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White-throated Grasswren (Amytornis woodwardi)

The white-throated grasswren is a small, shy, ground-dwelling bird endemic to rocky sandstone escarpments and plateaux of western Arnhem Land in the Northern Territory. It depends on mature spinifex, bare rock and boulder refuges, so clearing, access tracks, altered fire regimes and disturbance within occupied habitat can remove nesting cover and fragment small subpopulations on development sites.

Conservation status

Commonwealth, EPBC Act 1999: Vulnerable.

Northern Territory, Territory Parks and Wildlife Conservation Act 1976: Vulnerable.

Breeding season

The species is non-migratory in the supplied sources, with pairs maintained year-round and limited dispersal capacity. Breeding is concentrated in the northern wet season and can extend into the early dry season.

Seasonal timing is based on the documented breeding period. Field conditions, recent fire and local rainfall can alter breeding activity, so suitable habitat should be treated as potentially occupied outside the peak months.

  • Breeding: Breeding is reported from December to June, with the 2024 account describing typical breeding from December to April and possible extension to May or June. The peak months shown are December to April.
  • Young: Nests contain generally two eggs and are concealed close to the ground in mature spinifex. Dependent young are therefore most likely during the breeding period and shortly afterwards. The sources do not give an exact fledging or dependency period.
  • Highest clearing risk: Clearing and disturbance are most likely to harm the species from December to June because nests, eggs and dependent young may be present. Habitat loss is also a year-round risk because mature spinifex, refuges and territories are limited.

Identification

This is a secretive, fast-moving grasswren that is more often detected by its call or brief movement through spinifex than by a clear view. Identification should combine plumage, habitat and vocalisations, particularly because the species can resemble the Carpentarian grasswren.

The white-throated grasswren is robust and long-tailed. The head and upperparts are black with bold white streaks, the back and rump are chestnut, the wings and tail are black with chestnut edges, and the throat and upper breast are white. The lower breast has a black area with white streaking, forming a noticeable breastband. The tail is often held upright or half-upright when the bird is stationary, but is lowered when it moves.

Length: Approximately 20 to 22 cm.

Typical group size: Usually singly, in pairs or in small family groups. Groups of 3 to 6 birds have been reported.

  • Expect a shy, ground-dwelling bird that darts between spinifex clumps, rocks and boulders.
  • The species is noticeably larger than the common red-backed fairy-wren.
  • The published adult length is approximately 20 to 22 cm. No reliable weight is given in the supplied sources.

Identification: Sex and similar species

Males have a black whisker mark and rusty underparts. Females are brighter, with white lores and diagnostic dark rusty underparts. The Carpentarian grasswren is smaller, has less black, red-brown wings and no breastband, and occurs in the eastern Northern Territory and Queensland rather than the white-throated grasswren range.

  • Use the white throat, strongly streaked black head and upperparts, chestnut rump and breastband together rather than relying on one feature.
  • A bird seen in western Arnhem Land sandstone spinifex is more likely to be a white-throated grasswren than a Carpentarian grasswren, but location alone should not replace a full identification.

Identification: Calls and field signs

The song is a series of rising and falling trills and notes. Feeding groups produce animated chirping. The alarm call is a strong, sharp note repeated sporadically, described in the Northern Territory information sheet as a sharp “tzzzt”.

Most effective survey method in the 2021 to 2023 study: Bioacoustic audio recorders.

Survey result: Detected at 6 of 39 sites, with all six detections made by audio recorders.

  • Listen shortly after sunrise and in the late afternoon, when birds are active and call detection is most useful.
  • Search for mouse-like movement between mature spinifex hummocks, along bare rock, in boulder crevices and beside rocky gullies.
  • Nests are bulky, dome-shaped structures with thick roofs and wide entrances near the top. They are concealed close to the ground in hummocks of spinifex.
  • No diagnostic tracks, scats, sloughs or eyeshine signs are described in the supplied sources. Do not rely on these signs for detection.
  • Passive bioacoustic recorders detected birds at all six occupied sites in a 2021 to 2023 survey. Call playback and camera traps detected birds at only one of those six sites.

Distribution

The species is endemic to the Northern Territory and has a patchy distribution across western Arnhem Land sandstone country. The occupied range is remote and difficult to survey, so absence from a short site visit does not establish that a suitable patch is unoccupied.

The national range is confined to the Northern Territory. It extends across western Arnhem Land and the Arnhem Plateau, between approximately Katherine and Maningrida, with the range extending south-west to Nitmiluk National Park and north-east towards the Mann River. The wider Arnhem Plateau bioregion covers about 32,000 km2, but suitable habitat is highly fragmented within it.

Australian states and territories: Northern Territory only.

Broad range: Western Arnhem Land, from around Katherine to Maningrida, with records extending south-west to Nitmiluk National Park and north-east towards the Mann River.

Wider Arnhem Plateau region: Approximately 32,000 km2.

  • Known conservation reserves include Kakadu National Park and Nitmiluk National Park.
  • The broader range also includes Indigenous Protected Areas and Aboriginal Land Trusts, including Warddeken, Mimal and Djelk areas.
  • The species has been recorded in the Arnhem Land escarpment, sandstone plateaux, outcrops, gorges and associated rocky drainage lines.

Distribution: Strongholds and subpopulations

All populations are considered to have high conservation value. Important areas include Kakadu National Park, Nitmiluk National Park, Warddeken Indigenous Protected Area and Djelk Indigenous Protected Area. Recent collaborative surveys detected birds at six of 39 sites, all within Warddeken Indigenous Protected Area.

Recent targeted survey: 6 of 39 sites occupied, based on bioacoustic detections.

Kakadu long-term monitoring: Detected at 6 of 136 sites surveyed from 2001 to 2009; mean abundance declined from 0.09 to 0 across the survey periods reported.

2011 Kakadu survey: 30 individuals recorded at 11 of 156 sites.

  • The 2021 to 2023 survey detected birds at four Warddeken sites in 2022 and two further Warddeken sites in 2023.
  • Historic or previously reliable locations such as Gunlom, Lower Yurmikmik and Plum Tree Creek have had non-detections or reported declines, so past records should be treated as indicators of potential habitat rather than proof of current occupancy.
  • Subpopulation structure is poorly known. Earlier assessments considered subpopulations to be severely fragmented, potentially with fewer than 1,000 mature individuals each.

Distribution: Population size and trend

Population estimates have varied substantially because the range is remote and difficult to survey. The conservation assessment concluded that the number of mature individuals was decreasing and that the distribution was limited and severely fragmented. More recent fire management has been associated with an improved trajectory, but the species remains Vulnerable.

2010 mature individual estimate: 10,000.

2018 mature individual estimate: 1,000, with low confidence.

Estimated area of occupancy in the 2014 conservation advice: 1,000 km2.

Modelled suitable habitat in the 2024 study: 1,421 km2 using the higher suitability threshold, 2,631 km2 at a lower threshold and 536 km2 at a higher threshold.

  • Treat all suitable sandstone spinifex patches as potentially important unless current survey evidence demonstrates otherwise.
  • Use recent records, fire history, habitat modelling and local Traditional Custodian and ranger knowledge when assessing connectivity between patches.
  • A site assessment should not assume that a protected area or apparently extensive range means that a local population is secure.

Habitat

White-throated grasswrens occupy tropical sandstone country where mature spinifex, bare rock and boulders occur together. Habitat quality depends strongly on fire history, with long-unburnt patches and nearby unburnt refuge vegetation being important features.

Preferred habitat comprises flat, sparsely vegetated high plateaux and ridge-tops with bare rock, sandstone pavement or boulders, mature spinifex hummocks, intermittent herbs and a sparse shrub or tree layer. Acacia and Eucalyptus species are common overstorey components. Less suitable habitat includes steep ledges above gorges, stepped hillsides, tors, pinnacles and narrow side gullies, although these areas can still support birds.

Key vegetation: Mature spinifex, mainly Triodia species, with intermittent herbs and sparse Acacia and Eucalyptus shrubland or woodland.

Key substrate: Bare rock, sandstone pavement, boulders, rock crevices and rocky drainage lines.

Fire history associated with modelled occurrence: Lower surrounding area burnt, lower distance to unburnt vegetation and greater time since fire.

  • Map and retain mature Triodia hummocks, bare rock, boulder fields and rocky gullies as a connected habitat unit.
  • Inspect steep ledges, terraces, outcrops and drainage lines as well as flat plateaux. Birds may use several of these features within one territory.
  • The species occurs in tropical Arnhem Land sandstone environments. No reliable elevation limit is provided in the supplied sources.

Habitat: Habitat structure and fire history

The 2024 habitat model found that birds were typically associated with sites where vegetation had been retained nearby, vegetation cover was relatively low, and more of the surrounding patch had remained unburnt. The relevant local patch was assessed within a 400 m radius, approximately five times the typical home-range size.

Local fire and habitat assessment radius used in the model: 400 m.

Mature spinifex benchmark used in the study: Vegetation at least 5 years since fire was used as a modelled age category.

  • Retain unburnt spinifex refuges and mature hummocks within and around any work area.
  • Avoid broad-scale disturbance that breaks a plateau, ridge, gully or boulder field into isolated remnants.
  • Use current fire mapping and field inspection because modelled suitability can change after a fire.
  • Where works are unavoidable, have a suitably qualified ecologist assess the habitat before clearing and consider whether the area forms part of a larger unburnt patch or movement route.

Foraging habitat

The species feeds on the ground in the same rocky spinifex habitat used for shelter and nesting. It uses a range of plant and animal foods rather than a specialised single food resource.

The diet includes grass and sedge stems, seeds, insects and other invertebrates. Recorded or reported prey includes beetles, ants and grasshoppers. Birds forage over bare rock, in crevices under boulders, among leaf litter, on grass mats and through the leaves and stems of shrubs.

Food: Grass and sedge stems, seeds, insects and other invertebrates.

Foraging groups: Singly, in pairs or in small loose groups.

Daily activity: Feeds from shortly after sunrise through to mid-morning, then rests during the middle of the day.

Home range or territory scale: Territories average about 10 ha; the 2024 study used a 400 m radius to represent the surrounding local patch.

  • Search the ground layer, spinifex bases, rock margins, boulder crevices, leaf litter and low shrubs when assessing foraging habitat.
  • Retain a mosaic of mature spinifex, bare rock, leaf litter, herbs and sparse shrubs. Removing only the spinifex can still reduce food and cover at the same time.
  • Avoid unnecessary clearing, stockpiling, vehicle movement and repeated pedestrian traffic across rocky spinifex patches.

Foraging habitat: Foraging behaviour and survey implications

The birds follow a set course within their home range during the morning feeding period. Their small home ranges, reluctance to fly and limited dispersal capacity mean that a cleared or burnt patch may not be quickly recolonised.

  • Plan visual searches soon after sunrise and use passive acoustic recording through dawn and dusk where access is difficult.
  • Do not treat the absence of birds during a daytime inspection as evidence that the habitat is unused.
  • Retain foraging habitat around known nests and records, not just the immediate nest hummock.

Breeding habitat: Breeding biology

Breeding occurs close to the ground in mature spinifex within rocky sandstone habitat. Pairs may be assisted by other adults, and breeding territories can include several nearby habitat features.

White-throated grasswrens are thought to be socially monogamous, with pairs maintained year-round. Cooperative breeding has also been reported, with additional adults assisting in raising young. Nests are concealed close to the ground in dense hummocks of mature spinifex.

Breeding season: December to June, with breeding commonly reported from December to April and sometimes extending to May or June.

Clutch size: Generally two eggs.

Nest: Bulky, dome-shaped, thick-roofed structure with a wide entrance near the top.

Nest materials: Grass culms, Acacia, Eucalyptus and Grevillea leaves, and paperbark bark.

Incubation period: Not provided in the supplied sources.

Age at maturity: 2.3 years, but this value is extrapolated from fairy-wrens rather than measured directly for this species.

Generation time: 9.7 years, derived from the extrapolated age at first breeding and maximum longevity.

Maximum longevity: 17.0 years, with the value extrapolated from fairy-wrens.

Territory size: Approximately 7 to 10 ha, or around 10 ha.

  • Treat mature spinifex hummocks as potential nest sites during the breeding season, even when no nest is visible.
  • Before clearing, inspect dense hummocks, grass mats and sheltered edges of boulder fields by an experienced fauna ecologist.
  • Avoid disturbing an active nest or repeatedly approaching a suspected nest. Apply project fauna handling and nest protection procedures where a nest is found.

Breeding habitat: Breeding habitat features

Breeding territories occur on high plateaux, ridge-tops, stepped hillsides, rocky gullies and boulder-strewn areas where mature spinifex remains available. Fire can remove the mature hummocks needed for nesting and reduce the food available to adults and young.

  • Retain mature, unburnt spinifex hummocks and the surrounding bare rock, boulders and low shrubs.
  • Maintain habitat continuity across the territory scale where practicable. A small cleared footprint can still affect a pair if it removes a nest patch or divides access between feeding and shelter areas.
  • Use local Traditional Custodian and ranger knowledge when locating breeding areas or deciding whether a patch has been recently occupied.

Sheltering habitat

Shelter is provided by dense spinifex, rock crevices, boulder fields and cliff ledges. These features protect birds from predators, fire and heat and should be treated as fauna habitat even when no bird is detected.

Cliff ledges and rock crevices under boulders provide refuge from predators, fire and the sun. Birds also move through dense hummock grass, grass mats, narrow rocky gullies and shrub cover. The species is a weak flyer and is likely to have limited dispersal capacity, increasing the value of nearby refuges.

Documented refuges: Cliff ledges, rock crevices under boulders, dense spinifex hummocks, grass mats, rocky gullies and shrub cover.

Home range scale: Approximately 7 to 10 ha, or around 10 ha.

Specific refuge dimensions: Not provided in the supplied sources.

  • Protect boulder fields, rock overhangs, crevices, cliff ledges and dense spinifex from clearing, blasting, dumping and avoidable vehicle access.
  • Do not remove rocks or collapse crevices within or beside occupied spinifex habitat unless the impact has been assessed and approved.
  • Retain unburnt refuge patches within the area affected by any planned fire or construction activity.
  • Treat mature spinifex hummocks as potential shelter and nest cover. No minimum hummock, crevice or refuge size is provided in the supplied sources.

Sheltering habitat: Detection and handling considerations

The species can remain concealed in spinifex and rocks and may only give a brief call or movement. Audio recorders were more effective than call playback and camera traps in the recent 39-site survey.

Recent survey effort: Audio recorders were deployed for 4 to 6 weeks at survey sites.

Detection timing: Most calls were around dawn and dusk, with the longest songs in the 2 hours before sunset.

  • Use passive audio recording where the site is remote, rugged or difficult to search safely.
  • If a bird is flushed, allow it to move into cover and avoid chasing it through spinifex or boulders.
  • Record the habitat feature used, the direction of movement and the fire history of the patch.

Threats: Fire and habitat change

The main documented threat is altered fire, especially frequent, extensive and intense late dry season fire. Clearing and fragmentation can compound this threat by removing mature spinifex, reducing refuges and isolating small subpopulations.

High annual frequencies of large late dry season fires can remove mature spinifex and leave few functional unburnt refuges. The species may require access to long-unburnt sites for some life stages, although its exact fire response is not fully known. Progressive replacement of spinifex by annual sorghum may also reduce habitat suitability and support more intense fires.

  • Avoid burning occupied or potentially occupied spinifex habitat during the breeding season and avoid broad, hot fires that remove all nearby refuges.
  • Use fine-scale fire planning that retains mature spinifex and a network of unburnt patches.
  • Map fire history before clearing and assess whether the work area is part of a long-unburnt patch or a refuge after surrounding fires.
  • Do not assume that rocky ground will fully protect birds. Extensive and intense fires can leave no functional unburnt refugia.

Threats: Clearing, fragmentation and project disturbance

The species has a limited and severely fragmented distribution. Clearing of sandstone spinifex, boulder fields, rocky gullies or connecting habitat can reduce area of occupancy and isolate small subpopulations. The supplied sources do not provide species-specific studies of roads, construction noise or vehicle collision, but project access can directly remove or disturb the same habitat features used for feeding, nesting and refuge.

Fragmentation concern: Earlier assessments considered subpopulations to be severely fragmented, potentially with fewer than 1,000 mature individuals each.

Known project-related road impact: Not specifically documented in the supplied sources.

  • Avoid clearing mature spinifex, bare rock, boulders and rocky gullies wherever practicable.
  • Keep temporary laydown, access tracks, helicopter landing areas and spoil outside suitable habitat and known records.
  • Use pre-clearance surveys that include passive acoustic recording where the habitat is suitable and access is difficult.
  • Maintain buffers and habitat connections around known records, nests and occupied patches in accordance with project approvals and advice from the relevant regulator.
  • Stop work and obtain ecological advice if a grasswren, active nest or previously unknown occupied patch is found.

Threats: Predators, weeds and other pressures

Predation by feral cats is a proposed threat. Feral cat detections were recorded by camera traps during the 2021 to 2023 survey. The Australian Government also identifies feral cats and pigs, weeds and fire as management issues in Kakadu and associated conservation programs.

Documented predator of concern: Feral cat.

Other management pressures identified in Kakadu programs: Feral pigs, weeds and destructive fire.

  • Record feral cats and other pest animals during site surveys and report detections to the land manager or project environmental officer.
  • Do not introduce food, waste or conditions that attract feral predators to work areas.
  • Manage weeds and fire together where weed invasion increases fine fuels or replaces spinifex.
  • Disease, hydrology change and road mortality are not identified as established species-specific threats in the supplied sources. Assess them as general project risks only where the proposal changes habitat, drainage, access or vehicle movements.

Survey methodology: 1. Habitat assessment and survey planning

Survey this species in rocky sandstone habitat with mature spinifex, bare rock and boulders. It is shy, ground dwelling and difficult to detect visually, so combine passive acoustic recording with targeted call playback and, where practical, camera trapping.

Map sandstone plateaux, ridge tops, stepped or terraced hillsides, rocky gullies, boulder fields and spinifex patches before selecting survey sites.

Prioritise habitat with mature Triodia, bare rock or pavement, boulders, rock crevices and a history of at least several years without fire.

Use recent fire mapping to identify retained unburnt refuges and avoid relying only on general vegetation maps.

Treat the species as difficult to relocate because it has a restricted, patchy distribution, small home ranges and limited dispersal capacity.

Typical territory size: About 7 to 10 ha

Breeding period: December to June, with recent research describing breeding mainly from December to April

Known distribution: Western Arnhem Land and surrounding sandstone country in the Northern Territory

Survey methodology: 2. Bioacoustic audio recording

Use bioacoustic audio recorders as the primary detection method where access and approvals allow.

Place the recorder close to suitable spinifex and rocky habitat, in a position that captures sound across the surrounding habitat and is accessible for servicing.

Record continuously from 5 am to 8 pm where possible, or for 24 hours if the project design requires it.

Leave each recorder in place for 4 to 6 weeks.

Analyse recordings for the species' complex trills, chirps and alarm notes, using validated call recognition and manual confirmation rather than relying only on automated software.

Plan for substantial data handling, as the 2021 to 2023 study produced 1,488 recorder days, 25,767 hours and 6.5 terabytes of recordings.

Most productive calling periods: Around dawn and dusk, with the longest songs recorded in the 2 hours before sunset

Detection result from the recent study: Recorders detected birds at all 6 of the 39 surveyed sites

Recorder deployment: 4 to 6 weeks per site

Survey methodology: 3. Call playback surveys

Use call playback in suitable habitat during early morning or late afternoon, when birds are more active.

Survey defined plots on foot and record all responses, sightings and other relevant bird observations.

In the recent study, observers surveyed 2 ha plots for 30 minutes, broadcast the call six times, and allowed at least 5 minutes between broadcasts.

Use a reliable recording of the species' call and keep observers concealed behind spinifex, rock or shrubs where practical.

Record a positive response only after checking that the call or sighting is consistent with the species, because the bird is secretive and may respond without being seen.

Do not enter unsafe cliffs, gorges or boulder fields simply to increase survey coverage.

Recent survey effort: 145 call-playback plots across 26 sites

Plot area: 2 ha

Observation period: 30 minutes per plot

Playback schedule: Six broadcasts per 30 minute survey, with at least 5 minutes between broadcasts

Survey methodology: 4. Camera trapping and combined methods

Deploy motion detection cameras where a recorder or playback survey cannot adequately cover the site and where cameras can be secured without damaging spinifex or rocky refuges.

Use cameras as a supplementary method, not the sole method, because the species is small, ground dwelling and may pass outside the camera's detection zone.

In the recent study, cameras were used at 32 of 39 sites, while call playback was used at 26 sites and recorders at all 39 sites.

Combine methods at the same site where practicable and compare detections with fire history, spinifex maturity and the availability of bare rock and crevices.

Use passive recording as the preferred method for remote or rugged sites because it produced more detections than playback or cameras in the recent study.

Combined survey coverage in the recent study: 39 sites, 32 camera sites, 26 call-playback sites and 39 recorder sites

Detection outcome: Birds were detected at 6 of 39 sites, at all 6 sites by audio recorders, at 1 site by camera and at 1 site by call playback

Survey methodology: Minimum effort and reporting

  • Use a targeted survey design that covers all suitable rocky spinifex habitat within and near the proposed disturbance area, rather than surveying only cleared footprints.
  • Use recorders for 4 to 6 weeks where the species is a credible possibility, and add call playback and cameras where site access, safety and approvals permit.
  • Document the survey dates, start and finish times, weather, fire history, recorder locations, plot areas, playback schedule, camera deployment and all detections or non-detections.
  • Map each detection and retain the original audio, photographs, video and field notes so that records can be checked by an appropriately experienced ornithologist.
  • Report confirmed records and survey results to the relevant Northern Territory or other state wildlife database, and provide records to the project regulator and land manager where required.
  • If a project may significantly affect this nationally listed species, retain the survey evidence for an EPBC Act referral or approval assessment.

Before habitat disturbance: Avoid and minimise

Treat mature spinifex and rocky refuges as habitat, not as vacant ground. Avoid clearing occupied or suitable patches wherever practicable, especially patches that have remained unburnt for several years.

Redesign the footprint to retain flat sandstone plateaux, ridge tops, stepped hillsides, rocky gullies, boulder fields, bare rock, mature spinifex and nearby shrubs.

Retain connected patches of suitable habitat and avoid isolating small spinifex and rocky refuges between roads, pads, easements or construction compounds.

Give particular attention to habitat patches that are large enough to support a territory of about 7 to 10 ha, while recognising that all populations are considered to have high conservation value.

Avoid unnecessary removal of spinifex, rocks, boulders and vegetation around crevices, because these features provide nesting, feeding and refuge habitat.

Set project-specific no-go areas and buffers around confirmed detections and high-quality habitat, based on the footprint, fire risk, terrain and advice from the relevant wildlife authority.

Before habitat disturbance: Approvals and timing

Check the EPBC Act requirements before works because the white-throated grasswren is listed as Vulnerable nationally.

Check Northern Territory requirements, or the requirements of the relevant state or territory, for wildlife permits, clearing approvals, fauna handling and relocation.

Schedule clearing outside the December to June breeding period where practicable, and avoid disturbance to nests concealed in low spinifex during that period.

Obtain written advice from the regulator where breeding-season works cannot be avoided or where occupied habitat will be affected.

Before habitat disturbance: Plan and prepare the site

Prepare a fauna management plan that identifies suitable habitat, confirmed records, exclusion areas, survey methods, clearing stages, spotter catcher responsibilities, stop-work triggers and reporting requirements.

Complete the targeted pre-clearance survey before finalising the clearing boundary, including acoustic recording where the species may occur.

Mark retained spinifex, rock outcrops, boulders, crevices, gullies and other habitat features clearly on plans and on the ground.

Use exclusion fencing where it can protect retained habitat from machinery, vehicle movements, storage and accidental fire.

Brief all operators that this is a small, cryptic ground bird that may move through spinifex or behind rocks without being noticed.

During habitat disturbance: Daily controls and staged clearing

Use staged clearing and keep the spotter catcher, supervisor and machinery operator in direct communication. The aim is to prevent crushing, fire and avoidable loss of spinifex and rocky refuge habitat.

Recheck exclusion fencing, no-go markers, access routes and the day's clearing boundary before machinery starts.

Clear in small stages towards retained habitat so fauna has an opportunity to move into nearby suitable cover, where this can be done safely and lawfully.

Keep machinery outside marked retained habitat and prevent slash, spoil, fuel, vehicles and construction materials from covering spinifex, boulders or rock crevices.

Stop or modify work during conditions that create a high risk of uncontrolled fire through retained spinifex.

Have the spotter catcher inspect the next work area immediately before clearing and remain able to stop machinery.

During habitat disturbance: Spotter catcher and machinery protocol

The spotter catcher must have authority to stop work and must maintain clear communication with the operator and site supervisor.

The operator must wait for the spotter catcher's signal before entering each inspected section and must stop immediately when directed.

Search the ground, spinifex clumps, rock edges, boulder bases and crevices before machinery removes or drives over them.

Do not chase a bird into unsafe terrain, dense spinifex, a cliff or a boulder field.

Use only personnel authorised under the applicable state or territory rules to capture, handle, examine or relocate fauna.

During habitat disturbance: Fauna and habitat features

If a grasswren is found, stop work in the immediate area, keep people and machinery back, and allow the authorised fauna handler to assess whether the bird can move unaided into nearby retained habitat.

Do not handle the bird unless handling is necessary for its welfare, an approved relocation, veterinary treatment or another lawful purpose.

Do not relocate the bird to an unrelated site; if relocation is approved and needed, use nearby retained habitat with suitable mature spinifex, bare rock and refuge features.

Treat low spinifex clumps as potential nest sites during the breeding period from December to June, and do not disturb a suspected nest until the authorised person and regulator have decided what to do.

Treat rocks, boulders, logs, burrows and other ground features as general fauna habitat during clearing, but do not describe them as grasswren nest features unless confirmed by a qualified person.

If an injured bird is found, contain it only as directed by the authorised handler and arrange prompt assessment by a veterinarian or permitted wildlife carer.

During habitat disturbance: Stop-work triggers and records

Stop work if a grasswren is detected within the clearing area, a nest or dependent young is suspected, the clearing boundary is unclear, or machinery enters a retained habitat area.

Stop work if fire threatens retained spinifex or rocky refuge habitat, or if clearing conditions differ materially from the approved method.

Record the location, date, time, behaviour, photographs or audio, habitat condition, fire history, action taken, handler details and the final outcome for every detection.

Report any injury, death, unapproved handling, nest disturbance, escape from containment or clearing outside the approved boundary to the project environmental officer and relevant authority.

After habitat disturbance: Post-clearance checks

Check that retained habitat remains usable and that controls have not failed after clearing. Use confirmed detections, habitat condition and fire history to guide follow-up work.

Inspect the cleared boundary and retained patches for damaged spinifex, crushed refuges, new access tracks, debris, erosion and accidental fire.

Check that exclusion fencing and no-go markers remain intact and that machinery has not entered retained rocky habitat.

Undertake a post-clearance fauna check where the spotter catcher identifies unresolved risks, an animal was found, or clearing occurred close to occupied habitat.

Confirm that any relocated or treated animal was released, transferred or admitted to care and record the destination and outcome.

After habitat disturbance: Monitoring and adaptive management

Monitor retained habitat for grasswren calls and occupancy using the same methods and locations used for the pre-disturbance survey where comparison is needed.

Use audio recorders for repeated monitoring where practical, because the recent study detected the species at all six occupied survey sites with this method.

Record changes in spinifex maturity, bare rock cover, connectivity, fire extent and the condition of rocky refuges.

Review the monitoring results with the land manager, Traditional Custodians where relevant, ecologist and regulator, and change fire, access or weed controls if habitat quality declines.

After habitat disturbance: Reporting and offsets

Submit confirmed records, negative survey results where required, habitat mapping, incidents, monitoring data and rehabilitation outcomes to the relevant state or territory wildlife database and project regulator.

Update the EPBC Act compliance record if the project is subject to an approval, condition or referral involving the species.

Apply any approved offset, compensation or residual impact measure required by the EPBC Act or state or territory approval.

Do not use an offset as a substitute for retaining mature spinifex, rocky refuges and connected habitat within the project area.

Rehabilitation actions: Rebuild habitat structure

Rehabilitation should recreate the species' rocky spinifex habitat and reduce the fire conditions that caused historical fragmentation. Recovery will depend on retaining mature spinifex and maintaining unburnt refuges over time.

Re-establish hummock grasslands dominated by mature Triodia in disturbed areas that are suitable for the species.

Retain or reinstate bare rock, sandstone pavement, boulders and natural crevices, and avoid covering these features with spoil or mulch.

Restore sparse shrub and tree cover where it is part of the original habitat, using locally appropriate Acacia and Eucalyptus species rather than creating dense vegetation over spinifex.

Reinstate natural drainage and avoid creating barriers between retained and rehabilitated rocky spinifex patches.

Do not assume that nest boxes will benefit this species, because its nests are concealed close to the ground in spinifex rather than in tree hollows.

Rehabilitation actions: Fire, weeds and predators

Develop a fine-scale fire plan that retains long-unburnt spinifex patches and limits extensive, intense late dry-season fires.

Work with Traditional Custodians, Indigenous ranger groups, park managers and fire authorities to combine traditional burning practices with fire mapping and monitoring.

Use planned low-intensity burning only where it supports habitat objectives and does not remove the mature spinifex or unburnt refuges required by the species.

Control weeds that replace spinifex or increase the risk of intense fire, including annual sorghum where it is affecting habitat suitability.

Assess and manage feral cats where monitoring or project evidence identifies a risk, in accordance with approved control programs.

Rehabilitation actions: Success measures and monitoring

Set success measures for establishment and persistence of Triodia, retention of bare rock and boulders, connectivity between habitat patches, weed cover, fire extent and the condition of unburnt refuges.

Monitor rehabilitation sites through establishment and subsequent fire seasons, using repeat acoustic surveys at suitable times around dawn and dusk.

Use a longer-term monitoring program where the project affects a large patch or known population, because the species has a generation time of 9.7 years and recolonisation may be slow.

Investigate whether grasswrens return or continue to use the rehabilitated or retained habitat, while recognising that non-detection does not demonstrate absence.

Report failures such as poor spinifex establishment, repeated fire, weed invasion, feral predator activity or loss of connectivity, and implement corrective actions.

Generation time: 9.7 years

Recent management result: In Kakadu, strategic fire management reduced the area of stone country affected by fire from close to 50 per cent in 2014 and 2015 to 20 to 30 per cent in 2017, and reduced destructive late fires from about 30 per cent before 2015 to less than 4 per cent after 2016

Sources