Northern Nail-tail Wallaby (Onychogalea unguifera)

Conservation status

Northern Territory, Territory Parks and Wildlife Conservation Act 1976: Near threatened.

Breeding season

Breeding is reported as year-round in captivity, and the supplied documents do not provide reliable months for births, pouch emergence or dispersal in wild Northern Nail-tail Wallabies. The calendar therefore marks year-round potential activity and year-round clearing risk rather than a defined seasonal peak.

Month ratings are a precautionary planning guide based on the supplied information, not a confirmed wild breeding calendar.

• Breeding: No distinct breeding season is reported. Breeding is described as occurring throughout the year in captivity.
• Young: Females carry young in a pouch, but the timing of pouch young, emergence and dependence is not stated for this species.
• Movement and feeding: The species is generally solitary, feeds mainly at dusk and night, and moves between daytime cover and grassland. No seasonal migration or dispersal period is documented.
• Highest clearing risk: Risk is treated as year-round because breeding may occur throughout the year and the timing of dependent young is not known. Clearing can also remove feeding grassland and daytime refuge at any time.

Identification

The Northern Nail-tail Wallaby is a sandy-coloured wallaby with a distinctive dark dorsal stripe and a small keratin nail at the end of the tail. It is most likely to be detected at dusk, at night or around grassland and woodland edges.

The coat is sandy ginger, with pale underparts and pale cream cheek and flank stripes. A dark stripe runs from the lower neck along the back towards the tail, which has a dark tuft near its end. The ears are long and greyish, and the forearms are short relative to the body.

• Check the tail tip for the 3 to 6 mm keratin nail or horn, the defining field feature of the genus.
• Use the combination of sandy colouration, dark dorsal stripe, dark tail tuft and long tail when the tail tip cannot be inspected.

Identification: Size and sex

Males are larger and heavier than females. Adult males can reach 690 mm head and body length, 730 mm tail length and 9 kg. Adult females can reach 600 mm head and body length, 650 mm tail length and 7 kg.

Male head and body: 540 to 690 mm

Female head and body: 490 to 600 mm

Male weight: 6 to 9 kg

Female weight: 4.5 to 7 kg

• Visible testicles and larger forelimbs indicate a male.
• A pouch indicates a female, although the pouch may not be visible in a free-ranging animal.

Identification: Field detection

The supplied documents provide little species-specific information on tracks, scats, nests, burrows or eyeshine. The animal is described as timid and flighty, and may be difficult to observe directly.

• Search grass tussocks, grassland edges and adjacent woodland or shrubland during late afternoon, dawn and night activity periods.
• Treat a direct sighting as more reliable than an unverified macropod record, and photograph the tail tip, dorsal stripe and habitat where safe to do so.
• Record grunting vocalisations if heard. Grunting is reported from captive animals, but the documents do not establish its reliability as a field survey cue.

Distribution: States and bioregions

The species occurs across tropical northern Australia, in Western Australia, the Northern Territory and Queensland. Its broad range extends from the northern coast towards the 500 mm annual rainfall isohyet, with a further inland extension in north-western Australia.

In Western Australia, records and suitable habitat include the Kimberley, including the East and West Kimberley regions. In the Northern Territory, habitat includes the Barkly Tablelands, the Gulf region and central northern woodland and shrubland areas. In Queensland, the Gulf region is identified as habitat.

• Map records and habitat separately for the Kimberley, Barkly Tablelands, Gulf region, coastal plains and inland north-western areas.
• Do not assume that all of Arnhem Land or the Kimberley is suitable. The source describes avoidance of higher rainfall areas in Arnhem Land and the Kimberley.

Distribution: Records and population information

The supplied material does not provide a national population estimate, defined subpopulations or a reliable population density. A desktop database search for the Elliott Project recorded 33 Northern Nail-tail Wallaby sightings in two tenements, but this is a record count and not a population estimate.

Elliott Project database records: 33 sightings in tenements EL27186 and EL27544

National population size: Not stated in the supplied documents

Documented trend: Little evidence of broad distribution or abundance decline, with a reported exception in the West Kimberley; current population trend remains poorly known

• The source reports little evidence of a decline in geographical distribution or abundance during the last century, except in the West Kimberley, but also notes limited recent research.
• Treat local records as evidence of use of the project area rather than evidence that the species is common or secure there.

Habitat: Vegetation communities

Northern Nail-tail Wallabies occupy open, relatively dry tropical habitats where tussock grass, herbs and low vegetation occur beside woodland or shrub cover. They commonly use ecotones between sandy loams and clay.

Recorded habitat includes open woodland with a tussock grass understorey, tall grassland, shrubland with scattered trees or shrubs, and coastal plains with scattered Melaleuca thickets. Central Northern Territory examples include Coolabah and Eucalyptus microtheca open woodland, and Lancewood, Acacia shirleyi and Bullwaddy shrubland.

• Retain connected patches of tussock grassland and adjacent woodland or shrubland.
• Pay particular attention to the edges of black-soil plains, where tussock grassland meets woodland or shrubland.
• Avoid treating scattered trees and shrubs as low-value habitat. They provide daytime cover beside feeding areas.

Habitat: Climate and site structure

Most of the range lies between the northern coast and the 500 mm rainfall isohyet, with an inland extension in north-western Australia. The species tends to avoid higher rainfall areas of Arnhem Land and the Kimberley. No elevation limit is provided in the supplied documents.

Rainfall context: Main range lies between the northern coast and the 500 mm rainfall isohyet

Elevation: Not stated in the supplied documents

Key habitat boundary: Ecotones between sandy loams and clay

• Assess sandy loam to clay transitions, open grassy areas and nearby dense cover as one habitat unit.
• Record the condition and continuity of tussock grass, low shrubs, scattered trees and Melaleuca thickets before clearing.

Foraging habitat: Food and feeding sites

The species feeds mainly on plant material rather than animal prey. It moves from daytime cover into grassland and other open areas to feed, usually around dusk, night and dawn.

The diet is described as specialist feeding on herbs, succulents, vines and fruits, although the species is also classified in the source as a true grazer and eats grass. It may feed alone or in groups of up to four.

Main foods: Herbs, succulents, vines and fruits

Additional food: Grass

Feeding group size: Usually solitary, with groups of up to four reported when feeding

• Survey herbs, succulents, vines, fruits and grass tussocks within and beside proposed clearing areas.
• Give particular attention to grassland on black-soil plains, coastal plains and woodland or shrubland edges.
• Retain access between daytime woodland or shrub cover and nearby feeding grassland.

Foraging habitat: Foraging movement

The species shelters in adjacent woodland or shrubland during the day and moves to grasslands to feed at night. The supplied documents do not provide a home range, foraging distance or feeding density.

Known foraging period: Mainly dusk, night and dawn

Home range or foraging distance: Not stated in the supplied documents

• Schedule noisy or high-intensity works away from retained feeding habitat where possible during dusk, night and dawn activity periods.
• Keep habitat connections open between grassland and adjacent cover, rather than retaining isolated grass patches.

Breeding habitat: Breeding facts

Basic breeding biology of the Northern Nail-tail Wallaby is poorly documented. The husbandry source states that it can breed throughout the year in captivity, but several details are based on general macropod information or guidance from the related Bridled Nail-tail Wallaby and should not be treated as species-specific field measurements.

The species is reported to breed readily in captivity when compatible pairing, suitable environmental conditions and managed feeding are provided. There is no distinct breeding season reported in the supplied material.

Breeding season: No distinct season reported; breeding is described as occurring throughout the year in captivity

Litter size: Not stated for Northern Nail-tail Wallaby in the supplied documents

Gestation: Not stated for Northern Nail-tail Wallaby in the supplied documents

Age at maturity: Not stated in the supplied documents

Lifespan: Wild longevity is not recorded in the source. Captive longevity for the genus Onychogalea is reported as 6 to 10 years

Reproductive certainty: Species-specific field data are limited

• Treat all months as potentially containing mating, pouch young or recently independent young because breeding is reported as year-round.
• Do not use the related Bridled Nail-tail Wallaby as a substitute for confirmed Northern Nail-tail Wallaby reproductive data.

Breeding habitat: Breeding habitat and young

Females carry young in a pouch. The documents do not describe a breeding den, nest or specific birth site. Habitat that combines feeding grassland with nearby woodland, shrubland, tussock cover and refuge sites is the best-supported breeding habitat description.

• Retain dense grass tussocks and low cover near open feeding areas.
• Inspect vegetation scheduled for clearing for females with pouch young or recently emerged young, and follow approved animal welfare and spotter catcher procedures.
• Manage male access and provide refuge during captive breeding, as males may injure young females; this husbandry observation is not a wild population measure.

Sheltering habitat: Known refuges

Daytime shelter is provided by grass scrapes and cover in woodland or shrubland beside feeding areas. The supplied documents do not identify burrows, hollows or fixed den structures for this species.

The species rests in grass scrapes during the day. In natural habitat it shelters in adjacent woodland or shrubland and uses tussock grassland, shrubs and scattered trees for cover.

• Retain grass scrapes, dense tussocks, low shrubs and connected woodland or shrubland within and beside the work area.
• Search cover before clearing, particularly where grassland is directly adjacent to woodland, shrubland or Melaleuca thickets.
• Use gradual, supervised vegetation removal and fauna spotter catcher controls where suitable habitat is present.

Sheltering habitat: Structures not documented

No dimensions are given for grass scrapes, and no species-specific use of hollows, burrows, caves, nests or dens is reported. The animal is terrestrial and the supplied sources do not identify a fixed refuge size.

Known daytime refuge: Grass scrapes and adjacent woodland or shrubland

Refuge dimensions: Not stated

Burrows, hollows and nests: No species-specific use reported in the supplied documents

• Do not assume that the absence of a visible den means the area is unused.
• Record the location, cover type and condition of any occupied or recently used grass scrape or refuge found during pre-clearance checks.

Threats: Clearing and fragmentation

The Northern Nail-tail Wallaby is Near Threatened in the Northern Territory despite being broadly distributed and not EPBC listed. Clearing and loss of connected grassland, woodland and shrub cover are the main project-level concerns identified by its habitat requirements.

Clearing can remove tussock grassland used for feeding, grass scrapes used for daytime shelter and adjacent woodland or shrubland used as cover. Fragmenting these habitat components can interrupt movement between shelter and feeding areas.

• Avoid clearing habitat mosaics at woodland, shrubland and grassland edges.
• Retain connected corridors between open feeding areas and daytime refuge.
• Map all suitable habitat and direct impacts before works begin, not only areas where animals are sighted.

Threats: Fire, grazing and introduced predators

The supplied documents note poorly represented habitat in some managed Northern Territory parks and possible population decline there. They also identify cats and foxes as threats to northern Australian wildlife, particularly when rainfall produces more vegetation and prey resources for invasive predators. The documents do not quantify the effect of fire or grazing on this species.

• Assess recent fire history, grazing pressure and the availability of intact tussock cover before clearing.
• Avoid creating additional refuge loss or easy predator access through narrow isolated habitat remnants.
• Record cats, foxes and signs of grazing during fauna surveys and pre-clearance inspections.

Threats: Roads, hydrology and disease

The supplied documents do not provide species-specific evidence for road mortality, disease or hydrology change. Roads and altered drainage can still remove or divide the grassland and woodland habitat used by the species, so these impacts should be assessed at the project scale.

• Check road alignments, borrow pits, drains and altered water flow for loss or division of tussock grassland and adjacent cover.
• Use project fauna management controls for vehicle speed, night works and animal encounters where wallabies are recorded.
• Do not infer that the species is secure from its non-listing under the EPBC Act or from a broad distribution.

Survey methodology: 1. Nocturnal and crepuscular searches

Survey the Northern Nail-tail Wallaby where works may remove or fragment open woodland, tussock grassland, shrubland or coastal plain habitat. The supplied documents do not provide a formal project survey guideline or prescribed effort, so the methods below apply species ecology and must be scaled to the project footprint, risk and approval conditions.

Search from late afternoon through the first hours after dark, when the species feeds, and include dawn searches where access and safety allow.

Use vehicle or pedestrian spotlighting along habitat edges, access tracks and transects through open woodland, tussock grassland, shrubland and Melaleuca plain habitat.

Record the number of observers, start and finish times, route length, weather, moon conditions, spotlight type and area covered for every search.

The species is generally solitary and nocturnal, but may occur in groups of up to four when feeding, so record every animal separately where possible and note group size.

Typical activity: Feeding at dusk and dawn, with nocturnal activity also reported.

Group size reported in the supplied material: Usually solitary, with groups of up to four when feeding.

Survey methodology: 2. Habitat and sign inspection

Inspect ecotones between sandy loams and clay, open woodland with tussock grass, shrubland with scattered trees or shrubs, and coastal plains with scattered Melaleuca thickets.

Search adjacent shelter and feeding areas together, because the species shelters in woodland or shrubland by day and moves into grassland to feed at night.

Map records of wallabies, tracks, scats, feeding areas, grass scrapes and likely shelter sites, but treat signs as supporting evidence unless confirmed by a suitably experienced observer or camera record.

Use motion cameras at likely travel routes, feeding areas and habitat edges where spotlighting is impractical or where repeated detection is needed.

Survey methodology: 3. Targeted searches and detection records

Use repeated targeted searches when the first visit does not detect the species but suitable habitat is present, because the species is timid, difficult to observe and poorly studied.

Give priority to the edges of black soil plains and tussock grasslands, including the Barkly Tablelands and Gulf region habitat types described in the supplied material.

Do not treat a failure to detect the species as evidence of absence where suitable habitat remains connected to nearby woodland, shrubland or grassland.

If trapping, handling or camera deployment is proposed, obtain the required animal ethics, scientific or wildlife permits and use an approved macropod method operated by authorised personnel.

Survey methodology: Minimum effort and reporting

• Prepare a project-specific survey design that states the search area, number of visits, search duration, route length, observer effort and detection conditions, because the supplied documents do not prescribe nights, hours, trap nights, transect lengths or camera deployment periods.
• Survey all suitable habitat within the disturbance footprint and representative connected habitat that may be used for relocation or connectivity assessment.
• Repeat searches when rain, heat, access, visibility or construction activity is likely to reduce detection, and document the reason for any change in effort.
• Submit confirmed records, negative survey results where required, locations and associated habitat information to the relevant Northern Territory, Western Australian or Queensland wildlife database and to the project approval database.
• Report the species as Northern Nail-tail Wallaby, Onychogalea unguifera, and retain photographs, coordinates, date, time, observer and identification basis with each record.

Before habitat disturbance: Avoid and minimise habitat loss

Avoid clearing suitable habitat first, then reduce the area, duration and intensity of disturbance. The Northern Nail-tail Wallaby uses connected open woodland, tussock grassland and shrubland, and can move between daytime shelter and nocturnal feeding areas.

• Retain open woodland and shrubland shelter areas beside tussock grassland and other feeding areas.
• Retain ecotones between sandy loams and clay, edges of black soil plains, coastal plains with Melaleuca thickets and connected grassland patches.
• Keep habitat corridors between retained woodland, shrubland and grassland, and avoid creating isolated retained patches.
• Keep clearing footprints, access tracks, laydown areas and night lighting outside retained habitat wherever practicable.
• Do not assume that habitat is unimportant because the species is listed as Least Concern nationally; it is listed as Near Threatened in the Northern Territory and has recorded population concerns in parts of its range.

Before habitat disturbance: Approvals and work planning

Commonwealth status in the supplied project material: Least Concern, not listed as threatened under the EPBC Act in the supplied material.

Northern Territory status: Near Threatened.

• Confirm the current EPBC Act status before works commence and complete an EPBC referral or other Commonwealth assessment if the current law or project impacts require it.
• Check the wildlife, clearing, scientific, animal ethics and threatened species requirements in the state or territory where the project occurs.
• Prepare a fauna management plan that identifies survey results, retained habitat, spotter catcher roles, stop-work triggers, relocation sites, injury response and reporting arrangements.
• Stage clearing so that retained habitat remains available and connected until each work area has been searched and released.
• Schedule the highest risk clearing outside periods of greatest local activity where the project ecologist identifies a seasonal risk, noting that the supplied documents do not define a breeding season for this species.

Before habitat disturbance: Pre-clearance preparation

• Complete a pre-clearance inspection and targeted search immediately before clearing, with the timing and effort specified in the approved fauna management plan.
• Mark retained woodland, shrubland, tussock grassland, Melaleuca thickets, habitat edges, shelter sites, access routes and relocation areas before machinery enters the site.
• Install exclusion fencing where it can safely prevent entry into retained habitat, and inspect fencing daily for gaps, trapped animals and movement paths.
• Brief machinery operators on the species' sandy colour, dark dorsal stripe, dark tail tuft and nail at the tail tip so they can report sightings promptly.
• Plan a quiet holding and treatment area that allows authorised personnel to assess an animal without contact with machinery or visitors.

During habitat disturbance: Daily controls and machinery coordination

Keep a fauna spotter catcher in direct communication with the clearing crew. Stop work when an animal is found or when clearing exposes an unmanaged risk, and resume only after the authorised fauna lead releases the area.

• Conduct a pre-start inspection of the work area, exclusion fencing, retained habitat and known shelter or feeding sites each day.
• Use a staged clearing direction that allows an animal to move towards retained connected habitat rather than into active work areas, roads or isolated vegetation.
• Require the spotter catcher to remain where they can see the active clearing face and maintain radio contact with the operator and supervisor.
• Use low speed and short clearing stages around habitat edges, tussock grass, shrubland, Melaleuca thickets and other areas identified during pre-clearance checks.
• Stop machinery immediately on a sighting, injury, entrapment, unexpected shelter site, blocked escape route or breach of the approved fauna management plan.

During habitat disturbance: Animal encounters and handling

• Keep people, vehicles and dogs away from the animal and allow an uninjured wallaby to move to nearby retained habitat where safe.
• Only an authorised and suitably trained fauna handler may capture, restrain, transport or release the animal, under the relevant permit and project procedure.
• Do not chase the animal through dense vegetation or force it into contact with machinery, fencing, steep edges or water.
• Release an uninjured animal into nearby retained habitat that provides woodland or shrubland shelter and access to suitable grassland or other feeding habitat, subject to the approved relocation plan.
• Take an injured animal to an approved veterinarian or wildlife carer as soon as practicable, and record the injury, treatment, destination and outcome.
• Avoid the hind legs and feet during handling because they are powerful, and use appropriate personal protective equipment because the animal can scratch or bite when stressed.

During habitat disturbance: Habitat features and stop-work records

• Inspect grass scrapes, dense tussocks, logs, rocks, debris, depressions and other shelter features before they are disturbed, even though the supplied documents do not identify a species-specific den or nest feature.
• Do not remove a habitat feature containing an animal until the fauna lead has assessed it and approved a safe method of inspection or relocation.
• Treat any live Northern Nail-tail Wallaby, dependent young, injured animal or repeated sign within the active footprint as a stop-work trigger.
• Record the date, time, location, work activity, machinery, observers, animal condition, photographs, actions taken, relocation point, permits and release or treatment outcome.
• Notify the project ecologist and relevant regulator of any death, serious injury, repeated capture, unauthorised clearing or failure of exclusion controls.

After habitat disturbance: Post-clearance checks

Confirm that each work area is clear, retain fauna controls while the disturbance risk remains, and check whether the project has reduced access between shelter and feeding habitat.

• Complete a final systematic inspection of the cleared area, stockpiles, trenches, culverts, drains, fencing and machinery before the area is released to the construction team.
• Check retained woodland, shrubland, tussock grassland and Melaleuca habitat for animals displaced during clearing and for breaches in exclusion fencing.
• Backfill or cover trenches and pits at the end of each shift where practicable, or provide safe escape points and inspect them daily.
• Remove temporary fauna fencing only after the fauna lead confirms that construction no longer creates an entrapment or access risk.

After habitat disturbance: Monitoring and reporting

• Monitor retained habitat and relocation areas using the same approved detection methods and comparable effort used during pre-clearance surveys.
• Record sightings, road mortality, injured animals, carcasses, new tracks, habitat use and any change in connectivity during construction and the agreed operational monitoring period.
• Submit records and incident reports to the relevant state or territory wildlife database and regulator where required by approval or permit conditions.
• Review monitoring results with the project ecologist and change lighting, fencing, traffic controls or work staging if animals continue to enter the work area.

After habitat disturbance: Offsets and residual impacts

• Assess residual loss or fragmentation of suitable habitat under the applicable Commonwealth, state or territory offsets policy.
• Use any required offset or conservation measure to protect habitat that contains the same combination of woodland or shrubland shelter and grassland or other feeding habitat.
• Document why avoidance, minimisation and rehabilitation measures were insufficient before relying on an offset.

Rehabilitation actions: Restore habitat structure and food resources

Rehabilitation should restore the linked shelter and feeding habitats used by the Northern Nail-tail Wallaby. It should match local reference habitat and be checked until vegetation, access and fauna use are established.

• Re-establish open woodland, shrubland, tussock grassland and habitat edges appropriate to the local Northern Australian setting.
• Use locally appropriate native plants identified in the supplied husbandry material where they match the project site's original vegetation, including Acacia eriopoda, Acacia tumida, Acacia monticola, Grevillea wickhamii, Grevillea refracta, Triodia pungens, Megathyrsus maximus, Corymbia zygophylla and Ficus opposita.
• Retain or reinstate a mosaic of shaded shelter and open feeding areas rather than planting a uniform dense cover.
• Do not plant Jatropha gossypiifolia, which the supplied material identifies as toxic and invasive for this species' exhibit setting.
• Control weeds that replace tussock, herb, vine, succulent or fruit resources, and prevent rehabilitation works from increasing feral cat or fox access.

Rehabilitation actions: Reinstate shelter, connectivity and fire management

• Reinstate natural ground cover, grass tussocks, logs and other locally occurring shelter features removed by the project, where this is safe and consistent with the reference habitat.
• Reconnect retained woodland or shrubland with grassland and shrubland patches through planted or naturally regenerating corridors.
• Do not install hollow-bearing trees, nest boxes or wetland features as a default measure for this species, because the supplied documents do not identify them as Northern Nail-tail Wallaby habitat requirements.
• Use a site-specific fire management plan that maintains tussock and woodland structure, avoids repeated intense fire across all retained feeding and shelter habitat, and is approved by the relevant land manager.

Rehabilitation actions: Success measures and follow-up

• Set measurable rehabilitation targets for native plant establishment, tussock cover, weed cover, corridor continuity, erosion control and safe access between shelter and feeding habitat.
• Inspect rehabilitation after wet and dry seasons and after fire, flooding or major maintenance works, with the monitoring period set by approval conditions and project risk.
• Use spotlighting, camera monitoring and sign searches to test whether Northern Nail-tail Wallabies use rehabilitated habitat, and compare results with retained reference habitat.
• Repair failed plantings, fencing, drainage, erosion controls and animal crossings when monitoring shows that the site is not providing connected habitat.
• Report rehabilitation results, fauna records, incidents and corrective actions to the approval authority and relevant state wildlife database.

Sources

• 1, aszk.org.au: https://aszk.org.au/wp-content/uploads/2020/05/Mammals.-Northern-Nail-tailed-Wallaby-2012AE.pdf
• [PDF] EL27186, EL27187, EL27188, EL27189, EL27190 & EL27544, Northern Territory Government: https://geoscience.nt.gov.au/gemis/ntgsjspui/bitstream/1/76841/2/EL27544_2012_P_03_App1.pdf