Southern Heath Frog (Rawlinsonia watsoni)

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Breeding season

Southern Heath Frogs can call and breed throughout the year after good rainfall, with breeding concentrated in autumn and early spring. Eggs and tadpoles may remain in creek pools for several months, so clearing, draining and dewatering works can affect multiple life stages outside the main calling peaks.

Reproductive mode: Egg laying.

Clutch size: Not recorded.

Incubation: Not recorded.

Size at hatching or birth: Not recorded.

Age at maturity: Not recorded.

Nest or egg sites: Egg clusters are attached to twigs just below the water surface in creek pools.

Breeding frequency: Breeding can occur at any time after good rainfall, but is most common in autumn and early spring.

Confirm timing locally before works, using recent rainfall and seasonal temperature conditions to identify active calling, egg laying and tadpole development at the site.

• Calling: Calling is possible in January and December, occurs from February to November, and peaks in March, April, September and October. Calls have been recorded in every month.
• Egg laying: Egg laying is expected to follow the documented breeding pattern, with the strongest period in autumn and early spring. Breeding can also occur in any month after good rainfall, and eggs are attached to twigs just below the water surface in creek pools.
• Tadpoles: Tadpoles may be present in any month because breeding can follow rainfall at any time. They are black or dark grey, often remain near the water surface, and take around 3 to 4 months to develop into frogs.
• Froglets: Froglets may occur in any month because egg laying can occur after rainfall throughout the year and tadpole development takes around 3 to 4 months. The documents do not provide a direct month-by-month emergence calendar.
• Active period: A species-specific activity season is not recorded. Calling is possible in every month, so frogs should be treated as capable of moving through suitable moist habitat year-round, particularly after rainfall.
• Highest clearing risk: Risk is highest in March to May and September to October, when breeding and calling are concentrated. Eggs and tadpoles can remain in creek pools for around 3 to 4 months, and rainfall can extend the risk into other months.

Identification

This is a large frog with a grey or brown back, white belly and conspicuous red or orange colour on the hidden surfaces of the limbs and body. Confirm records by combining appearance, location and call where possible.

Adults reach nearly 7 cm in body length. The back is grey or brown, sometimes with brown mottling or flecks, and may have an indistinct longitudinal stripe. A dark brown stripe runs from the snout to the arm.

The pupil is horizontal and the iris is gold. The belly is white. The fingers are slightly webbed and the toes are nearly fully webbed, with large discs on both fingers and toes.

Adult body length: Up to nearly 7 cm

Weight: Not stated in the supplied documents

Identification: Distinguishing features

The bright red or orange colour in the armpits, groin, backs of the thighs and backs of the lower legs separates the Southern Heath Frog from similar Litoria ewingii and Litoria dentata, which lack this colour.

Litoria jervisiensis has a white stripe from beneath the eye to the top of the arm. This stripe is absent in the Southern Heath Frog.

Littlejohn's Tree Frog, Litoria littlejohni, cannot be separated reliably by appearance. The two species are distinguished by their calls and are not known to overlap in distribution.

Identification: Calls and field signs

The call is useful for separating the Southern Heath Frog from Littlejohn's Tree Frog. The Southern Heath Frog has a lower average number of pulses in each note.

The supplied documents do not describe tracks, scats, nests, sloughs or eyeshine. Eggs may provide a field sign during the breeding period: they occur in clusters attached to twigs just below the water surface in creek pools.

• Inspect creek pools and submerged or partly submerged twigs for attached egg clusters.
• Record frog calls where possible, particularly when visual identification is uncertain.
• Do not rely on appearance alone when Littlejohn's Tree Frog is a possibility.

Distribution: National range

The species occurs in south-eastern Australia. The supplied records identify New South Wales and north-eastern Victoria, with important records in the Illawarra and Morton National Park areas.

The known range extends through south-eastern New South Wales from near Wollongong to north-eastern Victoria.

The species is described as occurring from Budderoo National Park in the Illawarra region of New South Wales along the eastern fall of the Great Dividing Range. Four additional populations were found in late 2023 on sandstone monoliths within Morton National Park.

States recorded: New South Wales and Victoria

Bioregions specified: Illawarra and the eastern fall of the Great Dividing Range; no formal bioregion is given for the Victorian range

• New South Wales: Illawarra, Budderoo National Park and Morton National Park, with the broader range extending along the eastern fall of the Great Dividing Range.
• Victoria: north-eastern Victoria is included in the published range, although no Victorian sites or bioregions are specified in the supplied documents.

Distribution: Strongholds and population information

Known important areas include Budderoo National Park and sandstone monoliths in Morton National Park. Some newly discovered sites contain permanent breeding pools, allowing breeding in every year.

The supplied documents do not provide a total population estimate, density, home range or generation length. The four populations discovered in late 2023 expanded the known range, and monitoring indicated persistence at some sites after the 2019 to 2020 bushfires and the 2023 drought.

New populations found: Four populations, discovered in late 2023

Total population: Not stated

Population trend: Not quantified; some populations persisted after recent fire and drought

Habitat: Habitat setting

The Southern Heath Frog is associated with moist upland and sandstone habitats containing creek pools or other suitable breeding waterbodies. The documents do not define a complete vegetation community or elevation range.

Known habitat includes Budderoo National Park in the Illawarra region, the eastern fall of the Great Dividing Range, and sandstone monoliths in Morton National Park.

Breeding occurs in creek pools. Permanent breeding pools are present at some known sites and may support breeding every year.

Vegetation community: Not specified in the supplied documents

Elevation limit: Not specified

Climate association: Breeding is mainly associated with cold autumn and early spring conditions, with breeding also possible after good rainfall

• Retain creek pools and other standing waterbodies within or near work areas.
• Protect sandstone monolith sites and the surrounding habitat from disturbance.
• Maintain habitat connections between known populations and breeding sites where they occur.

Habitat: Habitat features

The documented breeding features are creek pools, twigs just below the water surface and, at some sites, permanent pools. The supplied documents do not give measurements for pool size, water depth, vegetation cover or surrounding terrestrial habitat.

• Include all creek pools and adjacent moist habitat in pre-clearance inspections.
• Avoid changing the water regime of pools that could support eggs or tadpoles.
• Use targeted surveys around sandstone monoliths and known or suspected permanent pools.

Foraging habitat: Diet and feeding

The supplied documents do not state the Southern Heath Frog's diet, feeding method or foraging range. Field protection should therefore focus on retaining the moist terrestrial and aquatic habitat associated with known populations.

Species-specific prey, food plants, feeding height and foraging distances are not provided in the supplied documents.

As a tree frog, it may use habitat around breeding pools as well as the pools themselves, but the documents do not provide enough information to define its foraging area.

Diet: Not stated

Key prey or food plants: Not stated

Foraging range: Not stated

• Do not clear moist cover around breeding pools solely because no frogs are seen in the water.
• Record frogs found in vegetation, ground cover and near water during nocturnal searches.
• Treat the area around known breeding pools as potential habitat until targeted survey results show otherwise.

Breeding habitat: Breeding biology

Breeding takes place in creek pools, particularly where twigs are available just below the water surface. Breeding can follow good rainfall and occurs mainly during cold autumn and early spring conditions.

Eggs are laid as clusters attached to twigs just below the water surface in creek pools. Tadpoles are black or dark grey, often remain near the water surface and take about 3 to 4 months to develop into frogs.

Breeding can occur at any time after good rainfall, but is most common in autumn and early spring.

Breeding season: Mainly autumn and early spring, with breeding possible at any time after good rainfall

Egg or clutch size: Not stated

Egg placement: Clusters attached to twigs just below the water surface

Tadpole development: About 3 to 4 months to develop into frogs

Gestation or incubation: Not stated

Age at maturity: Not stated

Lifespan: Not stated

Breeding habitat: Breeding-site requirements

Breeding sites require creek pools or comparable waterbodies that retain water long enough for tadpole development. Permanent pools at some known sites allow breeding every year.

Twigs or similar structures just below the water surface are used for egg attachment. Native and introduced fish are identified threats because they can prey on aquatic life stages.

• Inspect water margins, submerged twigs and pool surfaces for egg clusters before disturbing vegetation or carrying out in-water works.
• Prevent sediment, pollutants and altered inflows from reaching breeding pools.
• Keep native and introduced fish from being moved between waterbodies during construction activities.

Sheltering habitat: Known shelter information

Specific refuge sites and shelter dimensions are not described in the supplied documents. The species is associated with moist habitats around creek pools and sandstone sites, so these areas should be treated as potential daytime and non-breeding habitat.

The documents do not identify particular tree hollows, rock crevices, burrows, leaf litter depths, refuge dimensions or daytime roost sites used by the Southern Heath Frog.

The documented habitat includes creek pools and sandstone monoliths. Habitat disturbance at these sites is a recognised concern.

Hollows, dens or burrows: Not documented

Shelter dimensions: Not documented

Known refuge setting: Moist habitat around creek pools and sandstone sites

• Search moist vegetation, ground cover, rock edges and pool margins during suitable nocturnal and daytime inspections.
• Retain cover around creek pools and avoid unnecessary removal of twigs and low vegetation.
• Do not assume that an unoccupied pool margin is unused habitat.

Threats: Disease

The main documented threats are amphibian chytrid disease, fire, sand mining, climate change, habitat loss and fragmentation, and predation by native and introduced fish. These threats can interact on clearing and infrastructure sites.

Amphibian chytrid fungus, Batrachochytrium dendrobatidis, is identified as a threat to the Southern Heath Frog and other Australian frogs. The fungus can cause sporadic deaths in some populations and complete mortality in others.

• Apply approved hygiene and disease-control procedures between sites, waterbodies and items of amphibian survey equipment.
• Do not move water, sediment, aquatic plants or fish between pools.
• Report sick or dead frogs through the relevant project and wildlife disease channels.

Threats: Clearing, fire and development

Habitat disturbance from bushfire or sand mining is identified as a direct threat. More generally, habitat loss, destruction and fragmentation from human development threaten Australian frogs.

Clearing can remove moist habitat, damage pool margins and destroy egg attachment sites. Disturbance during breeding or tadpole development can affect eggs and aquatic young.

• Avoid clearing around creek pools, attached egg clusters and known sandstone monolith sites.
• Stage works to avoid breeding and tadpole-development periods where practicable.
• Protect permanent breeding pools from direct disturbance, sediment entry and changes to inflow or water retention.
• Manage fire planning so that known habitat is not exposed to unnecessary high-intensity or repeated fire.

Threats: Water and predators

Native and introduced fish can prey on Southern Heath Frogs or their aquatic life stages. The species depends on creek pools, and some sites rely on permanent breeding pools, so changes to water availability may reduce breeding opportunities.

The supplied documents do not provide species-specific evidence about roads, vehicle strike or particular hydrological thresholds.

• Keep fish and aquatic material from being transferred between pools during works.
• Avoid draining, infilling or isolating breeding pools.
• Monitor pools where construction may alter runoff, inflows, drainage or water retention.

Threats: Climate and isolation

Climate change, drought and fire are identified pressures on threatened Australian frogs. Habitat fragmentation from development may further isolate populations and limit recolonisation after local losses.

Saving our Species monitoring and genetic research are being used to assess dispersal, population viability, genetic population size, inbreeding and potential adaptive responses.

• Retain habitat connections between breeding pools and surrounding moist habitat.
• Record the location and condition of all pools and potential habitat affected by a project.
• Use pre-clearance and post-work monitoring to identify changes in occupancy and breeding activity.

Survey methodology: 1. Call surveys

Survey Southern Heath Frog, currently referred to as Rawlinsonia watsoni and formerly Litoria watsoni, before clearing or construction where suitable breeding or shelter habitat may be disturbed. The species is endangered and can breed after good rainfall, mainly in autumn and early spring.

Use nocturnal call surveys during autumn and early spring, particularly after good rainfall. The species may call and breed at other times after suitable rain.

Survey around creek pools, permanent breeding pools and other retained waterbodies associated with suitable habitat.

Record the date, start and finish time, rainfall, weather, water conditions, survey locations, call detections and recorded calls.

The supplied sources do not specify a required number of nights, survey hours, transect length or survey area. Set and document the effort in the project survey design, and do not treat a single quiet survey as evidence that the species is absent.

Survey methodology: 2. Nocturnal visual searches

Carry out night searches around creek pools, sandstone monoliths and other waterbodies where the species may occur, with particular attention after rain and during the main calling period.

Use a consistent search route and record the route length, search duration, weather, rainfall, water conditions and all frogs detected.

Check vegetation, pool margins and wet ground without entering or disturbing breeding pools unless the survey method has been approved.

The supplied sources do not give a prescribed number of nights, hours, transects or search area. The ecologist must set these values from the project risk, habitat extent and applicable survey guidance.

Survey methodology: 3. Egg and tadpole searches

Inspect creek pools and permanent breeding pools for egg clusters attached to twigs just below the water surface.

Look for dark grey or black tadpoles near the water surface. Tadpoles may take about 3 to 4 months to develop into frogs.

Avoid handling eggs or tadpoles unless an authorised aquatic fauna specialist has approved the method and handling is needed for identification or rescue.

Record the pool location, water condition, evidence of breeding, life stage and any disturbance or fish predation observed.

Survey methodology: 4. Identification and records

Confirm records using the species call as well as appearance, because Southern Heath Frog can be difficult to distinguish visually from Littlejohn's Tree Frog.

Record photographs, an audio file, precise coordinates, habitat description and the observer's identification basis for each detection.

Note the bright red or orange colour in the armpits, groin, backs of the thighs and lower legs, where visible without handling.

Treat an uncertain record as requiring expert review, particularly where Littlejohn's Tree Frog may occur.

Survey methodology: Minimum effort and reporting

• Complete the survey effort specified by the project approval, survey design and applicable state or territory guidance, because the supplied documents do not prescribe nights, hours, trap nights, transect lengths or survey area.
• Target surveys after good rainfall and during autumn or early spring, while recognising that breeding may occur at other times after rain.
• Map all detections, breeding pools, creek pools, permanent pools, sandstone monolith sites and areas searched.
• Submit verified records to the relevant state or territory wildlife database and retain the record identification, coordinates, photographs, recordings and survey metadata in the project file.
• Report any detection immediately to the project ecologist and environmental officer before habitat disturbance proceeds.

Before habitat disturbance: Avoid and minimise

Plan the works around known and potential breeding habitat. The species is known from south-east New South Wales to north-eastern Victoria, with NSW records including Budderoo and Morton national parks, and threats include chytrid fungus, bushfire, sand mining, climate change and predation by fish.

• Avoid clearing creek pools, permanent breeding pools and their immediate margins wherever practicable.
• Retain sandstone monolith sites, wet drainage features, connecting vegetation and other habitat linking known or potential populations.
• Keep construction access, stockpiles, spoil, sediment controls and lighting away from retained pools and wet habitat where practicable.
• Do not introduce or move fish, water, soil, plants or amphibian pathogens between sites.

Before habitat disturbance: Approvals and planning

• Check whether the action requires referral or approval under the EPBC Act because the species is listed as endangered.
• Check state or territory threatened species, wildlife handling, survey, clearing and translocation requirements before work starts.
• Prepare a fauna management plan that identifies survey timing, no-go areas, exclusion zones, fauna handling authority, stop-work triggers, hygiene controls and reporting responsibilities.
• Stage clearing so that retained breeding pools and habitat remain protected while the ecologist confirms each work area is clear.

Before habitat disturbance: Site preparation

• Complete the approved pre-clearance surveys before each clearing stage, with priority given to periods after rain and autumn to early spring.
• Mark breeding pools, creek pools, wet areas, retained vegetation, access routes and no-go areas on plans and on the ground.
• Install exclusion fencing where it can keep machinery, personnel, sediment and frogs out of retained habitat, and inspect the fencing before each work shift.
• Brief the fauna spotter catcher, operators and supervisors on the species' appearance, call, breeding evidence, hygiene requirements and stop-work procedure.

During habitat disturbance: Daily controls

Use daily environmental controls and keep the fauna spotter catcher in direct communication with machinery operators. Stop work when a frog, breeding evidence or an unplanned impact is found.

• Inspect exclusion fencing, sediment controls, access routes and no-go markers before work begins each day.
• Keep machinery, vehicles, workers, lighting and spoil outside marked breeding pools, creek pools and retained wet habitat.
• Clean and disinfect footwear, equipment, nets, buckets and vehicles before entering or leaving frog habitat, using a method approved for amphibian chytrid control.
• Do not move water, mud, aquatic plants, frogs, tadpoles or other aquatic material between pools or sites.

During habitat disturbance: Spotter catcher and machinery interface

• The fauna spotter catcher must remain able to see the active work area and must have a reliable stop-work signal to the operator.
• Move machinery only after the spotter catcher has checked the next work area and confirmed that the exclusion controls remain intact.
• Stop the relevant activity immediately if a frog, egg cluster, tadpole group, occupied pool or unplanned wet feature is found.
• Record the location, time, activity, person who found the animal, photographs, action taken and decision to recommence work.

During habitat disturbance: Animal handling and habitat features

• Only a person authorised under the project approval and relevant wildlife legislation may capture, handle or relocate the frog.
• Use clean, damp, single-use or disinfected equipment and minimise handling time.
• Relocate an uninjured frog only to nearby retained habitat selected by the authorised ecologist, with suitable cover and access to water, and record the release location.
• Do not disturb egg clusters or tadpoles unless an authorised specialist and the approval specifically allow rescue or relocation.
• If an injured or unwell frog is found, place it in an appropriate clean, secure container and contact the nominated amphibian veterinarian or licensed wildlife carer.
• Treat chytrid signs, unusual mortality, dead frogs or a suspected disease event as a stop-work and escalation matter.

After habitat disturbance: Post-clearance checks

Confirm that retained habitat and controls remain effective after each clearing stage. Use the results to update the project fauna management plan and any approval reporting.

• Complete a fauna spotter catcher inspection of the cleared footprint, retained pool margins, exclusion fencing and access routes before demobilising the clearing crew.
• Recheck retained creek pools and permanent breeding pools after rainfall and during autumn to early spring where the project risk warrants follow-up surveys.
• Search for stranded, injured or displaced frogs and record all findings, including evidence of breeding or mortality.
• Repair damaged fencing, sediment controls and no-go markers immediately.

After habitat disturbance: Monitoring and reporting

• Continue call, visual and breeding monitoring where the approval, fauna management plan or risk assessment requires it.
• Compare post-work records with pre-work records, including detections, calling activity, breeding evidence, habitat condition and disturbance events.
• Report EPBC Act matters, threatened species incidents, disease concerns and unauthorised impacts to the responsible environmental officer and relevant regulator.
• Submit verified new records to the relevant state or territory wildlife database and retain all survey, handling, relocation and mortality records.

After habitat disturbance: Controls and offsets

• Maintain exclusion fencing, pool protection, hygiene controls and sediment management until the environmental officer confirms that the work risk has ended.
• Apply any approved offset, restoration or conservation measure required by the EPBC Act approval, state approval or project condition.
• Use monitoring results to change work staging, protection measures or rehabilitation actions where the species continues to be detected.

Rehabilitation actions: Restore breeding habitat

Rehabilitation should restore the wet breeding features and connected habitat used by Southern Heath Frog. Give priority to creek pools and permanent pools that can support eggs and tadpoles, while preventing disease, sediment and fish impacts.

• Reinstate natural drainage and pool form where works have altered creek pools or other breeding waterbodies.
• Provide stable shallow-water margins and emergent or overhanging vegetation that can support egg clusters attached to twigs just below the water surface.
• Protect permanent pools identified as breeding sites from sediment, chemical runoff, vehicle access and stock or machinery disturbance.
• Do not stock or introduce fish into restored pools, because predation by native and introduced fish is a documented threat.

Rehabilitation actions: Rebuild shelter and connectivity

• Replant locally appropriate native vegetation around restored pools, creek lines and retained sandstone habitat, using the local ecological community as the species list source.
• Retain or reinstate ground cover, leaf litter, logs and rocks where they occur naturally and do not create barriers to movement between pools and surrounding habitat.
• Remove weeds that reduce native ground cover or encroach on breeding pools, using methods that prevent herbicide or contaminated runoff entering the water.
• Maintain connected retained habitat between known or potential populations wherever practicable.

Rehabilitation actions: Disease, fire and success measures

• Apply amphibian hygiene controls during all rehabilitation inspections and maintenance visits to reduce the risk of chytrid fungus spread.
• Manage fire planning so that restored pools, sandstone sites and connecting habitat are not unnecessarily damaged by planned or unplanned fire.
• Monitor restored sites for pool persistence, egg clusters, tadpoles, calling adults, frog detections, fish presence, weeds, sediment and chytrid concerns.
• Set success measures in the rehabilitation plan using the pre-work baseline and approval conditions, and record whether breeding evidence and habitat condition are maintained over time.

Sources

• Litoria watsoni | Australian Museum FrogID Project, frogid.net.au: https://www.frogid.net.au/frogs/litoria-watsoni
• Let's talk about frogs | News - Environment and Heritage, NSW Department of Climate Change, Energy, the Environment and Water: https://www.environment.nsw.gov.au/news/lets-talk-about-frogs
• Rawlinsonia watsoni - Species Profile, frogid.net.au: https://www.frogid.net.au/frogs/rawlinsonia-watsoni/