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Australasian Darter (Anhinga novaehollandiae)

The Australasian Darter, also called the snakebird, is a large waterbird of freshwater wetlands, rivers, dams, lakes and sheltered coastal waters across mainland Australia. Nests and resting trees can be affected by clearing, construction noise, access and changes to water levels, especially where several waterbirds breed together. It is least concern in Australia, but in Queensland a breeding place used by this colonial breeder requires a high risk species management program before it is tampered with.

Conservation status

Queensland, Nature Conservation Act 1992: Colonial breeder. Least concern in Queensland, but it breeds in colonies, so tampering with a breeding place needs a high risk species management program rather than the low risk program.

Breeding season

Australasian Darters can breed at any time when water levels and food supplies are suitable. Breeding is most often recorded from January to April in northern Australia and from August to October in southern Australia, with local conditions and flooding causing variation between years.

Breeding mode: Usually breeds as pairs, but may form loose or mixed colonies with cormorants, herons, spoonbills or ibises. In Queensland, this species is treated as a least concern colonial breeder for breeding place management.

Nest and breeding place: Large, wide, stick nests lined with reeds, leaves and rushes. Nests are usually in trees standing in water, partly submerged trees or trees overhanging water. Nests recorded at Lake Clarendon were 1 to 6 m above the water.

Clutch size: Usually 3 to 5 eggs. Four eggs is also recorded as typical.

Incubation: About 25 to 30 days in darters generally. Australasian Darter records also report about 28 days.

Young: Both parents care for the young. Chicks can swim at about four weeks and start to fly at about 50 days. Young may remain dependent for about two weeks after fledging.

Breeding frequency: Usually once each year. Breeding twice in one year can occur when there are two floods.

Colony recognition and care: An active breeding place may have attendant adults, sitting birds, eggs, nestlings, recently fledged young, fresh leafy nest material, and repeated adult movement to and from nests. Species specific colony sizes are not established, although 48 active nests were recorded at one Queensland wetland. Keep works outside the local nesting period where possible. Treat any active colony or shared breeding tree as a high sensitivity area. Maintain a site specific no entry buffer, avoid flushing adults, and keep machinery, people, noise and water level changes away from the colony. A 30 m observation distance was used for advanced young during field monitoring, and is a useful minimum starting point where disturbance is causing a response.

Timing varies with latitude, rainfall, flooding, water levels and food supply, so an active breeding place takes precedence over the usual calendar window.

  • Breeding and nesting, northern Australia: Breeding is most common in the northern wet season, but may continue while food and water remain suitable.
  • Breeding and nesting, southern Australia: Spring breeding is typical in southern Australia, with some nesting extending into summer and autumn.
  • Eggs, nestlings and dependent young: Eggs and dependent young may be present through much of the breeding period, and occasional breeding can occur outside the usual seasonal peaks.
  • Foraging, roosting and wing drying: Australasian Darters are generally present year round around suitable fresh or brackish wetlands, using trees, stumps, posts and branches near water for resting and wing drying.
  • Active colonies and breeding places: Wetland trees, dead trees standing in water and trees overhanging water may hold nests, sometimes among other colonial waterbirds. Flooding and water levels can determine whether nest trees remain usable.
  • Highest clearing risk: Clearing, construction, tree removal, loud activity and rapid water level changes are most likely to harm eggs, young or active colonies during the northern wet season and southern spring to autumn period, but active breeding places require protection in every month.

Identification: Appearance

The Australasian Darter is a large, slim waterbird with a long, kinked neck and a pointed bill. It is often seen swimming with only its head and neck above water, or drying its wings on a branch over water.

Adult males are mostly dark brownish black, with glossy upperwings marked by white, silver grey and brown. They have a white or pale brown stripe from the bill along the side of the neck, and a chestnut brown breast.

Females and immature birds are grey brown above and pale grey to white below. Their neck stripe is usually less distinct when young.

Length: 86 to 94 cm

Weight: About 2.6 kg

Bill: Long, sharply pointed and suited to spearing fish

Identification: Behaviour and flight

A swimming Darter usually keeps its body submerged, with the slender neck curved above the water. On land it moves clumsily, but in flight it can soar high on thermals and has a distinctive cross shaped silhouette.

After diving, it commonly perches with its wings spread to dry. Suitable drying posts include dead branches, tree trunks, stumps, fences and other structures beside water.

  • Look for the long neck and low swimming posture on open water.
  • Check dead branches and shoreline trees for birds drying their wings.

Identification: Calls and similar species

Australasian Darters are usually quiet away from the nest. They may make clicking sounds, while birds at the nest can give caws, hisses and clicks.

Cormorants are the main field comparison. A Darter has a longer, more obviously kinked neck and often swims with only the neck and head visible. Its flight silhouette is also more slender.

  • Use binoculars rather than approaching a perched or swimming bird.
  • Do not rely on call detection alone during a site inspection.

Identification: Field signs

Look for large, wide, dish shaped stick nests lined with reeds, leaves and rushes. Darter nests are often in partly submerged trees or trees overhanging water.

Nests in mixed waterbird colonies may be larger and less heavily coated with guano than nearby cormorant nests. Active nests may have an attending adult, eggs or young.

  • Whitewash or droppings on branches and below nest trees.
  • Fresh green nest material or recently repaired sticks.
  • Adult birds repeatedly entering or leaving the same tree.
  • Calls, hissing or clicking from a nest tree.
  • Fish remains are possible near roosts, but are not a reliable sign on their own.

Distribution: Australian range

The Australasian Darter occurs across mainland Australia wherever suitable water and nesting trees are available. It is generally resident or locally mobile, rather than a regular long distance migrant.

The species is mapped in New South Wales, the Northern Territory, Queensland, South Australia, Victoria and Western Australia. It occurs widely across mainland Australia, but is absent from the Great Sandy Desert, Great Victoria Desert and Nullarbor Plain.

It is an uncommon vagrant to Tasmania. Distribution is likely to be patchy in dry country and concentrated around permanent or seasonally reliable wetlands.

  • Rivers and billabongs.
  • Dams, lakes and reservoirs.
  • Swamps, lagoons and floodplain wetlands.
  • Sheltered estuaries and nearshore waters.
  • Wetland complexes with mature trees standing in or beside water.

Distribution: Range outside Australia

The Australasian Darter also occurs in lowland New Guinea, New Britain, the Moluccas and the Lesser Sunda Islands.

Distribution: What to check on a project site

Prioritise waterbodies with open water, fish habitat and trees, logs or posts used for perching. Search connected wetlands and downstream or upstream habitat if birds are present but no nest is found.

A Darter may move to deeper water as a wetland dries. An absence from a shallow section does not show that the species is absent from the wider wetland.

  • Record all sightings, flight paths and regular perches.
  • Map mature trees in water and trees overhanging the bank.
  • Inspect nearby wetlands if a bird leaves the work area.

Habitat: Wetland features

Australasian Darters use freshwater and brackish wetlands, usually where there is open water for diving and a structure above or beside the water for resting and drying. Habitat can be permanent or temporary, provided water, fish and suitable perches are available.

Look for rivers, dams, lakes, swamps, lagoons, billabongs and flooded depressions. The species commonly uses water more than 0.5 m deep, but local use will vary with water level and food availability.

Wetlands may be fresh, brackish or, less commonly, inland saltwater. Murky water and some salinity do not automatically exclude the species.

  • Open or lightly vegetated water suitable for swimming and diving.
  • Fish bearing pools and channels.
  • Vegetated banks and floodplain margins.
  • Fallen trees, logs and snags.
  • Mature trees standing in water or growing close to the bank.

Habitat: Vegetation and site structure

The most useful vegetation feature is a tree, stump or branch over water. Darters need these structures for resting, drying and, in some areas, nesting.

Search flooded woodland, river red gum or other wetland tree stands, wooded dam edges and trees overhanging lagoons. Reeds and rushes may occur in the nest, but the nest itself is usually supported by a tree.

  • Partly submerged trees.
  • Dead trees left standing after flooding.
  • Trees with broad branches above open water.
  • Reed and rush margins near nesting trees.
  • Quiet banks with limited access.

Habitat: Water level and management

Breeding is linked to suitable water levels and food supplies. Flooding can create or retain nesting trees standing in water, while falling levels can leave nest trees on dry ground. At one Queensland site, Darter nests in trees left on dry ground were not reused.

Plan dewatering, drawdown, impoundment changes and floodplain works with the breeding season and the wider wetland in mind.

  • Maintain access to open water around active nest trees where practicable.
  • Avoid sudden water level changes near an active colony.
  • Retain standing trees, snags and overhanging branches unless removal is authorised and unavoidable.
  • Inspect wetland edges again after flooding, drawdown or major rainfall.

Foraging habitat: Foraging areas

The Australasian Darter hunts underwater, usually in open water where it can swim and dive. It spears prey with its bill and returns to the surface or a nearby perch to swallow larger items.

Search deeper pools, channels, dams, lakes, rivers and quiet sections of estuaries. The species commonly dives to about 60 cm and may use water deeper than this when pursuing fish.

Sparse aquatic vegetation is generally more suitable for swimming and diving than dense mats or heavily choked margins.

  • Open pools beside vegetated banks.
  • Dam walls and quiet reservoir margins.
  • Flooded timber and snags beside clear swimming lanes.
  • Permanent pools in otherwise seasonal rivers.
  • Sheltered coastal water near wetland outlets.

Foraging habitat: Diet and feeding signs

Fish make up most of the diet. Other recorded food includes insects, freshwater shrimp, worms, aquatic beetles, water bugs, small crustaceans and other aquatic animals.

A bird may carry a large fish to a perch before swallowing it. Feeding perches can therefore be some distance from the exact dive location.

  • Repeated dives in the same pool.
  • Birds surfacing with prey.
  • Fish scales or remains below a regular perch, although these signs are not diagnostic.
  • Wing drying on a branch after feeding.

Foraging habitat: Site controls around feeding birds

Avoid blocking access between a nest or roost tree and nearby open water. Plant, equipment and temporary fencing can make a previously usable wetland edge difficult to use.

If birds repeatedly leave a feeding area when machinery approaches, pause and review the work method. Repeated disturbance can reduce use even when no nest is present.

  • Keep machinery away from regular feeding pools where practicable.
  • Use existing access tracks and avoid driving through shallow wetland margins.
  • Prevent fuel, sediment, concrete washout and other pollutants from entering water.
  • Keep lighting directed away from open water and wetland trees during night works.

Breeding habitat: Nests and nest trees

Australasian Darters usually nest in trees standing in water or in trees overhanging water. They may nest alone, but can also form loose groups with cormorants, spoonbills, ibis, herons and other tree nesting waterbirds.

The nest is a large, wide platform made of sticks and lined with reeds, leaves and rushes. It is commonly built in a fork or branch of a partly submerged tree.

Nests may be in bushy or open structured trees. At Lake Clarendon, recorded nest heights were 1 to 6 m above the water. Treat all nest trees as potentially important, including dead trees that remain standing in water.

  • Partly submerged trees.
  • Trees overhanging water.
  • Dead flooded woodland.
  • Large branches and forks above open water.
  • Mixed waterbird nesting trees.

Breeding habitat: Breeding timing

Breeding is responsive to water and food conditions. In southern Australia it most often occurs in spring, from August to October. In northern Australia it commonly occurs during the wet season, from January to March or April.

Breeding can occur outside these periods when food and water are suitable. A Queensland study recorded nesting throughout the year, with most nesting in spring and summer.

Clutch: Usually 3 to 5 eggs, with up to 4 recorded in one Queensland study

Incubation: About 28 days in the Australasian Darter account

Young: Chicks can swim at about 4 weeks and start to fly at about 50 days

  • Check for nests before clearing in any month.
  • Increase checks after flooding or when water levels rise.
  • Treat eggs, small young and attending adults as evidence of an active breeding place.

Breeding habitat: Recognising an active breeding place

An active breeding place may include one nest tree or a group of trees used by several waterbird species. Presence of an adult on a nest, eggs, young, fresh nest material or repeated nest visits should be treated as evidence of current use.

Do not climb, shake, cut or probe a nest tree to confirm activity. Use binoculars or a camera with a suitable lens from a safe distance.

  • Adult sitting on a nest.
  • Adult carrying sticks, leaves or green twigs.
  • Visible eggs or chicks.
  • Fresh droppings and whitewash below the nest.
  • Repeated flights to the same nest tree.
  • Nestlings calling, hissing or clicking.

Breeding habitat: Works near nests

Schedule tree removal, bank works, vegetation clearing and high noise activities outside the local nesting period where practicable. If works cannot avoid the breeding period, use a fauna ecologist to establish a site specific exclusion area and monitoring plan before work starts.

The Lake Clarendon study used about 30 m as a close approach limit for advanced young because closer approach caused chicks to jump into the water. This is an observation guideline from that study, not a universal construction buffer. A larger buffer may be needed for machinery, repeated access, aircraft, piling or other high disturbance activities.

  • Stop work if adults repeatedly flush, circle, alarm call or do not return to the nest.
  • Keep workers, vehicles, cranes and plant outside the agreed exclusion area.
  • Do not remove a nest tree or alter water around an active nest without the required approval.
  • Recheck the area after storms, flooding, drawdown or changes in water management.

Sheltering habitat: Roost and drying structures

Darters need safe places to rest, dry their wings and roost. These places are usually trees, branches, stumps, logs, fences or posts beside or over water.

Inspect trees and dead branches over water, shoreline snags, stumps and fences near pools. A Darter may use the same visible perch repeatedly, especially where it provides a clear view and quick access to water.

Roosting information for this species is limited, so retain a range of suitable structures rather than relying on one known perch.

  • Branches over open water.
  • Dead trees and logs at the wetland edge.
  • Stumps and posts.
  • Fences close to water.
  • Quiet trees beside rivers, dams and lagoons.

Sheltering habitat: Signs of regular use

Regular perches may have accumulated droppings, whitewash, feathers or worn bark. A bird may also leave the perch to dive and return to the same or a nearby structure.

Use binoculars to distinguish Darter signs from cormorant or other waterbird signs. Droppings alone do not confirm the species.

  • Repeated sightings at the same perch.
  • Whitewash on a branch, stump or fence.
  • Feathers or fish remains below a perch.
  • Multiple birds using nearby drying structures.
  • A clear flight path between perch and water.

Sheltering habitat: Protecting sheltering habitat

Retain roost and drying structures where practicable. Avoid placing access tracks, lighting, scaffolding, temporary offices or noisy plant directly beside regular perches.

If a perch must be removed, identify alternative structures nearby before works begin. Do not install or move structures into an active nest tree.

  • Keep a quiet area around regular roosts.
  • Limit night lighting on water and wetland trees.
  • Avoid clearing all shoreline trees at once.
  • Maintain open flight paths to feeding water.

Colonies and breeding places: What a colony or shared breeding place looks like

Australasian Darters are often solitary while breeding, but they can form loose colonies or join mixed waterbird colonies. A breeding place may therefore contain only a few Darter nests or many nests across several trees, and the wider site may support a large share of the local breeding population.

A Darter breeding place is usually a group of trees standing in water or overhanging a wetland. Nests may be spread through the trees rather than packed tightly together. Darters may nest among cormorants, spoonbills, ibis and herons.

At Lake Clarendon, 48 active Darter nests were recorded in March 1998. This is a documented site count, not a typical colony size. No standard colony size is available for the species.

  • Several nest trees in or beside open water.
  • Mixed nests of different sizes and construction styles.
  • Repeated adult flights between water and the same trees.
  • Concentrated droppings, calls and fallen nesting material.
  • Birds using nearby branches for roosting and drying.

Colonies and breeding places: Site fidelity and water dependence

Darters may return to suitable breeding trees while water, fish and access remain favourable. Nest trees left on dry ground as water receded were not reused in the Lake Clarendon study.

Flooding can create nesting habitat by surrounding trees with water. Drawdown, drought, tree death, fire or changed water releases can make a breeding place unsuitable.

  • Map the whole wetland edge, not just the visible nest tree.
  • Record water level and recent flooding or drawdown.
  • Retain flooded trees and surrounding open water where practicable.
  • Review the site after water level changes.

Colonies and breeding places: Colonial bird locations

Colonial waterbirds can use wetland trees, lignum, reedbeds, islands, sandbanks, riverbanks, cliffs, culverts, bridges and caves, depending on the species. Australasian Darters are associated mainly with trees and reeds near water, and with mixed tree nesting colonies.

Do not assume that a site is unimportant because Darter nests are widely spaced. Loose colonies still concentrate breeding activity and disturbance risk.

  • Wetland trees and flooded woodland are the main Darter breeding locations.
  • Lignum and reedbeds may support other colonial waterbirds and should be checked.
  • Islands and sandbanks can be important for other waterbird groups.
  • Culverts, bridges, cliffs and caves are not established Darter nesting places, but may shelter other colonial species on a mixed site.

Colonies and breeding places: Disturbance, buffers and flushing risk

Flushing adults can expose eggs and young, interrupt incubation and cause chicks to enter the water prematurely. In the Lake Clarendon study, approaching chicks too closely caused some to jump into the water, where their survival chances were poor.

Set an exclusion buffer around every active colony or mixed breeding place before works begin. The buffer should reflect the number of nests, access routes, plant size, noise, vibration, flight paths and the birds' response. Keep works outside the nesting period where practicable.

  • Use a qualified ecologist to mark the buffer on the ground and in work plans.
  • Stop or move back if adults flush repeatedly, circle, alarm call or fail to return.
  • Keep people and machinery out of the buffer, including access, storage and spoil placement.
  • Avoid sudden water level changes around nesting trees.
  • Reassess the buffer if colony size or bird behaviour changes.

Colonies and breeding places: Queensland approval point

In Queensland, the Australasian Darter is a least concern colonial breeder. Tampering with its breeding place requires a high risk species management program under the Nature Conservation (Animals) Regulation 2020, rather than the low risk program used for other least concern animals.

Before clearing, construction, nest tree removal or other disturbance, confirm the current approval pathway with the relevant Queensland department and have the breeding place assessed by a suitably qualified ecologist.

  • Treat a mixed waterbird colony as a breeding place until assessment shows otherwise.
  • Keep records of nest numbers, species, water level, disturbance and mitigation.
  • Do not rely on the species' least concern status as permission to disturb an active colony.

Threats: Clearing and construction

The Australasian Darter is least concern, but local breeding places can be lost quickly when wetland trees, open water or quiet access to nests are disturbed. Development controls should focus on retaining breeding structure, protecting water quality and preventing repeated flushing.

Removing flooded trees, overhanging branches, snags or shoreline vegetation can remove nests, roosts and flight paths. Piling, drilling, earthworks, traffic and repeated access can disturb adults even when the nest tree is retained.

Survey before clearing and mark active nest trees, nearby roosts and the work exclusion area on site plans.

  • Avoid clearing mature wetland trees where practicable.
  • Keep cranes, plant, stockpiles and access tracks away from breeding trees.
  • Use staged works so a complete wetland edge is not disturbed at once.
  • Stop work if birds show repeated flushing or alarm behaviour.

Threats: Water level changes and wetland degradation

Darters depend on suitable water depth, fish and trees standing in or beside water. Drainage, drawdown, altered releases, drought, filling and loss of floodplain connection can remove nesting and feeding habitat.

Plan water management around active breeding places and retain open water near nest trees.

  • Avoid rapid drawdown beside active nests.
  • Maintain fish passage and wetland connectivity where feasible.
  • Protect flooded woodland and standing dead trees.
  • Inspect for new colonies after flood events and rising water levels.

Threats: Water quality, pollution and fish habitat

Sediment, fuel, concrete washout, pesticides and other pollutants can reduce water quality and affect fish and aquatic prey. Loss of fish habitat can make a nest site unsuitable even if the trees remain.

Use sediment and spill controls, keep chemicals away from water and prevent contaminated runoff from entering pools, dams and rivers.

  • Install and maintain erosion and sediment controls.
  • Refuel and wash equipment away from water.
  • Protect vegetated banks and aquatic habitat.
  • Report and respond to spills immediately.

Threats: Disturbance and legal compliance

Repeated human presence, dogs, vehicles, drones, bright lighting and noise can flush adults from nests and cause young to enter the water. Mixed colonies can be particularly sensitive because disturbance may affect several species at once.

The species is not listed as endangered, vulnerable or near threatened in Australia, but that does not remove obligations around active breeding places. In Queensland, confirm the high risk species management program requirements before tampering with a Darter breeding place.

  • Keep dogs and unauthorised visitors away from colonies.
  • Do not fly drones over active nests or roosts.
  • Schedule noisy work outside the local breeding period where practicable.
  • Use an ecologist to oversee any unavoidable work near an active colony.

Survey methodology: 1. Desktop assessment

Survey wetlands, dams, rivers, lagoons, estuaries and other open water with suitable trees, logs, stumps or posts. Search both the water and the vegetation above and beside it, because Australasian Darters may be feeding, drying their wings, roosting or nesting in the same area.

Map open water, vegetated banks, partly submerged trees, dead trees standing in water, islands and known waterbird colonies. Identify proposed clearing, access tracks, plant crossings, piling, dredging, dewatering, bank works and changes to water levels.

Check records held by the relevant state agency, local councils, wetlands groups and landholders. Treat a record of a mixed waterbird colony as a potential Australasian Darter breeding place, even if the species has not been recorded separately.

  • Review aerial photographs from wet and dry periods where available.
  • Identify whether the site could support a loose colony or a shared roost with cormorants, herons, ibis or spoonbills.
  • Check whether the project could remove nest trees, isolate a colony, disturb access to water, or alter flooding and water levels.

Survey methodology: 2. Field detection

Search from the water edge and from elevated viewpoints where possible. Use binoculars to scan tree crowns, dead trees, branches over water, reedbeds and sheltered banks. Australasian Darters are often detected by their long neck above the water or by wing drying on a branch, stump, fence or post.

Look for large, wide, dish-shaped stick nests lined with leaves, reeds or rushes. Nests are often in partly submerged trees or trees overhanging water. They may occur singly or in loose mixed colonies.

  • Survey during daylight when birds are active and visibility is good.
  • Include calm periods when birds are likely to be swimming, diving or drying their wings.
  • Use a canoe or other low-impact platform only where authorised and where access will not disturb nesting birds.
  • Do not approach nests closely to improve the count. Use binoculars or a spotting scope.

Survey methodology: 3. Timing and effort

Repeat surveys where habitat is suitable, water levels are changing, or a colony may be seasonal. Breeding is linked to water and food conditions. In southern Australia it commonly occurs in spring, from August to October. In northern Australia it commonly occurs in the wet season, from January to March or April. Some sites can support nesting outside these periods.

At Lake Clarendon, nesting occurred throughout the year, with most nesting in spring and summer. This supports repeat surveys rather than relying on one seasonal visit.

  • Survey at least once before works and repeat when conditions change or works extend across a breeding period.
  • Inspect all potential nesting trees and the water around them.
  • Record the date, time, weather, water level, visibility, survey route, survey duration and observers.
  • Record adults, pairs, nests, eggs if visible, chicks, fledged young, roosting birds, flight paths and any mixed-species colony.

Survey methodology: 4. Recognising an active breeding place

Treat a nest as active when it contains eggs or young, or when an adult is attending it and the nest cannot be inspected safely. Repeated adult attendance, fresh green nest material, chicks, faecal staining and adults carrying food are useful indicators.

A colony may be a group of nests in dead or living trees standing in water, trees overhanging water, reedbeds or other wetland vegetation. Australasian Darters may nest with cormorants, herons, ibis or spoonbills. Colony size is poorly documented. One Queensland study recorded 48 active Darter nests at Lake Clarendon in March 1998.

  • Map the outer edge of the colony and every nest tree that can be seen.
  • Record the number of active and inactive nests separately.
  • Record the distance from nests to the proposed disturbance, access route, machinery and high-use work areas.
  • Assume a breeding place remains active until a suitably qualified ecologist confirms that breeding has finished.

Before habitat disturbance: 1. Avoidance and approvals

Plan the work around the wetland, not just around the footprint. A colony or shared breeding place can hold a substantial part of the local population, so avoid disturbance first and use controls that keep people, machinery, noise and water changes away from the site.

Redesign the footprint to retain nesting trees, dead trees standing in water, vegetated banks, islands and access to feeding water. Avoid removing a colony tree or isolating it from the surrounding wetland.

Obtain advice on approvals before work starts. Consider whether the action could affect a matter of national environmental significance and whether an EPBC Act referral is required. Obtain all relevant state or territory permits, wildlife authorities and local approvals.

  • In Queensland, treat the Australasian Darter as a least concern colonial breeder for project planning.
  • Obtain a high risk species management program under the Nature Conservation (Animals) Regulation 2020 before tampering with a Queensland breeding place of this species.
  • Do not rely on the low risk SMP used for other least concern animals where a colonial breeding place is involved.
  • Confirm requirements with the Queensland environmental regulator and the relevant state agency before clearing, nest tree removal, water works or disturbance.

Before habitat disturbance: 2. Colony and breeding place protection

There is no single species-specific disturbance distance that can be applied safely to every colony. Set a site-specific no-go buffer around the active colony, nest trees, flight paths and nearby roosts, using advice from the project ecologist and the regulator.

Use a wider buffer where birds flush readily, nests are close together, machinery is noisy, visibility is poor, water access is restricted, or the colony is large or mixed. Include overhead and water-based disturbance, not only ground clearing.

  • Fence and sign the buffer before machinery arrives.
  • Keep workers, vehicles, cranes, barges, boats, generators and lighting outside the buffer unless the approved management plan allows access.
  • Keep works outside the active nesting period where practicable. Do not assume the period is fixed because breeding responds to water levels and food.
  • Avoid rapid drawdown, filling, flooding or other water level changes that could strand nest trees or reduce access to feeding habitat.
  • Do not remove a nest, eggs, chicks or nest tree without the required approval and direction from the authorised fauna ecologist.

Before habitat disturbance: 3. Pre-clearance survey

Complete a pre-clearance survey close to the start of works. Recheck the site after rain, flooding, water level changes or a long delay between survey and clearing.

Inspect trees above and beside water, reedbeds, islands, banks, culverts, bridges and other structures that could be used by waterbirds. Australasian Darter breeding places are most often in trees over or standing in water, but associated waterbird colonies can extend into nearby vegetation.

  • Use binoculars or a spotting scope and avoid flushing birds from nests.
  • Mark all active nests, colony boundaries, roosts, access points and exclusion zones on the site plan.
  • Brief the spotter catcher and supervisor on the species profile, colony controls, stop-work rules and reporting chain.
  • Confirm that an authorised person is available to make decisions if an active breeding place is found.

Before habitat disturbance: 4. Induction and work controls

Give every worker a site induction before entering the wetland. Explain that a colony may look like scattered nests rather than a dense mass, and that adults can leave silently when disturbed.

Use low-noise methods where feasible. Schedule the most disruptive work away from the colony and avoid sudden movements, repeated passes and unnecessary boat approaches.

  • Show workers photographs or field descriptions of the Australasian Darter, its large stick nest and its snake-like swimming profile.
  • Explain that flushing adults can expose eggs and young and can cause young birds to enter the water prematurely.
  • Nominate one supervisor who can stop work immediately.
  • Keep dogs, recreational users and non-essential personnel out of the buffer.
  • Record daily checks of fencing, signs, water conditions and bird behaviour.

During habitat disturbance: 1. Sequential clearing

Use a staged, supervised approach. The fauna spotter catcher or authorised ecologist must have clear authority to stop work whenever birds show repeated flushing, an active breeding place is found, or the approved controls are not working.

Clear only the approved area and work from the least sensitive edge toward the retained habitat. Retain escape routes to open water and do not trap birds between machinery, fencing and the bank.

Stop before any tree, branch, reedbed, bank or structure that may contain a nest or colony. Reassess the work area each day and after any change in water level.

  • Remove loose debris progressively so it does not block water access.
  • Keep machinery outside marked buffers unless the approved plan specifically permits entry.
  • Use a spotter to watch the colony and the work zone continuously during high-risk activities.
  • Stop if birds circle repeatedly, call persistently, mob machinery, return immediately to a disturbed nest, or enter the water in response to works.

During habitat disturbance: 2. Finding a colony or active breeding place

If a nest, colony or shared roost is found, stop work in the affected area. Move people and machinery back without approaching the birds, then establish a temporary no-go area while the ecologist and regulator determine the response.

Do not attempt to move a nest, tree, egg or chick. A nest in a partly submerged tree may be part of a larger mixed colony that is not visible from ground level.

  • Record the location, nest condition, number of birds, signs of eggs or young, and the activity that caused the discovery.
  • Contact the project ecologist, fauna spotter catcher supervisor and relevant regulator or permit holder.
  • Extend the exclusion area if birds continue to flush or if more nests are found.
  • Resume only under a documented approval, revised method statement or regulator direction.

During habitat disturbance: 3. Handling and injured birds

Handle an Australasian Darter only when necessary, by an authorised and suitably trained person. Its long neck and sharp bill can cause injury, so do not restrain it casually or allow untrained workers to catch it.

Keep people quiet and reduce handling time. Place the bird in a secure, ventilated container suitable for its size and keep it away from heat, cold, noise and domestic animals.

  • Do not feed or give water unless directed by a wildlife carer or veterinarian.
  • Contact the approved wildlife rehabilitation provider or veterinarian immediately.
  • Record the location, condition, visible injuries, photographs where safe, handling time and destination.
  • If the bird is dead, do not dispose of it until the project ecologist has checked whether an incident report or specimen advice is required.

During habitat disturbance: 4. Records and stop-work reporting

Maintain a daily fauna log for the work area. Record observations even when no birds are present, because absence data helps assess whether the controls are effective.

Report any colony disturbance, nest damage, bird injury, death, unauthorised entry into a buffer or water level event to the project manager and ecologist on the same day.

  • Record species, number of birds, nest status, location, behaviour, disturbance source, duration and response.
  • Record the name of the observer and fauna spotter catcher, photographs, maps and relevant permit or approval conditions.
  • Document every stop-work decision and the direction that allowed work to restart.
  • Do not conceal minor incidents. Early reporting allows controls to be corrected before harm increases.

After habitat disturbance: 1. Post-clearance inspection

Finish with a careful inspection and a documented handover. Post-clearance checks should confirm that no animals, nests, chicks or retained habitat have been damaged and that the colony buffer remains effective during the next stage of the project.

Inspect the cleared area, retained trees, wetland edge, access routes and exclusion fencing after each clearing stage. Check for injured or trapped birds, damaged nests, fallen branches and blocked access to water.

Use binoculars to inspect retained nest trees from a distance. Do not enter a colony to obtain a closer count.

  • Check pits, trenches, pipes, culverts, temporary dams and sediment controls for trapped wildlife.
  • Check that floating debris, fencing and stockpiles do not obstruct birds moving between water and nesting trees.
  • Record any change in bird numbers, behaviour, nest attendance or colony location.
  • Arrange a repeat inspection after heavy rain, flooding, rapid drawdown or other major water level change.

After habitat disturbance: 2. Monitoring during construction

Continue monitoring where works remain near water, a colony, a roost or retained nest trees. The frequency should reflect the sensitivity of the site, the work intensity and the conditions of approvals.

A colony can shift within a wetland when water levels or food availability change. Do not treat the original mapped area as the only sensitive area.

  • Monitor before and during noisy or high-vibration activities.
  • Inspect the colony from the approved observation point and keep the agreed buffer in place.
  • Track nest attendance, young, fledged birds, flushing events, injured animals and changes in water levels.
  • Escalate repeated flushing, abandonment or new nests to the project ecologist.

After habitat disturbance: 3. Relocated or rescued animals

Release or relocate a bird only under the direction of the authorised wildlife carer, veterinarian, permit holder or ecologist. The release site must provide suitable open water, perches and safe access away from active works.

Do not release a bird into a colony or roost without checking that the release will not cause further disturbance or conflict.

  • Record the identification method, condition, treatment, holding time, release location and person responsible.
  • Monitor the release where required by the permit or rehabilitation advice.
  • Report animals that cannot be located, are not accepted by a carer, or die during care.

After habitat disturbance: 4. Reporting and incident review

Prepare a close-out report that links field observations to approval conditions and the fauna management plan. Review the controls after every colony or animal incident.

Use the review to improve the next work stage, especially where birds flushed, machinery entered a buffer, or water levels changed unexpectedly.

  • Summarise survey effort, active nests, colony observations, stop-work events, injuries, deaths and corrective actions.
  • Attach maps, photographs, daily logs, permits, regulator notifications and rehabilitation records.
  • Confirm whether further monitoring is required before demobilisation.
  • Brief the client, supervisors and contractors on lessons that apply to later wetland works.

Rehabilitation actions: 1. Wetland and bank restoration

Restore the wetland functions that support feeding, drying, roosting and nesting. Australasian Darters need open water, suitable depth, perches and trees or other structures near water, while colonies also depend on stable access to surrounding habitat.

Retain or replant native wetland vegetation along banks and around suitable open water. Restore fallen timber, dead trees standing in water and vegetated banks where this can be done safely and consistently with waterway requirements.

Maintain areas of sparse vegetation and open water for swimming and diving. Avoid creating a solid wall of dense emergent plants across all feeding habitat.

  • Stabilise disturbed banks with locally appropriate native species.
  • Remove invasive weeds without entering active colonies or damaging nest trees.
  • Prevent erosion, sediment release, rubbish accumulation and uncontrolled human access.
  • Restore natural wetting and drying patterns where the project has altered them, subject to waterway approvals.
  • Do not create isolated water bodies that lack perches or safe access to surrounding habitat.

Rehabilitation actions: 2. Nesting and roost structures

Australasian Darters most often nest in trees over or standing in water. Retain suitable trees before considering artificial structures. A nest box or bat box is not a standard substitute for a Darter nest and should not be installed unless a qualified ecologist has designed a site-specific solution.

Artificial nest platforms or other structures may suit some waterbird colonies, but they can attract several species and may increase disease, predation or conflict if poorly located.

  • Prioritise retention and protection of existing nest trees and nearby roost trees.
  • Do not install bat boxes as a Darter mitigation measure.
  • Use artificial nest sites only where the habitat, water level, structure, maintenance access and approvals are suitable.
  • Design any artificial nest site with advice from a waterbird ecologist and the relevant regulator.
  • Monitor any new structure for occupation, stability, fouling, predation and effects on nearby nests.

Rehabilitation actions: 3. Water management and lighting

Manage water levels so that nest trees are not stranded suddenly and feeding areas do not dry or become inaccessible during breeding. The species can move to deeper water when wetlands dry, but a project should not rely on this movement as mitigation.

Keep artificial lighting away from colonies, roosts, open water and flight paths. Use the lowest practical intensity and direct light only where needed.

  • Avoid rapid drawdown, sudden filling and unnecessary changes to wetland connectivity.
  • Keep pumps, hoses and temporary dams away from birds and maintain escape routes.
  • Use shielded, warm-coloured lighting where lighting cannot be avoided, subject to project safety requirements.
  • Turn off non-essential lighting when work stops.
  • Check water quality, fish availability and access to perches during rehabilitation monitoring.

Rehabilitation actions: 4. Long-term monitoring

Monitor restored wetland habitat through at least the next relevant breeding period, and longer where the project has changed water levels or removed nesting trees. Breeding timing varies with region and conditions, so use local observations rather than a fixed calendar alone.

Record whether birds return, whether retained or restored trees are used, and whether the colony remains free from repeated disturbance.

  • Survey during the expected local breeding period and after major flooding or water level changes.
  • Record nest numbers, active nests, young, roosting birds, water depth and condition of vegetation.
  • Inspect artificial structures after storms and before each breeding period if they have been approved and installed.
  • Remove failed structures, weeds, rubbish and unsafe materials promptly.
  • Use monitoring results to adjust buffers, access controls, water management and future rehabilitation designs.

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