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Yellow-spotted Tree Frog (Ranoidea castanea)

The Yellow-spotted Tree Frog is a large, critically endangered bell frog endemic to tableland regions of New South Wales. It uses ponds, wetlands and slow-moving waterways with abundant aquatic and submerged vegetation, so clearing, earthworks, altered drainage and disturbance near breeding water can affect habitat and breeding activity on development sites.

Conservation status

Commonwealth, EPBC Act 1999: Critically endangered.

Breeding season

Calling and breeding are concentrated from spring into early summer, with the strongest evidence for calling from October to December and egg laying from late October to mid-November. Clear aquatic vegetation, ponds and adjoining damp cover with care during this period, and treat summer as a likely period for larvae and young frogs even though their exact timing is not recorded.

Reproductive mode: Egg laying, with development through a larval stage

Clutch size: 2889 eggs reported in the supplied trait dataset

Incubation: Not recorded

Size at hatching or birth: Not recorded

Age at maturity: Not recorded

Nest or egg sites: Small egg clusters are laid in water and may sink and attach to submerged vegetation at the shallow edges of permanent ponds and lagoons. Breeding habitat includes large permanent ponds with emergent reeds and other vegetation.

Breeding frequency: One clutch per year reported in the supplied trait dataset

Confirm timing locally before works, using recent calling and rainfall records and checking whether temperature, rainfall and pond hydroperiod have extended or shifted breeding activity.

  • Calling: Calling was recorded from late October to late December in several breeding attempts, with additional records in January and possible calling in August and September. The strongest documented calling activity was from late October to December, but the sources do not identify a peak month.
  • Egg laying: Eggs were laid from late October to mid-November, with the strongest documented egg-laying period in November. Eggs are laid amongst submerged vegetation or as small clusters in shallow water at permanent ponds and lagoons.
  • Tadpoles: Species-specific months for tadpoles, hatching and development time are not recorded. As a general pattern for a pond-breeding frog in temperate eastern Australia, larvae may be present from late spring through summer after egg laying, depending on water permanence and temperature.
  • Froglets: The timing of metamorphosis and juvenile emergence is not recorded for this species. As general practice for a pond-breeding frog, inspect pond margins and adjoining damp vegetation from summer into early autumn for recently emerged froglets.
  • Active period: A species-specific annual activity period is not recorded, but calling records show activity in January and February, possible activity in August and September, and regular breeding-season activity from October to December. Frogs are recorded as both diurnal and nocturnal, so inspections should not be limited to night work.
  • Winter inactivity: Winter inactivity, shelter sites and use of underground refuges, logs, rock cracks or leaf litter are not recorded for this species. As general practice in the temperate part of its range, treat June to July as a period when frogs may shelter in damp cover and conduct pre-clearing searches of vegetation, wetland margins and adjoining ground.
  • Highest clearing risk: Risk is highest from October to March because breeding, egg laying and likely larval or froglet presence overlap during this period. October to November carries the strongest documented risk from calling, amplexus and egg laying amongst submerged vegetation, while summer works may affect tadpoles and emerging froglets.

Identification

This is a large green to golden-brown bell frog associated with permanent or semi-permanent freshwater habitats. Field identification should be confirmed from several features because other Ranoidea bell frogs can have similar overall colouration.

Adults are predominantly green or golden in colour and grow to about 50 to 85 mm snout to vent length. The most useful distinguishing feature is the presence of large yellow or cream spots in the inguinal region and on the rear of the thighs. The toes are entirely webbed.

The body mass can reach about 17.5 g, although a typical adult mass and sex-specific size ranges were not reported in the supplied sources.

Snout to vent length: 50 to 85 mm

Greatest reported length: About 80 mm

Greatest reported mass: 17.5 g

Identification: Distinguishing features

Check the groin and the backs of the thighs for large yellow or cream spots, which distinguish this species from other members of the bell frog group in the supplied references. The back is generally pale green or golden brown, and dark to black spots may be highlighted by bronze patches.

The species has fully webbed toes. It may be recorded on the ground, in water or in vegetation, and its reported activity includes both daytime and night-time periods.

Identification: Field signs and survey notes

No species-specific information was supplied for tracks, scats, nests, sloughs or eyeshine. Frogs, tadpoles, metamorphosing young and egg clutches are the most relevant field observations for this species.

Egg clutches consist of unpigmented eggs placed amongst submerged vegetation. During targeted searches, inspect aquatic vegetation, shallow margins and adjacent damp terrestrial cover, particularly from October to December.

Distribution: National range

The species is endemic to south-eastern Australia and is recorded from tableland regions of New South Wales. Historical records indicate separate northern and southern population areas, but the taxonomic and genetic relationship between these populations remains unresolved.

The species is known from New South Wales. Historical records covered the New England Tablelands, central tablelands and southern tablelands of the state.

The northern population was centred around Guyra on the New England Tableland, generally at elevations of 1000 to 1500 m. The southern population occurred between Canberra and Bombala on the Southern Tablelands, generally at 700 to 800 m.

Australian state: New South Wales

Bioregions and regions: New England Tablelands, central tablelands and Southern Tablelands

Historical northern elevation: 1000 to 1500 m

Historical southern elevation: 700 to 800 m

Distribution: Subpopulations and trend

The species was formerly recorded from northern, central and southern New South Wales. The northern population was known from a restricted area around Guyra, with 13 verified sites reported in the New England region.

A population was rediscovered in 2009 along about a four-kilometre section of slow-moving creek north of Yass in the Southern Tablelands. Repeated later surveys did not locate the species, and no further wild breeding was observed after the collection of four metamorphosing frogs in 2014.

Verified historical New England sites: 13 sites

Rediscovered creek section: About 4 km

Initial founders collected in 2010: 14 tadpoles and metamorphosing frogs

Additional animals collected: One in 2012 and four in 2014

Captive release production: 2162 juvenile frogs

Insurance population: More than 100 frogs retained

Population trend: Decreasing

Habitat: Habitat types

The Yellow-spotted Tree Frog is associated with freshwater habitats on elevated tablelands. It has been observed in ponds, wetlands and slow-moving waterways where aquatic and submerged vegetation is abundant.

Recorded and reported habitats include permanent water bodies, ponds, wetlands, swamps, freshwater lakes, freshwater marshes, rivers, intermittent rivers and slow-moving waterways.

The rediscovered population occupied a slow-moving creek passing through open pastoral land. The species is described as aquatic but may use aquatic, terrestrial and arboreal settings.

Habitat: Key structural features

Retain waterbodies with abundant aquatic and submerged vegetation, shallow margins and connected damp ground. Submerged vegetation is particularly important because egg clutches are laid amongst it.

The supplied sources do not identify particular plant species, vegetation communities, water depths or minimum pond sizes. On project sites, map and protect the full waterbody margin and nearby wet ground rather than retaining only open water.

Habitat: Elevation and climate

Historical records span about 700 to 800 m in the southern population and 1000 to 1500 m in the northern population. The known range is confined to tableland regions of New South Wales.

The species experienced breeding or larval survival problems during summer flooding associated with La Nina conditions at the rediscovered site, indicating that hydrology and flood timing can affect recruitment.

Foraging habitat: Diet and feeding sites

The supplied species accounts provide little direct information on diet, prey or foraging distances. Field assessment should therefore focus on retaining the wetland, waterway margin and nearby terrestrial cover used by a large bell frog.

Diet is not recorded in the supplied species-specific sources. The available account does not confirm particular prey types or food plants.

The species has been recorded in aquatic, terrestrial and arboreal settings and is reported as active during both day and night. Inspect aquatic margins, dense vegetation and adjacent damp ground when assessing potential foraging habitat.

Documented diet: Not reported in the supplied sources

Reported activity: Diurnal and nocturnal

Reported settings: Aquatic, terrestrial and arboreal

Foraging habitat: Foraging range

A species-specific foraging range, home range or movement distance was not reported. Do not use a narrow buffer around the waterbody as a proxy for the full habitat area without site-based evidence.

For clearing assessments, treat aquatic vegetation, the waterbody edge and adjoining damp terrestrial vegetation as potential foraging habitat, and search these areas during both daylight and night-time survey periods where conditions allow.

Breeding habitat: Breeding biology

Breeding is linked to freshwater habitats with submerged vegetation. The strongest available timing information comes from conservation breeding, so site conditions and local observations should be used to refine the timing for wild populations.

Breeding behaviour occurred mainly from October to December. Egg clutches were laid from late October to mid-November, amongst submerged vegetation, and the eggs were unpigmented.

The species is oviparous and develops through a larval stage. The supplied sources do not report species-specific gestation, incubation duration, age at maturity or lifespan.

Breeding season: Mainly October to December

Peak egg-laying period reported: Late October to mid-November

Reproductive mode: Egg laying, with a larval stage

Reported clutch size: 2889 eggs in the supplied trait dataset

Gestation or incubation: Not reported

Age at maturity: Not reported

Lifespan: Not reported

Breeding habitat: Breeding habitat features

Retain ponds, wetlands and slow-moving waterways with abundant aquatic and submerged vegetation. Protect submerged plants and shallow water margins during the October to December breeding period.

The species formerly bred in a slow-moving creek, but flooding at the site was associated with reduced breeding or larval survival in some years. Avoid changing inflows, drainage paths, hydroperiod or water quality without assessing effects on breeding and larvae.

Breeding habitat: Captive breeding evidence

Initial attempts were unsuccessful when founders were kept indoors or in small outdoor enclosures. Successful breeding occurred after transfer to a large outdoor enclosure, producing five clutches over three seasons from 2017 to 2019.

In 2024, six clutches were produced in one season in a dedicated indoor facility, with 60 percent of paired females laying eggs. These results show that breeding response can depend strongly on enclosure and environmental conditions.

Sheltering habitat: Likely refuge areas

Specific refuge structures and shelter dimensions have not been documented in the supplied sources. The species can use aquatic, terrestrial and arboreal settings, so surveys and impact controls should cover both the breeding waterbody and adjoining vegetated areas.

Retain submerged and emergent vegetation, wetland margins and damp ground beside ponds, wetlands and slow-moving waterways. These features provide the documented aquatic and near-water structure associated with the species.

The sources do not report species-specific use of hollows, burrows, caves, logs, rock piles, tree sizes or ground-cover heights. No refuge size or home-range dimension should be assumed from the supplied information.

Documented shelter settings: Aquatic, terrestrial and arboreal settings

Hollow, burrow or den dimensions: Not reported

Known refuge size: Not reported

Sheltering habitat: Site practice

Before clearing, inspect aquatic vegetation, damp ground and dense cover around suitable waterbodies, including areas that may hold frogs during daylight.

Keep machinery, spoil, sediment, pollutants and artificial drainage away from retained water, submerged vegetation and adjoining damp cover. Use a qualified fauna spotter catcher where a frog is found or where a confirmed population is present.

Threats: Disease

The species underwent a rapid decline in the late 1970s and was not recorded for about 30 years. Chytrid fungus is considered a likely primary driver, with habitat loss, fragmentation, hydrology change, flooding and introduced predators also relevant to project planning.

The decline in the late 1970s was consistent with amphibian chytrid fungus, Batrachochytrium dendrobatidis, being a primary driver. The rediscovered wild population was later affected by a chytrid outbreak.

Undertake disease hygiene and baseline disease screening in accordance with current amphibian biosecurity requirements. Do not move water, mud, equipment or amphibians between sites without appropriate hygiene controls.

Threats: Clearing and fragmentation

Loss or fragmentation of ponds, wetlands, slow-moving waterways, submerged vegetation and adjacent damp cover can remove breeding and non-breeding habitat.

Avoid clearing suitable wetland margins during the October to December breeding period. Where works are unavoidable, identify and retain aquatic vegetation, waterbody margins and connections to nearby damp habitat.

Threats: Hydrology and flooding

Flooding associated with La Nina conditions was linked with reduced breeding or larval survival at the rediscovered site. Changes to inflow, drainage, water levels, hydroperiod or sediment loads may affect eggs and larvae.

Design works to prevent sediment, chemicals and altered runoff from entering retained breeding water. Assess both direct filling and indirect changes to the timing and duration of inundation.

Threats: Predators and other pressures

Introduced fish and fish translocations are identified as potential threats to Australian bell frogs in the supplied species account. Avoid introducing fish or connecting previously isolated breeding waters to stocked waterways.

The supplied sources identify habitat alteration and loss as a general threat. They do not provide species-specific information on road mortality, fire response or predator densities, so these risks require site-based assessment.

Survey methodology: 1. Nocturnal spotlighting and call searches

Survey this species in and around permanent or seasonal wetlands, ponds and slow-moving waterways with aquatic or submerged vegetation. The available documents do not provide a prescribed survey guideline, number of nights, transect length or trap effort, so the project ecologist must apply the relevant state survey guideline and set effort from the habitat, risk and approval conditions.

Undertake targeted night searches around ponds, wetlands, creek margins and slow-moving waterways, including submerged vegetation where frogs may call, move or breed.

Give priority to October to December, when captive breeding activity was recorded, and to late October to mid-November, when egg clutches were observed.

Search during suitable warm, humid and still conditions where practicable, because weather affects frog movement and calling, and record the conditions for every survey.

The available documents do not specify the number of nights, search hours, transect length or survey area, so set these in accordance with the applicable state guideline and document the rationale.

Known breeding period: Primarily October to December

Egg-laying period recorded in captivity: Late October to mid-November

Known rediscovery site: A slow-moving creek in the Southern Tablelands of New South Wales

Survey methodology: 2. Wetland and aquatic habitat inspection

Inspect permanent water bodies, swamps, freshwater marshes, ponds, intermittent wetlands and creek edges for adults, metamorphs, tadpoles, egg clutches and characteristic frog calls.

Search amongst submerged and emergent vegetation, where captive clutches were recorded, and inspect shallow margins, connected wet areas and sheltered cover.

Map each wetland, drainage line, pond and creek section within and near the proposed disturbance area, including the four-kilometre creek section associated with the rediscovered population where relevant to the project area.

Record water permanence, flow, submerged vegetation, emergent vegetation, surrounding grassland and any barriers between wet areas.

Survey methodology: 3. Larval and metamorph survey

Use daytime and night-time searches of shallow wetland margins for tadpoles and metamorphosing frogs, particularly during or after the breeding period.

Use only survey techniques approved by the relevant state authority, and minimise disturbance to aquatic vegetation, egg clutches and larvae.

The species was originally detected through early life stages, and fourteen tadpoles and metamorphosing frogs were collected in 2010, so surveys must not rely on adult detection alone.

Founders collected in 2010: 14 tadpoles and metamorphosing frogs

Additional wild collection: 1 metamorphosing frog in 2012 and 4 metamorphosing frogs in 2014

Survey methodology: Minimum effort and reporting

  • Use the applicable state or territory threatened fauna survey guideline to specify the minimum number of nights, search hours, transect area, trap nights and repeat visits before fieldwork starts.
  • Repeat surveys across the October to December breeding period where habitat and timing allow, and include late October to mid-November if breeding habitat may be disturbed.
  • Record survey dates, start and finish times, weather, observers, methods, search area, water conditions, vegetation, calls, adults, juveniles, tadpoles and egg clutches.
  • Use appropriate amphibian hygiene between sites and equipment, and follow the project disease-control procedure because chytrid fungus is suspected to have contributed to the species' decline.
  • Submit verified records, including negative results where required, to the relevant state or territory wildlife database and provide records to the approving authority or project database.
  • Report the species under the name accepted by the approval and database, noting that Ranoidea castanea is also treated as Litoria castanea by some taxonomic sources.

Before habitat disturbance: Avoid and minimise habitat loss

Treat any suitable wetland, creek or pond habitat as a potential constraint until it has been assessed and surveyed. The species is nationally listed as Critically Endangered, and the documents describe a very restricted surviving population and a rapid conservation response after rediscovery.

  • Retain ponds, wetlands, slow-moving waterways, creek margins and aquatic or submerged vegetation wherever practicable.
  • Avoid changes to wetland water levels, drainage, flow paths, water quality and hydrological connection between breeding and refuge areas.
  • Retain native grassland and terrestrial cover around aquatic habitat where practicable, because the species is terrestrial as well as aquatic and arboreal.
  • Avoid works in occupied or potentially occupied habitat until targeted surveys, impact assessment and approval checks are complete.
  • Maintain movement links between retained wetlands and waterways, and avoid isolating a retained wetland with roads, stock fencing, spoil or construction compounds.

Before habitat disturbance: Approvals and project planning

Commonwealth status: Critically Endangered under the EPBC Act

Breeding activity recorded: Primarily October to December

  • Check whether the action requires referral or approval under the Commonwealth Environment Protection and Biodiversity Conservation Act because the species is listed as Critically Endangered.
  • Check the relevant state or territory threatened species legislation, scientific collection rules, wildlife handling permits and animal ethics requirements before survey, capture, relocation or works.
  • Prepare a fauna management plan that identifies mapped habitat, survey results, exclusion areas, wetland protection measures, hygiene controls, stop-work triggers, authorised personnel and reporting requirements.
  • Stage clearing outside the October to December breeding period where practicable, and avoid late October to mid-November if egg-laying habitat may be affected.
  • Obtain approval for any proposed relocation before works begin, and identify an appropriate nearby retained habitat area with suitable wetland or creek conditions.

Before habitat disturbance: Pre-clearance preparation

  • Complete a pre-clearance inspection immediately before works, with targeted checks of wetland margins, submerged vegetation, grass cover and damp refuge areas.
  • Mark no-go areas, wetland buffers, retained vegetation, creek margins, access routes and machinery exclusion zones on plans and on the ground.
  • Install exclusion fencing where it can prevent entry into retained wetland or creek habitat without blocking required frog movement between connected retained areas.
  • Brief all machinery operators and spotter catchers on the species' appearance, habitat, hygiene controls, stop-work triggers and the location of retained habitat.
  • Remove or redesign temporary drainage, sediment controls and access tracks that could drain, pollute or sever retained aquatic habitat.

During habitat disturbance: Daily work controls

Use daily ecological controls while machinery is operating near wetland, creek or pond habitat. A fauna spotter catcher must have authority to pause work when a frog, tadpole, egg clutch or suitable habitat feature is encountered.

  • Inspect exclusion fencing, wetland buffers, sediment controls, dewatering areas and access routes before work starts each day.
  • Keep machinery, spoil, fuels, concrete washout, chemicals and stockpiles outside retained wetlands, creek margins and mapped exclusion areas.
  • Prevent sediment, contaminated water and altered runoff from entering ponds, wetlands, slow-moving waterways or submerged vegetation.
  • Use amphibian hygiene procedures for boots, nets, containers, vehicles and other equipment between waterbodies and work areas.
  • Stop work and obtain ecological advice if an unplanned wetland, waterway connection, egg clutch, tadpole aggregation or threatened frog is found.

During habitat disturbance: Spotter catcher and machinery interface

  • Position the fauna spotter catcher where the active work face, machinery travel path and escape route can be seen safely.
  • Require operators to stop before vegetation, debris, wet ground or shallow water is moved if the spotter catcher cannot inspect it safely.
  • Use hand tools or staged removal near occupied wetland margins and aquatic vegetation where machinery could crush frogs, eggs or larvae.
  • Allow only appropriately authorised and permitted personnel to capture, handle or relocate the species.
  • Keep the spotter catcher outside exclusion zones unless the area has been made safe and entry is authorised.

During habitat disturbance: Animal, egg and habitat response

  • If a frog is found, stop the immediate activity, protect it from machinery and keep people and equipment away while its identity and condition are assessed.
  • Do not handle the frog unless handling is necessary for immediate protection, authorised survey, approved relocation or veterinary care.
  • If approved relocation is required, place the animal in a clean, secure, appropriately ventilated container and move it only to the pre-approved nearby retained habitat.
  • Do not move egg clutches or tadpoles without specific approval and a method prepared by the project ecologist and relevant authority.
  • Send an injured animal to a veterinarian or authorised wildlife carer through the approved wildlife response pathway.
  • Record the location, date, time, life stage, photographs, condition, action taken, release location, personnel and permit or approval details.
  • Use the species' discovery, injury, death, egg clutch or tadpole presence as a stop-work trigger until the ecologist confirms controls and approvals.

After habitat disturbance: Post-clearance checks

Do not treat completion of clearing as the end of the fauna response. Check retained habitat and drainage controls, verify that no animals or life stages remain at risk, and continue monitoring where the project may affect wetland function or connectivity.

  • Inspect the cleared edge, retained wetland margins, creek banks, access tracks, dewatering areas and exclusion fencing after each clearing stage.
  • Search for stranded frogs, tadpoles, egg clutches and injured animals before removing temporary controls or reopening an area to machinery.
  • Repair damaged fencing, sediment controls, wetland buffers and drainage controls immediately.
  • Confirm that no spoil, waste, sediment, contaminated water or altered runoff has entered retained aquatic habitat.
  • Update the habitat map with all detections, mortality records, relocated animals and areas requiring additional protection.

After habitat disturbance: Monitoring and reporting

  • Monitor retained ponds, wetlands, creek sections and submerged vegetation during the approved post-works period, with repeat timing that includes October to December where practicable.
  • Compare post-works observations with pre-works survey results, including calls, adults, juveniles, tadpoles, egg clutches, water conditions and vegetation condition.
  • Report all threatened species interactions, injuries, deaths, relocations, permit breaches and stop-work events to the project ecologist and relevant authority within the timeframe in the approval or fauna management plan.
  • Submit verified occurrence records to the relevant state or territory wildlife database.
  • Maintain wetland protection, hygiene, sediment and access controls for as long as they are required by the approval and management plan.

After habitat disturbance: Offsets and residual impacts

  • Reassess residual impacts if occupied habitat, breeding habitat, wetland hydrology or connectivity cannot be retained.
  • Apply any EPBC approval conditions, state approval conditions and approved offset requirements before finalising the project response.
  • Do not use an offset as a substitute for avoiding or minimising impacts to occupied or potential breeding habitat.

Rehabilitation actions: Wetland and vegetation restoration

Rehabilitation should restore functioning wetland and creek habitat, not only replace vegetation. The available species information points to ponds, wetlands and slow-moving waterways with abundant aquatic and submerged vegetation, surrounded by terrestrial habitat.

  • Reinstate or protect permanent and intermittent ponds, wetlands, freshwater marshes and slow-moving creek margins where they were affected by the works.
  • Use locally appropriate native wetland and submerged plant species to recreate dense aquatic and submerged vegetation, based on the reference wetland and advice from the relevant land manager.
  • Restore natural water levels, shallow margins, flow paths and wetland connections, and prevent erosion, sediment entry, pollution and artificial drainage.
  • Retain or restore native grassland and terrestrial shelter around aquatic habitat.
  • Control weeds using methods that do not contaminate water or harm frogs, tadpoles, egg clutches or aquatic vegetation.

Rehabilitation actions: Cover and fauna features

  • Retain naturally occurring damp ground cover, leaf litter, logs and rocks where they provide shelter, and replace displaced features with locally sourced material where approved.
  • Assess whether hollow-bearing trees, nest boxes or other non-aquatic fauna features are relevant to the broader site, but do not assume they are breeding requirements for this frog.
  • Keep restoration materials out of water unless their use has been approved and they will not alter water quality, flow or frog movement.
  • Control introduced predators and invasive fish where this is identified by the site assessment and approved management plan.

Rehabilitation actions: Fire, maintenance and success measures

Breeding period to include in monitoring: October to December

Early life stages to monitor: Tadpoles, metamorphosing frogs and egg clutches

  • Prepare a site-specific fire plan that protects retained and restored wetland margins, aquatic vegetation and terrestrial refuge during planned burns and wildfire response.
  • Monitor restored habitat through at least the approved establishment period and include surveys during October to December where practicable.
  • Measure success using survival of planted wetland vegetation, stable or improving water conditions, intact wetland connectivity, effective weed and predator control, and records of the species or its early life stages where detection is feasible.
  • Continue amphibian hygiene during monitoring and maintenance visits, especially when moving between waterbodies.
  • Record restoration actions, maintenance, survey effort, detections, mortality and corrective actions, then provide the results to the approval authority and relevant wildlife database where required.

Sources