Limnodynastes dumerilii, commonly referred to as the banjo frog, is a large species of amphibian that takes its name from its unique call that sounds similar to plucked banjo strings.
This species can be found throughout eastern Australia from Victoria to south-eastern South Australia in woodland, heathland, farmland and farm ponds as well as dams, ponds, streams and wetlands; its five subspecies exist.
Habitat
This species inhabits western Victoria and south-eastern South Australia, growing up to 7.5 cm long. This robust ground-dweller features grey or dark green back with irregular darker blotches, along with a pale stripe from nose to rump (hence its other common name ‘pobblebonk frog’) as well as bright orange or red or scarlet patches in its thighs and flanks that give this animal its distinctive colouring. Instead of its typical “croak”, however, this species emits a musical “plonk”, sounding similar to banjo strings being plucked, hence earning it another common name ‘pobblebonk frog”.
Calls of this frog can be heard between August and April in its natural environment. In ponds, marshes, or any small bodies of water it lays its eggs to hatch out as tadpoles before eventually turning into froglets in spring or summer – not unlike its aquatic cousins like rivers, dams, swamps or marshes! In addition, temporary bodies of water like rivers dams swamps or marshes also provide breeding sites.
In dry months, this species burrows deep into sandy soils to escape heat or rain; during wetter periods they are found near roadside ditches or road surfaces or delivered as soil to urban gardens. The moist conditions required for breeding must remain intact so as to attract breeding males to emerge and breed successfully.
Grace Gillard of UNSW’s Centre for Ecosystem Science and Australian Museum teamed up with Jodi Rowley from UNSW to conduct an analysis on banjo frog calls to determine their specific habitats. However, their results were astounding – their analysis demonstrated that variation in calls did not correspond with structure of habitat but were determined by interactions among numerous factors.
This research adds to our knowledge of frog behavior and is essential for conservation management of this species, since variation in advertisement calls indicates there may be different habitats where reproduction and survival can take place, rather than being limited by specific types of environments.
Breeding
The banjo frog is well known for its distinctive call, which sounds similar to plucked banjo string. This call serves to attract potential mates and can be heard throughout the night when weather conditions permit. By day they hide away in ponds or damp places; emerging after rain showers.
Male frogs begin calling during late winter and continue through to early summer when breeding begins. A female will lay an extensive foamy raft of eggs containing anywhere from 500-3,000, and place it safely under cover of water plants to avoid predators. Males then fertilise these eggs before devouring any that escape. Tadpoles will spend one year developing before becoming froglets.
Though they prefer damp forest or grassy heathland environments, frogs can breed anywhere with water sources. Garden ponds in rural areas often house them and they serve as great indicators of landscape health; additionally, they have the unique ability to move their eggs from one pond to the next – something very helpful when trying to control pest frog populations.
Frogs play an essential part in maintaining water cycles by helping keep waterways clear of debris and providing food sources for other wildlife. Thus, the removal of native plants around ponds may have serious repercussions for their wellbeing.
This large ground-dwelling frog reaches up to 7.5 cm in body length and features a brown or grey-brown back with dark greenish blotches and a pale raised stripe from below the eye to shoulder. Other distinguishing characteristics include prominent glandular ridge near its mouth and large glands on its legs which resemble lumps; its belly features mottled yellow and brown coloring while its throat can sometimes turn yellow; hence its common name of Banjo Frogs.
Reproduction
The distinctive call of the banjo frog can be heard throughout Hepburn Shire in spring. When multiple males call at different pitches at once, their chorus sounds similar to plucked banjo strings – making for an unforgettable sound associated with south-east Australian wetlands.
The Eastern Banjo Frog, more commonly known by its common name of Pobblebonk, can often be found in our local wetlands. Most commonly heard from October to January but may call at other times of year depending on weather conditions; as it burrows underground during most of its day.
During breeding season, male frogs develop dark throats and larger nuptial pads while females grow large flaps of skin called flanges on their first two fingers to carry air bubbles into pond water and oxygenate eggs. Frogs lay an egg-laden floating raft containing anywhere from 500-3,000 pigmented eggs that is typically concealed by water plants to protect it from predators; male frogs often remain nearby after spawning to guard these eggs.
Banjo frogs may only find shelter in small ponds or dams, but they are also found in coastal swamps and dams, irrigated pasture, sand-dune wetlands associated with forests and heathlands as well as underground shelters – an amazing ability that helps them avoid drying out during hot summer sun! As drought-dodgers they spend months or years underground to avoid being exposed to drying temperatures during their active period.
Eastern Banjo Frog populations have been on a decline across certain regions, which may be linked to heavy metal contamination from agricultural runoff such as lead and copper; however, other causes may include weeds and diseases as possible causes.
Hepburn Shire offers several protected areas where Eastern Banjo Frogs can be seen and heard, such as Lake George Wetlands and Mount Lofty Ranges National Park. To ensure their survival, our wetlands must remain free of pollutants that could threaten these precious environments.
Distinguishing Features
The banjo frog (sometimes known as the eastern pobblebonk or southern banjo frog) can be recognized by its distinct call, which mimics plucking banjo strings – hence its name. Other distinguishing features of this species include its short head with rounded snout and large eyes featuring vertical pupils; white to gold belly; backs can range in colour from green, brown or black with dark markings or flecking; well defined external ears (tympanum); distinct dark bands on its legs tympanum; and leg bands on its legs tympanum.
Adult chameleons range in length from 1.8 to 2.3 inches (4.6 to 5.8 centimeters), and feature warty skin replete with tiny spines that creates an unpleasant prickling sensation. Male and female specimens are visually similar; during breeding season however males develop additional spines on top of their warts for easy gender recognition.
The banjo frog can make up to six distinct calls, depending on its surroundings. When courting females, males produce high-intensity calls that mimic plucking of a banjo string while defending territory may produce series of grunts or growls.
From early spring through summer in our region, male birds begin calling as they search for mates and establish territories. Calls may continue into autumn in some locations.
This frog species is classified as near-threatened due to habitat loss caused by humans converting it for agricultural or residential uses, as well as being susceptible to fungal infections that have decimated its global population.
If you are fortunate enough to live in an area where banjo frogs exist, keep an ear open for their calls around the water’s edge in your yard or nearby pond. They prefer shallow pools of standing water where their eggs will hatch before moving onto creeks, streams and dams further afield; you might even catch sight of one if your backyard contains either a pool or pond!