be common throughout its range (Tyler 1992). Since about 1960, declines in the distribution and abundance of the species have been observed to the extent that it may now be regarded as rare (White and Pyke 1996). In New South Wales, the species has disappeared completely from all highland areas above 250m asl and coastal populations have been reduced in number and are more isolated from other populations (White and Pyke 1996). Osborne, Littlejohn and Thomson (1996) observed that the species had declined in the Australian Capital Territory and had not been recorded from the Southern Tablelands since 1980. Declines in abundance have been observed in New South Wales and the Australian Capital Territory (White and Pyke 1996; Osborne, Littlejohn and Thomson 1996; Lewis and Goldingay 1999; Goldingay and Lewis 1999), although no similar decline in distribution and abundance in Victoria is so far apparent (Gillespie 1996). Recent censuses of populations throughout the distribution of the species indicate that many are small, with most estimates being less than 20 adults (White and Pyke 1996). In New Zealand, where the species has been introduced, there are many thousands of individuals, but local declines have been observed with chytridiomycosis and introduced Gambusia fish being implicated.

Population Trend
Decreasing
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Life History, Abundance, Activity, and Special Behaviors

These frogs are non-climbers, and are commonly found perched on aquatic vegetation near breeding sites. Individuals are active during the day, and breed during the summertime (October though March, though as early as August). Males call from the water. Females deposit between three and ten thousand eggs in a floating gelatinous mat, which sinks after 6-12 hours. Tadpoles hatch around two days, and immature froglets appear around two months (Pyke 1990).

Tadpole diet includes bacteria, algae and organic detritus, while adult frogs feed on almost anything, including insects and other frogs (Pyke 1990). In short, the frogs are a voracious, cannibalistic species.

Their deep growling call has been described as a slow gutteral four-part 'craw-awk, crawk, crok, crok' (Cogger 1996).

  • Barker, J., Grigg, G. C., and Tyler, M. J. (1995). A Field Guide to Australian Frogs. Surrey Beatty and Sons, New South Wales.
  • Morgan, L. A., and Buttemer, W. A. (1996). ''Predation by the non-native fish Gambusia holbrooki on small Litoria aurea and L. dentata tadpoles.'' Australian Zoologist, 30(2), 143-149.
  • Cogger, H. G. (1996). Reptiles and Amphibians of Australia. Reed Books Australia, Port Melbourne.
  • Medway, L. and Marshall, A. G. (1975). ''Terrestrial vertebrates of the New Hebrides: origin and distribution.'' Philosphical Transactions of the Royal Society of London. Series B., 272, 423-65.
  • Pyke, G. H. (1999). ''Green and Golden Bell Frog.'' Nature Australia, 26(4), 50-59.
  • Pyke, G. H. and White, A. W. (1996). ''Habitat requirements for the Green and Golden Bell Frog Litoria aurea (Anura: Hylidae).'' Australian Zoologist, 30(2), 224-232.
  • Van De Mortel, T. F., and Buttemer, W. A. (1996). ''Are Litoria aurea eggs more sensitive to ultraviolet-B radiation than eggs of sympatric L. peronii or L. dentata?'' Australian Zoologist, 30(2), 150-157.
  • White, A. W. and Pyke, G. H. (1996). ''Distribution and conservation status of the Green and Golden Bell Frog Litoria aurea in New South Wales.'' Australian Zoologist, 30(2), 177-189.
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Threats

Major Threats
The cause(s) of the apparent declines observed in populations of all taxa within the L. aurea complex are unclear (Gillespie, Osborne and McElhinney 1995). Investigations of disappearances among the group have primarily focused on L. aurea and L. castanea and two major directions in research have been pursued: the role of increased ultraviolet radiation; and the impact of the introduced fish, Gambusia (Mahony 1999). It is also possible that disease, such as a viral infection or chytrid fungus, might have contributed to the decline of this species (W. Osborne pers. comm.). Chytrid fungus was detected in this species in Hoskinstown and Homebush Bay in Sydney, New South Wales.
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Life History, Abundance, Activity, and Special Behaviors

During the 1950's, Green and Golden Bell Frogs were abundant throughout New South Wales, in such numbers that they were commonly collected for dissection experiments and as food for captive snakes (White and Pyke 1996). Rapid declines were first noticed in the early 1990's, and extensive surveying has been conducted to locate sites and document population trends. The research of White and Pyke (1996) indicated a severe loss of populations throughout New South Wales after 1990, specifically the disappearance of frogs from 113 of a recorded 137 sites. The best long-term documentation comes from White's population records of the Eastlakes in Sydney, demonstrating a consistent decline from 138 adult frogs in 1968 to only 3 in 1993 (White and Pyke 1996).

The most probable causes for decline include habitat fragmentation, drainage alteration, and the introduction of predatory fish. A number of studies have shown correlation between L. aurea declines and the increasing distribution of Gambusia holbrooki (the "Mosquito Fish"), a native to North America that was introduced to control mosquito larvae. Morgan and Buttemer (1996) conducted laboratory experiments which demonstrated the high susceptibility of L. aurea tadpoles to predation by G. holbrooki, particularly small, newly hatched tadpoles. UVB experimentation (van de Mortel and Buttemer 1996) has not demonstrated any significant susceptibility of L. aurea to radiation exposure.

  • Barker, J., Grigg, G. C., and Tyler, M. J. (1995). A Field Guide to Australian Frogs. Surrey Beatty and Sons, New South Wales.
  • Morgan, L. A., and Buttemer, W. A. (1996). ''Predation by the non-native fish Gambusia holbrooki on small Litoria aurea and L. dentata tadpoles.'' Australian Zoologist, 30(2), 143-149.
  • Cogger, H. G. (1996). Reptiles and Amphibians of Australia. Reed Books Australia, Port Melbourne.
  • Medway, L. and Marshall, A. G. (1975). ''Terrestrial vertebrates of the New Hebrides: origin and distribution.'' Philosphical Transactions of the Royal Society of London. Series B., 272, 423-65.
  • Pyke, G. H. (1999). ''Green and Golden Bell Frog.'' Nature Australia, 26(4), 50-59.
  • Pyke, G. H. and White, A. W. (1996). ''Habitat requirements for the Green and Golden Bell Frog Litoria aurea (Anura: Hylidae).'' Australian Zoologist, 30(2), 224-232.
  • Van De Mortel, T. F., and Buttemer, W. A. (1996). ''Are Litoria aurea eggs more sensitive to ultraviolet-B radiation than eggs of sympatric L. peronii or L. dentata?'' Australian Zoologist, 30(2), 150-157.
  • White, A. W. and Pyke, G. H. (1996). ''Distribution and conservation status of the Green and Golden Bell Frog Litoria aurea in New South Wales.'' Australian Zoologist, 30(2), 177-189.
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There are many factors thought to be responsible for the dramatic decline of this species. Habitat fragmentation, the introduction of predatory fish and alteration of drainage regimes are all thought to be involved. Many studies have shown that losses of this frog are closely related to the introduction of the 'mosquito fish' (Gambusia holbrooki), native to North America and introduced as an attempt to control mosquito larvae. Laboratory studies have demonstrated that the tadpoles of the green and golden bell frog are extremely susceptible to predation by this fish (3). Other factors thought to affect this species include predation by introduced mammalian predators such as cats and foxes, changes to the quality of water, herbicide use, and loss of habitat through the destruction of wetlands (2). However, the recently identified Chytrid fungus appears likely to have led to at least some and perhaps most of the major declines observed through the 1970s and 1980s (7).
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Management

Conservation Actions

Conservation Actions
There has been a lot of research into threats to the species and movement towards a conservation strategy. Its range includes several protected areas. As an introduced species in New Zealand it has the potential to spread chytridiomycosis to areas inhabited by native frogs. There is a cooperative program between Taronga Zoo and a range of NSW agencies and NGO’s, involving breeding and release at a number of sites close to Sydney. This program is currently under review.
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Conservation

The green and golden bell frog has been the subject of much research and monitoring. This is very important, as well-informed conservation measures are likely to be more effective (1). Current work is focusing on the development of management measures to keep the introduced mosquito fish under control. Furthermore, strategies are being devised that will allow the development and improvement of suitable habitat in order to increase the reproductive success of the species. In parallel to these measures, community awareness programmes have also been proposed (2).
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Wikipedia

Green and golden bell frog

For the frog found in Southwest Australia, see Western green and golden bell frog.
"Green and golden frog" redirects here. It is not to be confused with Green and gold frog.

The green and golden bell frog (Litoria aurea), also named the green bell frog, green and golden swamp frog and green frog, is a ground-dwelling tree frog native to eastern Australia. Despite its classification and climbing abilities, it does not live in trees and spends almost all of its time close to ground level. It can reach up to 11 cm (4.3 in) in length, making it one of Australia's largest frogs.

Coloured gold and green, the frogs are voracious eaters of insects, but will also eat larger prey, such as worms and mice. Unlike most frogs, they are active at day, although this is mostly to warm in the sun. They tend to be less active in winter except in warmer or wetter periods, and breed in the warmer months. Males reach maturity after around 9 months, while for the larger females, this does not occur until they are two years old. The frogs can engage in cannibalism, and males frequently attack and injure one another if they infringe on one another's space.

Many populations, particularly in the Sydney region, inhabit areas of infrequent disturbance, such as golf courses, disused industrial land, brick pits, and landfill areas. Though once one of the most common frogs in south-east Australia, the green and golden bell frog has endured major population declines, particularly in highland areas, leading to its current classification as globally vulnerable. Its numbers have continued to fall and are threatened by habitat loss and degradation, pollution, introduced species, and parasites and pathogens, including the chytrid Batrachochytrium dendrobatidis.[1] As most of the remaining populations live on private land, the logistics of the conservation effort can be complicated. Despite the situation in Australia, the frog remains abundant in New Zealand and several other Pacific islands, where it has been introduced.

Taxonomy[edit]

Profile and dorsal views of a green and golden bell frog

The common name, "green and golden bell frog", was first adopted by Harold Cogger in his 1975 book Reptiles and Amphibians of Australia. Before this, its common names were "golden frog" and "golden tree frog". The green and golden bell frog has many physical and behavioural characteristics representative of ranids, hence its original classification as Rana. It has a pointy snout, long legs, and almost complete toe webbing; the tympanum is large and distinct; and the overall body shape is similar to many Rana species. Like many frogs in the Rana genus, green and golden bell frogs are mostly aquatic, and only travel over land during periods of rainfall. It was removed from the genus because of anatomical differences with the family Ranidae. The bone and cartilage structural formations of the green and golden bell frog are closest to those of species in the family Hylidae; it was therefore reclassified.

Litoria aurea (left) was first classed as a species of the genus Rana (right). There are many physical similarities, including a pointy snout, long legs, and almost complete toe webbing. The overall body shape is similar to many Rana species.

The green and golden bell frog was first described as Rana aurea by Lesson in 1827. It has changed classification 20 times; it was first named Litoria aurea in 1844 by Günther, and changed another 9 times before being named again as Litoria aurea.[2] The specific epithet aurea derived from the Latin aureus for 'golden'.[3] The species is now classified within the Litoria aurea complex, a closely related group of frogs in the Litoria genus.[4] This complex is scattered throughout Australia: three species occur in south-east Australia, one in northern Australia, and two in Southwest Australia.[4] The complex consists of the green and golden bell frog (L. aurea), growling grass frog (L. raniformis), yellow-spotted bell frog (L. castanea), Dahl's aquatic frog (L. dahlii), spotted-thighed frog (L. cyclorhyncha) and the motorbike frog (L. moorei).[4] The ranges of L. raniformis and L. castanea overlap with the green and golden bell frog;[4] this, as well as physical similarities, may make it difficult to distinguish between the species, and until 1972, L. raniformis and the green and golden bell frog were regarded as the same, when electrophoretic studies proved them to be distinct.[5] The tablelands bell frog has not been seen since 1980 and may now be extinct, although the large yellow spots present on its thighs help distinguish it from the green and golden bell frog. The growling grass frog, which is very similar to the green and golden bell frog, can only be readily distinguished by raised bumps on the dorsal surface. It has also been proposed that some populations of L. aurea located near Ulong, New South Wales, be a separate subspecies, L. a. ulongae, but this was not accepted.[5]

Litorea aurea is equally and most closely related to Li. castanes and L. ranaformis. A microcomplement fixation technique using serum albumins has indicated the species closest to L. aurea is L. ranifomis. Albumin immunological distance data suggest no differentiation between the two, and the green and golden bell frog evolutionally separated from the other two species about 1.1 million years ago. A 1995 study of protein variations showed four of 19 protein systems had variation and only two had differentiation.[5] Scientists believe the different species can still hybridise, as their distribution areas still overlap, and both L. raniformis and L. aurea have been seen sharing ponds in the Gippsland area of Victoria.[5] However, little evidence of hybridisation actually occurring has been found. Although there have been reports of frogs of mixed appearance in Gippsland, analysis of proteins and sera of the frogs showed two distinct species.[6] Samples in other area of distribution have shown no evidence of hybridisation in spite of cohabitation.[6]

Distribution[edit]

The historic (grey) and the current (black) distribution of the green and golden bell frog
The distribution of L. aurea in New Zealand

The green and golden bell frog is native to south-eastern Australia. Before its decline in population, its distribution ranged from Brunswick Heads, in northern New South Wales, to East Gippsland, in Victoria,[7] and west to Bathurst, Tumut and the Australian Capital Territory.[8]

The bell frog's current distribution now ranges from Byron Bay, in northern New South Wales, to East Gippsland, in Victoria; populations mostly occur along the coast.[1] In New South Wales, it has declined severely in range and abundance since the 1960s, although no similar declines have been reported in Victoria.[9] In New South Wales, it has disappeared from highland areas above 250 m (820 ft),[1] except for a population in Captains Flat. A study of populations along coastal New South Wales indicated many populations were very small, usually of fewer than 20 adults. According to a 1996 study, six populations of more than 300 frogs are known: two in the Sydney metropolitan area, two in the Shoalhaven, and two in the New South Wales mid-north coast.[10] There are now approximately only 40 sites in total where it is found, most of which are in the Sydney area.[11] The green and golden bell frog has disappeared from an estimated 90% of its former range.[12] Some specimens were apparently found in Armidale, but it turned out to be a misidentification of L. castanea.[11] The declines in Victoria have been more modest and mostly in at inland areas where habitats have disappeared.[13]

The green and golden bell frog survives in some areas of Sydney, such as the Brickpit at Sydney Olympic Park (the proposed site for the tennis courts for the 2000 Sydney Olympics). When the green and golden bell frog was found there, the tennis courts were built elsewhere, and the population has since been monitored. This frog has become an unofficial mascot for the Homebush Bay area.[14] It has also been introduced to places in Sydney in its natural habitat, without much success.[13]

The green and golden bell frog occurs on three islands off the east coast of Australia: Kooragang and Broughton Islands off Port Stephens, and Bowen Island at Jervis Bay.[1][12] It was introduced to New Zealand in the 1860s, and it is now common on the part of North Island north of Rotorua. In most places, it is the only frog species in the vicinity.[13] However, recent declines have been reported, suspected to be due to predatory fish. It was also introduced to the Pacific island countries of New Caledonia and Vanuatu in the 19th century, and has since become common there.[1][13]

No discernible variation in size or appearance in green and golden bell frogs between different geographic areas is found. Fluctuations in size and appearance between different populations are outweighed by variations within the populations themselves.[6] Females are more likely to be found away from breeding sites, while the opposite applies for males. Metamorphlings are divided in roughly equal numbers between males and females, while juvenile frogs are observed less often than their mature counterparts, although scientists are not sure whether this is due to lower abundance or increased reclusiveness.[15]

Description[edit]

A green and golden bell frog with a dark colouration

The green and golden bell frog is a large, stout frog; adults range from 4.5 to 11 cm (1.7 to 4.3nbsp;in) in length; typical specimens measure 6 to 8 cm (2.5–3.3 in).[10] The green and golden bell frog is therefore one of the largest Australian frogs.[9] Mature males are generally smaller than mature females, and the colour on their dorsal surfaces differ greatly from females. It may be almost completely green, of shades from dark pea-green to bright emerald, green with metallic, brassy, dull copper-brown, or gold markings; or almost completely bronze.[9][16] Generally, females tend to have more green patches than males.[6] During the cooler months (May–August), when the frogs are inactive, colouration may darken almost to black.[17] They can also darken in this way by simply staying in a dark place for a few minutes, and the colour can also change during the frogs' lifetimes.[17]

A creamy-white or pale yellow stripe, bordered above with gold and below with black, extends from behind the eye, across the typically copper-coloured tympanum to the groin. This stripe rises to form a dorsolateral fold towards the groin. Another stripe of the same colour begins below the eye and continues to the shoulder. The abdomen is cream or white, and has a coarsely granular texture. The legs are green, bronze, or a combination of both, and the inside thigh and groin are blue-green.[9][16] Mature males develop a yellowish colouration to the vocal sacs on their throats.[18] The tympanum is distinct and ovular in shape, and the species has enlarged toe discs to aid in climbing. As this species is often found in water, the fingers are free from webbing, while the toes are almost completely webbed.[16] When in breeding condition, males develop nuptial pads on their thumbs, which are used to grip females during mating. These are coloured brown during the breeding season, but are inconspicuous and paler during the rest of the year.[18] During the breeding season, females develop a blueish hue on their feet, while males' legs turn rusty orange.[19]

Ecology and behaviour[edit]

Green and golden bell frog demonstrating camouflage within reedy environments

As a member of the tree frog family, the green and golden bell frog spends much time basking in the sun on vegetation, rocks, and reeds, usually near water, or hopping around between such places.[20] Unlike most frog species, it is often active during the day. When handled, this species secretes a slimy acrid mucus,[21] which consists of 17 aurein peptides. Thirteen of these show broad-spectrum antibiotic and anticancer activity.[22] The secretion makes the frog slippery and hard to grip, and is poisonous to some other species of frogs, so it is a useful defensive tool for green and golden bell frogs.[23] Males often fight one another if they come within 1 m of each other, frequently leading to injuries.[23]

The green and golden bell frog has been detected in a wide range of habitats. It is generally associated with coastal swamps, wetlands, marshes, dams, ditches, small rivers, woodlands, and forests, but populations have also been found at former industrial sites (for instance, the Brickpit). It has even been found in human vessels such as bathtubs.[19] The requirements of its habitat have been difficult to determine, for it has been found in a wide range of water bodies except fast-flowing streams.[24] It is most typically found in short-lived freshwater ponds that are still, shallow, unshaded, and unpolluted, and it tends to avoid waters that contain predatory fish, whether native or introduced.[1] However, it is most often found in areas that have been affected by human habitation.[25] The frog prefers water bodies that support emergent vegetation, such as reeds and bullrushes, for basking, and winter habitats consist of available shelters around the breeding site, which can be vegetation, rocks, rubbish, or human debris and discarded building materials. Grassy habitats are usually close at hand to provide suitable terrestrial feeding grounds.[1][26] It prefers waterways with a substrate of sand, rock, or clay,[19] and can tolerate a wide range of water turbidities, pH and oxygen levels, and temperatures, although these can hamper physical growth.[19] Although its legs provide much grip, the frog does not choose to climb trees or live up them to any significant extent. It spends most of its time within 10 cm of the ground and rarely ventures more than a metre above the ground.[20] The green and golden bell frog also has the ability to sit still for several minutes.[20]

The green and golden bell frog can travel far in a single day or night; distances of 1.0 to 1.5 km have been recorded. Tagging experiments have shown that some can move up to 3 km in total, and that some travel several kilometres from the closest breeding habitat.[27] However, the species evidently tends to return to or remain at an identified site, provided the habitat stays appropriate for its needs, or else it will move away. The green and golden bell frog also favours areas with the greatest habitat complexity, and as such, this is a core component of habitat-based strategies to protect the species.[27] In general, the frogs stay within areas of 100–700 m2 The frog is well-equipped for survival on land. It can rehydrate by absorbing moisture through its ventral skin, and evaporative water loss occurs at a rate, indicative of a watertight skin.very low [25] Some have been observed up to 400 m from the nearest body of water.[20]

During the winter months, the frog tends to be inactive, staying in one place, whereas it moves around during the warmer months to search for food and mating partners. During winter, the frog does become active for brief periods during warm or wet weather. In cold conditions, the frogs are thought to hibernate, based on observations of some being uncovered in a "torpid" state, but this has yet to be proven with rigorous physiological studies.[20] Although the frog is active during the day, this is restricted to leaving its shelter to sunbathe. It tends to not actively feed or forage during the day, hunting insects only if they move into its vicinity.[20]

The green and golden bell frog's reproduction depends on salinity and water temperature. Salinity affects tadpoles' development and metamorphosis,[28] and breeding is significantly slowed for ponds that measure 20°C (68°F) or below.[25] The tadpoles can tolerate salinity levels of six parts per thousand (ppt) without any apparent effects, while salinity of 8 ppt or higher decreases growth rates and increases mortality rates.[19] On the other hand, salinity levels of at least 1–2 ppt can be beneficial to the green and golden bell frog because this kills pathogens such as the chytrid fungus. The pH of the pond is not found to affect the likelihood of the eggs to hatch for values between 4 and 10.[25][29]

Diet and predators[edit]

The voracious adults have very broad diets, including insects such as crickets, larvae, mosquito wrigglers, dragonflies, earthworms, cockroaches, flies, and grasshoppers.[30] They are also known to eat freshwater crayfish and slugs, and other frogs, even of the same species.[30] They have a strong tendency for cannibalism, and frequently these in the same enclosure devour each other. Studies and trials in the wild have shown cannibalism also occurs in the wild.[30]

The tadpoles feed on detritus, algae, and bacteria.[31] Tadpoles in more advanced phases of development may show a preference for vegetable matter, but also scavenge or become carnivorous on aquatic life. Captive tadpoles have eaten boiled lettuce and pet food in pellet form.[31] If population density is high, tadpoles have cannibalised one another.[20]

In captivity the green and golden bell frog is known to feed on crickets, fruit flies, maggots, silkworms, domestic flies, beetles, mealworms, larvae, slaters, cockroaches, molluscs, plague locusts, spiders, water snails, earthworms, and mice. A case of a small tiger snake being eaten has also been reported.[30] Captive frogs have a habit of not responding to stationary food items, which has helped to form the belief that the frog will eat most things that move.[30]

The hunting habits of the frogs change depending on their growth phase and thus physical size. Smaller, still-growing green and golden bell frogs tend to hunt small, especially flying, insects, often jumping to catch their prey. Adult frogs appear to show a distinct preference for larger, land-based insects and frogs,[30] although they also eat aquatic prey, such as tadpoles and other aquatic organisms. Recently metamorphosed individuals have also been seen enter to shallow water to capture mosquito wrigglers.[30] The relative proportion that various prey make up in the frog's diet is not known.[31] In observed studies of captive frogs, they eat less in cooler periods of the year, and frogs in the wild ate less during breeding periods.[31] Younger frogs were also seen to forage longer into the warmer months to build up food stocks than fully matured frogs.[26]

Natural predators include wading birds, such as reef egrets, white-faced herons, white ibises and swamp harriers. Other predators include snakes, skinks, red foxes, tortoises, and eels and other fish, such as redfin perch and European carp, several varieties of gudgeon, and a range of invertebrate predators, such as the large brown mantis.[31][32] Predation on adult frogs has been recorded for the red-bellied black snake, tiger snake,[31] laughing kookaburra, and sacred kingfisher; wading birds and other snakes, such as the green tree snake and the copperhead snake, are also believed to be predators of the frog.[18] The relative magnitude of the various predatorial threats to the frog and its tadpoles is not known.[31] Before the frog became rare, and when subsistence lifestyles were more common, it was hunted and eaten by Australian Aborigines. It was also used in dissection demonstrations in biology classes, and caught by humans for feeding pet reptiles.[23]

Reproduction[edit]

Development of green and golden bell frog

The green and golden bell frog breeds in the warmer months from October to March, although some cases have been recorded earlier at the end of winter. Reproduction appears to be influenced by geography. More southerly and highland populations appear to have a shorter window for breeding than their more northerly and lowland counterparts. The latter appear commence breeding earlier and end later than the former group.[18] During the breeding season, males call, usually while floating in the water, but sometimes on vegetation at the side of a pond, mainly at night. They do so with a deep growl that has been described as a four-part "walk-walk sound"—likened to the sound of a motorbike changing gears.[16][18] Males have been found to respond to recordings of the call, and this is why entire groups of males will then call in unison.[18] Males are also more likely to call under certain temperature ranges, 16–23°C for water temperature, and 14–25°C in the air. Calling is also more likely immediately after rain has occurred.[33]

Males appear to reach maturity at around 45–50 mm, at between 9 and 12 months, and at this size begin to develop a grey to brownish yellow wash beneath the chin. This indicates the development of a vocal sac and thus an ability to commence calling behaviour.[18] Females reach sexual maturity at two years; those smaller than 65 mm are not seen in amplexus; this length is not reached until the second season after metamorphosis.[34] The frog is not of a type that only breeds once.[34] Females can shed up to 26% of their weight when spawning, while males have also been seen to lose weight during breeding, because they are eating less.[33] The weight lost during the breeding season is typically regained from January to September.[35]

Amplexus between the male and female occurs mainly in water, but sometimes at substantial distances away on dry land. Observations of breeding sites have shown the males linger around the courting area for much longer times, while females mostly stay at other places to find food before meeting the males there. During amplexus, the males grab the females near their armpits after climbing on their backs.[18][33] In the wild, amplexus usually takes between 10 minutes and five days. Artificially induced amplexus in the laboratory has been observed to last 50 hours, but there have been reports of five days.[33] Sometimes, amplexus will not result in eggs being laid.[33]

The frogs may move up to 100 m during amplexus before the female lays her eggs.[33] During the laying of the eggs, the pair of frogs remain in amplexus and the male is assumed to fertilise the eggs with his sperm. Males are also seen to paddle their rear legs during this time, which is speculated to accelerate fertilisation. The egg-laying and fertilisation process takes around five minutes.[33] An average of 5,000 eggs are deposited amongst aquatic vegetation in a gelatinous mass; however, a clump of 11,682 has been recorded.[36] The female moves around while depositing, leaving a trail of eggs that sometimes entangles upon itself.[17] Initially, the mass floats, but sinks up to 12 hours after laying, or when disturbed.[25] The eggs are distinct from those of other frog species; they are 2–2.5 mm wide upon deposition and are bicoloured, black at one end and white at the other.[17] They immediately begin to expand, quickly reaching around 4 mm across, before sinking. When first laid, they float with the black pointing up, but after sinking, the orientation becomes disordered.[17] Two to five days later, the tadpoles hatch out, but the process can take only a few hours on occasions.[25] The hatching rate varies between 46 and 77%, and peaks at 22°C. Hatching is less likely in acidic waters, although alkaline conditions do not lead to a lower rate compared to neutral conditions. Given the large number of eggs that hatch per female and given the scarcity of mature frogs, tadpole survival rates are believed to be very low.[15]

Upon hatching, the tadpoles are around 2.5–3 mm in snout-vent length (SVL) and about 5–6 mm including the tail. Tadpoles in captivity increase exponentially over time in total length; their SVL increases from about 3 to about 9 mm within five weeks, and it triples again in the next five weeks.[25] In all, the growth rate is 0.2 mm per day in the first five weeks.[25] The tadpoles of the green and golden bell frog are large, reaching 80 mm (3.15 in) in length,[16] but size varies greatly and most are much shorter.[11] The body is usually as wide across as it is deep. The fin has a yellow tinge and is considerably arched. The musculature is moderate and tapers to a fine point, as does the fin.[17] The body wall is translucent yellow with darker areas over the abdomen. Just before its limbs form, the tadpole begins to develop the greenish colouration of the adult.[17] Tadpoles usually swim within 30 cm of the water surface, or remain stationary at the bottom. They often move together in groups akin to schools of fish.[35]

Towards the end of the tadpole phase, hind legs appear, followed by front limbs, and the phase ends when the front limbs are developed. This normally occurs between October and April due to the breeding season, but tadpoles been observed in the wild throughout the year, suggesting some tadpoles overwinter; this has been seen to occur for captive tadpoles. The length of the tadpole stage, in the wild and in captivity, is usually between 10 and 12 weeks, but can range from five weeks to a year. The slower-growing tadpoles usually progress during winter, as there is a positive correlation between growth rates and temperatures. Variation in growth rate across pH values of 4, 7 and 9 was insignificant. In the first four weeks, there was no significant dependence of the growth rate across the 18–26°C range, but from this point on, growth was significantly hindered at 18°C.[25] At the beginning of the metamorphing stage, all limbs are present and developed, along with a tail. During this phase, the tail is resorbed, and the only other visible change is the spiracle closing. Metamorphing tadpoles typically have a SVL of 22–28 mm,[25] and will complete metamorphosis between two and 11 months, depending on the temperature of the water and available food.[37] The process is slowed at low temperatures,[34] but generally takes between three to eight days after the tadpole stage is complete.[38] Breeding occurs in a significantly higher proportion of sites where no predatory fish are present, and water bodies are ephemeral rather than permanent. Populations in Victoria, however, have been recorded as breeding in permanent ponds as readily as they do in ephemeral ponds.[7]

Metamorphs resemble the adults and average about 2.6 cm (1 in) in length.[34] Recently metamorphosed frogs have been observed to rapidly leave the breeding site, especially when foraging habitat is nearby, and less so if food is not available away from the area. The tendency to migrate is often attributed to cannibalism practised by larger frogs on those that are still developing.[27] After metamorphosis is complete, the frog is around the same length. The juveniles initially grow rapidly, reaching 45 mm within two months, 50–60 mm within half a year, before growth slows.[38] months, and increase in length more slowly after that.[38] Once sexual maturity is reached, the frogs' physical growth is very slow.[38]

Metamorphs weigh about 2 g, while the largest adults can reach 50 g. Individual frogs can vary substantially in body weight due to changes in the amount of stored fat, recent eating, and egg formation.[33] While it is known to live 10–15 years in captivity, the frog's lifespan in the wild is not well understood.[34]

Conservation status[edit]

The numbers of green and golden bell frogs are estimated to have declined by more than 30% in the past 10 years.[39] It is listed as globally and nationally vulnerable, and as endangered under the New South Wales Threatened Species Conservation Act, 1995.[12] Although it is only classified as vulnerable at national level, the National Frog Action Plan classifies the green and golden bell frog as endangered.[40] In contrast to Australia, the frogs are abundant in New Zealand and classified as feral and unprotected.[40]

Many factors are thought to be responsible for the dramatic decline of this species in Australia, including habitat fragmentation, erosion and sedimentation of soil, insecticides and fertilisers contaminating water systems,[41] the introduction of predatory fish, and alteration of drainage regimes.[12] Population declines are closely related to the introduction of the eastern mosquitofish (Gambusia holbrooki),[12] a species native to North America that was introduced to control mosquito larvae.[42] Laboratory studies have demonstrated the eggs and tadpoles of the green and golden bell frog are extremely susceptible to predation by this fish,[12] and in 77 of the 93 sites in New South Wales where the green and golden bell frog was known to have disappeared before 1990, eastern mosquitofish were found to be present. The frogs have been known to inhabit waters containing the fish, but breeding is rarely successful there, pointing to the fish's voracious eating of eggs and tadpoles.[32] The fish are not yet present in eastern Victoria, where green and golden bell frog numbers have remained solid, but the fish likely will spread to rivers there, possibly inflicting heavy losses on the frogs.[43][44]

Other factors thought to affect this species include predation by introduced mammals, such as cats and foxes, changes to water quality at breeding sites,[12] herbicide use,[41] and loss of habitat through the destruction of wetlands.[12] The amphibian chytrid fungus appears to have led to at least some of the decline in numbers,[12] but the relative importance of the various factors is unclear.[45] The frogs may have become more susceptible to chytrid rather than the fungus being more common.[46] The genetic pool of the frogs has been found to be relatively small, attributed to habitat destruction, which has confined the smaller groups of frogs to isolated pockets and increased the incidence of inbreeding. This has led to proposals for frog populations to be mixed by human intervention in an attempt to reduce negative genetic effects and boost survival rates.[44][47]

The cannibalism of the frog has been speculated to cause its decline in some areas, because the smaller tadpoles can be toxic.[31] Other postulated causes of the decline include increased ultraviolet radiation due to the hole in the ozone layer, global warming, and increased drought. The first theory was tested and the results were inconclusive. Global warming is not thought to be a credible cause, as the extremities of the frog's range have not changed, while declines in population have occurred in both dry and wetter areas.[46]

The green and golden bell frog has been the subject of much research and monitoring, important to improving its conservation. Research focuses on the development of management measures to keep the introduced mosquitofish under control.[12] These include poisoning the fish, but the waterways are large and trials have given mixed results. Predators of the mosquitofish have also been tried.[44] Other strategies may allow for the development and improvement of suitable habitat, and to increase the reproductive success of the species. Parallel to these measures, community awareness programmes have also been proposed.[12] One difficulty in protecting the frog is that only 20% of the known populations in New South Wales since 1990 occur in conservation parks. Of the eight populations that occur in conservation parks, only five are wholly located within them and one of these is not breeding.[43] There have been calls for legislation to be introduced to stop habitat degradation on private land to prevent detrimental effects to the frogs.[44] Many proposed developments have been subjected to legal action to protect the habitat, and some communities have started "Friends of the Green and Golden Bell Frog" action groups.[48] As public awareness has increased, documentary and news segments on the deteriorating situation have become more frequent and references to the frog in environmental logos and artworks have increased.[49] The effort to increase public consciousness of the green and golden bell frog has also been aided because its colours are the same as the national colours.[50] Restrictions on logging close to areas inhabited by the frogs have been put in place.[51] As green and golden bell frogs are mostly observed in environments disturbed by humans, targeted environmental interference is seen as a possible means of enhancing habitats.[44]

In 1998, a captive-breeding program was set up by the herpetofauna staff at Taronga Zoo in Sydney, sponsored by the ASX Frog Focus. The purpose of the program was to help preserve declining populations of green and golden bell frogs in the Sydney region. It involved the captive breeding of wild frogs and releasing large numbers of tadpoles back into the wild, habitat restoration, and monitoring after releases.[52] The program was initially titled "Frog Focus Botany", as Botany was the original focus site. Thousands of tadpoles were released into a site in Sir Joseph Banks Reserve and postrelease monitoring was done by the local community. It was also the first time that school students had been involved with endangered species monitoring.[52] The program has since branched off into several other areas. Between 1998 and 2004, tadpoles were released into specially designed ponds and dams on Long Reef Golf Course at Collaroy in northern Sydney, with little success.[29][50] Although green and golden bell frogs had previously been located in the area, the population had since been lost. Mature male bell frogs are occasionally found there;[29] however, a permanent breeding population has yet to be established.[29] An attempted reintroduction at Marrickville in inner-Sydney has failed due to chytridiomycosis.[29]

Notes[edit]

  1. ^ a b c d e f g "IUCN Redlist - Information on classification and treats of Litoria aurea". Retrieved 2006-07-27. 
  2. ^ "American Museum of Natural History, Amphibian Species of the World - Synonyms of Litoria aurea". Retrieved 2006-07-27. 
  3. ^ Simpson, D.P. (1979). Cassell's Latin Dictionary (5 ed.). London: Cassell Ltd. p. 883. ISBN 0-304-52257-0. 
  4. ^ a b c d Mahony, p. 82.
  5. ^ a b c d Pyke and White, p. 568.
  6. ^ a b c d Pyke and White, p. 569.
  7. ^ a b Gillespie G.R. 1996. "Distribution, habitat and conservation status of the Green and Golden Bell Frog Litoria aurea (Lesson, 1829) (Anura: Hylidae) in Victoria." Australian Zoologist 30: 199–207.
  8. ^ Osborne W.S., Littlejohn M.J. and Thomson S.A. 1996. "Former distribution and apparent disappearance of the Litoria aurea complex from the Southern Tablelands of New South Wales and the Australian Capital Territory." Australian Zoologist 30: 190–198.
  9. ^ a b c d Egerton, p. 381.
  10. ^ a b White A.W. and Pyke G.H. 1996. "Distribution and conservation status of the Green and Golden Bell Frog Litoria aurea in New South Wales." Australian Zoologist 30 (2): 177–189.
  11. ^ a b c Pyke and White, p. 566.
  12. ^ a b c d e f g h i j k "Litoria aurea—Green and Golden Bell Frog Glossary". Environment.gov.au. Retrieved 2012-08-13. 
  13. ^ a b c d Pyke and White, p. 567.
  14. ^ "Whatever happened to our Olympic Bell Frog?". Sydney Olympic Park Authority. Archived from the original on 2006-12-30. Retrieved 2006-12-16. 
  15. ^ a b Pyke and White, p. 579.
  16. ^ a b c d e "Litoria aurea". Frogs Australia Network. 2005-02-23. Retrieved 2008-07-16. 
  17. ^ a b c d e f g Pyke and White, p. 565.
  18. ^ a b c d e f g h Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 29.
  19. ^ a b c d e Pyke and White, p. 570.
  20. ^ a b c d e f g Pyke and White, p. 575.
  21. ^ Barker, J.; Grigg, G.C.; Tyler, M.J. (1995) Surrey Beatty & Sons.. A Field Guide to Australian Frogs - The Litoria aurea complex, page 99.
  22. ^ Tomas Rozek, Kate L. Wegener, John H. Bowie, Ian N. Olver, John A. Carver, John C. Wallace and Michael J. Tyler. "The antibiotic and anticancer active aurein peptides from the Australian Bell Frogs Litoria aurea and Litoria raniformis the solution structure of aurein 1.2.". The FEBS Journal. Retrieved 2006-08-06. 
  23. ^ a b c Pyke and White, p. 578.
  24. ^ Pyke, GH; White, AW (May 1996). "Habitat requirements for the green and golden bell frog Litoria aurea (Anura: Hylidae)". Australian Zoologist. Retrieved 2006-08-01. 
  25. ^ a b c d e f g h i j Pyke and White, p. 571.
  26. ^ a b Pyke and White, p. 577.
  27. ^ a b c Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 31.
  28. ^ Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 35.
  29. ^ a b c d e Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 34.
  30. ^ a b c d e f g Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 27.
  31. ^ a b c d e f g h Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 28.
  32. ^ a b Pyke and White, p. 19.
  33. ^ a b c d e f g h Pyke and White, p. 573.
  34. ^ a b c d e Draft Recovery Plan for Green and Golden Bell Frog Litoria aurea (lesson 1829), p. 30.
  35. ^ a b Pyke and White, p. 574.
  36. ^ van de Mortel, T.F. and Goldingay, R. 1996. "Population assessment of the endangered Green and Golden Bell Frog Litoria aurea at Port Kembla, New South Wales." Australian Zoologist. 30(4):398–404.
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References[edit]

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