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Cotton Pygmy-Goose (Nettapus coromandelianus)

The Cotton Pygmy-Goose is a very small perching duck associated with vegetated freshwater bodies, including lagoons, lakes and ponds. In Australia it occurs mainly in Queensland, where clearing of aquatic vegetation, removal of hollow-bearing trees, disturbance of wetlands and changes to water availability can affect feeding and breeding habitat.

Conservation status

New South Wales, Biodiversity Conservation Act 2016: Endangered.

Breeding season

Timing varies with rainfall and water availability across the range. The Australian breeding period is mainly January to March, while wider winter dispersal is reported for the species.

Survey timing should be adjusted for local rainfall, water levels and recent records. The supplied sources do not provide a complete Australian seasonal calendar.

  • Breeding: In Australia, pairing and breeding are mainly reported from January to March and coincide with rains.
  • Young: Eggs take about 24 to 28 days to hatch. Chicks leave the tree hollow and follow their parents to water. The supplied sources do not give the duration of dependence.
  • Movement and dispersal: The species can disperse widely in winter and moves in response to rainfall and water availability. Timing may vary between sites and years.
  • Non-breeding use: Birds may remain on suitable waterbodies outside the main breeding period. Large winter flocks have been recorded elsewhere in the range.
  • Highest clearing risk: January to March is the highest risk period for clearing or disturbance in Australia because breeding, incubation and early chick dependence may occur. Retain hollow-bearing trees and wetland vegetation throughout this period.

Identification

The Cotton Pygmy-Goose is a compact, short-billed duck that is usually seen on freshwater rather than on land. It often sits low on the water in pairs or small groups and flies swiftly, often close to the water surface.

Adults are 26 to 37 cm long and have a short, deep-based, goose-like bill. The male has a predominantly white head, neck and underparts, a dark green to blackish crown and back, and a broad dark collar at the base of the neck during the breeding season.

The female is browner and duller. It has a brown eye stripe, a less distinct facial pattern and spotted or vermiculated markings where the male has a dark collar. Both sexes have dark plumage on the forehead and crown.

Male weight: About 410 g.

Female weight: About 380 g.

Iris and legs: The iris is red. Legs are black, or greenish in breeding males.

  • In flight, look for a dark wing with prominent white flight feathers or a white trailing edge, depending on sex.
  • The species usually takes off directly from the water without running across the surface.
  • Juveniles are duller, lack iridescence and have pale facial markings, a dark eye stripe and mottled brownish-grey underparts.

Identification: Field signs and behaviour

The call is described as a low, quacking call. Birds commonly occur in pairs or groups of pairs, and larger flocks can form in winter.

Breeding evidence is most likely to be found in trees beside water. Nests are placed mainly in natural tree hollows, and the chicks leave the hollow and follow the adults to water.

Nest height: A nest may be up to about 5 m above ground in a natural tree hollow.

Egg appearance: Eggs are white to ivory or creamy white.

  • Record calls, repeated use of a wetland edge, pairs entering tree hollows and birds carrying nesting material where observed.
  • Inspect trees beside occupied waterbodies for suitable hollows, but do not approach or block a suspected nest hollow.
  • No distinctive tracks, scats, sloughs or eyeshine features are described in the supplied sources.

Distribution: Australian range

The species is widely distributed from the Indian subcontinent through South-East Asia and New Guinea to Australia. The supplied material identifies Queensland as the Australian breeding range but does not provide a complete state by state or bioregional distribution.

In Australia, the eastern population is assigned to the subspecies Nettapus coromandelianus albipennis. The supplied sources describe this population as occurring in eastern Australia and extending to Queensland.

Australian records are associated mainly with lagoons and other freshwater bodies. Birds can disperse in response to rainfall and water availability, so local presence may vary between seasons and years.

Australian state specifically identified: Queensland.

Australian subspecies: Nettapus coromandelianus albipennis.

Bioregional distribution: No Australian bioregions are identified in the supplied sources.

  • Treat suitable freshwater habitat in Queensland as potential habitat, particularly vegetated lagoons and wetlands.
  • Do not assume that an unoccupied wetland is unsuitable without considering recent rainfall, water levels and seasonal movements.

Distribution: Strongholds and population information

The supplied material does not identify a national stronghold, a Queensland stronghold, a discrete Australian subpopulation or a population estimate. It also does not provide a reliable Australian population trend.

Globally, the species is listed as Least Concern in the supplied material. This does not remove the need to protect occupied wetlands and breeding trees on individual projects.

Global conservation status: Least Concern, IUCN 3.1 as reported in the supplied sources.

Australian population estimate: Not provided.

Australian population trend: Not provided.

  • Use current survey records and local wetland observations to define the site population rather than relying on the global listing.
  • Record flock size, pairs, repeated sightings and the condition of associated vegetation during project surveys.

Habitat: Wetland habitat

Cotton Pygmy-Geese use freshwater bodies with abundant aquatic vegetation and nearby trees. The most important site features are open water for swimming and feeding, emergent or floating vegetation, and trees with hollows close to the water.

Habitat includes small and large waterbodies, lakes, ponds and lagoons. In Australia, the species is reported mainly from lagoons.

The species is often found in wetlands with emergent vegetation. It may also use small village ponds and other modified waterbodies where suitable aquatic vegetation is retained.

Typical waterbodies: Lakes, ponds, lagoons and other small to large freshwater bodies.

Key vegetation: Emergent, floating and other aquatic vegetation.

Nearby terrestrial structure: Trees near water, including trees with natural hollows.

  • Map open water, emergent vegetation, floating vegetation and densely vegetated wetland margins before clearing or earthworks.
  • Retain a connected wetland margin and avoid unnecessary removal of vegetation used for feeding, cover and access to the water.
  • Check trees beside occupied or suitable wetlands for hollows before vegetation removal.

Habitat: Climate and elevation

The supplied sources link movements to rainfall and water availability and describe breeding as coinciding with rains. They do not provide an Australian elevation limit or a defined climatic boundary.

Water levels and wetland condition should therefore be considered when interpreting survey results, especially after dry periods or major rainfall.

  • Document recent rainfall, water depth and the extent of open water and aquatic vegetation during each survey.
  • Do not use elevation alone to rule out habitat because an Australian elevation range is not provided.

Foraging habitat: Food and feeding method

The Cotton Pygmy-Goose feeds mainly at the water surface among aquatic vegetation. It does not normally dive or up-end, and several pairs may forage close together on one waterbody.

Recorded food includes small fish, molluscs, crustaceans, insect larvae and plant matter. Plant foods include material from Ipomoea, Hydrilla and Ruppia, as well as other aquatic plants and seeds.

Birds forage while swimming at the surface and use wetlands with aquatic vegetation. Large winter flocks may form where food and water remain available.

Feeding zone: Mainly the water surface, particularly among emergent or other aquatic vegetation.

Recorded animal prey: Small fish, molluscs, crustaceans and insect larvae.

Recorded plant food: Ipomoea, Hydrilla, Ruppia, other aquatic plants and some seeds.

  • Inspect the open-water and vegetated interface for feeding birds, especially during calm periods when surface feeding is easier to observe.
  • Retain aquatic vegetation and avoid sudden changes in water level that expose or remove feeding areas.
  • Record the plant communities and visible invertebrate or small-fish resources associated with occupied wetlands.

Foraging habitat: Foraging area

The supplied sources do not provide a home range, commuting distance or minimum wetland size. Several pairs may use one waterbody, and large flocks have been recorded in winter.

Home range: Not provided.

Largest flock reported in the supplied material: Nearly 6,000 birds at Chilka Lake, India.

  • Assess the whole wetland and nearby connected waterbodies rather than limiting the assessment to the point of observation.
  • Map flight paths between open water, vegetated margins and nearby trees where repeated use is recorded.

Breeding habitat: Breeding biology

Breeding is associated with the rainy period and with freshwater bodies that have nearby trees containing suitable hollows. The female is thought to incubate the eggs alone, while the male assists with locating nest sites.

Australian breeding season: Mainly January to March.

Other reported breeding period: Breeding coincides with rains. June to August is reported for India, and July to August is reported for Thailand.

Clutch size: Usually 6 to 12 ivory-coloured eggs. A range of 8 to 15 eggs is also reported.

Incubation: About 24 to 28 days.

Age at maturity: Not provided.

Lifespan: Not provided.

Nest type: Mainly a natural tree hollow, generally in a tree beside water.

Recorded nest height: Up to about 5 m above ground in a natural hollow.

Breeding habitat: Breeding site features

Suitable breeding habitat combines open or vegetated freshwater with nearby hollow-bearing trees. Chicks leave the nest hollow and follow the adults to the water, so the route between the hollow and water should remain unobstructed.

The sources do not specify a minimum hollow diameter, tree diameter, wetland area or distance between the nest tree and water.

  • Retain hollow-bearing trees beside occupied or suitable wetlands until a fauna ecologist has assessed them.
  • Keep water access and low-disturbance movement routes between potential nest trees and the wetland.
  • Schedule tree removal and intensive works outside the local breeding period where practicable, particularly January to March in Australia.
  • Use a qualified fauna spotter catcher to inspect hollows where tree removal cannot be avoided.

Sheltering habitat: Roosting and nesting refuges

The species roosts and nests in trees near water, with natural hollows used for nesting. It also rests on the water and may shelter in aquatic vegetation or along vegetated wetland edges.

Adults are reported to roost on trees near water. Natural tree hollows are the main documented nest refuge, and nests may be several metres above the ground.

The sources do not describe a specific hollow entrance size, preferred tree diameter or required amount of ground cover.

Documented refuge: Natural tree hollows near water.

Documented roost: Trees near water.

Known hollow or burrow dimensions: Not provided for wild birds.

  • Retain trees standing beside occupied wetlands, particularly trees with visible hollows, broken limbs or cavities.
  • Avoid lighting, repeated vehicle movements and noisy works beneath likely roost trees where birds are present.
  • Inspect trees from the ground and use qualified personnel where a hollow requires closer assessment.

Sheltering habitat: Aquatic cover

Emergent and other aquatic vegetation provides the main documented wetland structure associated with the species. Birds may remain on the water within or beside this vegetation while feeding or resting.

  • Retain patches of emergent and floating vegetation within and around the waterbody.
  • Avoid draining, infilling or rapidly dewatering occupied wetland areas before checking for birds and dependent young.
  • Maintain a clear but vegetated connection between open water and nearby roosting or nesting trees.

Threats: Project-related habitat loss

The species depends on freshwater habitat, aquatic vegetation and nearby hollow-bearing trees. Project impacts are most likely where wetland water regimes are changed, aquatic vegetation is removed, or trees beside occupied waterbodies are cleared.

Clearing or infilling of lagoons, ponds and other freshwater habitat can remove feeding and resting areas. Removing aquatic vegetation can reduce access to plant food, small aquatic prey and cover.

Removing trees beside wetlands can eliminate roosts and potential nest hollows. Fragmenting the wetland from nearby trees may also interrupt movement between nesting hollows and water.

  • Avoid clearing emergent aquatic vegetation and hollow-bearing trees beside occupied wetlands.
  • Fence exclusion areas around water, wetland margins and retained trees before construction starts.
  • Keep stockpiles, access tracks and spoil out of wetland depressions and drainage paths.
  • Recheck retained wetland habitat after heavy rainfall and during the breeding season because birds may move into newly suitable areas.

Threats: Hydrology and disturbance

The species moves in response to rainfall and water availability. Drainage, dewatering, altered inflows, changed hydroperiods and water pollution can therefore change whether a site supports feeding or breeding birds.

Noise, lighting, machinery and repeated human activity near occupied water and nest trees may cause birds to leave or interrupt breeding. The supplied sources do not provide species-specific disturbance distances.

  • Maintain natural inflows and avoid sudden drawdown of occupied waterbodies.
  • Time high-disturbance works away from the local breeding period where practicable.
  • Use low-impact access routes and keep machinery away from wetland edges and roost trees.
  • Do not apply a species-specific buffer distance unless it has been set by the project ecologist or approval conditions.

Threats: Predators, hunting and disease

Rock pythons have been recorded preying on the species. Historical threats included shooting and collection of eggs, although those records relate mainly to South Asia.

Blood parasites and several intestinal parasites have been recorded. The supplied sources do not establish the importance of these parasites to Australian populations.

Documented predator: Rock python.

Documented parasites: Plasmodium circumflexum, cestodes and trematodes.

  • Do not disturb or remove potential nest hollows during the breeding period without an ecological assessment.
  • Prevent domestic dogs and other avoidable predators from entering occupied wetland margins on project sites.
  • Report sick or dead birds through the relevant wildlife disease and biosecurity channels rather than handling them unnecessarily.
  • Avoid transferring aquatic plants, mud or water between wetlands because the species uses aquatic habitats and disease pathways are not well defined in the supplied material.

Threats: Roads, fire and fragmentation

The supplied sources do not document a species-specific road mortality rate, fire response or Australian fragmentation threshold. These pressures should still be considered where roads, fire controls or vegetation removal affect wetlands, aquatic vegetation or hollow-bearing trees.

  • Keep new roads and haul routes away from wetland margins and known flight paths where practicable.
  • Avoid burning wetland-edge vegetation or hollow-bearing trees used for roosting or nesting.
  • Retain links between open water, aquatic vegetation and nearby trees when designing access, drainage and fire-management works.
  • Record any road deaths, fire impacts or repeated disturbance events so project effects can be assessed over time.

Survey methodology: 1. Wetland and waterbody searches

Survey effort should focus on wetlands, lagoons, ponds and other waterbodies with emergent or other aquatic vegetation, plus nearby trees that may provide roosting or nesting hollows. The supplied documents do not provide a species-specific Australian survey guideline or minimum effort, so the methods below are general waterbird practice tailored to the Cotton Pygmy-Goose.

Search all waterbodies within and near the disturbance footprint, including small ponds, lagoons and wetlands with emergent vegetation.

Survey adjoining trees because the species roosts and nests near water and may use natural tree hollows.

Record the waterbody type, area searched, aquatic vegetation, nearby hollow-bearing trees, bird numbers, behaviour and flight direction.

Australian breeding period reported: January to March

Recorded nest height: Up to 5 metres above the ground

  • Complete searches when birds are likely to be using the waterbody, with repeat visits where water levels, rainfall or seasonal conditions change.
  • Include the full waterbody margin and suitable vegetation rather than relying only on searches from access tracks.

Survey methodology: 2. Dawn and dusk observation

Undertake quiet observation from concealed positions at wetland margins and likely roost trees.

Watch for pairs, groups of pairs and larger winter flocks, as well as birds arriving from or departing to other waterbodies.

Record birds flying low over the water, birds landing in vegetation, and birds entering or leaving tree hollows.

Typical social pattern: Pairs or groups of pairs; larger flocks can form in winter

Largest flock reported in the supplied material: Nearly 6,000 birds at Chilka Lake

  • Use binoculars or a spotting scope where available and avoid approaching roosting birds closely.
  • Repeat observations after rain or when water has recently returned to a previously dry wetland, because movements are associated with rainfall and water availability.

Survey methodology: 3. Nocturnal and roost checks

Use quiet spotlighting around wetland edges and nearby roost trees where daytime searches do not establish whether birds are present.

Check for birds roosting in trees near water, while avoiding direct illumination of birds for extended periods.

Record the date, start and finish times, weather, water conditions, search area, observer positions and all detections.

  • Treat spotlighting as a supplementary method because the supplied documents describe the species as active on water by day and do not provide a validated nocturnal survey protocol.
  • Do not use call playback unless it is authorised under the project survey plan and relevant wildlife requirements.

Survey methodology: 4. Nest and hollow inspection

Inspect suitable hollow-bearing trees beside wetlands for entrances, nest material, faecal traces, feathers and repeated bird movements.

Carry out inspections from the ground unless a suitably qualified person is authorised and equipped for an elevated inspection.

Plan searches around the Australian breeding period, January to March, while recognising that breeding is associated with rainfall and may vary with local conditions.

Clutch size reported: 6 to 12 ivory-coloured eggs

Nest location reported: Natural tree hollows, including hollows up to 5 metres above ground

  • Do not climb, open or block a hollow during a fauna survey.
  • Record tree location, species if known, diameter if measured, hollow height, entrance orientation and evidence of current use.

Survey methodology: Minimum effort and reporting

  • Use repeat visits when the initial search is affected by poor visibility, high wind, heavy rain, flooding, dense vegetation or unsuitable access.
  • Document survey dates, start and finish times, weather, water levels, aquatic vegetation, area searched, observers, equipment, limitations and all detections, including zero records.
  • Submit confirmed records and relevant photographs or sound recordings to the relevant state wildlife database.
  • Retain spatial records for all occupied or potentially occupied wetlands, roost trees and nesting hollows.
  • Obtain advice from the relevant state wildlife agency where the project may disturb a listed population or active nest.

Before habitat disturbance: Avoid and minimise

Avoid disturbing occupied wetlands and the trees associated with them. The species uses waterbodies with good aquatic vegetation, roosts and nests in trees near water, and can move between wetlands in response to rainfall and water availability.

  • Retain wetlands, lagoons, ponds and aquatic vegetation within and adjoining the project area wherever practicable.
  • Retain trees beside waterbodies, particularly hollow-bearing trees that could provide nest sites.
  • Maintain movement routes between retained waterbodies and nearby roosting trees.
  • Keep sediment, spoil, fuels and concrete washout away from waterbodies and aquatic vegetation.
  • Avoid lighting that shines across roost trees or wetland margins at night.

Before habitat disturbance: Approvals and timing

  • Check the current Commonwealth and state conservation status before work starts, noting that the supplied project information identifies the species as endangered in New South Wales and not listed under the EPBC Act.
  • Determine whether state wildlife permits, threatened species approvals or other waterway approvals are required for survey, handling, relocation or habitat disturbance.
  • Schedule clearing and high-noise work outside the local breeding period where practicable, noting that breeding in Australia is reported mainly from January to March and is associated with rainfall.
  • Stage works so that retained waterbodies and their vegetated margins remain available while other parts of the site are cleared.

Before habitat disturbance: Site preparation

  • Complete a pre-clearance survey of every wetland, lagoon, pond and nearby tree that may be affected by works.
  • Mark retained waterbodies, aquatic vegetation, hollow-bearing trees, roost trees and exclusion areas before machinery enters the site.
  • Use exclusion fencing where it can protect wetland margins, aquatic vegetation and retained trees from machinery, spoil and vehicle access.
  • Brief machinery operators on the marked exclusion areas, stop-work triggers and the fauna spotter catcher's authority.

During habitat disturbance: Daily controls

The fauna spotter catcher should keep the work area under active observation and coordinate each clearing step with the operator. Waterbodies, aquatic vegetation and nearby hollow-bearing trees require particular control because the species feeds on the water surface and nests in tree hollows.

  • Inspect exclusion fencing and wetland controls before work each day and repair breaches promptly.
  • Check retained waterbodies and nearby trees for birds before starting clearing, demolition or high-noise work.
  • Keep machinery, spoil, refuelling and washdown areas outside marked wetland and aquatic vegetation exclusion zones.
  • Use a slow, staged clearing sequence that allows birds and other fauna to move towards retained habitat before the next area is disturbed.

During habitat disturbance: Spotter catcher and machinery

  • Position the fauna spotter catcher where the active clearing face, nearby trees and wetland margins can be seen safely.
  • Require the operator to stop immediately when the spotter catcher gives the agreed stop signal.
  • Inspect each hollow-bearing tree before felling and, where authorised, retain it or use an approved staged felling procedure under the fauna management plan.
  • Do not allow machinery to chase, corner or drive birds from the waterbody.

During habitat disturbance: If a bird is found

  • Stop work and establish a quiet exclusion area around the bird and the immediate work zone.
  • Do not catch or handle the bird unless the person is authorised, trained and acting under the approved fauna management plan and relevant permit.
  • Allow an uninjured bird to leave on its own where it can move safely to nearby retained wetland or roost habitat.
  • If relocation is authorised, move the bird only to suitable nearby retained habitat with water and aquatic vegetation, following agency requirements.
  • Place an injured bird in a suitable secure container with minimal handling and arrange prompt transfer to a veterinarian or authorised wildlife carer.
  • Do not disturb an active nest or handle eggs or chicks unless specifically authorised.

During habitat disturbance: Stop-work triggers and records

  • Stop work when a Cotton Pygmy-Goose is found within the clearing zone, when an active nest or occupied hollow is identified, or when exclusion controls fail.
  • Stop work if birds repeatedly return to the work area or are unable to reach retained water or roost habitat safely.
  • Record the date, time, location, number and life stage of birds, behaviour, habitat used, action taken, handler details, relocation destination and outcome.
  • Report injuries, deaths, nest disturbance, unauthorised handling and permit incidents to the project environmental officer and relevant authority.

After habitat disturbance: Post-clearance checks

Post-clearance checks should confirm that no birds, nests or occupied hollows were missed and that retained wetlands remain functional. Continue controls while construction noise, lighting, traffic and altered drainage could affect the species.

  • Inspect the cleared area, retained trees and wetland margins after each clearing stage for birds, nests, injured fauna and damaged habitat.
  • Check that retained aquatic vegetation, water access and roost trees remain undisturbed.
  • Remove temporary fencing only when the environmental officer confirms that machinery and construction activities no longer threaten the retained habitat.

After habitat disturbance: Monitoring and reporting

  • Monitor retained waterbodies during and after construction for Cotton Pygmy-Geese, breeding activity, changes in aquatic vegetation and use of nearby trees.
  • Repeat observations after substantial rain or changes in water levels because the species moves in response to rainfall and water availability.
  • Compare monitoring results with pre-clearance records and report detections, incidents, habitat loss and management actions to the approval authority where required.
  • Submit verified post-construction records to the relevant state wildlife database.

After habitat disturbance: Ongoing controls and offsets

  • Maintain sediment, erosion, lighting, access and vegetation controls around retained wetlands for the duration of the project.
  • Repair damaged wetland margins, aquatic vegetation and exclusion fencing promptly.
  • Implement any approved offset or compensatory habitat measure required by Commonwealth, state or project approvals.

Rehabilitation actions: Wetland and vegetation reinstatement

Rehabilitation should recreate shallow, vegetated water habitat connected to retained trees and other wetlands. The aim is to provide feeding areas on the water surface and nearby roosting and nesting opportunities.

  • Reinstate or create ponds, lagoons or wetland areas with shallow margins and emergent aquatic vegetation suited to local conditions.
  • Use locally appropriate native aquatic and wetland plants, and avoid introducing weeds or non-local species.
  • Reconnect rehabilitated wetland areas with retained waterbodies where this can be done without creating erosion, flooding or fish passage problems.
  • Protect new wetland margins from vehicle access, sediment deposition and stock or pest damage.

Rehabilitation actions: Trees, hollows and nest sites

Natural nest site reported: Tree hollows

Reported nest height: Up to 5 metres above ground

  • Retain existing mature trees beside rehabilitated waterbodies wherever safe and practicable.
  • Retain suitable fallen timber and natural structures only where they do not create a safety, fire or pest risk.
  • Install nest boxes only where a qualified ecologist and the relevant authority identify them as suitable for the site, because the supplied documents describe natural tree hollows as the normal nest site but do not provide a validated nest-box design for this species.
  • Record the location, design and maintenance requirements of any installed nest box.

Rehabilitation actions: Management and success measures

  • Control weeds around rehabilitated wetlands and maintain native aquatic vegetation.
  • Manage feral predators and other introduced animals in accordance with the approved fauna management plan and relevant law.
  • Use fire planning that protects wetland vegetation, retained trees and nest structures from inappropriate burning.
  • Monitor rehabilitated sites for Cotton Pygmy-Goose presence, pairs, breeding behaviour, use of aquatic vegetation and use of nearby trees.
  • Define success using approved project targets for wetland establishment, native vegetation survival, water retention, absence of significant weed invasion and confirmed use by the species.

Sources