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Giant Banjo Frog (Limnodynastes interioris)

The giant banjo frog is a large, burrowing Australian frog associated with freshwater wetlands, streams, dams and floodplain habitats. It spends most of its time underground and emerges after rain to feed and breed, so clearing can affect both breeding waterbodies and less obvious terrestrial refuge areas.

Conservation status

Victoria, Flora and Fauna Guarantee Act 1988: Endangered.

Breeding season

Giant Banjo Frogs spend most of the year underground and emerge after rain. Breeding is concentrated from spring to early summer, with breeding and tadpoles extending into autumn after heavy rain, so clearing near water and potential burrows carries the greatest risk from September to autumn.

Reproductive mode: Egg laying. Eggs are contained in a large foamy mass.

Clutch size: Up to 5000 eggs has been reported, but a species-specific clutch dataset is not recorded.

Incubation or gestation: Not recorded.

Size at hatching or birth: Hatchling length: 1.7 mm.

Age at maturity: Females are thought to first reproduce at 2 to 3 years.

Nest or egg sites: Foam nests are laid on the surface of ponds, dams, flooded ditches and stream pools, among aquatic vegetation, at waterbody edges or in flooded burrows.

Breeding frequency: One clutch per year is reported.

Confirm timing locally before clearing, draining or dewatering, because rainfall, heavy downpours and dry summer or winter conditions can shift calling, breeding, emergence and tadpole development.

  • Calling: Calling is reported in spring, with males in Victoria calling almost year round except during dry summer conditions. Peak calling is assigned to September to November, while calling from March to August may occur after suitable rain.
  • Egg laying: Egg laying occurs in spring and summer, usually September to November, and may continue into autumn after heavy rain. Autumn spawning is possible from March to May when rainfall is adequate.
  • Tadpoles: Tadpoles occupy slow-moving or still water, including ponds, dams, wetlands and flooded burrows. Development takes around two and a half months, so autumn breeding after rain can extend tadpole presence into winter.
  • Metamorphs: Metamorphosed frogs probably appear over summer. The main period is marked as November to February, but autumn breeding after heavy rain may shift metamorph emergence into March to May.
  • Active period: Adults emerge after rain to feed, call and spawn, and are mainly active at night. They can be active in any month when rainfall provides suitable conditions, although dry summer periods may suppress activity.
  • Winter inactivity: Adults spend most of their lives underground in burrows, including burrows beside streams, dams and pools. No winter-only inactive period is recorded, so sheltering adults should be assumed to occur year round, especially during dry conditions.
  • Highest clearing risk: Risk is highest from September to November, when calling, foam nests and adults are commonly associated with breeding water. Risk remains elevated through autumn, and may extend into winter after late autumn breeding because tadpole development takes around two and a half months; burrowing adults remain at risk in all months.

Identification

This is a large, powerfully built burrowing frog with a deep call and distinctive orange or yellow markings. Identification is most reliable when body pattern, the orange facial stripe and the call are assessed together.

Adults are 65 to 90 mm long and have a robust body suited to burrowing and jumping. The back is commonly pale brown, yellow, fawn or red-brown, with dark flecks, spots or irregular markings. Broad coppery-orange bands may occur along the sides.

A raised cream, yellow or orange stripe runs from below the eye towards the arm. The belly is yellow, often with black flecks, and the groin is marbled yellow and black. The back is moderately warty or smooth to finely granular, while the belly is smooth.

Adult length: 65 to 90 mm

Toe webbing: About one-quarter webbed in the south-west NSW guide; described more generally as webbed in the Victorian fact sheet

Tadpoles: Large and ovoid, brown-black, with dark grey fins and possible dark flecks

Identification: Calls and field signs

The advertisement call is a short, deep, hollow note resembling a low ‘bonk’, ‘gunk’ or ‘donk’. Males may call in chorus, producing a rapid series of notes.

Males call from floating or emergent vegetation, debris, burrows and the edges of streams, dams or pools. A call heard after rain near suitable water is a useful detection record, even when no frog is visible.

  • Look for large foam nests concealed among aquatic vegetation, at the edges of dams or pools, or in flooded burrows.
  • Record the exact calling location, waterbody type, nearby vegetation and whether the call came from water, a bank burrow or debris.

Identification: Similar species

The call is similar to that of the eastern banjo frog, Limnodynastes dumerilii, but the giant banjo frog has a much lower-pitched, deep resonating note. Its large size, yellow belly, prominent orange facial stripe and orange lower-leg gland help separate it from other banjo and marsh frogs.

The supplied documents do not provide a diagnostic comparison of males and females. Males are identifiable by their calling behaviour, while females are reported to first reproduce at 2 to 3 years of age.

Distribution: States and regions

The giant banjo frog is endemic to Australia and has a patchy distribution in the southern inland parts of the country. The supplied documents identify populations in the western NSW slopes region and along the Murray River floodplains in Victoria.

In New South Wales, the species occurs along the western edge of the NSW slopes region. In Victoria, it is largely restricted to the Murray River floodplains and is described as fairly uncommon.

The supplied documents do not provide a national range map, records from other states, elevation limits or named strongholds outside these areas.

New South Wales: Western edge of the NSW slopes region

Victoria: Murray River floodplains; fairly uncommon

Known population change: The Victorian fact sheet states that range and population size do not appear to have undergone substantial changes

Population size: Not reported

Distribution: Project interpretation

Records may be concentrated around floodplain wetlands, dams, streams and other waterbodies, but the species can occur away from open water because adults spend most of their lives underground. A lack of surface records does not show that a proposed clearing area is unused.

For project assessments, search both mapped and unmapped wet areas and the surrounding woodland, grassland, heathland and cleared pasture, particularly after substantial rain.

Habitat: Broad habitat types

The species uses a mix of terrestrial and freshwater environments. It is associated with relatively dry land as well as permanent, seasonal and temporary waterbodies used for breeding.

Documented terrestrial habitats include woodlands, heathlands, grasslands, cleared pastures and dry forest associated with floodplains.

Documented waterbodies include large permanent dams and wetlands, streams, permanent and seasonal rivers, swamps, floodplains, ponds, ephemeral claypans and flooded burrows.

Terrestrial settings: Woodlands, heathlands, grasslands, cleared pastures and dry floodplain forest

Aquatic settings: Dams, wetlands, streams, rivers, swamps, floodplains, ponds, claypans and flooded burrows

Habitat: Features to retain

Retain breeding water, emergent vegetation, aquatic debris, stream banks and terrestrial ground that may contain burrows. Slow-moving or still water is particularly relevant for tadpoles.

The supplied documents do not give an elevation range, vegetation community names, minimum waterbody size or required distance between breeding sites and refuge areas.

  • Map permanent and seasonal waterbodies, floodplain depressions, claypans, stream margins and dams before clearing.
  • Treat dry woodland and pasture adjoining these features as potential habitat, especially where burrows or recent frog activity are present.

Foraging habitat: Where feeding occurs

Adults emerge from underground refuges after rain to feed and breed. The supplied documents do not identify prey, food plants or a measured foraging distance.

Potential feeding habitat includes the woodland, heathland, grassland, pasture and dry floodplain forest surrounding breeding waterbodies. Adults may also use damp ground, stream banks, wetland edges and areas with cover after rainfall.

Because the species spends most of its life underground and emerges after rain, short survey windows following substantial rainfall are likely to provide the best opportunity to detect active adults.

Diet: Not specified in the supplied documents

Foraging distance: Not reported

Foraging trigger: Rainfall and emergence from underground refuges

Foraging habitat: Field application

Do not limit habitat assessment to the waterline. Search adjacent terrestrial areas for active frogs, burrow openings and suitable ground cover, particularly where clearing connects dry forest or pasture with dams, wetlands or streams.

Avoid disturbing wetland margins and adjacent ground during and immediately after rain when adults may be above ground and moving between feeding and breeding areas.

Breeding habitat: Breeding biology

Breeding follows rainfall and occurs in spring to early summer in the south-west NSW account, and in spring, summer and autumn after heavy downpours in the Victorian account. Males call from water, floating vegetation, debris or bank burrows.

Breeding season: Spring to early summer in south-west NSW; spring, summer and autumn after heavy rain in Victoria

Egg number: Not reported

Egg form: Pigmented eggs in a large foam mass

Incubation period: Not reported

Age at maturity: Females are thought to first reproduce at 2 to 3 years

Lifespan: Not reported

Tadpole habitat: Slow-moving or still water, including dams, pools, wetlands and flooded burrows

Breeding habitat: Breeding sites

Eggs are laid in large floating foam masses among aquatic vegetation, at the edges of dams or pools, or in flooded burrows. Males commonly call from emergent vegetation, floating vegetation, debris or burrows along stream banks.

Retain both the breeding waterbody and its bank margins. Foam nests may be concealed, and tadpoles may remain in still or slow-moving water after adults stop calling.

  • Inspect aquatic vegetation, flooded banks, debris and shallow wetland edges for foam nests.
  • Keep sediment, pollutants and clearing debris out of dams, pools, streams and floodplain wetlands.
  • Record breeding activity before dewatering, infilling or works near water.

Sheltering habitat: Refuges

The giant banjo frog is primarily a burrowing species. Underground refuges are likely to be present in both dry terrestrial habitat and the banks of breeding waterbodies.

Adults spend the majority of their lives underground and emerge after rain. Documented refuge locations include burrows, flooded burrows and burrows along stream banks, dams and pools.

The supplied documents do not provide burrow diameter, depth, density, construction method or a standard buffer distance.

Known refuge type: Underground burrows, including burrows along stream banks and flooded burrows

Refuge dimensions: Not reported

  • Check soil banks, damp ground, floodplain forest, pasture and woodland adjoining waterbodies for burrow openings and recent emergence signs.
  • Avoid collapsing, filling or compacting potential burrow areas during access construction, stockpiling, grading and vehicle movement.
  • Keep excavations, trenches and temporary drains covered, ramped or checked regularly so frogs cannot become trapped.

Sheltering habitat: Detection conditions

Surface activity is most likely after rain, when frogs emerge to feed, call and spawn. Dry-weather searches may under-record the species because adults remain underground.

  • Time searches after suitable rainfall and include night listening for deep calls near dams, pools, wetlands and stream margins.
  • Use a qualified fauna spotter catcher for clearing where potential burrows, foam nests or active frogs are present.

Threats: Clearing and habitat modification

The documented threats are habitat loss, vegetation clearing, habitat modification, poor water quality and exotic weeds. The species is listed as threatened under Victoria's Flora and Fauna Guarantee Act 1988.

Clearing floodplain forest, woodland, pasture or wetland margins can remove underground refuges and disconnect them from breeding water. Earthworks can collapse burrows, alter drainage or remove emergent vegetation used for calling and egg-laying.

Habitat loss is identified as the biggest threat in the general species account. The Victorian fact sheet specifically identifies vegetation clearing, habitat modification and exotic weeds as potential threats.

  • Avoid clearing around dams, wetlands, streams, floodplain depressions and likely burrow areas wherever practicable.
  • Keep aquatic vegetation, bank structure and terrestrial cover intact at breeding sites.
  • Control weeds without allowing herbicide, sediment or contaminated runoff to enter breeding water.

Threats: Water quality and hydrology

Poor catchment management and poor water quality may affect wetlands, dams, streams and tadpole habitat. Drainage, infilling, dewatering and altered floodplain flows can remove or change breeding sites.

Tadpoles are associated with slow-moving or still water, while breeding may occur in permanent and seasonal waterbodies. Both loss of water and uncontrolled inflow of sediment or pollutants should be considered.

  • Prevent sediment, hydrocarbons, concrete washout and other pollutants from entering breeding water.
  • Maintain natural or approved water levels and drainage patterns during construction.
  • Inspect temporary water storage, sumps and drains for trapped frogs and tadpoles.

Threats: Disease and other pressures

Chytrid fungus causes lethal chytridiomycosis and is identified as a major cause of frog decline generally in the south-west NSW guide. Apply hygiene measures when moving between wetlands or handling frogs.

The supplied documents do not provide species-specific evidence about road mortality, fire, introduced predators or fragmentation effects. These pressures should be assessed for the particular project rather than assumed to be absent.

  • Clean and disinfect footwear, nets, buckets and other equipment before moving between waterbodies.
  • Do not transfer water, tadpoles or aquatic material between sites.
  • Record road crossings, nearby drains, barriers and fire history as project-specific risks where relevant.

Survey methodology: 1. Call surveys after rain

Survey this large, burrowing frog at its breeding wetlands and nearby terrestrial habitat. The species is most detectable after rain, when males call from water, floating vegetation, debris or burrows.

Target spring to early summer, when the NSW guide records breeding, and also survey after heavy rain because the Victorian fact sheet records breeding after heavy downpours.

Listen for the deep, resonating call described as a short ‘bonk’, ‘gunk’ or ‘donk’. Males may call in choruses and may call from dams, pools, streams, floating vegetation or burrows beside water.

Primary breeding period: Spring to early summer in the NSW guide; spring, summer and autumn after heavy rain in the Victorian fact sheet

Call: Deep, resonating ‘bonk’, also described as ‘gunk’ or ‘donk’

  • Survey permanent and seasonal dams, large ponds, swamps, floodplain wetlands, streams and suitable pools within and adjacent to the project area.
  • Include wetland edges, emergent vegetation, debris and flooded burrows in the search area.
  • Record the date, start and finish time, recent rainfall, waterbody condition, observer position, call locations and the number of calling males or choruses detected.
  • Use audio recordings where possible so calls can be checked by an experienced frog identifier.

Survey methodology: 2. Night searches and visual checks

Conduct night searches during or soon after suitable rainfall, when adults emerge from underground burrows to feed and spawn.

Search slowly around wetland margins, stream banks, dams, ponds, flooded burrows and adjacent woodland, heathland, grassland and cleared pasture.

Adult size: 65 to 90 millimetres in the NSW guide; up to 90 millimetres in the Victorian fact sheet

Detection condition: Most likely to emerge after rain, particularly heavy rain

  • Use a spotlight to scan shallow water, emergent vegetation, debris, wet ground and burrow entrances.
  • Check dry terrestrial habitat as well as wetland margins because adults spend most of their lives underground and may be widely dispersed between breeding events.
  • Record each observation with a location, time, habitat description, photograph where appropriate and an estimate of adult size.
  • Do not excavate or probe burrows unless this is authorised under the project fauna management plan and carried out by suitably authorised personnel.

Survey methodology: 3. Breeding habitat and tadpole checks

Inspect still or slow-moving water for foam nests, eggs and tadpoles during the breeding period.

The species lays pigmented eggs in large floating foam masses, including among aquatic vegetation, at dam or pool edges and in flooded burrows.

Egg mass: Large frothy or floating foam mass

Tadpole habitat: Slow-moving or still water

  • Search emergent vegetation, flooded burrows, shallow margins and floating foam masses without disturbing them.
  • Record waterbody type, water permanence, aquatic vegetation, flow condition, foam nests, eggs, tadpoles and evidence of recent breeding.
  • Treat a breeding wetland, its margins and connected stream banks as habitat requiring protection during planning and clearing.
  • If tadpoles are present, obtain advice from the project ecologist before altering water levels, draining the site or moving aquatic material.

Survey methodology: Minimum effort and reporting

  • Use repeated surveys across suitable weather and rainfall conditions rather than relying on a single dry-weather visit.
  • The supplied documents do not specify a standard number of nights, hours, trap nights, transect length or survey area for this species, so set effort in the project fauna survey plan using the applicable state survey guidance and the size and habitat complexity of the site.
  • Document survey dates, times, weather, recent rainfall, observers, methods, search areas, habitat conditions, call or animal records and survey limitations.
  • Submit confirmed records to the relevant state wildlife or biodiversity database and retain the original photographs and audio files with the project records.
  • Escalate any record in Victoria to the project ecologist because the species is identified in the supplied Victorian fact sheet as threatened under the Flora and Fauna Guarantee Act 1988.

Before habitat disturbance: Avoid and minimise habitat loss

Plan around breeding wetlands and the species’ use of underground refuges. Avoid removing wetland margins, stream banks, burrows and connected terrestrial habitat where practicable.

  • Retain permanent and seasonal dams, large ponds, swamps, floodplain wetlands, streams and pools used for calling or breeding.
  • Retain emergent aquatic vegetation, wetland edge debris, flooded burrows and stream-bank cover used for calling and egg laying.
  • Retain adjoining woodland, heathland, grassland and pasture habitat because adults may spend most of their lives underground away from water.
  • Keep retained wetlands and stream banks connected to nearby terrestrial habitat and avoid isolating them with roads, stockpiles or hardstand.
  • Prevent sediment, polluted runoff, weeds and altered drainage from entering retained waterbodies.

Before habitat disturbance: Approvals and work planning

  • Confirm the current national and state conservation listing before work starts and obtain all required approvals, permits and wildlife handling authorities.
  • Check whether the proposed action requires an EPBC Act referral, noting that the supplied profile records the species as not nationally listed.
  • In Victoria, check the requirements that apply to a threatened species listed under the Flora and Fauna Guarantee Act 1988.
  • Schedule clearing and wetland disturbance outside the main spring to early summer breeding period where practicable, and avoid works after heavy rain when adults may be moving and breeding.
  • Stage works so that retained wetlands, stream banks and nearby terrestrial refuges remain available while each work area is cleared.
  • Prepare a fauna management plan that identifies survey triggers, exclusion zones, fauna handling authority, stop-work requirements, relocation arrangements and reporting responsibilities.

Before habitat disturbance: Pre-clearance preparation

  • Complete a pre-clearance survey using call searches and night searches in suitable conditions before machinery enters habitat.
  • Mark no-go areas around breeding wetlands, wetland margins, stream banks, foam nests, flooded burrows and confirmed refuge areas.
  • Mark access routes, machinery pads, spoil areas and drainage controls so they do not encroach on retained habitat.
  • Install exclusion fencing where it can prevent frogs entering the work area without blocking movement between retained wetland and terrestrial habitat.
  • Brief machinery operators and spotter catchers on the frog’s appearance, deep ‘bonk’ call, burrowing behaviour and the locations of retained habitat.

During habitat disturbance: Daily controls

Use a spotter catcher during ground disturbance in known or potential habitat. Control machinery, water movement and material handling so frogs, burrows and breeding habitat are not damaged.

  • Inspect exclusion fencing, wetland controls, drainage diversions and no-go markers at the start of each shift and after rain.
  • Recheck the work area after heavy rain because adults may emerge from underground refuges and move towards breeding water.
  • Keep machinery, vehicles, lighting, spoil, fuels and washdown water out of retained wetlands, stream banks and marked refuge areas.
  • Prevent sediment, contaminants and turbid runoff from entering dams, ponds, streams, swamps and seasonal pools.
  • Maintain a clear communication channel between the spotter catcher, machine operator, supervisor and project ecologist.

During habitat disturbance: Spotter catcher and machinery procedure

  • Have the spotter catcher inspect the next work area before vegetation removal, topsoil stripping, excavation, trenching or drainage works.
  • Require the operator to stop immediately on the spotter catcher’s instruction and keep the bucket, blade or vehicle stationary until the animal and its refuge have been assessed.
  • Search disturbed soil, wet ground, debris, burrow entrances, wetland edges and stream banks before material is removed or stockpiled.
  • Do not chase, crush, bury, wash or relocate a frog without following the approved fauna management plan and the handler’s legal authority.
  • Use a clean, damp, suitable container for any authorised temporary holding and minimise handling and holding time.

During habitat disturbance: Animal finds and stop-work triggers

  • Stop work if a Giant Banjo Frog, foam nest, eggs, tadpoles, flooded burrow or unassessed breeding wetland is found in the disturbance area.
  • Keep people and machinery clear while the authorised handler confirms identification, assesses injury and determines whether the animal can remain in place.
  • Relocate a healthy animal only when authorised and only to nearby suitable retained habitat agreed in the fauna management plan, preferably with access to appropriate wetland and terrestrial cover.
  • Place an injured animal in a clean, secure container and transfer it promptly to an authorised wildlife carer or veterinarian through the project’s approved wildlife response arrangement.
  • Do not release an animal into another waterbody or move eggs or tadpoles unless this is specifically authorised and directed by the responsible wildlife authority or project ecologist.
  • Record the location, time, weather, habitat, action taken, release location, handler and animal condition for every find.

After habitat disturbance: Close-out checks

Complete a final habitat and fauna check before the work area is signed off. Continue controls around retained wetlands and monitor any relocation or habitat disturbance response.

  • Inspect the cleared area, wetland margins, stream banks, stockpiles, trenches and drainage controls for frogs, burrows, foam nests and trapped animals.
  • Remove or make safe fauna traps such as open pipes, pits, trenches and containers before leaving the site overnight.
  • Confirm that retained dams, ponds, swamps, pools, streams, aquatic vegetation and stream-bank cover remain intact and connected to nearby terrestrial habitat.
  • Repair damaged exclusion fencing and maintain no-go markers until the project ecologist confirms that the risk has ended.

After habitat disturbance: Monitoring and reporting

  • Repeat call and night searches during spring to early summer and after suitable heavy rain where habitat has been disturbed or animals have been relocated.
  • Monitor retained wetlands for calling males, foam nests, eggs and tadpoles, and record changes in water condition, aquatic vegetation, weeds and sediment.
  • Report all finds, injuries, mortalities, relocations, stop-work events and permit breaches to the project ecologist and relevant regulator.
  • Submit confirmed records to the relevant state wildlife or biodiversity database and retain the project survey and fauna handling records.
  • Apply any approval conditions, rehabilitation obligations or offset requirements identified during the environmental assessment.

Rehabilitation actions: Wetland and terrestrial habitat repair

Rehabilitation should restore breeding water and nearby dry habitat used for burrowing and shelter. The supplied documents identify water quality, vegetation clearing, exotic weeds and habitat modification as risks.

  • Reinstate shallow margins, emergent aquatic vegetation and suitable still or slow-moving water at dams, ponds, swamps and pools affected by the works.
  • Maintain or restore seasonal water regimes rather than creating only permanent deep water, because the species uses permanent and seasonal waterbodies.
  • Restore stream-bank habitat and avoid concentrating runoff or altering flows into retained breeding sites.
  • Revegetate cleared woodland, heathland, grassland and pasture margins with locally appropriate native plants suited to the site, while retaining open access to breeding water.
  • Retain or replace natural ground cover, leaf litter, coarse woody debris and other shelter near wetlands without blocking drainage or creating machinery hazards.
  • Do not introduce non-local frogs, tadpoles or aquatic plants into restored wetlands.

Rehabilitation actions: Burrows, weeds and water quality

  • Protect existing burrows and flooded burrows during earthworks and avoid compacting soil in areas used by burrowing frogs.
  • Control exotic weeds around wetlands, stream banks and terrestrial refuge areas using methods that prevent herbicide or sediment entering water.
  • Install erosion and sediment controls until bare ground is stable and runoff is clear.
  • Keep restored wetlands free of rubbish, chemical contamination and excessive sediment.
  • Use fire planning appropriate to the local vegetation community and project approvals, and avoid unplanned fire impacts on retained wetland margins and terrestrial refuge areas.

Rehabilitation actions: Success measures and maintenance

  • Inspect rehabilitation after rainfall and through at least one spring to early summer breeding period where the project program allows.
  • Use repeat call searches and night searches to check for returning adults and breeding activity.
  • Record the presence of ‘bonk’ calls, adults, foam nests, eggs and tadpoles, together with water persistence, aquatic vegetation cover, weed cover, erosion and connectivity to retained habitat.
  • Repair failed erosion controls, replace dead plants, remove weeds and correct drainage problems when inspections identify them.
  • Set site-specific completion targets in the rehabilitation plan because the supplied documents do not provide numerical success thresholds for planting density, wetland area, monitoring duration or frog abundance.

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