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Hamelin Ctenotus (Ctenotus zastictus)

The Hamelin Ctenotus is a small, surface-active skink known only from a restricted area south of Hamelin homestead in the Shark Bay region of Western Australia. Its habitat is Triodia grassland with eucalypts on red sand, and clearing, spinifex damage, stock access and disturbance to its small known range may affect its persistence on development sites.

Conservation status

Commonwealth, EPBC Act 1999: Vulnerable.

Western Australia, Biodiversity Conservation Act 2016: Vulnerable.

Breeding season

Hamelin Ctenotus is an egg-laying skink that is thought to breed from spring into early summer. Clearing risk is highest during this period, when females may be carrying eggs, eggs may be in burrows and young may be present, although exact monthly timing is not recorded.

Reproductive mode: Egg laying.

Clutch size: Five leathery eggs.

Incubation: Not recorded.

Size at hatching: Not recorded.

Age at maturity: Not recorded.

Nest or egg sites: Burrows.

Breeding frequency: Not recorded.

Confirm timing locally before works, particularly against local rainfall and temperature conditions that affect insect availability, surface activity and the start of breeding.

  • Mating: Breeding is thought to occur in spring and early summer, when adults find insects and mates. Exact mating months are not recorded, so September to December represents the documented seasonal window rather than a measured monthly peak.
  • Gravid females: No records identify when Hamelin Ctenotus females carry eggs. This window follows the species breeding season and egg-laying period, with no species-specific peak identified.
  • Egg laying: Females dig and lay clutches of five leathery eggs in burrows. Laying is reported in spring and early summer, but the documents do not give more precise months.
  • Incubation: Eggs are laid in burrows, but incubation length and the period eggs remain in the soil are not recorded. September to December is an inferred work-planning window based on the documented laying season, not a measured incubation period.
  • Hatchlings: The documents state only that young fend for themselves after hatching. October to December is a general inferred emergence window following spring and early summer laying; exact hatching months and abundance are not recorded.
  • Active period: The species is diurnal and has been observed active in May, August and November. Activity timing is not known specifically, but peak activity is expected in spring and early summer under warm to hot conditions, so September to December is shown as the likely peak window.
  • Highest clearing risk: Risk is highest during the spring and early summer breeding window because clearing may affect mating adults, gravid females, eggs in burrows and newly hatched young. Intact Triodia tussocks, burrows and sandy habitat should still be checked and protected outside this period because the species' full seasonal activity pattern is not known.

Identification

The Hamelin Ctenotus is a small to medium-sized skink with a long tail and a distinctive black, striped and spotted pattern. Identification should be confirmed carefully because several similar Ctenotus occur in the broader Shark Bay area.

The species has well-developed front and hindlimbs, with five digits on each limb. Its body has narrow pale paravertebral, dorsolateral, midlateral and ventrolateral stripes, together with a single series of pale spots between the paravertebral and dorsolateral stripes and between the dorsolateral and midlateral stripes. The ground colour is blackish and the belly is pale with a greenish tinge.

Maximum snout to vent length: About 60 millimetres.

Tail: Long and slender, more than twice the snout to vent length; about 140 millimetres is reported.

Limbs and digits: Front and hindlimbs well developed, with five digits on each limb.

Ear feature: Like other Ctenotus, it has rounded white scales along the edge of the ear openings.

Identification: Distinguishing features

The combination of a blackish ground colour, sharply defined narrow pale stripes and lines of pale spots helps separate the Hamelin Ctenotus from other Ctenotus in the region. Potentially similar species include Ctenotus australis, also referred to as C. lesueurii in Western Australian literature, C. fallens, C. mimetes, C. pantherinus, C. schomburgkii, C. severus and C. youngsoni.

Ctenotus identification can be difficult, and cryptic species may occur in the genus. A record outside the known distribution should therefore be supported by a tissue sample for verification.

Identification: Field signs and handling

Individuals have been observed moving around the fringes of Triodia tussocks during the day. When pursued, they shelter in spinifex tussocks. The species also shelters in burrows or under vegetation during hot parts of the day.

No species-specific information is provided on tracks, scats, calls, sloughs or eyeshine. Do not rely on these signs for detection. Minimise disturbance to spinifex during searches and trapping because the known habitat is limited.

  • Record clear photographs of the body pattern, head, limbs, digits and ear opening where possible.
  • Use an experienced reptile ecologist or fauna spotter catcher for identification and handling.
  • Treat records outside the known range as requiring additional verification, including tissue sampling where authorised and appropriate.

Distribution: National range

The Hamelin Ctenotus has an extremely restricted known distribution in Western Australia. No confirmed populations outside the Shark Bay region are identified in the supplied documents.

The species is known only from a small area in the Shark Bay region of Western Australia, approximately 20 kilometres south of Hamelin homestead along the track to Coburn homestead. The five individuals in the type series were collected 16 to 17 kilometres south of Hamelin homestead.

  • State: Western Australia only, based on the supplied records.
  • Region: Shark Bay, including the south-eastern part of the Shark Bay World Heritage Area.
  • Bioregion: A formal IBRA bioregion is not specified in the supplied documents, so it should be confirmed from current spatial datasets for a project site.

Distribution: Known stronghold and population information

The known stronghold is a single patch of mallee, described in the survey profile as Triodia grassland with eucalypts on a red sandplain. Studies in other areas with suitable habitat have not found the species. The full geographic range and current conservation status remain insufficiently resolved.

Individuals in type series: Five.

Known habitat area: About 150 square kilometres.

Population size: Not known.

Population trend: Not known; further survey and ecological research are required.

  • The known locality should be treated as sensitive habitat during planning and field activities.
  • Do not infer absence from apparently suitable habitat without an appropriately designed survey.
  • Report any apparent new locality promptly and arrange specialist confirmation because of the species' restricted known range and identification difficulties.

Habitat: Habitat type

The Hamelin Ctenotus occupies dry, sandy terrestrial habitat dominated by spinifex and scattered eucalypts. The documented habitat is a red sandplain and the species appears closely associated with Triodia tussocks for cover.

The only documented habitat is Triodia grassland with eucalypts on a red sandplain. A Shark Bay conservation assessment also describes the known locality as a single patch of mallee on two adjacent pastoral properties south-east of Hamelin homestead.

Dominant ground cover: Spinifex, Triodia grassland.

Woody vegetation: Eucalypts, with the locality also described as a patch of mallee.

Substrate: Red sandplain.

Recorded habitat area: About 150 square kilometres.

Habitat: Structural features and site condition

Triodia tussocks provide shelter and the species has been observed moving around their fringes. Retaining intact tussock structure and sandy ground is therefore important when assessing clearing or construction impacts.

The supplied documents do not provide an elevation range, rainfall limit, required tussock density or minimum patch size. These variables should be recorded during site assessment rather than assumed.

  • Map Triodia cover, eucalypt or mallee patches, bare red sand and tracks before clearing.
  • Avoid driving, slashing, trenching or storing materials through intact spinifex where practicable.
  • Assess whether the site connects with the known habitat patch and whether the proposed works would reduce or fragment suitable ground cover.

Foraging habitat: Diet and feeding activity

The Hamelin Ctenotus is a diurnal insectivorous skink that searches around spinifex tussocks. The supplied information indicates that it eats insects and spiders, but does not define a foraging home range or particular prey species.

The species is reported to feed on insects and spiders. Like related Ctenotus, it is surface active and has been observed moving around the fringes of Triodia tussocks by day.

Activity is likely to peak in spring and early summer under warm to hot conditions. Individuals are also described as becoming active in the early morning and evening, although the detailed account does not establish a species-specific daily schedule.

Known food: Insects and spiders.

Foraging setting: Surface activity around the fringes of Triodia tussocks.

Foraging range: Not documented.

  • Search the edges of Triodia tussocks during warm daylight periods, with attention to early morning and late afternoon activity.
  • Do not remove or heavily disturb tussocks while searching for foraging animals.
  • Record prey observations if made, because species-specific dietary information is limited.

Breeding habitat: Breeding requirements

Breeding is thought to occur in spring and early summer in the same sandy spinifex habitat used for shelter and foraging. Females lay leathery eggs in burrows, but most reproductive details remain unknown.

Suitable breeding habitat is expected to include red sandplain substrate, Triodia cover and access to burrows or other protected sandy sites. The documents do not identify a specific nest structure, burrow depth or breeding territory.

Females dig and lay clutches of leathery eggs in burrows. Young fend for themselves after hatching, so there is no documented prolonged parental care.

  • Protect intact spinifex and sandy ground during the spring and early summer breeding period.
  • Inspect areas proposed for clearing for burrows and maintain exclusion zones around any occupied animal or active breeding feature in accordance with approvals and handling procedures.
  • Do not excavate or collapse suspected burrows before assessment by a suitably qualified person.

Breeding habitat: Reproductive facts

Breeding season: Spring to early summer.

Clutch size: Five eggs reported.

Egg type: Leathery eggs laid in burrows.

Incubation period: Not documented.

Age at maturity: Not documented.

Lifespan: Not documented.

Parental care: Young fend for themselves after hatching.

Sheltering habitat: Known refuges

Shelter is provided mainly by Triodia tussocks, vegetation and burrows in the red sandy substrate. Shelter features should be retained because animals may be difficult to detect when inactive or pursued.

When pursued, Hamelin Ctenotus shelters in spinifex tussocks. It is also reported to shelter in burrows or under vegetation during the heat of the day.

The documents do not provide dimensions for burrows, tussocks or other refuges. They also do not identify tree hollows, rock shelters or fallen timber as required shelter features.

Known refuge: Triodia tussocks.

Other reported shelter: Burrows or vegetation.

Refuge dimensions: Not documented.

  • Retain intact Triodia tussocks and avoid crushing them with vehicles or machinery.
  • Check beneath and around vegetation cautiously during hand searches, without unnecessary removal of cover.
  • Keep spoil, equipment and temporary access tracks away from intact sandy shelter habitat.

Threats: Clearing and construction

The main management concern is loss or disturbance of the species' very restricted habitat. The supplied documents specifically identify the need to protect the known location from stock, feral goats and rabbits, and to minimise disturbance to spinifex during surveys.

Clearing of Triodia grassland, mallee or eucalypt habitat on red sandplain can remove cover, foraging areas and burrow sites. Fragmentation may be significant because the known distribution is confined to a single small area and the full range is unresolved.

Vehicle movements, grading, trenching, stockpiles and repeated pedestrian activity can damage spinifex tussocks and sandy shelter sites even where vegetation is not completely cleared.

  • Avoid the known locality where practicable and clearly mark no-go areas before works begin.
  • Minimise the footprint of access tracks, laydown areas, easements and temporary work zones.
  • Use pre-clearance searches by suitably qualified personnel, with a species-specific plan for capture, handling and release if animals are found.
  • Do not claim absence from a work area solely because no animals were seen during casual inspection.

Threats: Grazing, introduced animals and fire

The Shark Bay assessment recommends fencing the single known location to exclude stock, feral goats and rabbits. These animals can damage ground cover and alter the condition of the sandy spinifex habitat.

The supplied documents do not provide a species-specific fire response or fire interval. Fire planning should therefore consider the need to retain spinifex shelter and avoid broad loss of the documented habitat.

  • Prevent stock, goats and rabbits from entering retained habitat where project controls allow.
  • Keep construction waste and food that could attract introduced animals away from retained habitat.
  • Do not burn or clear spinifex for access without assessing the effect on shelter and breeding habitat.

Threats: Roads, fragmentation, disease and hydrology

The supplied documents do not identify species-specific road mortality, disease or hydrology threats. Roads and altered drainage should nevertheless be assessed for direct mortality, habitat fragmentation, erosion or changes to the red sandplain and spinifex cover.

Any risk assessment should distinguish documented threats from project-specific pathways that require field investigation.

  • Record roadkill and live observations along project roads during fauna monitoring.
  • Prevent runoff, sediment deposition and concentrated drainage from damaging sandy habitat or spinifex tussocks.
  • Report unusual illness or mortality through the project's fauna incident process and seek specialist advice.

Survey methodology: 1. Confirm habitat and survey timing

Survey for Hamelin Ctenotus should target warm conditions when this diurnal skink is active around Triodia tussocks. The species is known from a small area of red sandplain habitat in the Shark Bay region, so survey work must avoid unnecessary disturbance to spinifex.

Map Triodia grassland, eucalypts, red sandplain and the condition of all potential habitat within and adjoining the project area.

Prioritise surveys in spring and early summer under warm to hot conditions, when activity is expected to be highest.

Include suitable warm daytime periods outside spring and early summer where possible, because individuals have been observed active in May and the type series was collected in August and November.

Known habitat area: About 150 square kilometres of Triodia grassland with eucalypts on red sandplain

Activity: Diurnal, with likely peak activity in spring and early summer under warm to hot conditions

Survey methodology: 2. Diurnal visual searches

Search during the day when temperatures are suitable, concentrating on the edges of Triodia tussocks and open ground between tussocks.

Walk slowly through representative habitat and record the search route, date, start and finish times, weather, temperature if measured, habitat condition and all reptiles observed.

Minimise trampling, cutting or moving of spinifex because the known habitat is limited and the species shelters in Triodia tussocks when pursued.

Photograph suspected Hamelin Ctenotus where this can be done without disturbing the animal.

  • Search the fringe of each selected Triodia patch before entering the tussock itself.
  • Treat a visual record as provisional where identification from photographs is uncertain, because several Ctenotus species occur in the broader Shark Bay area.

Survey methodology: 3. Pitfall trapping

Use pitfall trapping during the species' active period, because Ctenotus species are readily pitfall trapped when active.

For a targeted search, install a pitfall line with six 10 litre buckets distributed along a 15 metre fence.

Place trapping lines only where they will not cause avoidable damage to Triodia tussocks or other retained habitat.

Inspect traps at a frequency consistent with animal welfare requirements, weather conditions and the project fauna management plan, and release non-target animals promptly by an authorised person.

Targeted trap line: Six 10 litre buckets along a 15 metre fence

  • Record the number and size of buckets, drift fence length, trap opening and closing times, weather, trap condition, captures and non-target mortality.
  • Do not describe a negative result as proof of absence unless the survey effort and site conditions provide an effective evaluation of absence.

Survey methodology: 4. Identification and verification

Check suspected animals against the species' diagnostic combination of a black background, narrow pale paravertebral, dorsolateral, midlateral and ventrolateral stripes, and single rows of pale spots between the stripes.

Confirm that the animal has well-developed front and hind limbs with five digits on each limb, a maximum snout to vent length of about 60 millimetres and a tail more than twice the snout to vent length.

Use photographs and, where required and legally authorised, tissue sampling to verify records outside the known distribution because Ctenotus species can be difficult to distinguish and cryptic species may occur.

Submit unusual or uncertain records to an appropriately qualified reptile taxonomist or relevant museum for confirmation.

  • Do not extend the known distribution from an unverified field identification.
  • Take a tissue sample only under the required approval, animal welfare and collection arrangements.

Survey methodology: 5. Minimum effort and reporting

  • Use the six bucket, 15 metre fence arrangement as the minimum targeted pitfall configuration stated in the species profile, and add diurnal visual searches of all suitable Triodia habitat.
  • Report survey dates, timing, weather, conditions, methods, trap effort, search routes, habitat disturbance, records, photographs, identification checks and any limitations.
  • Provide a clear map of searched and unsurveyed habitat, including the location of all records and proposed disturbance areas.
  • Submit confirmed records, including negative survey results where appropriate, to the relevant Western Australian wildlife database and the project regulator or land manager.
  • Retain photographs, field sheets, specimen or tissue accession details and fauna handling records with the project environmental records.
  • Contact the relevant Australian Government assessment section before the survey if the proposed effort or design differs materially from the guideline.

Before habitat disturbance: Avoid and minimise

Treat all suitable Triodia and red sandplain habitat as potential Hamelin Ctenotus habitat until survey and impact assessment show otherwise. The species has a very restricted known distribution, so avoid clearing wherever practicable.

  • Retain Triodia grassland, eucalypts, red sandplain and the spaces between tussocks within and beside the work area.
  • Keep the known or suspected habitat patch intact rather than creating isolated cleared remnants.
  • Use existing access tracks and previously disturbed areas for plant, parking, stockpiles and services wherever practicable.
  • Avoid unnecessary entry into spinifex during survey, pegging and construction preparation.

Before habitat disturbance: Approvals and planning

National status: EPBC Act Vulnerable

  • Check whether the proposed action may significantly impact this EPBC Act Vulnerable species and obtain project specific advice or referral advice before works.
  • Confirm Western Australian fauna permits, survey authorisations, animal welfare requirements and any land manager approvals before trapping, handling or collecting tissue.
  • Prepare a fauna management plan that identifies the species, habitat to be retained, survey method, fauna spotter catcher responsibilities, stop-work triggers, release locations and reporting requirements.
  • Schedule clearing and ground disturbance outside the expected spring and early summer activity peak where the project program allows.

Before habitat disturbance: Pre-clearance preparation

  • Complete the required pre-clearance survey in suitable warm daytime conditions using diurnal searches and the targeted pitfall arrangement where appropriate.
  • Mark retained Triodia patches, red sandplain habitat, exclusion areas, access routes and the limits of approved clearing before machinery arrives.
  • Use exclusion fencing or other clearly visible barriers where they can keep machinery and workers out of retained habitat without damaging Triodia.
  • Brief all operators and workers on the species' appearance, habitat, exclusion areas, reporting process and stop-work requirements.

During habitat disturbance: Daily controls

Keep clearing within the approved footprint and use a fauna spotter catcher who can see the work face and stop machinery immediately. The spotter catcher should focus on Triodia edges and open ground where this diurnal skink may move during the day.

  • Inspect exclusion fencing and clearing limits before work starts each day.
  • Walk the active clearing area and the edge of retained Triodia before machinery enters it.
  • Use slow, staged clearing so the spotter catcher can inspect the work face, ground surface and tussock edges.
  • Keep machinery, vehicles, spoil, materials and workers out of retained habitat and release areas.
  • Suspend clearing during conditions that prevent effective visual detection or safe fauna handling, as required by the fauna management plan.

During habitat disturbance: Spotter catcher and machinery

  • Position the fauna spotter catcher where the operator can see and respond to clear stop signals.
  • Clear in short stages, allowing the spotter catcher to inspect each area before the next section is disturbed.
  • Direct the operator to stop immediately when a suspected Hamelin Ctenotus, another native animal or an unsafe fauna handling situation is detected.
  • Do not allow workers to chase animals through Triodia or break apart tussocks unnecessarily.

During habitat disturbance: Animal handling and release

  • Stop work and establish a safe exclusion area if a Hamelin Ctenotus is found.
  • Have the animal handled only by a person authorised and competent under the project fauna management plan and applicable Western Australian requirements.
  • Keep handling to the minimum needed for identification, protection and release.
  • Release an uninjured animal into nearby retained, suitable Triodia habitat that is outside the work area and connected where practicable to the retained patch.
  • Place an injured animal in a secure, suitable container and arrange assessment by a veterinarian or authorised wildlife carer.
  • Do not collect a tissue sample or retain an animal unless the required approvals and qualified personnel are in place.

During habitat disturbance: Stop work and records

  • Stop work if an animal is found, if clearing moves outside the approved footprint, if exclusion fencing fails, or if the spotter catcher cannot inspect the active work area safely.
  • Record the location, date, time, activity, habitat, weather, identification evidence, photographs, handling, release location, injury and mortality for every fauna incident.
  • Notify the project environmental officer and regulator or land manager of any confirmed record, injury, death or material departure from the fauna management plan.
  • Review the clearing method and controls before restarting after a stop-work event.

After habitat disturbance: Post-clearance checks

Post-clearing checks should confirm that the approved footprint was not exceeded and that retained Hamelin Ctenotus habitat remains intact. Keep fauna controls in place while construction continues beside retained habitat.

  • Inspect the cleared edge and retained Triodia for trapped, injured or isolated reptiles before demobilising the spotter catcher.
  • Check that exclusion fencing, habitat markers and access controls remain in place around retained habitat.
  • Compare the final cleared area with the approved design and record any changes or accidental disturbance.
  • Repeat targeted diurnal searches in retained habitat if a fauna incident occurred or if the project fauna management plan requires follow-up.

After habitat disturbance: Monitoring and reporting

  • Monitor retained habitat for Hamelin Ctenotus during suitable warm daytime conditions, with effort and timing set out in the approved management plan.
  • Record all detections and non-detections with the method, effort, weather, location and habitat condition.
  • Submit confirmed records to the relevant Western Australian wildlife database and provide required reports to the Australian Government and state regulator.
  • Maintain records of clearing, fauna observations, handling, relocation, injury, mortality, rehabilitation and any corrective action.

After habitat disturbance: Ongoing controls and offsets

  • Maintain exclusion fencing and no-go areas until construction risks to retained habitat have ended.
  • Prevent storage, vehicle access, weeds, rubbish and unapproved fire or disturbance within retained Triodia habitat.
  • Assess whether an offset or other compensatory measure is required under the EPBC Act approval, state approval or project conditions.

Rehabilitation actions: 1. Recreate habitat structure

Rehabilitation should recreate the structure of the species' known habitat, with Triodia grassland and eucalypts on suitable red sandplain where those communities are appropriate to the site. The documents do not specify a planting list, rehabilitation density or monitoring duration, so use an approved local restoration design rather than inventing targets.

  • Reinstate a stable red sandplain surface and avoid compaction that prevents establishment of native spinifex and other local groundcover.
  • Replant or encourage locally appropriate Triodia and eucalypt vegetation consistent with the pre-clearing community and approved rehabilitation plan.
  • Retain natural tussock spacing and a mix of tussock edges and open ground, because the species has been observed moving around the fringe of Triodia tussocks.
  • Keep rehabilitation connected to retained suitable habitat wherever practicable.

Rehabilitation actions: 2. Protect the rehabilitating area

  • Exclude vehicles, stock and unauthorised access until vegetation has established and the site is no longer vulnerable to disturbance.
  • Control weeds and avoid introducing non-local soil, plant material or rubbish that could alter the Triodia grassland.
  • Manage fire in accordance with the approved local fire strategy, considering the need to retain established Triodia habitat and avoid damaging the small known habitat type.
  • Control introduced predators and herbivores where required by the approved management plan and relevant land manager.

Rehabilitation actions: 3. Monitor success

  • Monitor establishment of Triodia, eucalypts, groundcover, soil stability, weed presence, fire impacts and connectivity with retained habitat.
  • Use repeat diurnal searches in suitable warm conditions to check whether Hamelin Ctenotus uses rehabilitated habitat once the vegetation structure is established.
  • Record search effort and conditions, not just presence or absence, because a negative result is not evidence of absence without effective validation.
  • Set site specific completion criteria in the rehabilitation plan, including vegetation establishment, absence of unacceptable weeds or erosion, protection from further disturbance and results of fauna monitoring.

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