Purple-crowned Fairywren (Malurus coronatus)

Conservation status

Commonwealth, EPBC Act 1999: Endangered.

Queensland, Nature Conservation Act 1992: Vulnerable.

Western Australia, Biodiversity Conservation Act 2016: Endangered.

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

Breeding season

The species is sedentary and can breed in most months, but laying is concentrated in July to September with a possible second peak from March to May. Timing of dependence after hatching is not specified in the supplied documents.

Month values are January to December. A value of 0 means not typical, 1 means occurs, and 2 means peak.

• Breeding and laying: Breeding occurs in most months. Most laying is from July to September, with a possible second peak from March to May.
• Young: Dependent young may be present after breeding, but the supplied documents do not give the nestling or dependence period. Treat occupied territories as potentially supporting dependent young during the breeding periods.
• Dispersal: The subspecies is sedentary. Dispersal is sex-biased, with most subordinate males remaining in or near their natal territory and females generally moving farther. No seasonal dispersal period is given.
• Highest clearing risk: Clearing or disturbance is most likely to harm the species during the main laying periods from March to May and July to September, when territories may contain nests or dependent young. Occupied habitat should be treated as sensitive year-round because territories are maintained throughout the year.

Identification

This is a small, active fairywren usually detected in pairs or family groups in dense river-edge vegetation. Identification is most reliable from the combination of habitat, plumage and its distinctive call.

The bird is approximately 14 cm long, with a wingspan of about 16 cm and a weight of 9 to 13 g. The adult male in breeding plumage is brown above and buff-white below, with a blue tail, purple forehead, crown and nape, a black crown spot, and a black facial mask extending into a collar around the nape.

Males outside the breeding season have a mainly brown cap, a brownish to blackish mask and an off-white to pale grey orbital ring. Females resemble non-breeding males but have a brownish-grey to bluish-grey cap, a clean white orbital ring and a chestnut mask. Juveniles are duller and resemble females.

Identification: Similar species and behaviour

The western subspecies has no similar species in its range according to the survey guidelines. It is shy but inquisitive, gregarious, and usually seen in pairs or small groups.

The call is distinctive and loud. Birds may call in flight or before leaving a roost, and experienced observers can distinguish the call from those of other malurids.

• Use the call together with the dense riparian habitat to support identification.
• Check plumage carefully where the eastern subspecies may occur, because the eastern subspecies is smaller and has a slightly bluer crown and nape.

Identification: Field signs and survey detection

The supplied documents do not provide reliable diagnostic information on tracks, scats, nests or other non-visual signs. Field detection should therefore focus on sightings and calls.

Birds are active, noisy and conspicuous in the early morning, but may rest quietly and become difficult to detect in the heat of the day. Area searches of suitable riparian habitat should be undertaken early in the morning, with broadcast surveys also effective at obtaining call responses.

Survey effort guide: For areas less than 50 ha, the guidelines specify 12 hours over 3 days for area searches and 12 hours over 3 days for broadcast surveys.

• Search dense river-edge vegetation by sight and call during the early morning.
• Use experienced observers for call identification.
• Where access along the riverbank is not feasible, canoes may be used for area searches.

Distribution: Range and strongholds

The western subspecies has a restricted and patchy distribution in northern Australia. It is confined mainly to river systems in the Kimberley of Western Australia and the Victoria River area of the Northern Territory.

In Western Australia, the subspecies occurs along the Fitzroy, Isdell, Drysdale, Durack and Pentecost river systems in the Kimberley. In the Northern Territory, it occurs along the Victoria River system.

The strongest documented population areas include the Drysdale, Victoria, Fitzroy and Isdell river systems, although the species has declined or disappeared from parts of its former range. The Ord River population disappeared after 2003, and only a short stretch of the Pentecost River catchment remained occupied when the conservation advice was prepared.

• Do not assume that apparently suitable river-edge vegetation is occupied. Occupancy is patchy and should be checked by targeted survey.
• The eastern subspecies occurs in the Gulf of Carpentaria drainage of western Queensland and north-eastern Northern Territory. This profile concerns the western subspecies.

Distribution: Subpopulations and population trend

The western subspecies occurs as six genetically distinct subpopulations that differ in size and isolation. The loss of the Ord population left the Victoria River populations isolated from Kimberley populations by about 250 km, a distance the subspecies is unlikely to cross.

The distribution has contracted substantially. Historical losses include approximately 150 km of former occurrence on the lower Fitzroy River, more than 150 km from the Ord system, and more than 50 km, or about 90 percent of the original subpopulation, from the Pentecost catchment.

Estimated total population: Approximately 5,000 to 9,500 mature individuals in assessments cited by the conservation advice, with a later estimate of no more than 9,000.

Kimberley estimate: Approximately 2,800 to 4,800 individuals, equating to about 2,000 to 3,000 breeding individuals.

Victoria River estimate: Fewer than 5,000 individuals, with fewer than about 4,500 likely to be breeding individuals.

Recent trend: The total population was estimated to have declined by 14 percent over the preceding 25 years, with a continuing decline projected.

Drysdale trend: The Drysdale subpopulation declined by up to 70 percent over three generations, from an estimated 1,500 individuals in 1993 to about 400 to 700 in surveys conducted in 2009.

Habitat: Vegetation communities

The western Purple-crowned Fairywren is a riparian specialist of the wet-dry tropics. Occupied habitat is usually a narrow strip beside permanent water with dense understorey and canopy cover.

Preferred habitat has a well-developed mid-storey beneath a dense canopy of emergent Eucalyptus and Melaleuca species. Kimberley sites commonly contain dense Pandanus aquaticus or Barringtonia acutangula, a freshwater mangrove, with other shrubs.

Along the Victoria River, and formerly along the lower Fitzroy River, the species is commonly associated with dense river grass, including Chionachne cyanthopoda. The survey guidelines also describe dense canegrass thickets, river pandanus and mixtures of the two.

Habitat: Structural requirements

Key features are dense ground and understorey cover, a continuous or connected riparian strip, and permanent water. Occupied areas at the Drysdale River supported twice as many pandanus stems as unoccupied areas.

Emergent river red gums, coolibahs, cadjead trees and figs provide refuge when floods inundate nesting and feeding habitat. Some birds also use dense grasslands up to about 100 m from the river.

• Map dense riparian vegetation within at least 10 m of permanent water as potential habitat.
• Retain dense pandanus, canegrass, river grass, shrubs and emergent trees through the construction footprint and access design process.
• Treat narrow vegetated strips as habitat even where the surrounding land is pastoral or otherwise highly modified.

Habitat: Climate and elevation

The documents describe the species as occurring in the wet-dry tropics of northern Western Australia and the Northern Territory. They do not provide an elevation limit.

Foraging habitat: Diet and feeding sites

Pairs and family parties forage in shade, on the ground and through the undergrowth. Foraging habitat is closely linked to dense riparian cover rather than open ground alone.

The diet consists of a range of insects, other invertebrates and small quantities of seeds. Birds forage in shaded areas, on the ground and in dense understorey vegetation.

Suitable feeding sites include pandanus thickets, canegrass, river grass, shrubs and other dense vegetation along permanent water. Dense grasslands can also be used where they occur up to about 100 m from the river.

• Retain ground cover and understorey vegetation within riparian buffers.
• Avoid stock access, trampling, weed replacement and clearing that simplify the understorey or expose the ground.
• Inspect proposed works areas along both the river edge and nearby dense grassland, rather than searching only immediately beside the channel.

Foraging habitat: Foraging area

The documents do not provide a separate foraging radius. Territories are maintained year-round and are usually reused in the same area each year, so the territory length is a practical indicator of the river frontage used by a breeding group.

Documented territory length: About 180 to 230 m at Timber Creek and approximately 300 m at Drysdale River Crossing.

Breeding habitat: Breeding biology

The species is a cooperative breeder and depends on suitable riparian territories for reproduction. Only the dominant pair in a group breeds, while subordinate birds help raise the offspring.

Breeding can occur in most months. Most laying occurs from July to September, with a possible second laying peak from March to May.

The number of eggs, incubation period, age at first breeding and lifespan are not stated in the supplied documents. Subordinate birds may remain non-reproductive for several years, and females generally disperse farther than subordinate males.

Breeding season: Breeds in most months; most laying occurs from July to September, with a possible second peak from March to May.

Clutch size: Not stated in the supplied documents.

Incubation period: Not stated in the supplied documents.

Age at maturity: Not stated. Subordinate individuals can remain non-reproductive for several years.

Lifespan: Not stated in the supplied documents.

Breeding system: Cooperative breeding. Only the dominant pair reproduces, and subordinate birds help raise the young.

Breeding habitat: Breeding habitat features

Breeding territories are maintained throughout the year and are usually used repeatedly. The required habitat includes dense riparian vegetation, a developed mid-storey, dense canopy cover and suitable ground or understorey cover for nesting and shelter.

Livestock trampling, intense fire, weed invasion, erosion, flooding and loss of riparian structure can reduce breeding success. Increased flood energy has destroyed riparian vegetation and is likely to affect breeding success.

• Avoid clearing or disturbing occupied riparian strips during the main laying periods from March to May and July to September.
• Retain connected vegetation around known territories, including dense mid-storey and ground cover.
• Check whether works could increase flood energy, erosion or access by stock and feral herbivores to breeding habitat.

Sheltering habitat: Cover and refuge

Shelter is provided by dense riparian vegetation and emergent trees. These features are also important when floods inundate ground-level feeding and nesting habitat.

The species uses dense pandanus, canegrass, river grass, shrubs and other understorey vegetation for cover. Birds forage and move through shaded undergrowth and may become difficult to detect when resting during the heat of the day.

Emergent river red gums, coolibahs, cadjead trees and figs provide refuge when rivers flood and the nesting and feeding habitat is inundated.

• Retain continuous dense cover along the river margin and avoid creating isolated cleared gaps through occupied vegetation.
• Protect emergent trees within and beside riparian habitat, even where they are not known to contain hollows.
• Do not treat flood refuge trees as separate from the riparian habitat requiring protection.

Sheltering habitat: Roosts and other structures

The documents refer to roosts and report that birds may call before leaving a roost, but they do not specify roost tree dimensions, nest dimensions, nest height, hollows, burrows or den requirements.

• Record any observed roosting, nesting or repeated shelter locations during pre-clearing surveys.
• Use early morning searches because birds are more active and conspicuous at that time.

Threats: Clearing, fragmentation and access

The main risk is loss, degradation and fragmentation of dense riparian habitat. Construction impacts can be significant where they remove narrow strips of vegetation, interrupt connectivity or change erosion and flood conditions.

Clearing riparian vegetation removes foraging, nesting and shelter habitat. Fragmentation isolates territories and disrupts dispersal, and the subspecies has limited ability to recolonise isolated river sections.

About 77 percent of suitable Kimberley habitat occurs on pastoral land, where grazing and trampling remain a high risk. Habitat within conservation areas can also be affected by cattle, horses, buffalo and pigs.

• Avoid clearing dense vegetation beside permanent water and retain connectivity between occupied habitat patches.
• Design access tracks, laydown areas, crossings and service corridors to avoid dividing riparian strips.
• Control stock and feral herbivore access to retained habitat, and provide alternative watering points away from the river margin.

Threats: Fire, weeds and predation

More frequent or intense fire can damage riparian vegetation, particularly where weeds provide heavy fuel loads. Weed invasion has replaced native vegetation in parts of the former range.

Feral cats and black rats are predators. Habitat degradation can reduce shelter and increase exposure to predation, while weeds may increase black rat abundance.

• Prevent construction activities from increasing fire frequency or intensity in riparian vegetation.
• Manage weeds without removing the dense native cover needed by the species.
• Assess feral cat and black rat risks where works reduce cover or increase access to occupied habitat.

Threats: Hydrology, erosion and extreme events

Increased flood energy associated with rangeland degradation has destroyed riparian vegetation. Erosion is widespread in the Victoria River District and may be worsened by large floods.

Flooding can reduce adult survival, territory occupation and nesting success. Climate change is projected to increase the frequency of extreme events such as flooding, with degraded habitat likely to be more affected.

• Assess whether crossings, embankments, drainage, vegetation removal or altered flow paths could increase flood energy or bank erosion.
• Protect riparian vegetation that provides flood refuge and stabilises the river margin.
• Keep works, spoil placement and drainage out of dense riparian habitat wherever practicable.

Threats: Disease and road impacts

The supplied documents do not identify a particular disease affecting this subspecies. They also do not quantify road mortality or identify roads as a separate documented threat.

Roads and construction access can nevertheless cause habitat loss and fragmentation where they cross narrow riparian strips. Any project-specific risk assessment should consider these effects together with vehicle disturbance and increased access by predators or herbivores.

• Avoid new river crossings through occupied habitat where an alternative alignment is available.
• Record sick or dead birds and refer suspected disease events to the relevant wildlife authority or project ecologist.
• Manage vehicle speeds and access near occupied riparian habitat as a project control where disturbance or collision risk is identified.

Survey methodology: 1. Area searches

Survey the western subspecies in dense riparian vegetation, particularly thickets close to permanent water. Use experienced observers who can identify its distinctive call and complete surveys during the cooler, more active part of the day.

Recommended effort: 12 hours over 3 days in areas smaller than 50 hectares.

Typical group size: Pairs or small groups.

• Search suitable riparian habitat in the early morning for birds seen in pairs or small groups and for their distinctive loud calls.
• Target dense thickets of river pandanus, canegrass or mixed riparian shrubs, usually within 10 metres of permanent water.
• Search the ground, understorey and shaded areas because the species forages on the ground and in dense vegetation.
• Use a canoe where riverside access is not feasible, subject to site safety and approval requirements.

Survey methodology: 2. Transect surveys

Recommended effort: 12 hours over 3 days in areas smaller than 50 hectares.

Detection: Sight and call.

• Use transects through or alongside suitable riparian habitat, with detection by sight and call.
• Record the transect route, length, survey time, observers, weather, habitat condition and all detections.
• Survey in the early morning when birds are active and conspicuous, and avoid relying on midday searches when they may rest quietly in the heat.

Survey methodology: 3. Broadcast surveys

Recommended effort: 12 hours over 3 days in areas smaller than 50 hectares.

Best detection feature: Distinctive loud call.

• Use playback at suitable riparian habitat to solicit call responses from birds that are present but not immediately visible.
• Conduct broadcast surveys with experienced observers who can distinguish the species' call from those of other fairy-wrens.
• Record the playback locations, timing, weather, response time, response type and any birds seen after the response.
• Do not use playback in a way that causes repeated disturbance to a territory or breeding group.

Survey methodology: Minimum effort and reporting

• Use area searches, transects or both, and add broadcast surveys where dense vegetation limits visual detection.
• Complete surveys in the early morning and record whether heat, flooding, fire, grazing, weeds or poor access reduced detection.
• Repeat surveys where the initial survey does not adequately cover retained riparian habitat or where conditions were unsuitable.
• Map all detections and potentially occupied habitat, including the occupied length of river frontage where the habitat is linear.
• Submit confirmed records and survey results to the relevant state or territory wildlife database and provide records required by project approvals.
• Report the taxon at the correct level, Malurus coronatus coronatus, where the western subspecies can be identified.

Before habitat disturbance: Avoid and minimise

Treat dense riparian vegetation as potential habitat wherever the project occurs within the western subspecies' known range. The project footprint, access routes, compounds and disposal areas should be planned to avoid direct loss and fragmentation of riverine habitat.

Preferred habitat: Dense riparian vegetation with a well-developed mid-storey beneath emergent Eucalyptus and Melaleuca trees.

Typical occupied territory length: About 180 to 300 metres of river frontage.

• Retain dense river pandanus, canegrass, shrubs and the emergent trees that provide refuge when flooding inundates nesting and feeding areas.
• Avoid clearing riparian vegetation, particularly vegetation within 10 metres of permanent water, wherever practicable.
• Maintain continuous or reconnectable strips of riparian vegetation between occupied territories and other suitable habitat.
• Keep machinery, vehicle access, stockpiles and site compounds out of retained riparian vegetation.
• Prevent livestock and feral herbivores from entering retained habitat, because grazing and trampling can rapidly reduce habitat quality.

Before habitat disturbance: Approvals and work planning

Main laying period: July to September.

Secondary laying peak: March to May.

Breeding pattern: Breeds in most months.

• Check whether the action is likely to have a significant impact on the EPBC Act listed taxon and obtain advice on, or make, an EPBC Act referral before work starts where required.
• Confirm state and territory threatened species listings, permit requirements, survey requirements and fauna handling requirements for the work location.
• Prepare a fauna management plan that identifies known and potential habitat, survey results, exclusion areas, clearing limits, fauna handling arrangements, stop-work triggers and reporting requirements.
• Schedule clearing outside the main laying period of July to September where practicable, and avoid the secondary laying peak from March to May where practicable.
• Stage works so that retained riparian habitat remains connected and birds can move away from the active work area.

Before habitat disturbance: Site preparation

• Complete a pre-clearance area search or transect survey of all suitable riparian habitat that could be disturbed.
• Use playback where dense vegetation or access conditions could conceal birds, and document any response or sighting before clearing.
• Mark the approved clearing boundary and retained habitat in the field before machinery enters the site.
• Install exclusion fencing or other visible barriers where they can prevent accidental entry into retained riparian vegetation.
• Brief all machinery operators and contractors on the species, the marked exclusion areas, the stop-work procedure and the authorised fauna handler.

During habitat disturbance: Daily controls

Keep disturbance inside the approved footprint and maintain active supervision where works approach riparian habitat. The fauna spotter catcher should control the interaction between wildlife and machinery, rather than relying on operators to detect birds in dense vegetation.

• Inspect exclusion fencing, clearing limits and retained habitat before work starts each day.
• Use a fauna spotter catcher to inspect the active work area and the next section to be cleared before machinery begins.
• Clear progressively in small sections, directing machinery away from retained riparian vegetation and towards safe, connected habitat where practicable.
• Keep machinery, vehicles, spoil, washdown activities and temporary access out of retained habitat and waterway margins.
• Suspend work during conditions that increase risk to birds or habitat, including flooding, unsafe access or fire affecting retained riparian vegetation.

During habitat disturbance: Fauna handling and habitat features

• Do not catch, handle or relocate a bird unless the person is authorised under the relevant approval and state or territory requirements.
• If a fairy-wren is found, stop the immediately affected activity, keep people and machinery back, and allow the authorised fauna handler to assess the bird.
• Relocate a healthy bird only when authorised and only to nearby retained riparian habitat that provides dense cover and connectivity.
• Take an injured bird promptly to an appropriately qualified veterinarian or authorised wildlife carer, following the project fauna management plan.
• Inspect dense vegetation before removal and retain river pandanus, canegrass, shrubs and emergent trees wherever they are outside the approved footprint.
• Do not remove, bury or burn habitat features that are supporting shelter, nesting or feeding unless they are within the approved clearing area and their removal is authorised.

During habitat disturbance: Stop-work triggers and records

• Stop work and notify the site environmental officer if a purple-crowned fairy-wren is found inside the clearing area, if an active nest is suspected, or if clearing extends beyond the approved boundary.
• Stop work if exclusion fencing fails, retained riparian vegetation is damaged, or machinery enters a marked exclusion area.
• Record the date, time, location, habitat, activity, bird identity, action taken, handler, release location and outcome for every fauna interaction.
• Photograph and map any damage to retained riparian vegetation, erosion, weed spread, fire impact or flood damage associated with the works.
• Escalate any repeated detections, mortality, injury or loss of connectivity to the project ecologist and the approval holder before work resumes.

After habitat disturbance: Post-clearance checks

Check the completed work area and retained habitat before demobilisation. The project should leave riparian vegetation, habitat connectivity and site controls in the condition required by approvals and the fauna management plan.

• Complete a final inspection of the cleared area, access routes and retained riparian vegetation for trapped, injured or displaced fauna.
• Check that no fairy-wren remains isolated by fencing, spoil, fallen vegetation, erosion or other project material.
• Remove temporary barriers only after the environmental officer confirms that the work area is safe and the approved controls are no longer needed.
• Stabilise disturbed banks and drainage lines where erosion could remove riparian vegetation or increase flood energy.

After habitat disturbance: Monitoring and maintenance

• Monitor retained habitat for purple-crowned fairy-wrens using early morning area searches, transects or broadcast surveys where required by the fauna management plan.
• Inspect retained habitat for grazing, trampling, weed invasion, fire damage, erosion and flood impacts during the monitoring period.
• Maintain exclusion fencing, alternative livestock watering arrangements and other controls for as long as they are required to protect riparian vegetation.
• Compare post-work detections, habitat condition and occupied river frontage with pre-work records.

After habitat disturbance: Reporting and offsets

• Provide survey, clearing, fauna interaction, injury, mortality, rehabilitation and monitoring records to the approval holder and relevant regulators.
• Submit confirmed species records to the relevant state or territory wildlife database.
• Report any approval breach, unexpected habitat loss, injury or mortality through the project's incident and regulator notification process.
• Implement any approved offset or compensatory measure where residual impacts cannot be avoided or minimised.

Rehabilitation actions: Riparian habitat restoration

Rehabilitation should rebuild dense, connected riparian cover rather than create isolated plantings. Prioritise the vegetation structure and waterway condition used by the western subspecies for shelter, nesting and foraging.

Habitat structure: Dense riparian mid-storey beneath a dense canopy of emergent Eucalyptus and Melaleuca.

Common associated plants: Pandanus aquaticus, Barringtonia acutangula and dense river grass, including Chionachne cyanthopoda in parts of the range.

• Re-establish dense mid-storey vegetation along the waterway, including locally appropriate Pandanus aquaticus, Barringtonia acutangula and native river-grass or canegrass communities where these occur naturally at the site.
• Retain or replant emergent Eucalyptus and Melaleuca trees, which can provide refuge when flooding inundates lower vegetation.
• Use local provenance plants where available and match planting locations to the site's natural water regime.
• Restore continuous vegetation between retained habitat patches so that territories are not further isolated.

Rehabilitation actions: Threat reduction

• Exclude cattle, horses, buffalo, pigs and other feral herbivores from rehabilitated riparian vegetation until it is established and protected from trampling.
• Provide alternative livestock watering points away from rehabilitated riparian areas where stock access is retained nearby.
• Control weeds that replace native riparian vegetation or increase cover for black rats.
• Apply a fire regime that reduces the frequency of intense fires affecting riparian vegetation.
• Use erosion control measures that protect banks and reduce loss of riparian vegetation during large floods.
• Assess and manage feral cat and black rat impacts where monitoring shows predation risk.

Rehabilitation actions: Monitoring and success measures

Survey effort for areas smaller than 50 hectares: Area searches or broadcast surveys, 12 hours over 3 days for each method used.

• Inspect rehabilitated areas after planting and after major floods, fires and grazing events.
• Measure plant survival, native mid-storey cover, structural complexity, weed abundance, bank stability and continuity with retained habitat.
• Use early morning area searches, transects or broadcast surveys to record purple-crowned fairy-wren presence and calls in rehabilitated and reference habitat.
• Set project-specific completion and maintenance criteria in the rehabilitation plan, based on increasing native cover, stable banks, effective herbivore exclusion and no ongoing weed-driven loss of riparian structure.
• Continue monitoring for the period required by approvals and revise weed, grazing, fire or erosion controls when success measures are not met.

Sources

• T, Australian Government DCCEEW: https://www.environment.gov.au/biodiversity/threatened/species/pubs/64442-conservation-advice-31102015.pdf
• Survey guidelines for Australia's threatened birds, Australian Government DCCEEW: https://www.agriculture.gov.au/sites/default/files/documents/survey-guidelines-birds-april-2017.pdf