Northern Free-tailed Bat (Ozimops lumsdenae)

Conservation status

New South Wales, Biodiversity Conservation Act 2016: Vulnerable.

Breeding season

The species breeds during the tropical wet season, with births reported during Southern Hemisphere summer. Exact state-specific breeding dates, gestation and dispersal periods are not provided, so the calendar below uses a broad wet-season pattern rather than a precise state-wide schedule.

Confirm local wet-season timing and roost occupancy before clearing. The supplied documents do not provide exact mating dates, gestation length, weaning age or state-specific breeding calendars.

• Breeding: Females give birth throughout the tropical wet season, described as Southern Hemisphere summer. December to February are marked as the likely peak part of that period, with November and March treated as possible wet-season months rather than confirmed universal dates.
• Young: Single young are born during the wet season. Dependent young are therefore most likely during the summer wet-season period, but the duration of dependency is not provided.
• Roost use: The species is nocturnal and emerges from tree roosts after dark. Tree hollows, caves and buildings may be used throughout the year.
• Movement and foraging: No migration pattern is documented. Individuals forage at night across open airspace above vegetation and watercourses, and may move between roosts and feeding areas throughout the year.
• Highest clearing risk: Clearing and roost disturbance are most likely to harm the species during the wet-season birth and dependent-young period. December to February are marked as peak risk, but local wet-season timing varies across northern Australia.

Identification

The Northern Free-tailed Bat is a large, heavy-set free-tailed bat with brown to greyish-brown fur and a paler underside. It is substantially larger than other Australian Ozimops species and is most reliably identified by a combination of body size, triangular ears and acoustic or genetic confirmation.

Adults have a head and body length of 59 to 68 mm, a tail length of 33 to 38 mm, ears 12 to 17 mm long and a forearm length of 35 to 41 mm.

The fur is brown to greyish brown above and lighter below. The species has a large, sturdy skull and a heavy build compared with other Australian Ozimops species.

Weight: 11 to 19 g.

Echolocation: Peak frequency is about 24 kHz.

Identification: Sex and similar species

Females have a long clitoral projection. Males have a relatively small penis, about 4 mm long, with a cylindrical glans and a large bulbous bacular mound.

The triangular ears help separate this species from the White-striped Free-tailed Bat, Austronomus australis, and the Greater Northern Free-tailed Bat, Chaerephon jobensis, which have rounded ears.

The Northern Free-tailed Bat is much larger than other Australian Ozimops species. Definitive separation from similar free-tailed bats may require measurements, echolocation analysis or genetic testing.

Identification: Field signs and detection

The most useful field sign is an acoustic detector record with a call consistent with the species, although call overlap can make species-level identification uncertain.

The species is nocturnal and usually emerges from tree roosts after dark. It flies at high speed, reported at 32 to 35 km/h, and has limited manoeuvrability compared with more agile microbats.

No reliable information is provided on diagnostic tracks, scats, nests, sloughs or eyeshine. Scat searches and visual searches should therefore be treated as supplementary to targeted acoustic and roost inspections.

Typical emergence: After dark.

Flight speed: About 32 to 35 km/h.

Distribution: National range

The species has a broad northern Australian range, following the coast in a wide arc and extending inland into semi-arid areas. Records in New South Wales are limited compared with the northern part of the range.

The range extends from the Pilbara region of Western Australia through the Northern Territory and across most of Queensland to the north-eastern corner of New South Wales.

The species is associated with northern coastal and subcoastal areas but can occur inland. Published accounts place the inland limit at about 600 to 700 km from the coast.

For New South Wales, the available material describes little distributional information. The only confirmed state record cited is a colony in the roof of a house at Murwillumbah, with additional call detections from a few locations in far northern New South Wales.

States and territories: Western Australia, Northern Territory, Queensland and north-eastern New South Wales.

Inland extent: About 600 to 700 km inland, depending on the published account.

New South Wales evidence: One confirmed colony record at Murwillumbah and call detections from a few other far northern locations are cited.

Distribution: Subpopulations and trend

No named strongholds, discrete subpopulations or population estimates are provided in the supplied documents.

The species is described as regularly recorded across its range, with a high estimated number of mature individuals and a large area of occupancy in the IUCN account reproduced in the source material.

Population trends are not known. The species may be declining in areas affected by continuing clearance and degradation of native vegetation.

Population size: No numerical population estimate is provided.

Population trend: Unknown, with possible declines where native vegetation is cleared or degraded.

Conservation status in supplied material: IUCN Least Concern; not listed under the EPBC Act; Vulnerable in New South Wales.

Habitat: Vegetation communities

The Northern Free-tailed Bat uses a wide range of tropical and subtropical habitats. It is recorded from both dense vegetation and open woodland, with watercourses and mature trees important at some sites.

Documented habitats include rainforest, riverine floodplains, paperbark and pandanus wetlands, eucalypt woodland and savanna, and watercourses lined with river red gum.

In semi-arid and desert areas, the species is associated with watercourses and permanent water. It can also occur in towns and cities where suitable roosts are available.

The species occurs across a broad rainfall gradient, from about 200 to 1500 mm per year.

Recorded habitat types: Rainforest, riverine floodplain, paperbark and pandanus wetland, eucalypt woodland, savanna and river red gum watercourses.

Annual rainfall range: About 200 to 1500 mm.

Habitat: Structural features

Old trees with suitable hollows provide important day-roosting opportunities. Buildings and caves can also provide roosts, including in developed areas.

Watercourses, wetlands and permanent water may support habitat use, particularly in semi-arid parts of the range.

Retain hollow-bearing trees, riparian vegetation, mature river red gums and connected woodland where practicable during site planning and clearing.

Habitat: Climate and elevation

The supplied documents describe a broad tropical and subtropical distribution and do not provide a defined elevation limit.

The species occurs across wet, seasonal and semi-arid environments, including areas with annual rainfall from about 200 to 1500 mm.

Elevation limit: Not provided in the supplied documents.

Foraging habitat: Diet

The Northern Free-tailed Bat is an aerial insectivore that usually hunts in open airspace above vegetation. Its fast, direct flight is suited to open areas, and it may also take insects from tree trunks or the ground.

Beetles and moths have been identified in stomach contents. The species is presumed to take other flying insects while airborne.

The Northern Free-tailed Bat has also been observed scurrying after insects on the ground and is reported to take prey from tree trunks.

Recorded prey: Beetles and moths.

Feeding mode: Mainly aerial capture of flying insects, with some prey taken from the ground or tree trunks.

Foraging habitat: Foraging places and flight

The species hunts above the canopy and uses open airspace over woodland, savanna, floodplains and watercourses.

Its reported flight speed is 32 to 35 km/h, but it generally has limited manoeuvrability. Retain open flight paths over retained vegetation and watercourses where possible.

No foraging range or nightly travel distance is provided in the supplied documents.

Foraging height: Above the canopy is reported in the species account; a separate New South Wales profile records the species in surveys flying below 15 m at one project site.

Foraging range: No numerical foraging range is provided.

Breeding habitat: Breeding biology

Breeding is seasonal in the tropics and is linked to the wet season. The species requires secure roosts near suitable foraging habitat, but detailed maternity-roost requirements are not provided.

Females give birth to one young during the tropical wet season, which occurs during Southern Hemisphere summer.

The supplied documents do not provide a gestation period, age at sexual maturity or lifespan. They also do not describe a specific maternity-roost structure or colony size for this species.

Breeding season: Tropical wet season, generally Southern Hemisphere summer.

Litter size: One young.

Gestation: Not provided.

Age at maturity: Not provided.

Lifespan: Not provided.

Breeding habitat: Breeding habitat

Potential breeding habitat includes old hollow-bearing trees, caves and buildings that can support day roosts and colonies.

Retain occupied or potentially occupied roosts and avoid clearing mature hollow-bearing trees during the wet-season birth and dependent-young period unless a qualified ecologist has assessed the risk and any approved controls are in place.

Sheltering habitat: Roost types

The species roosts during the day in tree hollows and can also use caves and buildings. Roosts may occur in natural vegetation, rural structures and urban areas.

The main recorded roost type is a hollow in an old tree. Caves and buildings are also used, including house roofs and other structures in developed areas.

The species can form small groups of up to 50 individuals in roosts. The New South Wales profile also notes that buildings may support large colonies.

Recorded roosts: Old tree hollows, caves and buildings.

Roost group size: Small groups of up to 50 individuals are reported; larger colonies may occur in buildings.

Confirmed New South Wales roost: A colony was found in the roof of a house at Murwillumbah.

Sheltering habitat: Site controls

Before clearing, inspect old trees, dead limbs, buildings, roofs and accessible caves for bats, roost staining, guano and entry points.

Do not assume that an apparently empty hollow or building is unused because this nocturnal species may be absent during a daytime inspection. Use acoustic monitoring, emergence observation or other targeted assessment where a potential roost may be affected.

Retain hollow-bearing trees, connected vegetation and nearby watercourses where practicable. If a building or tree roost must be removed, obtain species-specific advice on timing, exclusion and replacement roost measures.

Threats: Clearing and fragmentation

The best documented threats are loss and degradation of native vegetation, including clearing for agriculture, mining and urban expansion, and altered fire regimes. Infrastructure projects should also manage direct disturbance to roosts and changes to water-associated habitat.

Continued habitat loss through agricultural, mining and urban clearing is identified as a threat, particularly in Queensland.

Clearing old trees can remove hollows used for daytime shelter and breeding. Clearing riparian vegetation, wetlands and river red gum corridors can reduce habitat used for roosting and foraging.

Keep clearing footprints narrow, retain hollow-bearing trees and maintain links between roosts, watercourses and feeding habitat where practicable.

Threats: Fire and hydrology

Changes in fire regimes across the range are identified as a potential cause of decline.

The species uses riverine floodplains, wetlands, watercourses and permanent water in some parts of its range. Drainage alteration, loss of wetland vegetation or changes to watercourse condition may therefore reduce habitat, although a species-specific hydrology impact threshold is not provided.

Threats: Infrastructure and operational risks

Windfarm monitoring recorded 40 positively identified calls at one project, but the assessment considered collision with turbine blades or towers unlikely because the species was recorded below the rotor-swept area at that site.

The same assessment noted that bat flight height can vary between species and that local impacts can still occur. Maintain records of bat activity, carcass searches and fauna interactions during construction and operation.

Road mortality, predation and disease are not identified as significant species-specific threats in the supplied documents. Feral cats and European Red Foxes are recognised as general threats to native fauna, but the project assessment states that microbats are generally not vulnerable to them.

Project call record: 40 positively identified Northern Free-tailed Bat calls across two surveys at one windfarm project, 30 in May and 10 in September.

Collision assessment at that project: Unlikely, because recorded flight was below the rotor-swept area at that site.

Threats: Roost disturbance

Disturbance or removal of occupied tree hollows, caves and buildings can affect sheltering and breeding habitat.

Schedule inspections and exclusion works outside the wet-season birth period where possible. Use a fauna spotter catcher and a documented response procedure if bats are found during clearing or demolition.

Survey methodology: 1. Desktop review and habitat inspection

Survey this bat as a nocturnal, fast-flying species associated with old tree hollows, caves, buildings, watercourses and a wide range of northern Australian vegetation. Detection is most likely through ultrasonic call recording and targeted searches around likely roost and watercourse habitat.

Review recent records, aerial imagery, vegetation mapping, previous acoustic data and proposed clearing before field work begins.

Map old trees with hollows, caves, buildings, watercourses, permanent water, river red gum areas, wetlands, rainforest, paperbark and pandanus vegetation, open woodland and savanna within and near the disturbance area.

Treat towns, cities, mine areas and infrastructure with suitable roost structures as potential habitat because the species can roost in buildings and occurs in human-dominated areas.

Search for records under Ozimops lumsdenae and the former name Mormopterus lumsdenae, and check whether calls may have been reported only as Ozimops sp.

Survey methodology: 2. Ultrasonic acoustic survey

Deploy full-spectrum or suitable diagnostic ultrasonic detectors along watercourses, near old hollow-bearing trees, around caves or buildings, and at the edge of open woodland and rainforest.

Record throughout the night, including the period after emergence and the hours before dawn, because the species is nocturnal and emerges from tree roosts after dark.

Use call analysis that can distinguish Ozimops lumsdenae from other free-tailed bats, particularly Chaerephon jobensis, other Ozimops species and Taphozous species.

The species has a relatively low echolocation peak frequency of about 24 kHz, so confirm that the detector and analysis settings can record and assess calls in this range.

Record weather, detector location, start and finish times, habitat, water availability and call identification confidence for every deployment.

Reported call frequency: Peak frequency about 24 kHz

Documented project effort: Two survey periods, May and September, across four impact and four control sites, with 40 positively identified calls

Survey methodology: 3. Roost and emergence searches

Inspect hollow-bearing trees, caves, roof spaces, buildings and other structures that could support a colony before clearing or demolition.

Undertake emergence observations from before sunset until activity has clearly declined, with acoustic detectors operating at the suspected roost and along nearby flight paths.

Use daylight inspection only where it can be completed safely and lawfully, and do not enter caves, roof spaces or confined structures without a suitable risk assessment and specialist approval.

Give priority to old trees and buildings near watercourses, because the species is reported from tree hollows, caves and buildings and is often associated with watercourses.

Known roost group size: Small groups of up to 50 individuals

Breeding period: Single young are born throughout the tropical wet season, during Southern Hemisphere summer

Survey methodology: 4. Spotlighting and flight-path searches

Spotlight watercourses, canopy edges, open forest, woodland clearings and areas above the canopy after dark, while keeping observers and vehicles clear of likely roost entrances.

Use spotlighting as a supplementary method because this fast-flying bat may pass quickly and may be difficult to identify visually.

Where safe, combine spotlighting with thermal imaging and ultrasonic recording to improve detection of bats flying above the canopy or along drainage lines.

Do not treat a lack of visual detections as evidence that the species is absent, particularly where acoustic records, suitable roosts or nearby watercourses are present.

Survey methodology: Minimum effort and reporting

• Use the current Australian and relevant state fauna survey guidance for the project region to set the number of survey nights, detector locations, survey seasons and repeat visits, because the supplied documents do not provide a species-specific minimum effort standard.
• Include at least one survey period that represents the local wet season where practicable, because breeding and births occur during the tropical wet season.
• Repeat surveys where the first visit is affected by rain, strong wind, low temperature, smoke, flood conditions, equipment failure or poor detector placement.
• Report detector make and settings, detector nights, survey dates, nightly hours, weather, habitat, roost inspections, call files, identification method, confidence level, negative results and all limitations.
• Submit verified records, including coordinates, date, observers, evidence and identification confidence, to the relevant state wildlife database and the Atlas of Living Australia where appropriate.
• Retain original call files and analysis outputs so records can be reviewed if the species is confused with another free-tailed bat.

Before habitat disturbance: 1. Avoid and minimise habitat loss

Plan around the species' use of old hollows, caves, buildings, watercourses and open flight paths. Avoid removing roosts and retain connected foraging habitat wherever practicable.

• Retain old hollow-bearing trees, dead trees with suitable cavities, caves, buildings used by bats and vegetation along watercourses.
• Avoid clearing rainforest, riverine vegetation, paperbark and pandanus wetlands, eucalypt woodland and savanna where these habitats provide roosting or foraging opportunities.
• Keep retained habitat connected to nearby watercourses, wetlands, tree roosts and known or suspected colonies.
• Keep machinery, access tracks, laydown areas, lighting and spoil outside retained roosts and watercourse vegetation wherever practicable.
• Do not remove a suspected roost tree or building until a suitably qualified ecologist has assessed it and the relevant approval and fauna management requirements have been met.

Before habitat disturbance: 2. Check approvals and set controls

• Check the current EPBC Act status, the current NSW listing and any other state or territory listing before works start, because the supplied documents contain inconsistent status information for this species.
• Obtain any required state fauna handling, relocation, scientific, clearing, cave, wildlife rehabilitation and tree removal approvals before a fauna spotter catcher begins work.
• Complete an EPBC Act referral check if the species is nationally listed or if the proposed action may affect a nationally listed species or its habitat.
• Prepare a fauna management plan that identifies survey results, no-go areas, roost controls, clearing sequence, fauna spotter catcher responsibilities, stop-work triggers, records and escalation contacts.
• Include the species in the project's bird and bat management plan where wind turbines, tall structures, night lighting or other infrastructure could affect flight paths.

Before habitat disturbance: 3. Stage the works and prepare the site

• Schedule tree, building and cave disturbance outside the local wet season where practicable, while avoiding the period when dependent young may be present.
• Stage clearing so retained vegetation, watercourses and nearby refuge habitat remain available while each work area is checked and cleared.
• Complete a pre-clearance survey shortly before disturbance, including a search for roosting bats, fresh guano, staining, calling, emergence activity and occupied hollows.
• Mark retained trees, caves, buildings, watercourses, exclusion zones, access routes and habitat features on the ground and in construction drawings.
• Install exclusion fencing only where it will not block bat flight paths, isolate water or trap animals, and inspect it regularly.
• Brief all operators on the species' appearance, likely roosts, reporting process and the requirement to stop work when a trigger is reached.

During habitat disturbance: 1. Daily clearing controls

Use a qualified fauna spotter catcher during all relevant clearing and demolition. The spotter catcher must have authority to stop machinery and must work in direct communication with the supervisor and operators.

• Hold a pre-start briefing each day covering the approved clearing boundary, no-go areas, weather, known roosts, fauna handling arrangements and stop-work contacts.
• Inspect the work area at first light and before clearing for bats, injured fauna, fallen hollow material, occupied buildings, fresh roost signs and changes to exclusion fencing.
• Clear progressively from the edge of the approved area towards retained habitat so mobile fauna can move away from machinery.
• Keep machinery outside marked hollow-bearing trees, caves, buildings, watercourses and retained vegetation unless the approved method specifically allows access.
• Stop clearing during unsafe weather, fire, flood, smoke or visibility conditions that prevent effective fauna observation.

During habitat disturbance: 2. Spotter catcher and machinery protocol

• Position the fauna spotter catcher where the operator can see and hear the stop signal before each tree, structure or habitat feature is disturbed.
• Use a staged approach for hollow-bearing trees and large dead trees: inspect, remove non-habitat branches where approved, pause, recheck hollows and only then proceed under the approved method.
• Use a suitably qualified person to inspect roof spaces, caves and confined structures, and do not direct workers to enter unsafe roost sites.
• Keep a clear escape route towards retained habitat and do not chase bats, block entrances or use smoke, water, noise or chemicals to force an animal out.
• Limit handling to authorised personnel using approved equipment and methods, and follow the relevant state permit conditions.

During habitat disturbance: 3. Habitat feature handling

• Retain hollow-bearing trees wherever practicable and leave felled hollow logs on site if they can be retained safely in suitable nearby habitat.
• Place salvaged hollow logs, dead timber and other approved roost features in retained vegetation near the original habitat, without blocking drainage or creating a public safety risk.
• Protect caves, rock crevices, buildings and bridges that may be used as roosts, and do not seal or illuminate entrances without an approved method and inspection.
• Protect watercourses and wet areas from sediment, fuel, concrete washout, rubbish, weeds and unnecessary night lighting.
• Do not assume that a tree or building is unoccupied because no bat is seen during a daylight inspection.

During habitat disturbance: 4. Animal response, stop work and records

Roost group size reported in the literature: Up to 50 individuals

Project acoustic record: 40 positively identified calls in the documented wind farm surveys

• Stop work immediately if a Northern Free-tailed Bat is found, if a suspected roost is identified, if dependent young are present, or if bats are injured, trapped or repeatedly flushed.
• Keep people, vehicles and machinery away from the animal and allow the spotter catcher to assess whether it can leave unaided.
• Do not capture, handle or relocate the bat unless the person is authorised and the action is permitted under the relevant state approval.
• If relocation is approved, place the bat in nearby retained habitat that provides shelter and connection to water or other suitable habitat, following the approved wildlife handling method.
• Take an injured or grounded bat to an appropriately experienced wildlife carer or veterinarian through the approved fauna rescue pathway, and do not attempt treatment on site.
• Record the date, time, location, habitat feature, action taken, handler, photographs, identification, condition, release location and outcome.
• Notify the project environmental officer and regulator where required by the approval, fauna management plan or permit.

After habitat disturbance: 1. Post-clearance checks

Post-clearance work must confirm that animals were not left in structures or isolated from retained habitat. Use monitoring results to adjust controls while construction and operation continue.

• Inspect cleared areas, felled trees, demolished buildings, stockpiles, trenches and exclusion fencing after each clearing stage.
• Check for grounded, trapped, injured or dead bats and escalate every record through the approved fauna incident process.
• Reinspect retained trees, caves, buildings and watercourse vegetation after vibration, blasting, major earthworks or other activities that could affect roost stability.
• Remove or cover trenches and other artificial pits at the end of each shift, or provide escape structures that are checked by the spotter catcher.

After habitat disturbance: 2. Monitoring and adaptive management

• Continue ultrasonic monitoring at retained watercourses, suspected roosts and project boundaries where construction, lighting, turbines or tall structures could change bat activity.
• Use the pre-construction survey locations and methods where practicable so activity can be compared over time.
• For wind farm or other tall infrastructure projects, maintain the bird and bat monitoring required by the approved management plan and review collision or barotrauma records.
• Investigate repeated bat activity near a hazardous work area, repeated roost disturbance, injured bats or unexpected mortality, and revise lighting, timing, access or work methods.

After habitat disturbance: 3. Reporting and ongoing controls

• Provide the project owner and regulator with clearing areas, dates, habitat features removed or retained, fauna interactions, injuries, mortalities, relocations, monitoring results and corrective actions.
• Maintain no-go markers, exclusion fencing, roost buffers, drainage protections and lighting controls until the responsible ecologist confirms they are no longer required.
• Update the fauna management plan when new roosts, records, mortality patterns or changes in activity are identified.
• Apply any required offsets, rehabilitation obligations, compensatory habitat measures or approval conditions for unavoidable impacts.

Rehabilitation actions: 1. Restore roosting and foraging habitat

Rehabilitation should restore roosting opportunities, connected foraging habitat and access to water. The species uses several tropical and subtropical vegetation types, so planting and habitat replacement must match the local vegetation community.

• Replant locally native rainforest, riverine, paperbark, pandanus, eucalypt woodland or savanna species that match the pre-clearing community and site hydrology.
• Prioritise revegetation along watercourses and around retained old trees, wetlands and other known or suspected roost areas.
• Retain naturally forming dead timber and place salvaged hollow logs in safe positions within retained habitat where this is allowed by the rehabilitation design.
• Install artificial hollows or bat boxes only where a qualified ecologist has shown that they are suitable for the local climate, species and maintenance arrangements.
• Do not remove natural hollows or mature trees solely because artificial boxes have been installed.

Rehabilitation actions: 2. Protect restored habitat

• Control weeds so planted and naturally regenerating vegetation can develop into suitable woodland, riverine or wetland habitat.
• Prevent feral animal access and manage predators in accordance with the approved fauna management plan, while recognising that the supplied documents identify invasive flora as a potential habitat pressure.
• Maintain natural drainage, watercourse vegetation and wet areas, and prevent sediment, chemicals and rubbish from entering them.
• Use fire planning that maintains the local vegetation community and avoids unnecessary loss of hollow-bearing trees, dead timber and roost structures.

Rehabilitation actions: 3. Measure success

• Monitor plant survival, weed cover, erosion, retained hollow trees, salvaged logs, artificial roost features, watercourse condition and connectivity to retained habitat.
• Use ultrasonic detectors and targeted emergence checks to test whether bats continue to use retained and rehabilitated areas, with survey timing and effort set under current regional guidance.
• Record occupied roosts, call identifications, injuries, mortalities and changes in activity, and submit verified records to the relevant state wildlife database.
• Set rehabilitation completion criteria in the management plan, including stable drainage, established native vegetation, functioning roost features, maintained access to retained habitat and no unresolved fauna hazards.

Sources

• Ozimops lumsdenae Reardon, McKenzie & Adams 2014, explore.openaire.eu: https://explore.openaire.eu/search/result?id=doi_dedup___::0111d74ae8e9ac8b9cd15169f0885456
• [PDF] Green tick = found in the Wellington region in 2024., NSW Government: https://landcare.nsw.gov.au/groups/mid-macquarie-landcare/mml-resources/sos_nsw_microbat_species_profiles_wellington_2024.pdf
• Part4of7 IR response EA supporting information - A-EA-AMD-100480009; Environmental Authority Amendment Application for MMG Dugald River Pty Ltd EPML00731213, Queensland Government: https://environment.desi.qld.gov.au/__data/assets/pdf_file/0026/346823/a-ea-amd-100480009-ir-response-ea-support-info-part4of7.pdf