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Gilled Slender Bluetongue (Cyclodomorphus branchialis)

The Gilled Slender Bluetongue is a small, ground-dwelling skink restricted to a small area of Western Australia. It is crepuscular and nocturnal, and may occur in rocky outcrops, deep leaf litter, hummock grass, fallen timber and spinifex vegetation. Clearing and disturbance can remove shelter sites and fragment its already restricted habitat.

Conservation status

Western Australia, Biodiversity Conservation Act 2016: Vulnerable.

Breeding season

The species is live bearing, but its mating, pregnancy and birth months are not recorded. Related species suggest mating from late winter to spring, pregnancy through spring and early summer, and births mainly in January. Plan clearing as a year-round risk because the species shelters in leaf litter, hummock grass, fallen timber, stumps and rocks.

Reproductive mode: Live bearing, also described as ovoviviparous.

Litter size: Typically 2 to 3 large young.

Gestation: Not recorded.

Size at hatching or birth: 42 mm snout to vent length is reported for a hatchling or juvenile.

Age at maturity: Not recorded.

Nest or egg sites: Not applicable for a live bearer. Specific birth sites are not recorded. Documented shelter features include deep leaf litter, hummock grass, spinifex, fallen timber and rocks.

Breeding frequency: Not recorded.

Confirm timing locally before clearing, using local records and weather conditions, because rainfall and temperature may alter activity and breeding timing across the species' Australian range.

  • Mating: Timing is not recorded for this species. Related species show mating around late winter to spring, with a peak in October in one related species and late August in another.
  • Gravid females: Pregnancy is not recorded for this species. Related species carried developing follicles, eggs or embryos from late September or October through December or January.
  • Births: Birth timing is not recorded for this species. Related species in the group gave birth mainly in January after pregnancies extending through spring and early summer.
  • Newborns: Newborn timing is not recorded for this species. January births in related species indicate that newborns are most likely to be encountered in January and may remain present into February.
  • Active period: No seasonal activity period is documented. The species is crepuscular and nocturnal, so surface activity may occur in every month, subject to local temperature and weather.
  • Winter inactivity: Brumation or a defined winter inactivity period is not recorded. As a general planning assumption for cooler southern sites, reduced surface activity and sheltering may occur from May to August, while northern and warmer sites may not show this pattern.
  • Highest clearing risk: No species-specific peak clearing-risk period is established. Risk is present year round because clearing can destroy ground shelters, and may increase around January births or during cooler-month sheltering at southern sites.

Identification

The Gilled Slender Bluetongue is a ground-dwelling skink in the Cyclodomorphus branchialis species group. The supplied documents do not provide a field description, body measurements, weight or diagnostic colour pattern for this species.

It is a smaller relative of the large bluetongue skinks and is associated with the genus Cyclodomorphus. The species group is defined by scale characters, including broadly contacting nasal scales, separated prefrontal scales, a distinct postnarial groove and paravertebral scales that are much broader than adjacent dorsal body scales.

Adult size: Not stated in the supplied documents

Adult weight: Not stated in the supplied documents

Identification: Field separation

Identification should be confirmed by an experienced reptile ecologist or by reference to an appropriate regional key. The species was separated taxonomically from related Cyclodomorphus taxa using scalation and distribution, so superficial resemblance to other bluetongue skinks should not be treated as sufficient for identification.

The supplied documents do not provide a comparison with other skinks occurring in the Mount Magnet or Dalgaranga area.

Identification: Field signs

No species-specific tracks, scats, calls, nests, sloughs or eyeshine characteristics are described in the supplied documents. Because the species shelters in ground cover and under fallen timber, direct searches should include careful inspection of leaf litter, hummock grass, logs and stumps where disturbance is proposed.

  • Treat a skink found beneath ground cover or fallen timber as potentially significant until it has been identified.
  • Record the shelter feature, vegetation type, rocky habitat and exact location for each observation.

Distribution: Known range

Cyclodomorphus branchialis has a restricted distribution in Western Australia. The supplied sources do not provide a complete statewide range map or a confirmed list of bioregions.

The taxonomic revision restricts the species to a small area of Western Australia, described as the lower west coast and hinterland. The available project assessment records five threatened fauna database records from Mount Magnet, approximately 65 km south east of the Dalgaranga survey area. All five records are dated 2005.

  • State: Western Australia.
  • Other Australian states or territories: none are identified in the supplied documents.
  • Named locality in the supplied records: Mount Magnet.

Distribution: Subpopulations and trend

The project assessment describes the species population as severely fragmented. The supplied documents do not provide a total population estimate, abundance estimate, generation length or quantified population trend.

The five Mount Magnet records include survey and vouchered specimen records. They demonstrate regional occurrence but do not establish the size or continuity of the local population.

Population estimate: Not stated in the supplied documents

Population trend: Not quantified in the supplied documents

Fragmentation: Population thought to be severely fragmented

Habitat: Habitat types

The species uses dry ground habitats with substantial cover. Habitat descriptions include both deep litter in coastal spinifex vegetation and more recent records from rocky outcrops.

Reported habitat includes rocky outcrops and other rocky areas, hummock grass, leaf litter, Acacia cover, fallen logs and stumps. The species appears to prefer deep leaf litter on sandy beaches vegetated mainly with coastal spinifex, although recent records are mostly from rocky outcrops.

Habitat: Structural features

The most relevant habitat features for site assessment are continuous ground cover, deep leaf litter, hummock grass, fallen timber, stumps and rock cover. Retaining these features is particularly important where rocky habitat is patchy or separated by cleared areas.

  • Map rocky outcrops, scree, rock piles and other exposed or concealed rock habitat before clearing.
  • Inspect deep leaf litter, hummock grass, Acacia cover, fallen logs and stumps within the clearing footprint.
  • Assess whether suitable cover remains connected to nearby rocky or vegetated habitat.

Habitat: Elevation and climate limits

The supplied documents do not state an elevation range, rainfall limit, temperature limit or other climatic boundary for the species.

Elevation range: Not stated in the supplied documents

Climate limits: Not stated in the supplied documents

Foraging habitat: Feeding habitat

The supplied documents do not provide a species-specific diet or measurements of foraging range. They identify the species as a ground-dwelling skink associated with leaf litter, hummock grass, spinifex and rocky habitat.

Foraging is expected to occur on or close to the ground in the same covered habitats used for shelter, including deep leaf litter, hummock grass, spinifex vegetation and rocky outcrops. The documents do not state whether the species feeds mainly on insects, other invertebrates, vertebrates, plant material or fruit.

Diet: Not stated in the supplied documents

Key food plants or prey: Not stated in the supplied documents

Foraging range: Not stated in the supplied documents

  • Retain ground cover and connected refuge habitat around rocky outcrops during site works.
  • Avoid assuming that apparently open ground is unsuitable if it contains nearby litter, hummock grass, logs, stumps or rocks.

Breeding habitat: Known breeding information

The supplied documents state that reproduction was described in the taxonomic revision but do not include the breeding details needed to define a breeding season or reproductive habitat precisely.

No breeding site, mating period, birth period or specific breeding substrate is given in the supplied material. The habitat features most likely to support breeding are the species' documented cover features, including deep leaf litter, hummock grass, spinifex vegetation, fallen timber and rocky habitat.

Breeding season: Not stated in the supplied documents

Clutch or litter size: Not stated in the supplied documents

Gestation or incubation: Not stated in the supplied documents

Age at maturity: Not stated in the supplied documents

Lifespan: Not stated in the supplied documents

  • Treat connected patches of deep litter, hummock grass, spinifex, fallen timber and rocks as potential breeding habitat unless field evidence shows otherwise.
  • Do not remove shelter features from occupied habitat during the period when breeding timing is unknown.

Sheltering habitat: Documented refuges

The species shelters at ground level. Its documented refuges are readily affected by clearing, grading, vehicle movement and removal of coarse ground cover.

Sheltering habitat includes hummock grass, leaf litter, Acacia cover, fallen logs and stumps. Deep leaf litter on sandy sites and rocky outcrops are also associated with the species. No dimensions for refuges, logs, litter depth or rock features are provided.

Refuge size: Not stated in the supplied documents

Burrows or dens: Not reported in the supplied documents

Hollows: Not reported in the supplied documents

  • Search beneath or beside fallen logs, stumps, dense hummock grass, deep litter and rocks before these features are disturbed.
  • Retain undisturbed cover around rocky outcrops and within habitat patches where possible.
  • Use hand searches or supervised staged removal where clearing must occur in potential habitat.

Threats: Clearing and fragmentation

The main project risks are loss and fragmentation of rocky and litter-rich ground habitat, together with direct mortality when shelter features are cleared or moved.

The species has a restricted range and is thought to have a severely fragmented population. Clearing rocky outcrops, deep leaf litter, hummock grass, spinifex vegetation, logs or stumps can remove shelter and foraging habitat and further isolate local groups.

  • Avoid clearing rocky outcrops and connected patches of ground cover.
  • Fence exclusion areas around retained habitat before vegetation and ground disturbance begins.
  • Inspect and manage logs, stumps, rocks and deep litter within the clearing footprint rather than treating them as non habitat.

Threats: Construction and roads

The supplied documents do not quantify road mortality or construction impacts. Vehicle access, earthworks and stockpiling can nevertheless crush animals or remove the leaf litter, hummock grass, timber and rock cover used for shelter.

  • Keep vehicles and machinery out of retained rocky and litter-rich habitat.
  • Limit night lighting and unnecessary night traffic near occupied habitat because the species is crepuscular and nocturnal.
  • Check work areas after disturbance and report any captured or injured skink to the fauna spotter catcher.

Threats: Fire, predators and other pressures

The supplied documents do not identify species-specific effects of fire, introduced predators, disease or hydrology change. They also do not provide evidence for a hydrology requirement. Any change that removes or dries out litter, hummock grass, spinifex or rocky refuge should be assessed as a potential local impact.

  • Record recent fire history and the condition of ground cover during habitat assessment.
  • Prevent avoidable disturbance to retained cover during fire management, weed control and rehabilitation works.
  • Do not infer absence from a single unsuccessful search, particularly where suitable rocky or litter-rich habitat remains.

Survey methodology: 1. Map and assess habitat

Use targeted habitat assessment and nocturnal searches where clearing may affect rocky outcrops, hummock grass, deep leaf litter, Acacia cover, fallen logs or stumps. The supplied documents do not provide a species-specific survey guideline or prescribed effort, so the survey design should be set by the disturbance footprint, habitat quality and approval conditions.

Map rocky outcrops and other rocky areas, hummock grass, deep leaf litter, Acacia cover, fallen logs and stumps before selecting search sites.

Record the extent, condition and connectivity of these features across the proposed clearing area and nearby retained habitat.

Treat rocky outcrops as a priority search habitat because recent records are associated mainly with rocky outcrops, although the species has also been reported from deep leaf litter on sandy sites with coastal spinifex.

Survey methodology: 2. Nocturnal searches

Conduct searches during the species' crepuscular and nocturnal activity period, including the period after dusk when animals are more likely to be active.

Use systematic walking searches and spotlighting along mapped rocky habitat, hummock grass, leaf litter, Acacia cover and fallen timber.

Record the date, start and finish time, weather, wind, recent rain, observers, route, search area and all detections or non-detections.

The supplied documents do not specify a required number of nights, hours, transect length or spotlight intensity, so set and justify effort in the survey plan and increase effort where suitable habitat is extensive or fragmented.

Survey methodology: 3. Targeted refuge searches

Search carefully beneath and around fallen logs, stumps, accumulated leaf litter and other ground cover where this ground-dwelling skink may shelter.

Inspect rocky outcrops and crevices without dismantling habitat unless the method has been approved and a qualified fauna handler is present.

Use daytime habitat searches to identify likely shelter sites, then target those sites during nocturnal searches.

Avoid unnecessary disturbance of leaf litter, logs and rocks because these features provide shelter and may be difficult to replace.

Survey methodology: Minimum effort and reporting

  • Set the minimum survey effort in the project fauna survey plan, based on the area and quality of suitable habitat, the season, access and the proposed clearing method.
  • Use experienced reptile ecologists and fauna spotter catchers familiar with nocturnal searches and rocky habitat.
  • Document survey limitations, including inaccessible rocks, poor weather, incomplete access and any habitat that could not be searched.
  • Treat nearby records as relevant context: the assessment reported five threatened-fauna database records, all from 2005 at Mount Magnet, approximately 65 km south east of the survey area.
  • Submit verified records and voucher information to the relevant Western Australian wildlife database and provide records required by the project approval or permit.

Before habitat disturbance: Avoid and minimise

Plan the works on the assumption that the species may occur where suitable rocky or ground-shelter habitat is present. The desktop assessment rated it as possibly occurring because regional records and potential rocky habitat were present.

Retain rocky outcrops, rock piles, hummock grass, deep leaf litter, Acacia cover, fallen logs and stumps wherever practicable.

Keep retained habitat connected to nearby suitable areas rather than leaving isolated small patches within the clearing footprint.

Place temporary access tracks, laydown areas and exclusion zones away from rocky habitat and concentrated ground cover.

Do not remove shelter features solely to make the site easier to inspect or operate.

Before habitat disturbance: Approvals and work planning

Confirm the Western Australian threatened fauna status, permit requirements and any conditions that apply before survey, capture, handling or relocation.

The species is not listed under the EPBC Act in the supplied project information, so an EPBC referral is not indicated on the basis of this species alone; check the full project and other listed matters before relying on that conclusion.

Prepare a fauna management plan that identifies habitat, survey effort, authorised personnel, stop-work triggers, capture and release procedures, incident reporting and contacts for injured wildlife.

Stage clearing so retained habitat and release areas are available before habitat is disturbed.

Before habitat disturbance: Pre-clearance preparation

Complete a pre-clearance inspection and targeted nocturnal survey of all suitable habitat within and immediately beside the work area.

Mark rocky outcrops, rock piles, logs, stumps, dense hummock grass, deep leaf litter and Acacia cover that must be retained or checked before disturbance.

Fence or otherwise clearly mark retained habitat and approved release areas where plant, vehicle or machinery access could damage them.

Brief operators and supervisors on the species' appearance, shelter habitat, nocturnal activity and the stop-work procedure.

During habitat disturbance: Daily controls and machinery interface

Keep a fauna spotter catcher present for all work that can disturb suitable ground or rocky habitat. Use slow, staged clearing so the handler can inspect shelter features before machinery moves them.

Complete a daily pre-start check of exclusion fencing, marked habitat, access routes, weather and the planned clearing sequence.

The fauna spotter catcher must work in direct communication with the operator and remain clear of moving plant, suspended loads and unstable rocks.

Clear from the least suitable edge towards retained habitat where this is safe and approved, allowing animals to move towards protected areas rather than becoming surrounded.

Use a stop signal that every operator understands, and stop machinery immediately when the spotter catcher identifies a possible animal, shelter feature or unsafe condition.

During habitat disturbance: Handling habitat and animals

Inspect logs, stumps, leaf litter, hummock grass and rocks before they are moved, crushed or buried.

Do not dismantle rocky outcrops or search beneath unstable rocks while machinery is operating or people could be injured.

If the skink is found, stop the relevant work, keep people and machinery back, and allow the authorised fauna handler to assess it.

Only an appropriately authorised person should capture or handle the animal, using the least stressful safe method and following the permit and fauna management plan.

Release an unharmed animal into nearby retained habitat with suitable shelter, subject to approval, habitat suitability and advice from the relevant wildlife authority.

Take injured animals to an appropriately qualified veterinarian or approved wildlife carer, and record the transfer.

During habitat disturbance: Stop-work triggers and records

  • Stop work if a Gilled Slender Bluetongue is located, if an uninspected log, stump, rock pile or dense shelter patch is about to be disturbed, or if exclusion fencing or a release area is damaged.
  • Stop work if the spotter catcher cannot maintain a safe view of the clearing activity or if heat, wind, rain, dust or darkness prevents effective searching.
  • Record each detection, attempted capture, relocation, injury, death, habitat feature affected, location, time, personnel, machinery and action taken.
  • Notify the project environmental officer and the relevant wildlife authority of incidents or mortalities in accordance with the approval, permit and fauna management plan.

After habitat disturbance: Post-clearance checks

Check the cleared area and retained habitat after each stage, then verify that retained shelter and movement routes remain functional. Use the results to adjust later clearing stages and rehabilitation.

Complete a fauna spotter catcher inspection after clearing and before the area is handed over for construction or access.

Search remaining logs, stumps, leaf litter, hummock grass and rocky edges for animals that may have remained in the work area.

Inspect exclusion fencing, retained rocky habitat and release areas for damage, erosion, sediment deposition or vehicle entry.

Record the cleared area, retained habitat, search effort, detections, relocations, injuries, mortalities and corrective actions.

After habitat disturbance: Monitoring and reporting

Monitor retained and rehabilitated habitat using repeat searches suited to the species' crepuscular and nocturnal activity period.

Use the same routes and recording methods where possible so detections and habitat condition can be compared between stages.

Report results, incidents and any change to the approved clearing footprint to the project environmental officer and relevant authorities.

Maintain fauna controls until the risk of vehicle access, construction disturbance and unauthorised habitat removal has ended.

Rehabilitation actions: Recreate shelter habitat

Rehabilitation should recreate the ground shelter and rocky structure used by the species. Prioritise local habitat features over cosmetic revegetation, and monitor whether they remain connected and usable.

Retain and redistribute suitable local logs, stumps, rocks and leaf litter in stable arrangements that provide shelter without creating hazards for people or machinery.

Re-establish hummock grass and locally appropriate Acacia cover where these formed part of the pre-clearing habitat.

Protect rocky outcrops and reconstructed rock features from vehicle traffic, unnecessary firewood collection and repeated ground disturbance.

Do not remove natural leaf litter during maintenance unless it presents a demonstrated safety or weed-management risk.

Rehabilitation actions: Manage threats and site condition

Control weeds where they displace hummock grass, Acacia regeneration or the leaf-litter layer used for shelter.

Manage introduced predators and other identified threats where required by the approved management plan and where control is lawful and effective.

Plan fire management to retain the hummock grass, shrub, leaf-litter and woody shelter structure used by the species.

Keep rehabilitation areas connected to retained rocky habitat and prevent new barriers from isolating them.

Rehabilitation actions: Monitor success

Set success measures for survival of planted or regenerating hummock grass and Acacia, persistence of leaf litter, logs and rocks, weed cover, connectivity and protection from vehicles.

Inspect rehabilitated areas after establishment and following major rainfall, fire or construction maintenance.

Use repeat crepuscular or nocturnal searches in suitable weather to check for the species, while recognising that non-detection does not prove absence.

Adapt planting, shelter placement, weed control, predator management or access controls if habitat features fail or monitoring identifies ongoing disturbance.

Sources