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Narrow-eared Roundleaf Bat (Hipposideros stenotis)

The Narrow-eared Roundleaf Bat is a small, insect-eating cave-roosting bat endemic to northern Australia. In Queensland it is known only from the Mt Isa region and is listed as Vulnerable under the Nature Conservation Act 1992, so rocky roosts, nearby water and low vegetation corridors require careful assessment before clearing or construction.

Conservation status

Queensland, Nature Conservation Act 1992: Vulnerable.

Breeding season

The species is not known to migrate, and the supplied documents do not define seasonal movements. The following timing reflects the reported breeding period and the Queensland survey guidance.

There is no published information in the supplied Queensland guidance identifying the best time of year for surveys. Warm, calm and dry nights are preferred whenever possible.

  • Breeding, births: Births are reported between October and January.
  • Young dependent: October to February is treated as the breeding season in Queensland guidance, when females may be pregnant, carrying young or nursing crèched young.
  • Roosting and foraging: The species is resident in the supplied accounts. No seasonal migration or dispersal period is reported.
  • Highest clearing risk: Disturbance is most likely to harm the species from October to February because females may be pregnant, have attached young or be nursing crèched young. January and February are included because the Queensland guidance identifies the breeding season through February.

Identification

This is a small brown hipposiderid with a complex noseleaf and long, sharply pointed ears. It is most reliably identified by its morphology and its distinctive high frequency echolocation call.

The back is brown and the belly is slightly paler. The forearm is 42 to 46 mm long and the body is 40 to 46 mm long. Weight is about 5 to 7 g, although a broader published range is 4 to 6.4 g.

The noseleaf covers much of the face and has two supplementary leaflets. A wart-like protuberance occurs near the centre of the noseleaf, with a smaller wart on the upper edge of the upper leaflet. Box-like cavities occur in the upper posterior noseleaf, with another small secondary wart in the centre.

Identification: Similar species and call

It is very similar to Semon's Leaf-nosed Bat, Hipposideros semoni, but is smaller. The supplied Queensland guidance states that the distributions do not overlap, which assists identification in the field. H. semoni has a forearm length of about 42 to 50 mm and larger wart-like projections on the noseleaf.

The call consists of high frequency constant frequency pulses at 102 to 106 kHz. Pulses are 10 to 20 milliseconds long, low intensity and finish with a brief downward frequency modulated sweep. The call is reported to be distinguishable from other microbats within its range.

Echolocation frequency: 102 to 106 kHz

Pulse duration: 10 to 20 milliseconds

Identification: Field detection

Flight is slow and fluttery, with frequent changes in direction. The bat usually flies close to vegetation and has been recorded flying within 1 m of the ground. It may be detected with a high frequency bat detector, particularly along gullies, gorges, scarps, creeks and waterholes.

There are no species-specific tracks, scats, nests or sloughs described in the supplied documents. Eyeshine is not reported. Roost searches should focus on small caves, shallow overhangs, sandstone splits, boulder piles and cliff fissures, including features that could be missed during a general site inspection.

  • Use acoustic recordings to confirm suspected records where possible.
  • Begin active transects at dusk and continue for at least 2 hours.
  • Record GPS tracks and survey effort for each transect.
  • Use only trained and vaccinated personnel for capture and handling.

Distribution: States and bioregional areas

The species is endemic to Australia and has a broad but discontinuous northern distribution. Records are sparse, and the Queensland population is geographically separated from the main Northern Territory and Western Australian records.

The species occurs in north-eastern Western Australia, the northern Northern Territory and north-western Queensland. In Queensland, the only supplied records are from the Mt Isa region.

The Western Australian range includes the Kimberley. The Northern Territory range extends across the Top End. The Queensland records may represent an outlying population because the next closest known records are in the Northern Territory.

Queensland: Mt Isa region

Northern Territory: Top End

Western Australia: North-east Western Australia, including the Kimberley

Distribution: Population information

The species is recorded at low densities and is thought to be genuinely rare. Modelling suggests small, restricted and isolated populations across its range.

Population size and population trends are unknown. The available assessment states that the population is probably not greatly fragmented and is not declining markedly, but the Queensland listing remains Vulnerable.

Estimated population size: Unknown

Population trend: Unknown; one assessment reports no marked decline

Known roost group size: 6 to 12 bats in small maternity colonies

Distribution: Project implications

A lack of records should not be treated as evidence that the species is absent. Small, shallow roosts and splits in sandstone cliffs can be overlooked, and the species has low density and limited survey information.

For projects in the Mt Isa region, the potential for an isolated Queensland population means that rocky outcrops, escarpments, gorges, boulder piles, caves, mines, creeks and waterholes should be assessed before clearing.

Habitat: Vegetation communities

The Narrow-eared Roundleaf Bat uses a wide range of northern Australian habitats but is strongly associated with rocky country and nearby water. It appears to select sites that provide both suitable low-humidity roosts and low, manoeuvrable flight paths near vegetation.

Records come from monsoon thickets, tall open forest, open eucalypt woodland, floodplains, open grassland and spinifex hills.

Recorded eucalypt communities include Darwin woollybutt, Eucalyptus miniata, Darwin box, Eucalyptus tectifica, Darwin stringybark, Eucalyptus tetradonta, and round-leaved bloodwood, Eucalyptus latifolia, with grassland or shrubland understoreys.

In the Kimberley, records include creeks and pools fringed by broad-leaved paperbarks, Melaleuca leucadendra and Melaleuca argentea, Pandanus species and rock fig, Ficus platypoda.

Habitat: Key structural features

The species is closely associated with steep hills, rocky outcrops, escarpments, gorges and waterholes. Creeks and pools may provide important flight and feeding routes.

Suitable sites can contain sandstone or limestone caves, cliff splits, boulder piles, shallow overhangs and disused mines. Roosts are generally near cave entrances, within 50 m.

Typical roost distance from entrance: Less than 50 m

Recorded elevation range: Unknown

Habitat: Climate and survey conditions

The supplied documents do not define a specific elevation limit or climatic boundary. Survey guidance recommends warm, calm and dry nights where possible, although this is a survey condition rather than a confirmed habitat requirement.

Foraging habitat: Diet and feeding method

This is an insectivorous bat that hunts flying insects close to vegetation. Its slow, highly manoeuvrable flight allows it to use cluttered edges, woodland and open country.

The diet consists mainly of flying insects. No particular insect taxa are identified in the supplied documents.

The bat forages in woodland and on open, hilly plains. Flight is slow and fluttery, with frequent changes in direction, usually close to vegetation and sometimes within 1 m of the ground.

Foraging habitat: Foraging features

Suitable foraging areas include open eucalypt woodland, tall open forest, monsoon thickets, floodplains, open grassland and spinifex hills. Creeks and pools with fringing vegetation are also relevant, particularly where they connect to rocky roosting habitat.

The supplied documents do not provide a measured foraging range or home range. Because roosts are concentrated at localised sites and the species forages through a range of vegetation communities, clearing should retain connected vegetation around rocky roosts, waterholes, creek lines and other likely flight paths.

Measured foraging range: Not reported

Typical flight height noted in survey guidance: Within 1 m of the ground in some observations

Breeding habitat: Breeding biology

Breeding occurs in small maternity colonies in suitable low-humidity roosts. Roost disturbance during the breeding period can harm pregnant, lactating or newly volant bats.

Breeding and birth period: Females give birth between October and January; Queensland guidance treats October to February as the breeding season

Young per birth: One young

Gestation: Not reported

Age at maturity: Not reported

Lifespan: Not reported

Maternity group size: Usually 6 to 12 bats

Breeding habitat: Maternity habitat

Maternity colonies use sandstone and limestone caves, boulder caves, cliff fissures, shallow overhangs and disused mines. Roosts are generally close to the entrance and have low humidity.

Individuals may roost alone or in well separated pairs outside the maternity period. Potential maternity sites should be checked before rock removal, blasting, mine rehabilitation, access track construction or works near cave and cliff entrances.

  • Avoid entering occupied caves or mines during the day.
  • Keep people and equipment away from occupied roost entrances during breeding works.
  • Do not remove rubble, rock or other material from a potential roost to improve access or search efficiency.

Sheltering habitat: Roost types

The species roosts in small rocky features and disused mines, usually in dry, low-humidity areas near the entrance. Roosts may be difficult to detect during standard fauna inspections.

Known or potential roosts include sandstone and limestone caves, abandoned or disused mines, boulder caves, boulder piles, shallow overhangs, splits in sandstone cliffs and other rock fissures.

Many roosts are small and shallow. Individuals may roost alone or in well separated pairs, while maternity colonies contain 6 to 12 bats.

Roost microclimate: Low humidity

Typical position within a roost: Close to the entrance, less than 50 m

Maternity colony size: 6 to 12 individuals

Sheltering habitat: Site inspection and protection

Before clearing, inspect project areas for caves, mines, rock fissures, gullies, boulder piles and cliff lines. Ground searches may require several hours per day because small overhangs and sandstone splits can be overlooked.

Do not enter a cave or mine known to be occupied during the day. Keep entry numbers low and work quietly at roost entrances. Do not remove rubble or other material from a roost.

  • Map all rocky roost features and retain them where practicable.
  • Check potential roosts before blasting, excavation, rock removal, mine closure or changes to access.
  • Use an experienced bat ecologist for any inspection or handling at a suspected roost.

Threats: Clearing and construction

The main project risks are loss or disturbance of small roosts, removal of rocky habitat and degradation of connected foraging areas. The species is naturally rare or occurs at low density, so local impacts may be difficult to detect through routine monitoring.

Destruction and disturbance of roosts are identified threats. Clearing or excavation can remove shallow overhangs, sandstone splits, boulder piles, cave entrances and disused mines that may function as day roosts or maternity sites.

Habitat loss and degradation may affect open woodland, forest, floodplain, grassland, spinifex hills, creek lines and waterholes used for foraging. Fragmentation may reduce connections between rocky roosts and nearby feeding areas.

  • Search and map rocky roost features before vegetation clearing and earthworks.
  • Avoid blasting, rock breaking and heavy vehicle activity near occupied or potentially occupied roosts.
  • Retain vegetation around creeks, pools, waterholes, gullies, escarpments and rocky outcrops.

Threats: Predators and disease

Predation by feral cats has been reported as a threat. The supplied documents do not provide a measured level of predation or a project-specific control threshold.

Australian bat lyssavirus is a handling risk for people working with bats. Only fully vaccinated and appropriately trained personnel should handle captured bats.

  • Do not leave harp traps or mist nets unattended.
  • Check traps regularly, particularly in warm conditions, near midnight and before dawn.
  • Release bats close to the capture point while it is dark, after allowing torpid bats to warm before release.

Threats: Fire, roads and hydrology

The supplied species accounts do not identify fire, roads or hydrology change as separately measured threats. These pressures should nevertheless be assessed where they remove roost rock, alter creek and pool vegetation, increase access to roosts or reduce insect-rich foraging habitat.

No species-specific response to fire, road mortality or altered water levels is provided. Project assessments should focus on direct loss or disturbance of roosts and on changes to vegetation and water features used for flight and feeding.

Survey methodology: 1. Acoustic detection and spotlighting

Survey this species in rocky areas, caves, mines, creek lines and waterholes, especially near steep hills, escarpments and boulder piles. Use more than one method because the species is naturally rare, occurs at low densities and has no published detection probability.

Walk transects from dusk for at least two hours on each survey night. Focus on gullies, gorges and scarps with caves, creek lines, pools and vegetation near rocky habitat.

Use a bat detector with high sensitivity, greater than 9 for an Anabat, where applicable. Other detectors with a higher frequency response may improve detection.

Identify calls in the 102 to 106 kHz range. The calls are high-frequency, long-duration CF pulses with a brief downward FM sweep and are distinguishable from other microbats in the species’ range.

Use a spotlight while walking. Look for slow, fluttery flight with frequent changes of direction, usually within one metre of the ground or close to vegetation.

Keep GPS tracks and record the detector settings, survey start and finish times, weather, habitat, call files and any visual observations.

Minimum effort: 16 detector hours per 100 hectares over at least 4 nights

Preferred conditions: Warm, calm and dry nights within the survey period

Survey methodology: 2. Harp traps and mist nets

Set multibank harp traps with 3 to 5 banks where capture is appropriate. Position traps beside or over water, along escarpments, beside creek lines with riparian vegetation, through dense vegetation gaps and among boulder piles.

Cover vegetation gaps around harp traps where practicable, because this species flies close to vegetation.

Use mist nets only with trained and competent personnel. Do not place nets across cave or mine entrances unless the number of bats inside is known and is not large.

Monitor nets constantly and close them when unattended. Remove bats quickly and gently, and stop trapping if catches exceed the team’s safe handling capacity.

Minimum effort: 8 trap nights per 100 hectares over at least 4 nights for harp traps

Minimum effort: 8 mist net hours per 100 hectares over at least 4 nights

Survey methodology: 3. Roost searches

Before fieldwork, identify mapped caves and mines and check known roosts for evidence of use.

Search for additional caves, rock fissures, gullies, boulder piles and cliff lines. Small, shallow overhangs and splits in sandstone cliffs can be easily overlooked.

Inspect potential roosts from the ground where possible. Do not enter occupied caves or mines during the day, and keep people and noise at the entrance to a minimum.

Prioritise low-humidity roosts close to entrances, generally within 50 metres. The species may roost alone, in separated pairs or in small maternity colonies of 6 to 12 bats.

Minimum effort: 2 hours of roost searches per survey day

Known roost types: Sandstone and limestone caves, abandoned mines, crevices and boulder caves

Survey methodology: 4. Timing, breeding and verification

The guidelines do not identify a best season for detecting this species, so survey during the project’s suitable survey period and use warm, calm and dry nights where possible.

Apply additional care from October to February, when females may be pregnant, carrying young or nursing crèched young. Avoid methods that could cause abandonment or dislodgement of young.

Use recorded calls for independent verification. Retain call files, detector outputs, photographs, capture details and precise locations with the project records.

If a suspected record is obtained, seek confirmation from a suitably experienced bat ecologist before relying on the record for impact decisions.

Breeding information: Females give birth to a single young between October and January, and maternity colonies occur

Roosting distance from entrances: Usually less than 50 metres

Survey methodology: Minimum effort and reporting

  • Apply the stated effort per 100 hectares, increase the survey area or effort where habitat is fragmented or access is limited, and document any shortfall.
  • Use a combination of acoustic monitoring, spotlighting, capture methods and roost searches rather than relying on one method.
  • Record the survey area, number of nights, detector hours, trap nights, mist net hours, roost-search hours, weather, habitat, personnel, equipment settings and results.
  • Submit confirmed records and negative survey results to the relevant Queensland or other state wildlife database, and provide call files and location data in the format requested by the database manager.
  • Report any suspected occupied roost, maternity colony or injury to the project ecologist and the relevant state wildlife authority before disturbance proceeds.

Before habitat disturbance: Avoid and minimise

Treat rocky roosts and nearby foraging habitat as potentially occupied even when no bats are seen during a single visit. The species is listed as Vulnerable in Queensland and has a small, restricted and potentially isolated distribution in the state.

  • Retain sandstone and limestone caves, abandoned mines, rock fissures, boulder piles, shallow overhangs, cliff lines, gullies, escarpments, creek lines and waterholes wherever practicable.
  • Avoid disturbance to roosts, particularly low-humidity roosts close to cave entrances and roosts within 50 metres of an entrance.
  • Establish project-specific no-go areas around confirmed and potential roosts, with boundaries marked on plans and on the ground before clearing starts.
  • Retain connected movement and foraging habitat around rocky features, including open eucalypt woodland, tall open forest, monsoon thickets, floodplains, open grassland and spinifex hills.
  • Do not enter or modify a cave, mine, fissure or boulder cave to improve access or survey effectiveness.

Before habitat disturbance: Approvals and work planning

  • Confirm the species status and approval requirements for each state or territory before works begin; in Queensland, check the requirements applying to its Vulnerable status under the Nature Conservation Act 1992.
  • Check whether the proposal triggers any Commonwealth approval or EPBC Act referral requirement, noting that this species is not listed under the EPBC Act in the supplied species information.
  • Prepare a fauna management plan that identifies potential roosts, retained habitat, survey results, exclusion areas, clearing limits, fauna handling arrangements, stop-work triggers and reporting responsibilities.
  • Stage clearing so that retained roosts and nearby foraging habitat remain available while works are assessed and completed in sections.
  • Schedule disturbance outside October to February where practicable. If this cannot be achieved, obtain species-specific advice and apply the breeding-season handling controls in the fauna management plan.

Before habitat disturbance: Site preparation

  • Complete the targeted survey before finalising the clearing footprint, using the recommended methods and effort for the project area.
  • Mark caves, mines, fissures, boulder piles, cliff lines, creek lines, pools and other retained habitat on construction drawings and with visible field markers.
  • Fence or otherwise protect exclusion areas where machinery, personnel or materials could enter a roost or its approach, provided fencing will not block bat movement.
  • Brief machinery operators, supervisors and fauna spotter catchers on the species’ appearance, call frequency, roost types, breeding period, handling limits and stop-work procedure.
  • Check all proposed access tracks, laydown areas, spoil areas, blasting zones and lighting locations for potential effects on roost entrances and flight paths.

During habitat disturbance: Daily controls and machinery coordination

Keep machinery away from retained rocky habitat and potential roosts. A fauna spotter catcher should work under the project fauna management plan and have authority to pause work when an animal, roost or unexpected habitat feature is found.

  • Inspect exclusion fencing, signs and marked habitat before each shift and repair or reinstate controls immediately if they are damaged.
  • Keep machinery, spoil, fuels, lighting and personnel outside marked roost and habitat exclusion areas.
  • Use a fauna spotter catcher during clearing near caves, mines, boulder piles, fissures, cliff lines, creek lines and pools, with clear communication between the spotter, operator and supervisor.
  • Clear in short sections and stop machinery whenever the spotter cannot see the work area or when dust, darkness, noise or unstable rocks prevents safe inspection.
  • Do not remove rubble, alter cave entrances, block corridors or damage rock features during searches or construction.

During habitat disturbance: Animal finds and handling

  • Stop the immediate activity if a bat is found, keep people and machinery back, and notify the fauna spotter catcher and project ecologist.
  • Only fully vaccinated, trained and authorised personnel may handle the bat. Apply Australian bat lyssavirus precautions and do not allow untrained workers to touch it.
  • Avoid handling during October to February unless it is necessary for the bat’s welfare or an authorised wildlife response.
  • Place a captured bat in a dry calico bag, one bat per bag, keep the bag off the ground, and do not retain the bat for more than one hour without specialist care.
  • Release a healthy bat close to its capture point while it is dark. If it has entered torpor, allow it to warm before release.
  • Obtain veterinary or authorised wildlife carer assistance for an injured, weak, dehydrated or otherwise compromised bat, and transport it only under the approved fauna procedure.

During habitat disturbance: Habitat features and stop-work triggers

  • Stop work and reassess if a bat, maternity group, occupied roost, previously unknown cave, mine, fissure, boulder cave, cliff feature or other potential roost is discovered.
  • Do not move rocks, boulders, rubble or other roost material unless the project ecologist and relevant authority have approved the action and a qualified fauna response is in place.
  • Keep creek lines, pools and waterholes clear of sediment, spoil, fuel and construction waste where they are retained as foraging or capture habitat.
  • Stop trapping immediately if bats cannot be checked safely, if weather conditions create a welfare risk, or if more animals are caught than the team can process safely.
  • Resume work only after the ecologist has inspected the location, documented the finding and confirmed the revised controls.

During habitat disturbance: Records and reporting

  • Record each fauna interaction, including date, time, exact location, activity, habitat feature, species identification, condition, photographs, call files, handling and release details.
  • Record all stop-work events, changed exclusion boundaries, injured animals, relocations, roost findings and interactions with authorities or wildlife carers.
  • Report a confirmed roost, maternity colony or unexpected concentration of bats to the project environmental officer and relevant state wildlife authority before the feature is disturbed.
  • Maintain daily clearance records signed by the fauna spotter catcher, machine operator and site supervisor.

After habitat disturbance: Post-clearance checks

Post-clearance work must check that retained roosts and foraging features remain usable and that controls have not failed. The recovery plan links management success with follow-up surveys and stable or increasing populations at managed sites.

  • Inspect the cleared edge, retained caves, mines, fissures, boulder piles, cliff lines, creek lines and pools for damage, blocked entrances, rubble movement, erosion, sediment or unauthorised access.
  • Complete a fauna spotter catcher check of machinery, stockpiles, trenches and temporary structures before demobilisation from each work area.
  • Confirm that exclusion fencing, signs and no-go boundaries remain intact after heavy rain, earthworks and vehicle movement.
  • If a roost has been disturbed or a bat is found after clearing, stop the relevant activity and repeat the authorised fauna response and reporting process.

After habitat disturbance: Monitoring and reporting

  • Repeat acoustic monitoring, spotlighting, capture or roost inspections where the project has affected a known or potential roost, using the same methods and effort where practicable so results can be compared.
  • Monitor priority sites for evidence of continued use, including bat presence, maternity use, damaged entrances and changes to the roost microclimate.
  • Use follow-up surveys to assess whether populations at managed sites are stable or increasing, as specified by the recovery criteria.
  • Provide the landholder, regulator and relevant wildlife database with confirmed records, survey data, incident reports, rehabilitation results and any required compliance reports.

After habitat disturbance: Ongoing controls and offsets

  • Keep retained habitat protection, access controls and roost exclusion measures in place for the duration of the project and any required monitoring period.
  • Repair impacts to roost entrances, rocky features, creek lines and pools promptly where this can be done without entering or modifying an occupied roost.
  • If residual impacts remain after avoidance and mitigation, obtain advice on any legally required offset or conservation measure and ensure it protects habitat relevant to this species.
  • Do not treat an offset as a substitute for retaining occupied or potential roosts on the project site.

Rehabilitation actions: Restore habitat features

Rehabilitation should restore the rocky roost and near-roost foraging conditions used by the northern leaf-nosed bat. The supplied documents provide habitat and species information but do not prescribe a planting list, fire regime, nest-box design or rehabilitation success thresholds.

  • Retain and stabilise sandstone and limestone caves, boulder piles, rock fissures, cliff lines, gullies, escarpments and shallow overhangs rather than reshaping them for convenience.
  • Keep roost entrances open and preserve the low-humidity conditions and near-entrance roost locations preferred by the species.
  • Reinstate natural drainage to creek lines, pools and waterholes and prevent sediment, rubbish, lighting and vehicle access from affecting retained features.
  • Do not install nest boxes as a substitute for natural caves or mines unless a bat ecologist and the relevant authority approve a site-specific design and monitoring program.

Rehabilitation actions: Revegetate foraging areas

  • Restore open eucalypt woodland, tall open forest, monsoon thickets, floodplain vegetation, open grassland and spinifex hill habitat where those communities occur naturally at the site.
  • Use local provenance plants suited to the pre-disturbance community, including locally appropriate eucalypts, Melaleuca, Pandanus and Ficus where they are part of the site’s recorded habitat.
  • Maintain vegetation close to retained rocky features, creek lines and pools because the species forages slowly and close to vegetation.
  • Control weeds and prevent new access tracks from fragmenting retained rocky and riparian habitat, using the site’s approved rehabilitation methods.

Rehabilitation actions: Predators, fire and monitoring

  • Assess feral cat activity during rehabilitation and apply approved predator control where it is identified as a risk to the species.
  • Set fire management actions with the land manager so that fire does not damage retained roost entrances, boulder piles, riparian vegetation or regenerating foraging habitat.
  • Monitor rehabilitated areas for roost integrity, vegetation establishment, water quality, access damage and bat activity using acoustic surveys, spotlighting and roost checks where appropriate.
  • Use project-specific success measures that include retained or restored roost features, functioning creek and pool habitat, suitable vegetation structure and stable or increasing bat activity at monitored sites.
  • Submit monitoring results and confirmed records to the relevant state wildlife database and update the fauna management plan if the species is not detected or habitat controls fail.

Sources