The giant banjo frog, giant pobblebonk frog, giant bullfrog, or great bullfrog (''Limnodynastes interioris'') is a species of
frog
A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...
, endemic to Australia, in the family
Limnodynastidae
Limnodynastidae, commonly known as the Australian ground frogs, is a family (biology), family of frogs found in Australia, New Guinea, and the Aru Islands Regency, Aru Islands. They were formerly considered a subfamily of the Myobatrachidae, the ...
. Fry
was the first to recognise the species of Giant Banjo Frog (''Limnodynastes interioris)'' as a distinct subspecies of Banjo Frog (Genus: ''
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 ...
)'', differing from the similar Southern or Eastern Banjo Frogs (
''Limnodynastes dumerili'') which occupied most of eastern Australia.
Description
The Giant Banjo frog grows to an average length of between 7 and 9 cm. The skin on its back is mostly brown with irregular black markings and a bumpy texture while its underside is pale to bright yellow and smooth. Along the sides of the body, the coloring ranges from red-brown to fawn with black and grey flecks with a black stripe from its snout down to its sides.
The iris is a dark specked gold and the pupil is horizontal. Front feet are
unwebbed and back feet are semi-webbed with a large, shovel-shaped metatarsal
tubercle
In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal.
In plants
A tubercle is generally a wart-like projectio ...
on the under-surface of each foot. The toes are strong, without discs and are predominantly for burrowing beneath the surface of soil.
The eggs appear pigmented and are spawned within a large foam mass situated within flooded burrows and surrounded by vegetation. The
tadpole
A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...
s are quite large in comparison to other Banjo Frog species, growing up to 9.5 cm in length, and are dark brown, or black in color with gold clusters and dark grey fins.
Taxonomy
Fry
was the first to recognise the species of Giant Banjo Frog (''Limnodynastes interioris)'' as a distinct subspecies of Banjo Frog (Genus: ''
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 ...
)'', differing from the similar Southern or Eastern Banjo Frogs (
''Limnodynastes dumerili'') which occupied most of eastern Australia (see Scientific classification for full taxonomy).
Ecology
Distribution
The Giant Banjo Frog is
endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to Australia and inhabits the arid region of central New South Wales and northern Victoria. It is largely restricted to
Murray-Darling Basin and the floodplains of the
Murray River
The Murray River (in South Australia: River Murray; Ngarrindjeri language, Ngarrindjeri: ''Millewa'', Yorta Yorta language, Yorta Yorta: ''Dhungala'' or ''Tongala'') is a river in Southeastern Australia. It is List of rivers of Australia, Aust ...
. The area of occurrence of the Giant Banjo Frog covers an area of approximately 214,800 km
2 (see Distribution map).
Population
The Giant Banjo frog has a large and stable population with a
conservation status
The conservation status of a group of organisms (for instance, a species) indicates whether the group still exists and how likely the group is to become extinct in the near future. Many factors are taken into account when assessing conservation ...
of least concern.
However, their
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
is threatened by
habitat loss
Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
due to
hydrological
Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and drainage basin sustainability. A practitioner of hydrology is called a hydro ...
modifications of the
Murray-Darling Basin which significantly disrupts inland
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...
frog communities.
Despite a general negative impact of
introduced species
An introduced species, alien species, exotic species, adventive species, immigrant species, foreign species, non-indigenous species, or non-native species is a species living outside its native distributional range, but which has arrived ther ...
on inland frog communities, the presence of Common Carp (''
Cyprinus carpio
The common carp (''Cyprinus carpio''), also known as European carp, Eurasian carp, or simply carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Ark ...
'') was shown to have a positive effect on the abundance of the Giant Banjo Frog, this could be due to indirect effects of Common Carp on the survival of predators to the tadpoles of the Giant Banjo Frog.
Habitat
The Giant Banjo Frog spends the majority of its time underground and tends to only emerge after rain to feed and lay eggs.
Their natural
habitat
In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...
is usually close to freshwater
floodplain
A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...
s,
marsh
In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
es,
swamp
A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
s and
pond
A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...
s but can also be found in dry
temperate forest
A temperate forest is a forest found between the tropical and boreal regions, located in the temperate zone. It is the second largest terrestrial biome, covering 25% of the world's forest area, only behind the boreal forest, which covers about 3 ...
s,
grassland
A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...
and dry
savanna
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...
.
The Giant Banjo Frog is dissimilar to many other arid-adapted
amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s in the fact that it spends a large stage of its life-cycle in
aquatic environments.
Eggs are
spawned in water, found mostly in flooded burrows,
dam
A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use, aqua ...
s,
swamp
A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
s, and
pond
A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...
s and;
tadpole
A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...
s live in either slow moving or still water.
The Giant Banjo Frog occurrence was found to be higher at permanent wetlands away from the main river channel of the
Murray River
The Murray River (in South Australia: River Murray; Ngarrindjeri language, Ngarrindjeri: ''Millewa'', Yorta Yorta language, Yorta Yorta: ''Dhungala'' or ''Tongala'') is a river in Southeastern Australia. It is List of rivers of Australia, Aust ...
and with more complex vegetation structure.
Diet
The Giant Banjo frog is a carnivore. Adults feed on a wide variety of insects, worms and spiders.
Its refuge among complex vegetation sources provides a substrate for food sources.
Environmental Adaptations
For individuals to survive during periods of extended
drought
A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...
, the Giant Banjo Frog has adapted stronger and shovel-shaped limbs to increase its burrowing ability. This is a specific adaptation of frogs that are found in
arid regions with variable rainfall. The development of a larger body and capacity to burrow has allowed the relatively long-lived species to become more resilient to the
arid climate
The desert climate or arid climate (in the Köppen climate classification ''BWh'' and ''BWk'') is a dry climate sub-type in which there is a severe excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in desert ...
and therefore it is seen to be of lower susceptibility to future
climate change
Present-day climate change includes both global warming—the ongoing increase in Global surface temperature, global average temperature—and its wider effects on Earth's climate system. Climate variability and change, Climate change in ...
s. The Giant Banjo Frog is a non-cocoon forming species and therefore tends to dig deeper during periods of
drought
A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...
to maintain adequate moisture.
Life-History Traits
Lifespan
Similar to other species of frogs, the Giant Banjo Frog lives an average lifespan of 10 years in the wild. During hotter and drier months, the frog spends prolonged periods
aestivating where they are in a state of
dormancy
Dormancy is a period in an organism's Biological life cycle, life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolism, metabolic activity and therefore helps an organism to conserv ...
.
Nesting
Eggs are spawned in a nest made up of a large foamy mass situated on the surface of the static or slow flowing water in flooded burrows, ponds, dams or stream pools. The nest is constructed around vegetation to keep it from moving too far, the
tadpole
A tadpole or polliwog (also spelled pollywog) is the Larva, larval stage in the biological life cycle of an amphibian. Most tadpoles are fully Aquatic animal, aquatic, though some species of amphibians have tadpoles that are terrestrial animal, ...
s are then able to drop into the still water below to mature.
Reproduction
Giant Banjo Frogs breeds during spring and summer and occasionally autumn if rainfall is adequate.The reproductive cycle of the Giant Banjo Frog requires semi-permanent bodies of water, where each female can lay up to 4000 eggs. After the spawning phase eggs will hatch within a few days and tend to remain on the bottom of the water. The next stage of larval development where tadpoles mature into frogs takes around two and a half months.
Behaviour
Calls
The peak calling period of the Giant Banjo Frog is between September and November.
Males call from vegetation or flooded burrows. The genus of
Banjo Frogs is known for its distinctive "bonk" sound, similar to that of a Banjo being plucked, with the Giant Banjo Frog having a short deep note with a similar, but lower dominant frequency, to that of the Southern or Eastern Banjo Frog (''
Limnodynastes dumerili).'' Males often synchronise their calls with surrounding frogs which causes a rapid series of "bonk" sounds.
Evolutionary relationships
Giant Banjo Frogs have been known to take advantage of Malleefowl (''
Leipoa ocellata'')
incubation mounds, which provide high moisture content and soft enough soil with which to dig, providing optimal
aestivation
Aestivation ( (summer); also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered m ...
sites.
This has allowed giant banjo frogs to live on agricultural land when soil can typically be too dry and compacted for them. This relationship has the potential to impact this type of habitat for Giant Banjo Frogs due to predation by foxes of the Malleefowl, which is listed as a
vulnerable species
A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...
under the
EPBC Act 1999.
Threats
Environmental
Although the Giant Banjo Frog is relatively resilient to periods of
drought
A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...
, other indirect effects such as retreating
water table
The water table is the upper surface of the phreatic zone or zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with groundwater, which may be fresh, saline, or brackish, depending on the loc ...
s or an increase in
groundwater
Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...
salinity
Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
has the potential to limit their ability to thrive throughout extended dry periods.
Human Interaction
An increase in agricultural practices, manufacturing and land-use around the
Murray-Darling Basin has led to a decline in health of the area and its inhabitants. The
Murray-Darling Basin is an
ecological hotspot for not only the Giant Banjo Frog but many other native plants, fish, reptiles, amphibians, birds and mammals.
Conservation
The Giant Banjo Frog is currently listed as species of
Least Concern
A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...
under the
EPBC Act 1999. There is currently no conservation efforts in place for the Giant Banjo Frog, but management of the
Murray-Darling Basin includes plans to mitigate overall
habitat loss
Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
and conserve Australia's natural landscape in the area.
References
{{Taxonbar, from=Q520353
Limnodynastes
Amphibians of New South Wales
Amphibians described in 1913
Taxonomy articles created by Polbot
Frogs of Australia