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Olongburra Tree Frog (Drymomantis olongburensis)

The Olongburra tree frog is a small, nocturnal frog restricted to coastal wallum habitats from far northern New South Wales to south-eastern Queensland, including nearby islands. It uses permanent acidic ponds, creeks, lakes and swamps with emergent reeds, so clearing, drainage, altered water levels, machinery access and disease management need to be considered on development sites.

Conservation status

Commonwealth, EPBC Act 1999: Vulnerable.

Breeding season

This frog calls and breeds after rain from spring through autumn, with calling peaking in October and November. Clearing, draining and dewatering are most likely to affect eggs, tadpoles, metamorphs and sheltering adults from September to May, but wet-weather activity can occur at other times.

Reproductive mode: Egg laying, with a larval tadpole stage.

Clutch size: 75 to 160 eggs; eggs may be laid singly in water at the base of sedges.

Incubation: Not recorded.

Size at hatching or birth: Hatchling length reported as 0.9 to 1.2 mm.

Age at maturity: Age not recorded; size at maturity reported as 20.4 mm.

Nest or egg sites: Under the water surface on reeds, grasses or sedges in permanent ponds, swamps and lakes. Breeding also occurs in acidic, tannin-stained swamps with thick emergent vegetation.

Breeding frequency: One clutch per year reported.

Confirm timing locally before works, because rainfall, water levels and temperature can shift calling, breeding, tadpole development and frog movements.

  • Calling: Males call from January to May and August to December. Calling peaks in October and November, and is not reported in June or July.
  • Egg laying: Breeding occurs in spring, summer and autumn after rain, so egg laying may occur from September to May. Eggs are attached under water to reeds, grasses or sedges, or laid singly at the base of sedges.
  • Tadpoles: Tadpoles may be present across the year because breeding extends from spring into autumn and development takes around 3 months. They are usually near the water surface or resting and grazing on matted sedges.
  • Metamorphs: Metamorphs are expected from December to August, based on the reported 3 month tadpole period following spring to autumn breeding. The exact emergence months are not recorded.
  • Active period: Adults may be active throughout the year. The species shelters among sedges, reeds and ferns in all seasons, moves away from breeding areas during wet periods, and is nocturnal.
  • Winter inactivity: No winter inactivity, hibernation or brumation is recorded. During winter, frogs may shelter among sedges, reeds and ferns, particularly during dry conditions.
  • Highest clearing risk: Risk is highest from September to May, when breeding, eggs, tadpoles and metamorphs may overlap. October and November are peak calling months, but rainfall can shift breeding and clearing risk within the year.

Identification

This is a small reed and sedge associated frog that may be detected by call or by spotlighting emergent vegetation around acidic wallum waterbodies. Identification should be confirmed by an experienced amphibian observer where similar Drymomantis species occur.

Adults reach up to 3.5 cm in body length. The back is bright green or bronze, with a dark brown stripe extending from the snout to the side. A white stripe runs from below the eye towards the arm and becomes spots along the side. The belly is white.

The pupil is horizontal and the iris is gold. The backs of the thighs may be blue, orange or purple. Fingers are slightly webbed, toes are about two-thirds webbed, and both have small discs.

Greatest recorded length: 34.1 mm snout to vent

Greatest recorded mass: 0.57 g

Activity: Nocturnal

Identification: Sex and call

Males have brown flecks on the throat. Females often have a green throat. The call is high pitched and has been described as a 'creeeek. crik' pattern.

Calling has been recorded from January to May and from August to December. June and July are reported as periods with no calling.

Identification: Similar species and field detection

The species can look very similar to Drymomantis cooloolensis and Drymomantis fallax where their distributions overlap. Brown throat flecks are a useful field character, but photographs, call recordings and expert confirmation may be needed.

No species-specific information was provided for tracks, scats, eyeshine, nests, sloughs or other terrestrial field signs. Search effort should therefore focus on nocturnal call surveys and spotlighting reeds, sedges and other emergent vegetation around suitable water.

  • Check the dark snout-to-side stripe, white facial stripe, horizontal pupil and coloured backs of the thighs.
  • Record the call and the calling location where possible.
  • Treat small frogs in suitable wallum habitat as potential Olongburra tree frogs until identification is resolved.

Distribution: National range

The Olongburra tree frog is endemic to Australia and has a narrow coastal distribution in New South Wales and Queensland. The supplied sources describe its range by coastal region and wallum habitat rather than by named IBRA bioregion.

The species occurs along the coast from far northern New South Wales to south-eastern Queensland, including nearby islands. It is associated with the coastal wallum zone and its sandy, acidic wetlands.

Australian states recorded: New South Wales and Queensland

Named bioregions: Not provided in the supplied documents

  • New South Wales: far northern coastal areas.
  • Queensland: south-eastern coastal areas.
  • Nearby coastal islands are included in the recorded distribution.

Distribution: Population and strongholds

The supplied sources do not name specific strongholds or describe separate subpopulations. The reported wild population is approximately 10,000 to 50,000 individuals, and the population trend is decreasing.

Estimated wild population: About 10,000 to 50,000 frogs

Population trend: Decreasing

Conservation status: Vulnerable under the EPBC Act and Vulnerable under the IUCN Red List

Habitat: Wetland types

The species depends on coastal wallum wetlands with sandy soils, acidic water and emergent vegetation. Suitable habitat may be permanent or seasonally intermittent, although the breeding description focuses on permanent ponds, swamps and lakes.

Recorded habitats include permanent ponds, creeks, lakes and swamps with emergent reeds. The broader habitat description includes subtropical or tropical swamps, wallum swamps, freshwater lakes, intermittent freshwater lakes, and freshwater marshes.

Habitat: Key site features

Suitable sites have sandy wallum soils, acidic water and emergent reeds, sedges or other vegetation rising from the water. Dense wetland vegetation provides calling and attachment sites and may connect aquatic habitat with nearby terrestrial and arboreal areas.

Elevation limit: Not reported

Climate setting: Subtropical or tropical coastal Australia

  • Map permanent and intermittent waterbodies within or near the works area.
  • Inspect emergent reeds and sedges, wetland margins and nearby wallum vegetation.
  • Record water permanence, acidity where measured, sandy soils and any hydrological connections before clearing or earthworks.

Foraging habitat: Feeding information

The supplied documents provide little direct information on diet or feeding behaviour. The species is reported as aquatic, arboreal and terrestrial, and it is nocturnal.

A specific diet, prey list, hunting method and foraging range were not recorded in the supplied species information. As a general practice for a small nocturnal frog, retain wetland vegetation, shaded margins and connected habitat around breeding ponds during works because these areas may provide feeding surfaces and access to prey.

Known diet: Not reported in the supplied documents

Foraging range: Not reported

Activity period: Nocturnal

  • Avoid unnecessary removal of reeds, sedges and dense wetland margin vegetation.
  • Limit night lighting near occupied wetlands because the species is nocturnal.
  • Keep machinery, spoil, sediment and chemical products away from ponds, swamps and drainage lines.

Breeding habitat: Breeding biology

Breeding occurs in wet weather during spring and summer. Permanent ponds, swamps and lakes with submerged or emergent reeds provide the reported breeding conditions.

Mating and breeding are reported in spring and summer, often after rain. Females attach eggs to grasses and sedges, and the breeding description indicates that eggs are attached under the water surface to reeds.

Tadpoles are dark brown, may reach 4.5 cm in total length, often remain near the water surface, and take about 3 months to develop into frogs.

Breeding season: Spring and summer, often after rain

Eggs per clutch: 75 to 160 eggs

Clutches per year: One per year reported

Egg placement: Under the water surface on reeds, grasses or sedges

Tadpole development: About 3 months

Age at maturity: Not reported

Lifespan: Not reported

Breeding habitat: Breeding-site requirements

Breeding sites are permanent ponds, swamps and lakes with acidic water and emergent reeds or sedges. Maintaining water levels and the vegetation supporting egg attachment is important during the breeding and tadpole period.

  • Do not clear emergent reeds or sedges from occupied or potentially occupied breeding waterbodies without an approved management response.
  • Prevent sediment, contaminants and altered drainage from entering breeding ponds and swamps.
  • Check waterbodies after rain and during spring and summer when calling and breeding activity are most likely.

Sheltering habitat: Known refuge features

Specific shelters, refuge dimensions and overwintering sites were not described. The species uses aquatic, arboreal and terrestrial settings, with dense wetland vegetation likely to provide the most relevant cover identified in the supplied documents.

The sources identify reeds, sedges and wetland vegetation as important habitat features, including surfaces used for egg attachment. No measurements are provided for shelter size, retreat distance, burrows, hollows, roosts or ground-cover depth.

Shelter dimensions: Not reported

Burrows, hollows and dens: Not reported

Known habitat use: Aquatic, arboreal and terrestrial

  • Retain dense emergent vegetation around ponds, lakes, creeks and swamps.
  • Search vegetation and wetland margins at night, when the species is active.
  • Avoid clearing, slashing or burning wetland margins without first checking for frogs and breeding activity.

Threats: Habitat loss and hydrology

The species is Vulnerable and decreasing. Habitat loss and degradation are the main documented concerns, with invasive plants and chytrid fungus also identified as threats.

Clearing or filling wallum swamps, ponds, marshes and wetland margins can remove breeding and shelter habitat. Drainage, groundwater changes, altered runoff and changes to the permanence or acidity of ponds may reduce habitat suitability.

  • Avoid clearing emergent reeds, sedges and wetland margins where suitable waterbodies occur.
  • Maintain natural drainage to permanent and intermittent wetlands.
  • Control sediment, concrete washout, fuels and other contaminants near acidic wallum waterbodies.

Threats: Fragmentation, roads and construction

The supplied documents identify habitat loss as a threat but do not provide species-specific road mortality rates, movement distances or fragmentation thresholds. General amphibian protection practice should be applied where roads, access tracks, trenches or construction areas divide wetlands and adjacent vegetation.

  • Use fauna spotters and exclusion controls around suitable ponds, swamps, creeks and wetland vegetation during clearing.
  • Inspect open trenches, pits and other excavations regularly and provide escape measures where required.
  • Use temporary barriers or other controls to keep frogs away from active work areas when suitable habitat is being disturbed.

Threats: Fire, invasive plants and disease

Invasive plants and chytrid fungus are documented threats. The supplied documents do not give a species-specific fire regime or fire response, so avoid burning that removes wetland vegetation or changes wetland structure without site-specific ecological advice.

Disease hygiene is important for works near occupied wetlands because chytrid fungus is identified as a major contributor to population decline.

  • Clean and disinfect footwear, nets, traps, tools and other equipment before moving between frog habitats.
  • Prevent the spread of invasive plants through machinery, soil, mulch and water movement.
  • Do not move frogs, tadpoles, water, sediment or wet vegetation between waterbodies unless authorised and managed under an approved protocol.

Survey methodology: 1. Nocturnal call and spotlight surveys

Survey the Olongburra tree frog where works may affect permanent or intermittent ponds, creeks, lakes or swamps with emergent reeds, acidic water and sandy wallum soils. The species is small, nocturnal and most detectable when calling after rain, particularly in spring and early summer.

Survey at night when frogs are active and calling, using a combination of listening and spotlighting along the margins of ponds, creeks, lakes and swamps.

Prioritise surveys after rain and during the main calling period, especially October and November, with additional effort in September, December and January to April.

Search emergent reeds, sedges and low vegetation at the water edge, and scan the water surface and nearby vegetation for small frogs up to about 3.5 centimetres long.

Record weather, recent rainfall, start and finish times, survey route, waterbody type, water condition, vegetation searched and all frog calls heard.

Activity: Nocturnal

Peak calling months: October and November

Main breeding period: Spring and summer after rain

Maximum reported body length: About 3.5 centimetres

  • Use the species call, described as a high pitched call with a pattern similar to "creeeek. crik", as one identification feature, but confirm records where possible by observing the frog or obtaining a clear recording.
  • Treat May and August as possible calling months, and do not rely on call surveys alone from June to July because the available species profile reports no calling in those months.

Survey methodology: 2. Aquatic habitat and tadpole searches

Inspect permanent ponds, swamps and lakes with emergent reeds, including acidic waterbodies near sandy wallum soils, for adults, eggs, tadpoles and suitable attachment sites.

Search reeds and sedges at and just below the water surface because eggs are reported to be attached under the water surface to reeds, although the eggs themselves have not been described.

Use appropriate amphibian hygiene procedures between waterbodies, including cleaning and disinfecting footwear, nets and other equipment, to reduce the risk of transferring chytrid fungus and other pathogens.

Record waterbody location, water permanence, acidity where measured, emergent vegetation, recent disturbance, weeds and evidence of breeding.

Tadpole development time: About three months

Tadpole appearance: Dark brown, with a white or silver lower body when viewed from the side

Egg attachment sites: Under the water surface on reeds in permanent ponds, swamps and lakes

  • Where aquatic sampling is authorised and safe, inspect shallow margins and emergent vegetation for dark brown tadpoles that may reach about 4.5 centimetres in total length.
  • Use visual searches and call surveys alongside any tadpole sampling because tadpoles take about three months to develop and may not be present outside the breeding period.

Survey methodology: 3. Survey timing and effort design

Schedule the main survey effort for spring and summer, with priority after rainfall and during October and November when calling is reported to peak.

Include all suitable waterbodies and their vegetated margins within the project area and any areas that may be affected by access, drainage, sediment, dewatering, noise or construction runoff.

No species-specific survey guideline, minimum number of nights, survey duration, transect length, trap-night requirement or survey buffer is provided in the supplied documents, so set effort through a documented risk assessment and confirm it with the relevant regulator before works begin.

Increase coverage where habitat is fragmented, access is difficult, the project may alter hydrology, or an initial survey detects the species or suitable breeding habitat.

  • Do not treat a failure to detect the species in winter as evidence of absence because the profile reports no calling from June to July.
  • Use repeat visits across suitable weather and seasonal conditions where the project risk is high, rather than relying on one visit.

Survey methodology: Minimum effort and reporting

Document the survey area, methods, dates, times, weather, rainfall, personnel, equipment, hygiene measures, habitat searched, detections and identification evidence.

Map each detection and each occupied or potentially occupied waterbody, including the location of calling males, adults, tadpoles and breeding habitat.

Have records reviewed by a suitably experienced amphibian ecologist where identification is uncertain, particularly because the species can resemble Drymomantis cooloolensis and Drymomantis fallax.

Submit verified records and relevant negative survey information to the relevant state wildlife database, and provide records to the project regulator and approval authority where required.

Retain call recordings, photographs, field sheets, spatial data and chain of custody information for any captured or relocated frog.

Before habitat disturbance: Avoid and minimise

Avoid impacts to acidic wallum wetlands and their connected vegetated margins before clearing or construction starts. The species occurs only along the coast from far northern New South Wales to south-east Queensland, including nearby islands, and depends on wet habitats with emergent reeds or sedges.

Redesign the project to retain permanent and intermittent ponds, creeks, lakes and swamps with emergent reeds, sedges and other wetland vegetation.

Retain sandy wallum soils and avoid filling, draining, deepening, isolating or contaminating suitable waterbodies.

Maintain connections between retained wetlands and nearby suitable wetland vegetation where practicable, because the species uses aquatic, arboreal and terrestrial environments.

Keep construction runoff, sediment, concrete washout, fuels, chemicals and contaminated water away from acidic wetlands and their margins.

  • Do not remove emergent reeds or sedges from suitable breeding water unless the impact has been assessed and approved.
  • Do not introduce soil, water, aquatic plants or equipment from another site without appropriate controls against weeds and amphibian disease.
  • Use site-specific no-go areas and exclusion fencing around retained wetlands and their vegetated margins, with the extent set by the project ecologist and approval conditions.

Before habitat disturbance: Approvals and work planning

Check whether the proposed action requires referral under the Environment Protection and Biodiversity Conservation Act because the species is listed as Vulnerable nationally.

Check state and local requirements for clearing, wetland disturbance, fauna handling, capture, relocation, rehabilitation and works near waterways before mobilisation.

Plan high-risk works outside the main spring and summer breeding period where practicable, especially after rainfall and during the October to November calling peak.

Stage works so that suitable wetlands and their vegetated margins remain undisturbed until surveys, approvals, exclusion controls and fauna procedures are in place.

National listing: Vulnerable under the EPBC Act

Reported range: Coastal far northern New South Wales to south-east Queensland, including nearby islands

  • Prepare a fauna management plan that identifies suitable habitat, survey results, exclusion areas, wet weather controls, spotter catcher responsibilities, stop-work triggers, handling procedures and reporting requirements.
  • Include a wetland protection plan covering drainage, dewatering, sediment, water quality, access routes, lighting and machinery movement.

Before habitat disturbance: Prepare the site

Complete a pre-clearance survey in suitable weather and at a suitable time of year, using nocturnal call and spotlight searches of all affected and adjacent suitable wetlands.

Mark retained wetlands, emergent reed and sedge beds, access limits, machinery exclusion zones and any areas requiring hand clearing.

Brief all workers on the species appearance, nocturnal activity, call, hygiene requirements, reporting chain and stop-work procedure.

Install and inspect exclusion fencing where it is suited to the site, ensuring that fencing does not block essential drainage or trap frogs in the work area.

  • Confirm that the fauna spotter catcher is appropriately authorised for the state and task before any capture, handling or relocation occurs.
  • Provide clean equipment, sealed containers suitable for temporary amphibian holding, clean water where directed by the fauna specialist, head torches and disinfectant supplies.

During habitat disturbance: Daily controls and spotter catcher duties

Control access, water movement and machinery around retained or disturbed wetland habitat. A fauna spotter catcher must be able to stop work, inspect the area and direct machinery before vegetation, soil or wetland features are disturbed.

Inspect exclusion fencing, wetland protection controls, sediment controls and access routes before work starts each day and after heavy rain.

Keep the fauna spotter catcher present during clearing or other activities that may affect suitable wetland habitat, as required by the approved fauna management plan.

Use staged clearing, slow machinery movement and hand removal around wetland margins and emergent reeds where frogs may be concealed.

Maintain amphibian hygiene between waterbodies by cleaning and disinfecting footwear, nets, containers and other equipment.

  • The spotter catcher must have authority to stop machinery immediately when a frog, tadpole, breeding site, unapproved impact or failed control is identified.
  • Machinery operators must stop on the spotter catcher's instruction, lower attachments safely and wait for the area to be inspected and cleared.
  • Keep lighting, noise, vehicle movement and access routes away from retained wetlands where practicable, particularly during night works and the calling season.

During habitat disturbance: Finding and handling a frog

If a frog is found, stop work in the immediate area and keep people, vehicles and machinery clear until the authorised fauna handler assesses it.

Do not allow untrained workers to catch, hold, photograph closely or relocate the frog.

Handle the frog only when authorised and necessary, using clean, powder-free gloves or another approved method that protects the animal's skin and prevents disease transfer.

Relocate a healthy frog only under the approved fauna management plan and to nearby retained suitable habitat selected by the authorised fauna specialist.

Place an injured or unwell frog in an appropriate clean container and arrange prompt assessment by a veterinarian or authorised wildlife carer.

  • Record the species identification, exact location, time, condition, action taken, release location, handler and any photograph or call recording.
  • Do not release a frog into an isolated, dry, polluted or unsuitable location, or into a waterbody outside the approved relocation area.

During habitat disturbance: Wetland features and stop-work triggers

Treat emergent reeds, sedges, pond margins, shallow water, breeding waterbodies and connected damp vegetation as habitat features requiring inspection before disturbance.

Stop work if a frog, tadpole, suspected egg attachment site, occupied wetland, unexpected water discharge, sediment release or damaged exclusion control is identified.

Stop work and notify the project ecologist if dewatering, drainage alteration, filling, pollution or changes to wetland water quality occur outside the approved method.

Do not pump, discharge or divert water from a suitable wetland until the fauna and water management requirements have been checked.

  • Inspect any disturbed reed or sedge bed for frogs and tadpoles before removal, and use hand methods where the approved plan requires them.
  • Record daily clearance areas, habitat features inspected, animals found, relocations, injuries, mortality, stop-work events, incidents and corrective actions.

After habitat disturbance: Post-clearance checks

Keep protection measures in place until disturbed areas are stable and the project ecologist confirms that no further fauna risk remains. Check retained and rehabilitated wetlands for frogs, tadpoles, water quality and vegetation recovery.

Complete a final inspection of each cleared work area, wetland margin, access route and exclusion fence line for frogs, tadpoles, egg attachment sites and trapped animals.

Check pits, trenches, pipes, sumps, tanks and other excavations daily while open, and provide escape ramps or cover them when they are not in use.

Inspect retained wetlands after rainfall and after activities that may change drainage, sediment loads or water quality.

Keep fauna exclusion fencing, wetland buffers and sediment controls in place until the fauna specialist and approval authority requirements have been met.

  • Record all post-clearance searches, including date, time, weather, area checked, personnel, findings and corrective action.
  • Report any death, injury, disease concern, pollution event or unexpected occupied habitat through the project's incident and regulatory reporting process.

After habitat disturbance: Monitoring and compliance

Monitor retained and rehabilitated waterbodies during the spring and summer breeding period, with additional checks after rainfall and during the October to November calling peak.

Use repeat nocturnal call and spotlight surveys, supported by visual inspection of emergent vegetation and authorised tadpole searches where appropriate.

Compare monitoring results with the pre-construction records for calling activity, adults, tadpoles, water permanence, emergent vegetation and wetland condition.

Maintain records of rehabilitation actions, weed treatment, disease controls, water quality issues, fauna incidents and any changes to drainage or wetland vegetation.

Monitoring priority: Spring and summer, especially October and November, and after rain

  • If monitoring detects frogs in a work area, unexpected breeding activity or declining wetland condition, review the work method and implement the approved corrective action before continuing.
  • Provide monitoring and incident results to the approval authority and relevant state wildlife database where required.

After habitat disturbance: Offsets and close-out

Confirm whether an approved offset, conservation measure or rehabilitation commitment applies to the project because of residual impacts on nationally listed habitat.

Do not treat an offset as a substitute for avoiding and minimising impacts to suitable wallum wetlands and their vegetated margins.

Close out the fauna management plan only after required surveys, records, rehabilitation, monitoring, reporting and approval conditions are complete.

Rehabilitation actions: Wetland and vegetation restoration

Rehabilitate for a functioning wetland mosaic rather than only replacing cleared vegetation. The target condition should provide acidic or otherwise suitable wetland water, emergent reeds or sedges, sandy wallum-associated ground conditions and connected damp habitat.

Reinstate or protect permanent and intermittent ponds, swamps, lakes and creek margins where they formed part of the pre-work habitat.

Restore natural drainage and water retention patterns without creating polluted, isolated or excessively deep waterbodies.

Replant locally appropriate emergent reeds and sedges around suitable water margins, using locally sourced material where required by the rehabilitation plan.

Retain or re-establish a graded transition from open water through emergent vegetation to damp terrestrial cover.

  • Do not plant invasive aquatic or wetland species, and remove weeds that shade, choke or replace native reeds and sedges.
  • Keep livestock, vehicles and machinery out of recovering wetland margins.
  • Do not alter water chemistry or add materials that could reduce the suitability of acidic wallum wetland habitat.

Rehabilitation actions: Habitat structure and threats

Retain natural ground cover and damp terrestrial vegetation around rehabilitated waterbodies because the species uses aquatic, arboreal and terrestrial environments.

Manage weeds, sediment, altered drainage, pollution and other threats that could reduce wetland quality or emergent vegetation.

Apply predator and domestic animal controls where they are identified as a project risk, using methods approved for the site and relevant authorities.

Use fire planning that protects wetland vegetation, avoids damaging recovering reed and sedge beds and follows the site's ecological burn requirements.

  • Do not install hollows, nest boxes, logs or rocks as a substitute for the wetland and emergent vegetation features documented for this species.
  • Prevent chytrid and other pathogen spread through ongoing cleaning and disinfection of equipment used between rehabilitated waterbodies.

Rehabilitation actions: Monitoring and success measures

Monitor rehabilitated sites through at least the first spring and summer breeding period, including checks after rainfall and during October and November.

Use nocturnal call and spotlight surveys to assess whether frogs return to the rehabilitated wetland margins.

Inspect emergent reeds and sedges for breeding activity, and use authorised tadpole searches where they are included in the monitoring plan.

Assess success against site-specific measures including retained water, suitable wetland vegetation, weed control, stable drainage, clean equipment practices, no fauna mortality and detection of adults, calls or tadpoles.

Development period for tadpoles: About three months

Key seasonal monitoring window: Spring and summer, with peak calling in October and November

  • Set trigger levels for drying, sedimentation, pollution, weed cover, failed vegetation establishment and absence of expected habitat condition, then specify corrective actions before works begin.
  • Continue monitoring or adapt rehabilitation where the site does not provide suitable permanent or intermittent wetland habitat with emergent reeds or sedges.

Sources