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Grey Currawong (Strepera versicolor)

The Grey Currawong is a large, mostly sedentary Australian passerine found in forests, woodlands, mallee and adjoining open country across southern Australia and Tasmania. It is not listed under the EPBC Act, but the supplied listing identifies it as Endangered in South Australia. On development sites, retain mature trees, connected woodland and ground foraging habitat, and avoid disturbance to nests during the breeding season.

Conservation status

South Australia, National Parks and Wildlife Act 1972: Endangered.

Breeding season

The species is generally sedentary, with possible winter visits in some south-eastern areas. Breeding timing varies slightly between the broad species account and the Northern Territory account, but breeding activity is concentrated from July to December.

The documents do not identify peak breeding months, incubation length, fledging timing or a defined dispersal period.

  • Breeding: Breeding is reported from July to November in the Northern Territory and from August to December in the broader species account. Nests are built high in trees.
  • Young: Dependent young are expected during the breeding period. Both parents feed the young, but the documents do not give the fledging date or dependency period.
  • Movement or dispersal: The species is generally sedentary but may be a winter visitor in some south-eastern areas. The source does not specify the timing or extent of these movements.
  • Highest clearing risk: Clearing from July to December is most likely to affect nesting adults, eggs or dependent young. Nests may be high and difficult to detect, so mature trees should be checked before removal.

Identification

The Grey Currawong is a large, crow-like passerine with dark plumage, a heavy bill and bright yellow eyes. Plumage varies among the six recognised subspecies, from slate-grey through brownish grey to almost black.

Adults are about 48 cm long on average, with western birds reaching up to 50 cm head to body length. The sexes are similar in size and appearance.

Look for a large dark bird with a heavy black bill, black legs, a bright yellow iris, white patches in the wings and a white tip or band at the end of the dark tail. The wing patch extends from the base of the primary flight feathers towards the outer secondaries.

The species often moves on the ground by hopping or running. Its flight is described as undulating and silent.

Identification: Separating it from similar birds

Compared with other currawongs, the Grey Currawong can be distinguished by its generally paler plumage, the absence of white at the base of the tail, a straighter bill and different vocalisations.

Do not identify the bird from plumage colour alone because colour varies substantially among subspecies. Confirm the combination of body size, yellow eye, heavy bill, white wing markings, white tail tip and call.

Identification: Calls and field signs

The main call is a loud, resonant clinking or ringing sound, with variation among subspecies. Other vocalisations include softer musical calls and insistent squawks associated with begging.

Nests are cup-shaped structures placed on tree branches, usually high in the canopy. The supplied documents do not provide a nest diameter or branch height.

The documents do not describe diagnostic tracks, scats, roost signs or eyeshine. Ground activity and leaf-litter foraging can assist with interpreting direct observations, but these signs should not be treated as species-specific without a visual or acoustic record.

Distribution: States and regions

The Grey Currawong is endemic to Australia and occurs as six subspecies across the southern half of the continent. The supplied sources describe a broad southern distribution, with an historical central Australian and Northern Territory component that is now considered regionally extinct.

The species occurs from around the central coast of New South Wales through most of Victoria, southern South Australia and south-western Western Australia, and in eastern Tasmania.

The western subspecies has been recorded historically from south-western Western Australia across north-western South Australia and into the south-western corner of the Northern Territory.

In the Northern Territory, records were concentrated around the Petermann Ranges. The six database records were from 1969 to 1976, and the assessment concluded that the species is regionally extinct there.

The supplied documents do not provide a complete bioregional distribution for each state. The named regional areas are the Petermann Ranges in the Northern Territory, eastern Tasmania and the south-western, southern and south-eastern parts of mainland Australia described above.

Distribution: Population status

The species is described as having a large and relatively secure distribution in southern Australia, but the supplied documents do not provide a national population estimate or identify named strongholds or discrete subpopulations.

The Northern Territory population declined by 100 percent over the reported historical period and is assessed as regionally extinct. Historical records from the Northern Territory and adjacent arid areas were sparse and at the edge of the species' distribution.

Recognised subspecies: 6

Northern Territory records: 6 database records, from January 1969 to November 1976, with the final record considered doubtful in the assessment

Northern Territory population trend: 100% decline over the last 40 to 50 years before the 2018 assessment

Northern Territory mature individuals: 0 in the assessment

Generation length: About 10 years

Habitat: Habitat types

Grey Currawongs use a range of wooded habitats, including wet and dry sclerophyll forest, woodland, mallee and open country near forest. They also occur in modified wooded environments where suitable trees and food resources remain.

Recorded or described habitats include wet sclerophyll forest, dry sclerophyll forest, mallee scrubland, woodland, pine plantations, parks and farmland adjoining forest.

In central Australia, the species was reported from patches of tall acacia and river red gum woodland on flats near the foot of ranges.

The species is less arboreal than the Pied Currawong and spends substantial time on the ground. Development assessments should therefore consider both tree cover and the leaf-litter and ground-layer habitat beneath it.

Habitat: Structural features

Suitable sites include mature trees for nesting, connected or sufficiently extensive woodland for movement, and intact ground and litter layers that support invertebrate prey.

The documents do not provide a minimum tree diameter, canopy cover threshold, patch size or elevation limit. They also do not define a national habitat association with a particular vegetation community.

  • Retain mature trees and large branch structures wherever practicable.
  • Retain woodland links between cleared areas rather than leaving isolated tree clumps.
  • Protect leaf litter, fallen timber and ground cover where these occur beneath retained woodland.
  • Inspect trees and adjoining ground habitat before clearing, including trees in plantations, parks and farmland margins.

Foraging habitat: Food

The Grey Currawong is an opportunistic feeder that searches both trees and the ground. Its relatively high use of ground habitat is important when planning clearing, access tracks and machinery movements.

The reported diet includes berries, invertebrates and small vertebrates. In central Australia, insects obtained from leaf litter and while foraging on tree trunks were reported as the main food.

The supplied documents do not name particular food plants, quantify prey requirements or provide seasonal food densities.

Foraging habitat: Foraging behaviour

Birds forage on the ground and in trees, and may use different techniques to obtain food. The species has been observed using tools and other techniques to access food.

Individuals are commonly observed alone or in pairs, although larger groups may gather where food is concentrated.

No foraging home-range size, daily travel distance or feeding territory size is provided in the supplied documents.

  • Avoid unnecessary disturbance of leaf litter, fallen timber and ground cover beneath retained trees.
  • Maintain access to both tree canopies and the ground layer around retained woodland.
  • Limit vehicle and machinery activity through occupied woodland, particularly where birds are repeatedly observed feeding on the ground.

Breeding habitat: Breeding biology

Grey Currawongs build nests high in trees. The nesting period overlaps the main clearing and construction planning period in much of Australia, so pre-clearance inspections should include mature trees and canopy observations.

Breeding season: July to November in the Northern Territory account; August to December in the broader species account

Nest: Cup-shaped nest located on a tree branch, usually high in the tree

Clutch size: One to five eggs in the broader account; two to three oval eggs in the Northern Territory account

Incubation: Not reported in the supplied documents

Age at maturity: Not reported in the supplied documents

Lifespan: Not reported in the supplied documents

Parental care: Both parents are involved in feeding the young

Breeding habitat: Nesting habitat

Nests are placed high in trees, so mature trees with suitable branches are the main breeding feature identified by the sources.

The documents do not provide nest-tree species, nest height, tree diameter, nest density or breeding-territory size.

A nest may be difficult to detect from the ground because it is high in the canopy. Absence of a visible nest should not be treated as evidence that a mature tree is unused.

  • Schedule tree clearing outside the July to December breeding period where practicable.
  • Inspect mature trees from multiple viewpoints before removal, including the upper canopy where safe access and visibility allow.
  • Use an appropriately qualified fauna spotter catcher if a nest, incubating bird, dependent young or repeated territorial activity is detected.
  • Establish a site-specific exclusion area around an active nest based on the activity, visibility and disturbance source.

Sheltering habitat: Known shelter features

The supplied documents identify high tree branches as nesting sites but provide little information on roosts or other shelters. Grey Currawongs also spend substantial time on the ground while foraging.

The only described structure used directly by the species is the high tree branch supporting the cup-shaped nest.

The documents do not report communal roosts, tree hollows, nest cavities, burrows, rock shelters or specific night-roost structures.

Tall acacia and river red gum woodland on flats near ranges was associated with historical Northern Territory records, but the source does not state whether these trees were used for roosting, nesting or feeding.

Sheltering habitat: Site protection measures

Retain mature trees, canopy connections and ground cover in occupied woodland. These features provide the known nesting structure and the ground habitat used during foraging.

Because shelter requirements other than nesting are not documented, avoid removing additional trees or ground cover around confirmed activity unless the ecological need and disturbance controls have been assessed.

  • Check mature trees for nests before felling, trimming or heavy machinery access.
  • Keep retained trees free from avoidable branch damage and soil compaction around their root zones.
  • Maintain undisturbed ground cover and leaf litter beneath retained woodland where practicable.

Threats: Habitat loss and degradation

The strongest documented threats are habitat loss and degradation, reduced food availability, altered fire regimes and introduced predators. Evidence for roads, disease and hydrology change is not provided in the supplied documents.

Clearing of woodland and forest can remove nesting trees, feeding habitat and movement links. Habitat degradation may also reduce food availability.

In the Northern Territory assessment, habitat degradation affected the entire former Northern Territory range and was considered to have an extreme potential impact.

Feral herbivores, including camels, horses and rabbits, were identified as possible contributors to habitat degradation. Weeds, including buffel grass, were identified as encroaching into formerly suitable areas.

  • Avoid clearing mature trees and connected woodland where an alternative alignment or work method is available.
  • Stage clearing so that retained habitat remains connected and ground foraging areas are not isolated.
  • Control machinery access and weed spread in retained woodland and along habitat edges.

Threats: Fire and food supply

The Northern Territory assessment identifies major changes in fire regimes following the loss of traditional burning practices as a likely cause of habitat change.

Changes in fire frequency, intensity or timing may alter woodland structure, leaf litter and invertebrate availability. The supplied documents do not define a preferred fire regime for the species.

  • Protect retained woodland and mature nesting trees from avoidable construction-related fire.
  • Include leaf litter, fallen timber and ground-layer condition in post-fire habitat inspections.

Threats: Predators and other pressures

Feral cats and foxes were identified as potential predators. Ground foraging may increase exposure to these predators.

The supplied documents do not identify disease as a threat and do not provide evidence for impacts from roads, vehicle strike or hydrology change.

  • Do not leave food waste or other attractants around work areas that could increase feral predator activity.
  • Reduce unnecessary night lighting and night-time activity near retained woodland where practicable.
  • Record any predator observations, carcasses or repeated vehicle interactions during construction monitoring.

Survey methodology: 1. Habitat assessment and records search

Use habitat assessment and targeted bird searches to establish whether Grey Currawongs use the site before clearing. The supplied documents do not provide a species-specific survey protocol, so apply general bird survey practice and record the methods and conditions clearly.

Map all forest, woodland, mallee, wet and dry sclerophyll vegetation, pine plantations, farmland edges and open areas adjoining forest within and around the works footprint.

Search current state wildlife databases and the Atlas of Living Australia for Grey Currawong records before field work, noting that the species is generally sedentary but may be a winter visitor in some south-eastern areas.

Check for likely feeding and nesting habitat, including mature trees, tree branches suitable for nests, leaf litter, tree trunks, berries, invertebrate-rich ground cover and small vertebrate prey.

Treat records of the six subspecies separately where possible, because plumage, size and distribution vary between subspecies.

Survey methodology: 2. Diurnal searches and call detection

Undertake repeated searches on foot through suitable habitat, including retained vegetation, edges and areas proposed for clearing.

Search from ground level and scan tree canopies for the large, dark bird, yellow eye, heavy bill, white wing and undertail patches and white tail tip described for the species.

Listen for the distinctive clinking or ringing call and record the direction, time and location of each detection.

Give particular attention to ground foraging areas because Grey Currawongs spend more time on the ground than Pied Currawongs and may forage in leaf litter and on tree trunks.

Record birds seen alone, in pairs or in feeding groups, and map all observations with the habitat used.

Typical body length: About 48 cm, with head to body length reported up to 50 cm

Breeding season reported in the sources: July to November in central Australia, and August to December in a general species account

Survey methodology: 3. Targeted breeding and nest searches

During the breeding period relevant to the region, inspect mature trees and upper branches from a safe ground position for cup-shaped nests and adult birds carrying food.

Plan repeat observations because nests are high in trees and breeding habits are not well documented.

Do not climb, handle or disturb a suspected nest unless this is authorised under the project fauna management plan and relevant state requirements.

Record the tree location, nest height if it can be estimated safely, nest activity, adult behaviour and the distance from the proposed disturbance.

Eggs reported: Two or three eggs in central Australia, and one to five eggs in the general species account

Nest position: A cup-shaped nest on a tree branch, generally high in the tree

Survey methodology: 4. Detection conditions and survey coverage

Survey during calm conditions with good visibility and avoid periods of heavy rain or strong wind that reduce visual and call detection.

Cover the full disturbance footprint, access tracks, temporary work areas, laydown areas and nearby retained habitat that may receive displaced birds.

Use fixed transects or mapped search areas and record the area searched, start and finish times, observers, weather, vegetation type and any constraints.

Where Grey Currawongs are detected, repeat searches across different days and, where relevant, different seasons to distinguish a single passage record from regular site use.

Survey methodology: Minimum effort and reporting

  • Use a documented, repeatable diurnal search design that covers all suitable habitat in the disturbance footprint and nearby retained habitat; the supplied documents do not prescribe a minimum number of transects, nights or hours for this species.
  • Do not rely on spotlighting, call playback, trapping or mist-netting as the primary method because the supplied sources describe a large, distinctive diurnal bird and provide no species-specific justification for those methods.
  • Record every detection, including zero-detection results, with coordinates, date, time, observer, weather, behaviour, number of birds, habitat and photographs or sound recordings where available.
  • Report any active nest, repeated use of a site, injured bird or likely breeding territory immediately to the project ecologist and environmental officer.
  • Submit confirmed records and suitable evidence to the relevant state wildlife database and the Atlas of Living Australia, subject to project and database requirements.
  • Retain survey maps, effort logs, photographs, call recordings, database submission references and clearance decisions in the project environmental records.

Before habitat disturbance: Avoid and minimise

Plan the works around confirmed habitat use and avoid removing mature trees or connected woodland where practicable. Grey Currawongs use forests, woodlands, mallee, plantations and open areas adjoining forest, and forage both on the ground and in trees.

  • Retain mature trees, large branches, connected woodland, forest edges and ground cover that provide nesting, feeding and movement habitat.
  • Retain leaf litter and undisturbed ground where practicable because the species forages on the ground and in leaf litter.
  • Keep retained habitat connected to nearby woodland or forest rather than creating isolated remnants where the design allows.
  • Avoid disturbance to any active nest and establish a site-specific exclusion area approved by the project ecologist and relevant authority.
  • Place compounds, access tracks, stockpiles and temporary lighting outside retained habitat and known feeding or nesting areas.

Before habitat disturbance: Approvals and timing

  • Check the current EPBC Act status, state or territory listing and project approval conditions before works start; the species is recorded as not listed under the EPBC Act in the supplied sources, while state treatment varies between jurisdictions and the supplied South Australian status must be verified against the current state register.
  • Obtain any required state fauna, wildlife, clearing or nest disturbance permits before handling birds or disturbing nests, hollow-bearing trees or other habitat features.
  • Schedule clearing outside the locally relevant breeding period where practicable, noting breeding periods of July to November and August to December are reported in the supplied sources.
  • Stage clearing so that retained woodland and escape routes remain available while works progress.
  • Include species-specific controls, stop-work triggers, authorised handlers, reporting lines and rehabilitation commitments in the fauna management plan.

Before habitat disturbance: Site preparation

  • Complete a pre-clearance survey immediately before works, with additional checks for active nests and birds using trees, ground cover and forest edges.
  • Mark retained trees, active nests, exclusion areas, movement corridors and no-go habitat on site plans and in the field.
  • Install exclusion fencing where it can keep machinery and people out without blocking the bird's movement between retained habitat areas.
  • Brief machinery operators and the fauna spotter catcher on the species' appearance, yellow eye, heavy bill, white wing and undertail patches, ringing call and ground-foraging behaviour.
  • Confirm the location of the nearest suitable retained habitat, wildlife carer and veterinary service before clearing begins.

During habitat disturbance: Daily controls and machinery interface

Use a fauna spotter catcher to control the immediate risk from machinery and to manage unexpected fauna encounters. Grey Currawongs may be on the ground, in trees or near forest edges, so checks must cover both work faces and retained habitat.

  • Complete a fauna and nest check at the start of each shift and after breaks, weather changes, machinery moves or any unplanned disturbance.
  • Keep the fauna spotter catcher ahead of the clearing face and within clear communication range of the operator.
  • Stop machinery before the spotter catcher enters the exclusion zone or gives a stop signal.
  • Clear progressively in a direction that allows birds to move towards retained habitat, where safe and consistent with the approved clearing method.
  • Keep machinery, workers, vehicles, noise and lighting away from marked nests and exclusion areas.
  • Do not allow workers to chase, corner, feed or photograph a bird at close range.

During habitat disturbance: Habitat feature handling

  • Inspect mature trees and upper branches for nests before felling, limb removal or pruning.
  • Retain trees with active nests and apply the approved exclusion area until the nest is confirmed inactive by an authorised person.
  • Inspect logs, branches, leaf litter, rocks and ground cover before they are moved because Grey Currawongs forage on the ground and in leaf litter.
  • Move habitat features only when authorised by the fauna management plan and place them in nearby retained habitat where they will not obstruct fauna movement or create a work hazard.
  • Protect retained woodland edges and do not use them as unapproved spoil, equipment or material storage areas.

During habitat disturbance: Fauna encounter and stop-work response

  • Stop work if a Grey Currawong is within the machinery work zone, shows signs of injury, is trapped, is repeatedly unable to leave, or is associated with a suspected active nest.
  • Allow an able-bodied bird to leave naturally towards nearby retained habitat without pursuit or handling.
  • Only an appropriately authorised and experienced person may capture or handle the bird, and handling must follow the permit, fauna management plan and state requirements.
  • Relocate a captured bird only to nearby suitable retained habitat approved by the project ecologist, and do not move it long distances or across unsuitable habitat without specific authorisation.
  • Place an injured bird in a dark, ventilated container with minimal handling and transfer it promptly to a veterinarian or licensed wildlife carer.
  • Escalate any nest, repeated site use, mortality, injury or unauthorised habitat disturbance to the project environmental officer and record the decision before work resumes.

During habitat disturbance: Records and release to work

  • Record the date, time, location, bird condition, behaviour, habitat, action taken, handler, release location and outcome for every encounter.
  • Record all stop-work events, nest checks, exclusion-zone checks, injuries, mortalities, relocations and machinery breaches.
  • Resume work only after the fauna spotter catcher and project ecologist confirm that the relevant risk has been controlled and any required authority has been notified.
  • Submit reportable wildlife records and any required incident reports to the relevant state or territory authority.

After habitat disturbance: Post-clearance checks

Check the cleared area and retained habitat after each work stage. Use the results to correct controls before the next stage and to identify whether Grey Currawongs continue to use the site.

  • Inspect the completed clearing area, retained trees, forest edges and nearby habitat for stranded, injured or dead birds after each clearing stage.
  • Recheck marked nest trees and exclusion areas after machinery leaves to confirm that they remain intact and undisturbed.
  • Remove temporary hazards such as exposed wire, unsecured netting, open pits and waste that could trap or injure birds.
  • Confirm that access tracks, compounds and stockpiles have not encroached into retained habitat or blocked movement between habitat patches.

After habitat disturbance: Monitoring and reporting

  • Repeat mapped diurnal searches in retained habitat where pre-clearance surveys recorded Grey Currawongs or where clearing removes nearby feeding or nesting habitat.
  • Monitor active or recently used nest trees for the period specified in the approved fauna management plan and relevant permit.
  • Compare post-work observations with pre-clearance records, including bird numbers, behaviour, habitat use and any change in site occupancy.
  • Report survey results, incidents, injuries, mortalities, nest outcomes, corrective actions and database submissions in the project environmental report.
  • Maintain exclusion fencing, signage and habitat protection controls until the project ecologist confirms that they are no longer required.

After habitat disturbance: Residual impacts and offsets

  • Assess residual loss of mature trees, woodland, forest edge, feeding ground and connectivity against approval conditions and the applicable state or territory offset policy.
  • Implement any required offset, restoration or compensatory habitat measure through the approval holder and record its location, area, tenure, management actions and monitoring requirements.
  • Do not treat an offset as a substitute for retaining active nests or avoiding practicable direct impacts during construction.

Rehabilitation actions: Restore vegetation and structure

Rehabilitate cleared areas to restore connected woodland and forest structure used for nesting, feeding and movement. Grey Currawong habitat includes wet and dry sclerophyll forest, mallee, plantations and open areas adjoining forest.

  • Replant locally appropriate native trees and shrubs that match the pre-clearing forest or woodland community and provide mature branches, canopy cover, berries and insect habitat over time.
  • Reconnect isolated retained patches with native vegetation where the project footprint has created a break between woodland or forest areas.
  • Retain and redistribute suitable logs, large branches, leaf litter and other ground cover from the cleared area where this is safe and consistent with the rehabilitation design.
  • Do not remove naturally regenerating shrubs or ground cover solely to create a tidy site if they support foraging habitat.

Rehabilitation actions: Nests, trees and fauna features

  • Protect retained mature trees and allow replacement trees to develop into future nesting and feeding habitat.
  • Install nest boxes only where a habitat assessment identifies a genuine shortage of suitable nesting features and the project ecologist selects, positions and monitors them for local birds.
  • Do not assume that nest boxes replace the retention of mature trees or active nests.
  • Restore forest edges with gradual native vegetation transitions rather than abrupt cleared boundaries where space allows.

Rehabilitation actions: Threat and fire management

  • Control weeds and prevent weed encroachment into restored woodland, noting that the supplied source identifies buffel grass as a concern in the central Australian context.
  • Manage introduced herbivores and other ground-disturbing pressures where they threaten habitat recovery.
  • Design fire management with the relevant land manager and local ecological advice, considering the source's concern that changed fire regimes and the loss of traditional burning practices may degrade habitat.
  • Control feral cats and foxes where an approved predator management programme applies, because the species spends considerable time foraging on the ground and may be exposed to these predators.

Rehabilitation actions: Monitoring and success measures

  • Monitor plant establishment, weed cover, ground cover, tree survival, connectivity and the condition of retained and reinstated habitat against the approved rehabilitation baseline.
  • Undertake repeat diurnal bird searches using the same mapped methods as the pre-clearance survey and record Grey Currawong presence, number, behaviour and habitat use.
  • Treat successful rehabilitation as meeting the approved vegetation and habitat targets while maintaining safe access and avoiding new fauna hazards.
  • Continue monitoring until the project ecologist and approval authority agree that the rehabilitation targets have been met, and submit the results through the required project and government reporting channels.

Sources