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Hoary Wattled Bat (Chalinolobus nigrogriseus)

The Hoary Wattled Bat is a small insectivorous microbat found across northern Australia and along the north-east New South Wales coast. It roosts mainly in tree hollows and rock crevices and may be affected by clearing, hollow-bearing tree removal, wildfire and disturbance around active roosts on development sites.

Conservation status

New South Wales, Biodiversity Conservation Act 2016: Vulnerable.

Breeding season

The species is non-migratory in the supplied accounts, with activity and breeding information centred on northern and north-east Australian populations. Spring is the period of greatest concern for clearing occupied hollows because young may be present.

The documents do not provide a complete annual cycle for mating, weaning, torpor or dispersal. Confirm local timing through survey results and local expert advice before clearing.

  • Breeding: Births are reported in September and October by one source and October and November by another. The broader spring period is therefore used.
  • Young: One or two young are reported, but the duration of dependence is not provided. Treat occupied maternity hollows as sensitive through the reported birth period and until inspection confirms that the roost has vacated.
  • Movement and dispersal: No seasonal migration is described. The species is reported across its range in forest, woodland, scrub and open habitats, but seasonal movement distances are not provided.
  • Highest clearing risk: Risk is highest from late winter through spring and into early summer because breeding and births are reported from September to November and active hollow roosts may contain young.

Identification

Identification is based mainly on appearance, roost features and confirmed acoustic or handling identification. Field workers should treat uncertain microbat records as requiring specialist confirmation.

The Hoary Wattled Bat has shaggy dark grey to black fur with pale or white-tipped hairs, producing a frosted appearance. Queensland animals may appear almost black, while animals in Western Australia are described as having more obvious frosting. The underparts are grey-brown and the facial lobes are poorly developed.

Identification: Size and field separation

Body measurements and weight were not provided in the supplied documents. The combination of frosted dark fur, poorly developed facial lobes, fast flight below the canopy and use of hollow-bearing trees or rock crevices can support field assessment.

The supplied documents do not provide a diagnostic comparison table for similar wattled, forest or broad-nosed bats. Do not rely on colour alone, particularly in Queensland where the fur may be nearly black. Use an appropriately trained microbat ecologist and, where required, validated call analysis or specimen examination.

Identification: Field signs and roost evidence

There are no species-specific tracks, scats, nests, sloughs or eyeshine characteristics described in the supplied documents. The most useful field evidence is a bat using a hollow-bearing tree or rock fissure, or repeated early-evening emergence from such a feature.

The species may emerge early in the evening and can leave roosts in large numbers. Observe potential roost trees from a safe distance and avoid blocking entrances or disturbing the feature during emergence.

Distribution: National range

The Hoary Wattled Bat has a broad northern Australian distribution, with a south-eastern extension into north-east New South Wales. The supplied documents do not provide a reliable national population estimate or population trend.

The species occurs across northern Australia from the Kimberley region of Western Australia through the Northern Territory and Queensland. In north-east New South Wales it extends south to about Port Macquarie and north to the Queensland border.

The documented range includes coastal and sub-coastal parts of Queensland, tropical and northern woodland regions, the Kimberley, and the north-east New South Wales coast and hinterland. It is absent from the arid centre.

  • Western Australia: Kimberley region.
  • Northern Territory: northern Australia, with no records indicated from the arid centre.
  • Queensland: northern and coastal to sub-coastal regions, including areas from tropical savannah and vine forest to dry sclerophyll forest.
  • New South Wales: north-east coastal and near-coastal areas from the Queensland border south to about Port Macquarie.

Distribution: Strongholds and populations

The supplied documents do not identify national strongholds, separate subpopulations, population size or a population trend. The species was assessed in both the Upper North East and Lower North East New South Wales disturbance regions and received a reservation priority rank of 2 in both regions.

Local records should therefore be interpreted with the condition and continuity of suitable forest, woodland and hollow-bearing trees in mind, rather than with a national abundance estimate.

Population size: Not reported in the supplied documents

Population trend: Not reported in the supplied documents

Reservation priority rank: 2 in both the Upper North East and Lower North East disturbance regions

Habitat: Vegetation and climate

The species uses a broad range of forest, woodland, scrub and grassland settings, but generally requires roost features and open flight space below the canopy.

Recorded habitat includes vine forest, tropical savannah, dry sclerophyll forest, coastal scrub, open grassland, coastal-hinterland forest and woodland. In New South Wales, it is associated with dry open eucalypt forest, including Spotted Gum, box and ironbark forests, and heathy coastal forest with Red Bloodwood and Scribbly Gum.

The species occurs across tropical and subtropical regions but is absent from the arid centre. The supplied documents do not provide a reliable elevation limit.

Habitat: Structure and connectivity

Habitat is most suitable where mature or dead trees provide hollows and where the understorey is naturally sparse enough for fast flight below the canopy. Forest edges, tracks, clearings and other open flight paths may be used for movement or feeding, but the supplied documents do not define a standard foraging distance from roosts.

Retain hollow-bearing trees, dead stags, rocky fissures and connected forest or woodland around potential roosts. Avoid creating isolated retained trees where clearing can be shifted to retain a wider connected area.

Foraging habitat: Diet

The Hoary Wattled Bat is an insectivore that hunts below the canopy in relatively open forest and woodland structure.

Reported prey includes flies, moths, crickets, cicadas, ants and spiders. The species catches some prey in flight and may land and move quickly over surfaces to take non-flying prey.

  • Flying insects, including flies, moths, crickets and cicadas.
  • Ants and spiders, including non-flying prey taken from surfaces.

Foraging habitat: Foraging structure

The species flies fast below the canopy and is associated with forests that have a naturally sparse understorey. Dry open eucalypt forest, heathy coastal forest, coastal scrub, open woodland, vine thicket margins and open grassland with nearby trees may provide feeding habitat.

The supplied documents do not give a home range, foraging radius, flight height in metres or minimum patch size. Survey planning should therefore include the full area of suitable vegetation surrounding potential roost trees, rather than restricting assessment to the tree containing a roost.

Breeding habitat: Breeding biology

Breeding occurs in tree hollows and possibly other roost features within dry forest and woodland habitat. Active maternity roosts need protection from clearing and disturbance until the breeding cycle has finished.

The supplied documents do not provide gestation length, age at maturity, mating dates, weaning age or a confirmed species-specific maternity roost size. One source reports two young born in September and October, while another reports one or two young in October and November.

Breeding season: Spring, with reported births from September to November

Litter size: One or two young

Gestation: Not reported in the supplied documents

Age at maturity: Not reported in the supplied documents

Lifespan: Mean estimated reproductive lifespan 2.5 years, with an estimated range of 1 to 9 years; this is not a confirmed maximum lifespan

Breeding habitat: Breeding features

Breeding habitat is described as dry forest types with hollows. Tree hollows and rock crevices may both provide roosting habitat, but the supplied documents do not confirm which features are used specifically for maternity colonies.

Before clearing, inspect hollow-bearing trees and other potential roost features for bats. If a maternity site is found near the work area, retain a buffer and allow the breeding cycle to finish where practicable.

Sheltering habitat: Roost features

The main sheltering features are tree hollows and rock crevices. These features can occur in living trees, dead trees and retained forest remnants.

The species roosts in tree hollows and rock crevices. The supplied documents do not provide entrance dimensions, hollow depth, tree diameter, preferred tree species or the number of bats using an individual roost.

Potential roost trees include mature hollow-bearing eucalypts and dead stags in dry or open forest. Rock fissures should also be retained where they occur in or beside suitable forest.

Sheltering habitat: Site practice

Do not fell or burn hollow-bearing trees before they have been assessed for active roost use. If clearing an occupied roost cannot be avoided, use a fauna spotter-catcher and soft-felling procedures, with the roost feature lowered carefully and relocated into adjacent habitat where feasible.

Where a maternity roost is identified, retain the roost tree or rock feature and establish a clearly marked no-go area until the roost has vacated. Works should stop if bats are found during felling.

Threats: Clearing and fragmentation

The main project risks are loss of hollow-bearing trees and rock roosts, removal of feeding habitat and disturbance during the spring breeding period.

Clearing for forestry, agriculture, housing, roads and infrastructure can remove tree hollows, rock fissures and open forest used for feeding. Fragmentation can reduce the continuity of roosting and foraging habitat.

Retain hollow-bearing trees, dead stags, rock fissures and surrounding native vegetation. Mark clearing limits on the ground and prevent unauthorised access to retained habitat.

Threats: Breeding and construction disturbance

Felling an occupied tree can kill or injure bats. Clearing near a maternity roost during the breeding period can harm dependent young or cause the colony to abandon the feature.

Construction noise and vibration may alter behaviour or temporarily reduce use of nearby habitat. The supplied documents do not provide a species-specific disturbance distance, so buffers should be set by the project ecologist in consultation with the fauna spotter-catcher and relevant approval conditions.

Threats: Fire, predators and other pressures

Wildfire can remove hollow-bearing trees and feeding habitat. Predators reported for the species include pythons, hawks and owls.

The supplied documents do not identify species-specific risks from roads, disease or hydrology change. Project controls should still prevent unnecessary removal of riparian or wet drainage-line vegetation, avoid attracting pest animals to work sites and manage fauna interactions under the project's fauna management plan.

Survey methodology: 1. Desktop assessment and habitat mapping

Survey the Hoary Wattled Bat, Chalinolobus nigrogriseus, by combining habitat assessment with nocturnal detection. The provided documents do not prescribe a species-specific number of survey nights, detector hours, transect length or trapping effort, so the project ecologist should set effort according to the proposed clearing, habitat quality, season, approval conditions and relevant state guidance.

Map dry open eucalypt forest, including spotted gum, box and ironbark forest, heathy coastal forest, vine thicket, coastal scrub, woodland and open grassland with nearby trees.

Identify hollow-bearing eucalypts, dead limbs, mature trees, rock fissures, sparse-understorey areas, likely flyways below the canopy and retained vegetation that could provide feeding or roosting habitat.

Review existing records and submit any new records to the relevant state wildlife database or approved biodiversity information system.

Survey methodology: 2. Passive acoustic detection

Use ultrasonic detectors in suitable open forest, woodland, coastal scrub and other mapped habitat because the species flies fast below the canopy and may be difficult to observe directly.

Place detectors near hollow-bearing trees, forest edges, sparse understorey, tracks, clearings and other likely flight paths, while avoiding locations where vegetation or terrain blocks the microphone.

Run detectors during suitable nocturnal conditions and record detector location, start and finish times, weather, wind, rain, temperature, habitat and microphone height.

Have bat calls analysed by a suitably experienced person because identification from acoustic recordings can be difficult and should be confirmed where the record may affect approvals or clearing limits.

Survey methodology: 3. Evening observation and roost inspection

Use evening observation or spotlighting around hollow-bearing trees, rock fissures, forest edges and sparse-understorey flyways to detect bats emerging from roosts or foraging below the canopy.

Begin observations before emergence and continue through the main evening activity period, with the exact duration set by the project ecologist and recorded in the survey report.

Inspect potential roost features from the ground before clearing, without entering hollows or rock fissures, and use an experienced fauna spotter catcher if a feature may contain bats.

Treat a tree or rock fissure as occupied if bats, guano, staining, audible activity or other evidence indicates use, or if the feature cannot be safely assessed.

Survey methodology: 4. Timing and conditions

Give additional attention to potential maternity roosts before works planned for October and November, when females may give birth to one or two young.

Avoid interpreting a negative result as proof that habitat is unused, particularly where weather, wind, rain, cold conditions, equipment failure or poor microphone placement could reduce detection.

Repeat or extend survey effort when conditions are unsuitable, when suitable habitat will be cleared, or when initial results conflict with habitat evidence or previous records.

Survey methodology: Minimum effort and reporting

  • Set the number of survey nights, detector locations, observation hours and any trapping effort in a project-specific survey plan approved by the project ecologist and consistent with current state and Commonwealth guidance.
  • Do not use trapping, harp traps, mist nets or hand capture unless the method is justified, legally permitted, supervised by an appropriately authorised person and safe for the species and season.
  • Record negative as well as positive survey results, including survey dates, effort, weather, equipment, call identification method, habitat and limitations.
  • Report confirmed records and any occupied roost or maternity site to the relevant state wildlife database and include them in the project fauna register.
  • Check current state threatened-species requirements before fieldwork because the species is identified as vulnerable in NSW, while the supplied Queensland project document treats it as least concern under the Queensland legislation.

Before habitat disturbance: Avoid and minimise

Avoid removing roosts and feeding habitat wherever practicable. The main pre-clearing risks are loss of tree hollows and rock fissures, removal of open forest used for fast flight below the canopy, and disturbance of breeding or roosting bats.

  • Retain hollow-bearing eucalypts, dead limbs with hollows, mature trees, rock fissures and connected dry open forest or woodland within and beside the work area.
  • Retain naturally sparse understorey and forest edges that provide low, open flight paths below the canopy.
  • Keep clearing to the smallest area needed for the project and retain vegetation beside drainage lines, gullies, forest edges and other likely movement routes.
  • Avoid isolating retained trees or small habitat patches where a practical design alternative can retain a connected strip of vegetation.

Before habitat disturbance: Approvals and work planning

  • Confirm whether the proposed action requires state threatened-species approval, a biodiversity assessment, a wildlife licence or other fauna authority before survey, capture or clearing.
  • The supplied material identifies the species as not listed under the EPBC Act and as vulnerable in NSW, but the approval position must be checked against current legislation and the project location.
  • Prepare a fauna management plan that identifies survey results, habitat features, clearing limits, fauna roles, stop-work triggers, release sites, incident contacts and reporting requirements.
  • Plan staging so that retained habitat is available before each clearing stage and so that any identified maternity roost can remain undisturbed until the breeding cycle has finished where practicable.
  • Schedule pre-clearance and clearing controls around the October to November breeding period where the project can reasonably avoid that period.

Before habitat disturbance: Site preparation

  • Complete a pre-clearance inspection of all trees, limbs, rocks, logs and other features within the approved disturbance footprint and immediately beside it.
  • Mark no-go areas, retained hollow-bearing trees, rock fissures, buffers and approved access routes on the ground before machinery arrives.
  • Install fauna-friendly exclusion fencing where it will keep machinery and workers out of retained habitat without blocking bat movement between retained areas.
  • Brief all operators and subcontractors on the Hoary Wattled Bat, the marked habitat features, the stop-work procedure and the requirement to follow the fauna spotter catcher's directions.
  • Confirm that the fauna spotter catcher is appropriately authorised, vaccinated against lyssavirus where handling bats is required, and supported by a wildlife carer and veterinary contact.

During habitat disturbance: Daily site controls

Use staged, supervised clearing. A fauna spotter catcher must control the release of habitat features and must be able to stop machinery immediately when a bat, occupied roost or unsafe condition is found.

  • Inspect exclusion fencing, no-go markers, access routes and retained habitat at the start of each shift and after heavy rain, vehicle impact or other damage.
  • Keep machinery, spoil, lighting and stored materials out of retained hollows, rock fissures, forest edges and marked release habitat.
  • Limit night works near retained trees and known roosts where practicable, and direct temporary lighting away from retained vegetation and potential roost openings.
  • Maintain a clear communication link between the fauna spotter catcher, supervisor and machine operators throughout clearing.

During habitat disturbance: Supervised clearing and habitat features

  • The fauna spotter catcher must inspect each tree or limb immediately before it is felled and must have authority to delay or stop the operation.
  • Use soft felling for a tree or limb containing a roost feature when removal is unavoidable, cutting at least 50 centimetres from the roost feature and lowering the section carefully.
  • Relocate a retained roost feature into adjacent suitable habitat at a similar height where this can be done safely and lawfully.
  • Do not destroy a tree, limb or rock fissure that is occupied by bats until the fauna spotter catcher and project ecologist have confirmed the approved response.
  • Retain and relocate logs, rocks and other ground habitat only where the fauna management plan identifies them as suitable and the action will not injure hidden fauna.

During habitat disturbance: If a bat is found

  • Stop work immediately within the exclusion area if a bat, dependent young, occupied hollow or occupied rock fissure is found.
  • Keep people, machinery and light away from the roost and allow the fauna spotter catcher to assess whether the bat can remain undisturbed until dusk or until the breeding cycle has finished.
  • Only an appropriately trained and authorised person may capture, handle, contain or release the bat.
  • Outside the breeding season, the fauna spotter catcher may remove an individual and hold it in a suitable calico bag until release at dusk, provided this is authorised and safe.
  • Release an alert, uninjured bat into nearby retained habitat at dusk, using a release location selected by the fauna spotter catcher and project ecologist.
  • Do not handle a bat with bare hands, and do not permit untrained workers to open a hollow, extract a bat or attempt a release.
  • Stop work and obtain veterinary or wildlife-carer assistance for an injured, weak, grounded or dependent bat; transport it to the nominated veterinarian or wildlife carer in accordance with the fauna management plan.

During habitat disturbance: Stop-work triggers and records

  • Stop work if a bat or dependent young is found, a maternity roost is suspected, an unmarked hollow or rock fissure is exposed, fauna is injured, or clearing moves outside the approved footprint.
  • Record the date, time, location, habitat feature, species identification, number and condition of bats, action taken, release site, personnel, photographs and any veterinary or wildlife-carer transfer.
  • Recommence work only after the fauna spotter catcher and responsible environmental officer have confirmed that the feature is clear, the animal has been managed and all controls are reinstated.

After habitat disturbance: Immediate checks

Post-clearing checks should confirm that no bats, dependent young or occupied roost features remain in the work area and that relocated features and retained habitat are functioning as planned.

  • Inspect felled trees, limbs, hollows, rock fragments and the ground around clearing areas for bats, dependent young, injury or evidence of an occupied roost.
  • Complete a final walkover of each clearing stage before machinery, spoil or construction materials occupy the area.
  • Keep an exclusion zone around any live bat, dependent young or suspected roost until the fauna spotter catcher and project ecologist determine the response.

After habitat disturbance: Monitoring and maintenance

  • Inspect relocated roost features and retained hollow-bearing trees after installation, severe weather and any nearby construction activity.
  • Repair damaged exclusion fencing, no-go markers and buffers for the duration of construction.
  • Use repeat acoustic monitoring or evening observations where the project has removed known roost habitat, affected a maternity site, or where approval conditions require monitoring.
  • Compare post-clearing records with the pre-clearing habitat map and investigate any unexpected decline in detections or evidence of bat injury.

After habitat disturbance: Reporting and compliance

  • Report all captures, injuries, deaths, roost discoveries, relocations, non-compliance events and stop-work incidents to the project environmental officer and the relevant regulator where required.
  • Submit confirmed occurrence records to the relevant state wildlife database and retain the survey, clearing and rehabilitation data with the project environmental records.
  • Assess whether residual loss of vulnerable habitat requires an offset, restoration action or additional approval condition under the applicable state or Commonwealth scheme.

Rehabilitation actions: Restore habitat structure

Rehabilitation should restore open forest structure, roost opportunities and safe low-level flight paths. It should also protect retained habitat from repeat clearing, fire damage, weeds and predators.

  • Replant locally appropriate eucalypts and other native species that match the surrounding dry open forest, woodland, heathy coastal forest, vine thicket or coastal scrub community.
  • Use a mix of tree ages and retain naturally sparse understorey where that structure supports fast flight below the canopy.
  • Protect retained mature trees and allow replacement trees to develop into future hollow-bearing trees.
  • Where approved and safe, install suitable artificial hollows or nest boxes in retained habitat only after the project ecologist confirms that natural hollows are insufficient and the design is appropriate for bats.
  • Relocate suitable hollow-bearing limbs, logs and rocks into nearby retained habitat where they can remain stable and will not create a safety or fire hazard.

Rehabilitation actions: Protect restored areas

  • Control weeds so planted trees, natural regeneration and open flight paths are not smothered or closed by dense invasive understorey.
  • Manage cats, foxes and other predators under the approved pest management plan, particularly around release sites and retained roost habitat.
  • Apply fire planning that protects hollow-bearing trees, retained dead limbs and developing replacement trees while meeting the area's legally approved fire regime.
  • Prevent vehicle access, stock damage, unauthorised clearing and storage of materials in rehabilitation areas.

Rehabilitation actions: Monitoring and success measures

  • Inspect rehabilitation after establishment and after major weather or fire events, recording survival of planted trees, natural regeneration, weed cover, damage to hollows and condition of retained habitat.
  • Use repeat acoustic monitoring and targeted evening observations at retained and rehabilitated habitat where monitoring is required by approval conditions or where a pre-clearing record established a local population.
  • Treat rehabilitation as successful only when approved planting and habitat features are established, access controls remain effective, weeds and predator impacts are managed, and monitoring shows continued use or suitable roost and foraging conditions.
  • Document failed plantings, damaged artificial hollows, loss of retained trees and unexpected bat impacts, then implement corrective actions and continue monitoring until the approved completion criteria are met.

Sources