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Caspian Tern (Hydroprogne caspia)

The Caspian Tern is Australia's largest tern, using coastal and inland wetlands, estuaries, rivers, lakes and open coastal waters. It can be overlooked on works sites because birds may only fly over, forage briefly or gather at nearby roosts, but active colonies and listed migratory habitat need careful protection. It is listed as migratory under the EPBC Act through JAMBA, and is Vulnerable in Victoria.

Conservation status

Victoria, Flora and Fauna Guarantee Act 1988: Vulnerable.

Commonwealth, EPBC Act 1999: Listed migratory. Listed under JAMBA. Listed migratory species are a matter of national environmental significance, so a significant impact needs referral.

Queensland, Nature Conservation Act 1992: Special least concern. A least concern bird covered by an international migratory bird agreement. Tampering with its breeding place needs a high risk species management program.

Western Australia, Biodiversity Conservation Act 2016: Specially protected (migratory).

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.

Migration and breeding season

Caspian Terns breed in Australia, with breeding recorded from August to November in south-western Australia. The species is listed as migratory under JAMBA, but Australian records also describe it as a resident breeder, so local presence can occur throughout the year and timing varies between regions.

Breeding mode: Colonial breeder. Most Australian colonies contain several pairs, although larger colonies occur on islands and sandspits.

Colony size: The Penguin Island colony in south-western Australia contained approximately 60 pairs. A colony near Corner Inlet was recorded with up to 100 individuals.

Breeding places: Rocky offshore or nearshore islands and sandspits near river mouths are documented breeding places. No evidence supports nests in hollows, caves or burrows.

Clutch size: Not recorded.

Incubation: Approximately 26 to 28 days.

Fledging: Approximately 35 to 45 days.

Age at maturity and site fidelity: Not recorded. Do not assume that an apparently unused colony site is no longer important.

Timing varies between years and regions, and active colonies or communal roosts should be confirmed by a suitably experienced ecologist before clearing; no universal disturbance distance is established for this species, so buffers should be set for the site, activity, visibility, noise and observed flushing response.

  • Breeding colonies in Australia: Breeding colonies have been documented from August to November, including on rocky islands and sandspits near river mouths.
  • Eggs, chicks and dependent young: Eggs and dependent young may be present during and after the August to November breeding period because incubation lasts 26 to 28 days and fledging takes approximately 35 to 45 days.
  • Resident and non-breeding presence in Australia: Caspian Terns are described as resident breeders in Australia and may use coastal waters, estuaries, wetlands, lakes, lagoons and rivers throughout the year.
  • Local movement between colonies, roosts and feeding areas: Adults and fledglings can move between breeding islands, shallow feeding waters, exposed sandspits and communal roosts, and roost locations can shift between nearby sites.
  • Colony and roost disturbance risk: Avoid clearing, construction, noisy works, bright night lighting, vessel approach and water regime changes near active colonies from August to January, and protect roosts and feeding concentrations year-round.
  • Highest clearing risk: The highest risk is August to January, when colonies, eggs, chicks and recently fledged birds may be present; use a site-specific exclusion buffer and keep works outside the nesting period wherever practicable.

Identification: Appearance

The Caspian Tern is a large, robust tern with a heavy red bill. It is usually seen over water, flying strongly, loafing on exposed sand or plunge diving for fish.

Adults have a white body, grey mantle and upper wings, darker flight feathers, black legs and a heavy red bill with a dusky tip. The breeding-plumage crown is black, with black and white streaking from the bill to the nape and a short shaggy crest.

The sexes look alike. Younger birds are more mottled grey and brown, and immature birds resemble non-breeding adults.

  • Body length, 53 to 60 cm.
  • Average weight, about 680 g.
  • Long, slender, backswept wings.
  • Slightly forked tail.
  • Dark brown eye and black legs.

Identification: Calls and similar species

Calls are loud tern calls, often given by birds flying over a wetland or gathering at a roost. Use behaviour, size, bill shape and flight together when checking an identification.

The Caspian Tern is the largest tern species. Smaller terns can look similar at a distance, so confirm the heavy red bill, large body and powerful flight before recording a bird during clearance.

Identification: Field signs

Look for white droppings and whitewash on regularly used sand spits, islands, rocks, posts, bridges or other exposed roost surfaces. Fresh droppings, feathers, tracks and repeated bird activity can show that a roost is currently in use.

A breeding place may have scrape-like nests on bare sand, gravel or rock, eggs, downy chicks, adults sitting low, or adults repeatedly circling and calling over one location. Do not enter or inspect a suspected nest area closely without an approved survey and management plan.

  • Repeated adults flying to one exposed island, sandbank or spit.
  • Alarm calling, circling or dive attacks when people approach.
  • Adults standing guard while another bird remains low on the ground.
  • Chicks, eggs, shell fragments or concentrated feathers.

Distribution: Australian range

In Australia, the Caspian Tern has a wide but scattered distribution across coastal and inland water systems. It is mapped in New South Wales, the Northern Territory, Queensland, South Australia, Tasmania, Victoria and Western Australia.

The species occurs around coastlines, estuaries, wetlands, river systems, lakes, lagoons and ephemeral waterbodies. Records include the Peel-Harvey Estuary in south-western Australia, Roebuck Bay in Western Australia, the Fitzroy River and Dunganweate Lagoon in Queensland, and the Menindee Lakes in New South Wales.

In New South Wales it is widespread east of the Great Dividing Range, mainly in coastal areas, and also occurs in the Riverina and the Lower and Upper Western regions.

  • Coastal embayments and estuaries.
  • Freshwater and saline wetlands.
  • Rivers, creeks, reservoirs and farm dams.
  • Ephemeral lakes, including Lake Eyre.

Distribution: Overseas range

The Caspian Tern has a cosmopolitan distribution. Australian birds are associated with coastal and inland water networks, and some individuals move between breeding areas and non-breeding feeding sites.

Distribution: What records mean on a project site

A flying record does not show that a site is a breeding place. A bird flying over may be moving between a colony, feeding area and roost. Repeated records, feeding behaviour, roosting birds or birds defending a location need follow-up by an experienced ecologist.

  • Record the location, number of birds, behaviour, tide or water level and direction of travel.
  • Check connected wetlands and shoreline habitat beyond the immediate clearing footprint.
  • Treat nearby islands, sandbanks and exposed spits as potential roost or breeding areas.

Habitat: Waterbodies and shorelines

The species uses both fresh and saline environments, usually where there is open water and a clear view of fish. On a works site, inspect the water edge, exposed sediment, nearby islands and any connected wetland habitat.

Look for sheltered estuaries, lagoons, lakes, river pools, creeks, reservoirs, sewage ponds, saltworks and open coastal waters. Sandy or muddy margins are commonly used, especially where shallow water is next to an exposed resting surface.

  • Estuaries and river mouths.
  • Shallow coastal embayments and ocean-channel margins.
  • Freshwater, saline and ephemeral wetlands.
  • Permanent and temporary waterholes.

Habitat: Landforms and substrates

Large sandy spits beside shallow water are particularly useful. Rocky nearshore or offshore islands and sand spits near river mouths can support breeding colonies.

  • Beaches and sandbanks above the high-tide mark.
  • Exposed mudflats and dried mudflats.
  • Rocky islands and rock outcrops.
  • Sand and seagrass margins in shallow estuaries.

Habitat: Wetland condition and water management

Water levels can change where birds feed and roost. As wetlands dry, exposed margins may become available and fish may concentrate in remaining shallow water. Flooding can also remove nests, cover feeding areas or shift birds to higher islands and banks.

Before earthworks, drainage changes or floodplain works, check how the proposal will affect shallow water, exposed roost surfaces, fish access and connected wetlands across the full water-management cycle.

  • Avoid isolating or filling shallow wetland edges where practicable.
  • Maintain natural flows and fish access where the project allows.
  • Inspect again after flooding, drawdown or major water-level changes.
  • Keep sediment, fuel and contaminated water out of wetlands and estuaries.

Foraging habitat: Features to look for

Caspian Terns forage by sight in clear, shallow and productive water. They scan, hover and plunge dive, so open water beside a quiet exposed spit can be more valuable than a larger but deep or turbid waterbody.

Inspect tributary mouths, river mouths, shallow channels, sandy spits and areas where clear water meets sand or seagrass. Adjacent wetlands may also be used when water levels fall and fish become concentrated.

  • Shallow estuarine water.
  • Clear water with visible fish activity.
  • Tributary inflows and river mouths.
  • Sand and seagrass substrates.
  • Wetland margins connected to rivers or estuaries.

Foraging habitat: Behaviour indicating feeding habitat

Scanning birds often sit or fly low while watching the water. Hovering followed by a fast plunge dive is a strong sign of active foraging habitat. Recently fledged birds may practise feeding in shallow water.

  • Repeated plunge diving in one area.
  • Low flight and hovering over shallow water.
  • Birds moving between a roost and the same feeding area.
  • Juveniles foraging continuously in sheltered shallows.

Foraging habitat: Works controls

Keep plant, vehicles, vessels and people away from active feeding areas where practicable. Prevent fuel, concrete washout, sediment and other pollutants from entering the water. Avoid bright night lighting directed across wetland or estuary habitat.

  • Schedule noisy in-water work outside periods of highest bird use where practicable.
  • Use bunding, spill kits and sediment controls before starting work.
  • Set vessel approach limits around feeding and roosting birds through the site environmental plan.
  • Stop and reassess if birds repeatedly leave the feeding area because of works.

Breeding habitat: Known breeding settings

Australian breeding colonies are usually small, but a single site can hold a substantial share of the local breeding birds. Breeding habitat is generally open and isolated, rather than dense woodland or enclosed vegetation.

Breeding colonies can occur on rocky offshore or nearshore islands and on sand spits near river mouths. Breeding has also been recorded at the Menindee Lakes.

The largest recorded breeding colony in south-western Australia is on Penguin Island in Shoalwater Bay, where about 60 pairs were present in 2017 and 2018.

  • Rocky islands with little ground cover.
  • Sandy islands and spits above regular water levels.
  • Isolated sandbanks near river mouths.
  • Open margins of large inland lakes.

Breeding habitat: Breeding period and development

At Penguin Island, breeding occurs from August to November. Incubation takes about 26 to 28 days, and chicks fledge at about 35 to 45 days.

Local timing can vary with location, water levels and colony conditions. Confirm activity in the field rather than relying only on a calendar.

South-west Australian breeding period: August to November

Incubation: About 26 to 28 days

Fledging: About 35 to 45 days

Breeding habitat: Recognising an active breeding place

Look for adults repeatedly arriving at or leaving one open area, birds sitting low on the ground, eggs, chicks, shell fragments, down and concentrated droppings. Adults may alarm call, circle, mob people or dive at intruders.

Do not walk onto an island, sandbank or spit to check for nests unless the inspection has been planned by a suitably experienced person. Ground nests and chicks can be difficult to see and are easily trampled.

  • Repeated alarm calls or defensive flight.
  • Adults carrying fish towards one location.
  • Nest scrapes on bare sand, gravel or rock.
  • Chicks sheltering beside low vegetation, rocks or ground contours.

Sheltering habitat: Roost features

Roosts are exposed places where birds rest, preen and wait between feeding bouts. They may be close to feeding water and can shift when tides, flooding, water levels or disturbance change.

Inspect sand spits, beaches, islands, mudflats, shallow water edges and exposed rocks. In the Peel-Harvey Estuary, birds used sandy spits above the high-tide mark and later shifted to dried mudflats near Creery Island.

  • Dry sand above the high-tide line.
  • Quiet beaches and islands.
  • Exposed mudflats during low water.
  • Shallow water where birds can stand or rest.

Sheltering habitat: Roost size and site use

Roost counts can vary substantially. A Peel-Harvey roost held 84 birds on 28 November 2018 and 147 birds on several dates in January and February 2019. About 15 birds were previously recorded roosting in shallow water at Pink Lily Lagoon, and up to 40 were recorded in Roebuck Bay.

  • Record the full roost count where possible.
  • Map the roost boundary and the nearest feeding water.
  • Check nearby alternative roosts if birds disappear after disturbance.
  • Do not assume that an empty roost has been abandoned permanently.

Sheltering habitat: Protecting an active roost

Keep people, dogs, vehicles, boats and machinery away from active roosts. Use a site-specific buffer set by the project ecologist, based on bird behaviour, visibility, noise, terrain and the type of work. There is no single distance that suits every Caspian Tern roost.

If birds repeatedly flush, increase the separation distance and remove the disturbance source where practicable. Schedule works outside the period of highest use and avoid night lighting across the roost.

  • Use fencing, signs and clearly marked no-go areas.
  • Keep access routes away from the roost and its approach path.
  • Avoid sudden noise, vibration and bright lighting.
  • Stop work and seek ecological advice if birds cannot settle.

Colonies and breeding places: Colony locations

A colony is a group of Caspian Terns breeding close together. It may look like scattered adults on bare ground, but nests can be close and difficult to see. Colonies need special care because one disturbance event can flush many adults and expose eggs or chicks at once.

Search open, isolated places near reliable water. Caspian Tern colonies are known from rocky islands and sand spits near river mouths. The species is not generally associated with tree hollows, caves or burrows.

  • Rocky offshore and nearshore islands.
  • Sandbanks, beaches and spits above high water.
  • Islands near river mouths or estuary channels.
  • Open lake margins and inland wetland islands.

Colonies and breeding places: Colony size and density

Most Australian colonies are limited to several pairs, although larger colonies occur. Penguin Island supported about 60 pairs, and a colony on the outer barrier islands of Nooramunga Marine Park was recorded with up to 100 individuals.

Nest density is not well documented for Australian sites. Treat any close group of adults, nests or chicks as a colony until an ecologist confirms otherwise.

  • Do not estimate colony size from a single count at the water edge.
  • Count adults, nests and chicks separately where this can be done without entering the site.
  • Map the colony and the flight path to feeding and roosting areas.

Colonies and breeding places: Site fidelity and active breeding signs

Caspian Terns may return to established islands or spits, but colonies and roosts can shift after flooding, erosion, water-level changes or disturbance. The same landscape may therefore be important even when birds are absent on one inspection.

An active breeding place is indicated by defensive adults, repeated food deliveries, eggs, chicks, nest scrapes, down, shell fragments and concentrated droppings.

  • Check historical colony locations before planning access or clearing.
  • Survey likely sites before works and again if water levels change.
  • Keep works outside the active nesting period where practicable.
  • Maintain a project-specific buffer around the whole active colony, not only individual nests.

Colonies and breeding places: Legal and construction controls

In Queensland, tampering with the breeding place of a least concern colonial breeder requires a high risk species management program under the Nature Conservation (Animals) Regulation 2020. Caspian Tern is also a special least concern animal in Queensland because it is covered by JAMBA, so tampering with its breeding place requires the high risk pathway rather than the low risk pathway.

Under the EPBC Act, listed migratory species are a matter of national environmental significance. An action likely to have a significant impact on the species or its important habitat may need referral.

  • Get the required approvals before entering, disturbing or modifying a breeding place.
  • Keep clearing, blasting, piling, loud vehicle movements and shoreline works outside nesting where practicable.
  • Use qualified fauna personnel to inspect and monitor any colony buffer.
  • Stop work if an unrecorded colony or breeding place is found.

Migration and seasonal presence: Seasonal presence in Australia

Caspian Terns show a mixed pattern in Australia. Some are resident breeders, while the species is also listed as migratory under JAMBA and may move between colonies, estuaries, wetlands, rivers and coastal feeding areas.

There is no single national arrival or departure period that applies to all Australian Caspian Terns. In south-western Australia, the Penguin Island breeding colony is active from August to November, and adults travel with fledglings to nearby non-breeding feeding areas such as the Peel-Harvey Estuary.

Local birds may remain in Australia year-round. Passage and dispersal can occur through coastal and inland water networks, so a bird outside the breeding period still needs to be treated as a protected migratory species.

  • Breeding example, south-western Australia, August to November.
  • Non-breeding use, estuaries, wetlands, rivers, lakes and coastal waters.
  • Local movements, between feeding areas, roosts and breeding islands.
  • Broader seasonal timing, variable between regions and water conditions.

Migration and seasonal presence: Important habitat in Australia

Important habitat can include shallow nearshore waters, sheltered coastal embayments, open wetlands with clear water, river mouths, sandy spits, islands and connected wetland systems. Corner Inlet and the Peel-Yalgorup system are examples of landscapes containing important habitat features.

Assess the function of the whole site, not only the area to be cleared. Feeding, roosting, breeding and movement areas can be separated by several kilometres and still operate as one local network.

  • Regular feeding or roosting concentrations.
  • Habitat supporting a breeding colony.
  • Shallow water with exposed sand or mud nearby.
  • Wetlands connected to rivers, estuaries or coastal embayments.

Migration and seasonal presence: Survey timing for projects

Plan surveys around tides and water levels. Roost surveys are most useful within two hours either side of high tide, while feeding surveys are most useful within two hours either side of low tide. Repeat surveys across the likely period of use because one visit can miss birds or a shifted roost.

Avoid surveys and works during heavy rain, high winds or other conditions that cause birds to leave. Record abundance, behaviour, tide, water level, roost location and flight direction.

  • Survey both high-tide roosts and low-tide feeding areas.
  • Include the northern hemisphere breeding season where EPBC migratory survey guidance applies.
  • Use additional surveys during the local peak non-breeding period when site use is uncertain.
  • Refer a potentially significant action under the EPBC Act before work starts.

Threats: Disturbance and flushing

Development can affect Caspian Terns through habitat loss, disturbance, pollution and changes to water movement. The greatest immediate risk at a breeding place or major roost is repeated flushing of many birds.

People, dogs, four-wheel-drives, boats, fishing activity, machinery, loud unpredictable noise, vibration and bright night lighting can disturb feeding, roosting and breeding birds. Repeated flushing can expose eggs and chicks, interrupt feeding and make a site unsuitable.

Set buffers using observed behaviour and site conditions. Increase the buffer if birds alarm call, circle, mob workers or repeatedly leave the site.

  • Fence and sign no-go areas before construction.
  • Keep access tracks, vessels and work platforms away from active sites.
  • Use low-glare, directional lighting and avoid lighting wetlands at night.
  • Keep works outside nesting periods where practicable.

Threats: Habitat loss and water changes

Filling marsh, mudflat, shallow water or sandy roost surfaces can remove feeding and resting habitat. Drainage, altered flooding, bank works and changes to water levels can also shift or reduce fish access and expose breeding places to flooding or erosion.

  • Retain connected wetland, estuary and river habitat.
  • Avoid removing shallow margins and exposed spits.
  • Maintain suitable flows and fish passage where practicable.
  • Inspect for changed roosts after floods, drawdown and major earthworks.

Threats: Pollution and invasive species

Fuel or chemical spills can harm fish and other aquatic communities. Oiling can compromise feathers, flight and feeding. Sediment, weeds, ballast-water organisms and food waste can degrade habitat or attract rats, feral cats and foxes.

  • Use spill prevention, bunding and rapid response procedures.
  • Keep sediment and concrete washout out of water.
  • Clean vehicles and plant before entering wetland areas.
  • Secure food waste and inspect for pest activity around colonies and roosts.

Threats: Collision and project planning

Tall structures, overhead infrastructure and wind turbines can affect flight paths and create collision risk. Assess flight routes between colonies, roosts and feeding areas, especially where regular commuting flights cross the project footprint.

Record all Caspian Tern observations during pre-clearing checks and construction monitoring. Escalate repeated flight interactions, collision events or changes in roost use to the project ecologist and relevant regulator.

  • Map regular flight lines and movement corridors.
  • Avoid placing high-risk structures between a colony or roost and its feeding habitat where practicable.
  • Use environmental inductions so workers recognise alarm behaviour and stop-work triggers.
  • Apply Queensland breeding-place approvals and EPBC referral requirements before disturbance.

Survey methodology: 1. Desktop assessment

Survey for Caspian Terns should cover open water, shorelines, roosts and possible breeding places. Use experienced observers, record behaviour and habitat use, and repeat surveys when conditions or seasonal use make detection difficult.

Map estuaries, wetlands, lakes, lagoons, rivers, waterholes, reservoirs, saltworks and open coastal waters before field work.

Identify shallow clear water, sandy spits, beaches, islands, river mouths, ocean channels, mudflats and exposed sandbanks. These areas may support feeding, loafing or roosting birds.

Check for known colonies and roosts on rocky offshore or nearshore islands, sand spits near river mouths, beaches and islands. Include the wider connected wetland and estuary network in the assessment.

Treat a breeding colony, shared roost or regularly used feeding area as a site feature, not just an observation point.

Australian status: Resident breeder in Australia, and listed as migratory under the EPBC Act through JAMBA.

Known breeding timing: August to November in south western Australia.

Recorded colony scale: Most Australian colonies are limited to several pairs. About 60 pairs were recorded at Penguin Island, and a nearby breeding colony has been recorded with up to 100 individuals.

  • Review recent records and aerial imagery.
  • Check whether works may affect flight paths, water quality, fish habitat, tidal access or wetland water levels.
  • Confirm whether the site is in or near a Ramsar wetland, marine area, protected area or mapped important habitat.
  • Allow for use of the site by birds that breed elsewhere and travel to nearby feeding or roosting areas.

Survey methodology: 2. Field detection and survey effort

Search from a concealed or distant vantage point where possible. Scan the full waterbody, shoreline, islands, sand spits and nearby airspace with binoculars and a telescope.

Conduct high tide surveys within two hours either side of high tide to locate roosting birds. Conduct low tide surveys within two hours either side of low tide to locate feeding birds.

Where a project may affect a wetland or estuary, use at least four roost surveys and four foraging surveys during the period when the species is most likely to be present, where that guidance applies. Include one survey during the northern hemisphere breeding season for EPBC migratory bird assessments.

Repeat surveys across suitable tides and, where relevant, across the August to November breeding period. There is no single national arrival or departure period for Caspian Terns, so do not rely on one visit.

Avoid heavy rain and high winds. Delay surveys when weather, glare, dust, construction activity or recreational use prevents reliable detection.

Roost observations: Roost counts of 84 to 147 birds have been recorded at one Peel Harvey Estuary site.

Small groups: About 15 birds were previously recorded roosting in shallow water at Pink Lily Lagoon.

Roebuck Bay record: A maximum of 40 birds was recorded at a single site during surveys from December 2019 to February 2020.

  • Use a telescope to inspect distant rocky islets, islands and sandbanks.
  • Survey both the project footprint and nearby habitat that could be affected by noise, lighting, vessels, access or water management.
  • Watch for plunge diving, hovering, repeated feeding flights and birds carrying fish.
  • Allow birds time to settle before counting them.

Survey methodology: 3. What to record

Record the number of adults and juveniles, exact location, date, time, tide, weather, visibility, water level and observer effort.

Map feeding, loafing, roosting and flight areas separately. Record whether birds are using clear shallow water, a sand spit, beach, island, mudflat, river mouth or wetland edge.

Describe behaviour. Repeated alarm flights, circling, calling, birds carrying nesting material or fish, territorial behaviour and adults attending small young can indicate breeding activity.

Photograph the site and representative birds only where this can be done without causing disturbance.

  • Record the direction and height of flight where relevant to cranes, bridges, wind turbines, vessels or other structures.
  • Record vessels, people, vehicles, dogs, aircraft, lighting and other disturbance near birds.
  • Record any band, colour mark, injury, dead bird or evidence of predation.
  • Mark all active colonies, roosts and associated feeding areas in the project GIS and daily work maps.

Survey methodology: 4. Recognising a colony or active breeding place

A colony may be a small group of breeding pairs on a rocky island, offshore island, sand spit or other isolated ground. Caspian Tern colonies in Australia are often small, although larger colonies occur at suitable islands and sandbanks.

A maternity roost is not a breeding colony. A roost is a place where birds gather to rest, often on a sand spit, beach, island, mudflat or shallow water. Roosts may hold dozens or more than 100 birds and can shift when water levels or disturbance change.

Treat a place as active when birds are defending an area, repeatedly returning to the same nesting ground, sitting low on nests, carrying nesting material or food, attending eggs or chicks, or showing alarm behaviour around a discrete site.

Look for eggs, chicks, scrape nests, droppings, feathers, tracks and repeated adult movements. Do not enter an island, sandbank or colony to confirm breeding unless the inspection has been planned and authorised.

  • Use a telescope from outside the likely disturbance area.
  • Check adjacent water and feeding areas because adults may leave the colony to forage.
  • Record the colony boundary, estimated number of breeding birds, young present and access routes.
  • If breeding cannot be confirmed, manage the site as a potential active breeding place until an ecologist has assessed it.

Before habitat disturbance: 1. Approvals and legal checks

Plan works around the birds and the habitat they use, not just the clearing footprint. Avoid colonies, roosts, shallow feeding areas and flight paths wherever practicable, and obtain approvals before disturbance starts.

Have the environmental approvals team assess whether the action is likely to significantly impact the Caspian Tern as an EPBC Act listed migratory species. Refer the action under the EPBC Act when a significant impact is likely.

In Queensland, obtain advice on the Nature Conservation Act and the Nature Conservation (Animals) Regulation 2020 before tampering with a breeding place. A least concern colonial breeder requires a high risk species management program, not the low risk program used for other least concern animals.

In Queensland, treat this species as a special least concern animal because it is covered by JAMBA. Tampering with its breeding place therefore requires the high risk species management program.

Check state and territory wildlife, planning, marine park, fisheries, waterway and protected area requirements. Obtain any state permits, scientific licences, fauna handling authorities and land manager approvals before work.

  • Keep copies of approvals, permit conditions, maps and the approved fauna management plan at the site office.
  • Confirm who can approve a temporary stop work and who must be contacted if a breeding place is found.
  • Do not assume that a least concern listing removes breeding place protections.
  • Escalate any conflict between project timing and a permit condition before works begin.

Before habitat disturbance: 2. Avoidance, timing and buffers

Schedule noisy, bright or intrusive works outside the local breeding period where possible. In south western Australia, plan around August to November. Obtain local ecological advice in other regions because breeding timing and seasonal movements can vary.

Retain islands, sand spits, beaches, shallow water, wetland edges and other regularly used roosts. Maintain access to feeding areas and avoid changing water levels, tidal exchange or drainage without ecological assessment.

Set a site specific exclusion buffer around an active colony, nest or breeding place. The ecologist should consider terrain, visibility, noise, vibration, aircraft, vessels, lighting, predator access and the birds' response.

Increase the buffer if birds flush, circle repeatedly, call continuously or fail to return. Keep people, vehicles, dogs, vessels and plant outside the buffer.

  • Use fencing, bunting, signs and GPS exclusion layers to define the buffer.
  • Keep works outside the nesting period where practicable.
  • Use quiet plant and low disturbance access routes away from roosts and feeding areas.
  • Restrict night lighting directed toward colonies, roosts, water and flight paths.
  • Do not set a generic distance without a site assessment and approval condition.

Before habitat disturbance: 3. Pre clearance survey and site setup

Complete a pre clearance inspection immediately before works, and repeat it if work stops for more than a short period or conditions change. Inspect the footprint, access tracks, laydown areas, shoreline, waterbodies and nearby islands or sandbanks.

A qualified ecologist should confirm whether the area contains an active colony, breeding place, roost, feeding concentration or flight path. The fauna spotter catcher should receive the map and contact details before entering the site.

Establish exclusion zones before machinery arrives. Mark retained habitat, no go areas, access routes, lighting limits and emergency stop work areas.

Do not clear vegetation, drain water, drive through shallow water or occupy a sandbank until the pre clearance inspection is complete.

  • Inspect at a suitable tide where birds use intertidal habitat.
  • Check for eggs, chicks, adults attending nests, repeated alarm behaviour and fresh nesting signs.
  • Photograph and map all findings.
  • Brief the crew on the species, its colonial behaviour, the stop work trigger and the prohibition on handling birds without authority.

Before habitat disturbance: 4. Crew induction and contingency planning

Tell all workers that one breeding place can support a large share of the local population. Disturbance at a colony can flush adults, expose eggs and chicks, and cause repeated loss of feeding time.

Explain the difference between a roost and an active breeding place. Both require protection, but an active breeding place requires immediate stop work and ecological assessment.

Prepare a contact list for the project ecologist, fauna spotter catcher, wildlife carer, regulator, land manager and emergency services.

  • Use daily toolbox talks during work near wetlands, beaches, islands and estuaries.
  • Set clear stop work triggers for a new colony, nest, chick, injured bird, mass flushing event, pollution event or unexpected water level change.
  • Keep capture equipment, a ventilated container and clean cloth available only for authorised wildlife handlers.
  • Include spill, fire, flood, lighting and vessel disturbance responses in the site plan.

During habitat disturbance: 1. Sequential clearing and active supervision

Use a staged approach and keep a competent fauna observer involved while work is near water, shorelines or known bird habitat. Stop first, then assess. Do not chase, capture or relocate a Caspian Tern unless an authorised person directs it.

Clear in stages from the least sensitive edge toward the retained habitat, while leaving a clear escape route away from machinery and toward safe open habitat.

Use a fauna spotter catcher or suitably authorised ecologist to inspect each work area immediately before disturbance and to monitor high risk activities.

Stop work when birds begin repeated alarm flights, adults leave a colony, chicks are exposed, or birds cannot settle because of noise, vibration, lighting or vehicle movement.

Keep plant, people, vessels and temporary lighting outside mapped buffers. Reduce speed and noise near shorelines and wetlands.

  • Begin with a pre start fauna check each day.
  • Clear only the area released by the spotter catcher.
  • Use spotters on both sides of water crossings and near blind corners.
  • Pause work during heavy rain, high winds or poor visibility if the observer cannot safely assess birds.

During habitat disturbance: 2. If a colony, breeding place or roost is found

Call stop work and withdraw people and plant without approaching the birds. Keep the area quiet and prevent other workers, vehicles, dogs and vessels from entering.

Contact the project ecologist and approval holder. Reassess the buffer, activity timing, lighting, access and potential effects on nearby feeding habitat.

Do not move nests, eggs, chicks, scrape material, sand, rocks or vegetation from a breeding place. Do not attempt to flush birds to identify nests.

Treat a regularly used roost as a protected site while its function and sensitivity are assessed, even when breeding is not confirmed.

  • Mark a temporary exclusion zone from outside the disturbance area.
  • Record the birds' response and whether adults return after work stops.
  • Obtain written ecological and regulatory clearance before restarting.
  • Update the site map, induction and method statement before work resumes.

During habitat disturbance: 3. Handling and injured animal response

Only a person authorised under the relevant permit or wildlife authority may handle a Caspian Tern. Fauna spotters should not capture the bird unless their authority and training cover the action.

Keep uninjured birds away from people and allow them to leave naturally. Never herd a bird toward water, a road or machinery.

For an injured or grounded bird, stop nearby work, isolate the area, reduce noise and lighting, and contact the project wildlife carer or regulator. Follow their instructions for containment and transport.

Use a ventilated box or container only when directed by an authorised handler. Keep the bird dark, quiet and secure. Do not give food or water unless instructed by a wildlife professional.

  • Record the location, condition, visible injury, time found and action taken.
  • Check for collision, entanglement, oil, chemical exposure and vehicle strike hazards.
  • Keep members of the public and workers away from the animal.
  • Arrange transfer to an approved wildlife rehabilitator or veterinarian.

During habitat disturbance: 4. Daily records and incident control

Record all observations, stop work events, breeding places, roosts, injuries, mortalities, flushing events and changes to water or habitat.

Document the activity underway, equipment, weather, tide, bird numbers, behaviour, exclusion zone, people notified and time work stopped and restarted.

Report any event required by an approval, permit, SMP, incident plan or regulator condition within the required timeframe.

  • Keep daily fauna logs with the project environmental records.
  • Attach photographs, GPS points and updated maps.
  • Record any breach of a buffer or lighting condition as an environmental incident.
  • Review controls before restarting after any incident.

After habitat disturbance: 1. Post clearance and daily completion checks

Post work checks should confirm that birds, breeding places, roosts and feeding habitat remain usable. Follow up promptly after clearing, waterway works, night work, spills, collisions or any event that caused birds to leave.

Inspect the completed work area and retained habitat for stranded birds, injured animals, exposed nests, damaged banks, waste, oil, sediment and new access points.

Check that exclusion fencing, signs, lighting controls and no go areas remain in place. Remove temporary hazards only after the ecologist confirms that they are no longer needed.

Where a colony or roost is nearby, complete a quiet follow up observation from outside the buffer. Confirm whether birds have returned and whether feeding and roosting areas remain available.

  • Inspect water crossings, trenches, pits, culverts and temporary dams before they are closed or filled.
  • Check disturbed shorelines and sand spits for erosion or changed access.
  • Record bird numbers and behaviour using the same locations and methods as the baseline survey.
  • Escalate any continued absence, repeated flushing or reduced feeding activity.

After habitat disturbance: 2. Monitoring and relocated animals

Monitor retained habitat and any active breeding place at a frequency set by the ecologist, approval condition or SMP. Increase checks after storms, floods, water level changes, high disturbance or predator activity.

Do not assume that a bird has relocated successfully because it is absent from one site. Search nearby islands, sand spits, beaches, mudflats and shallow water for the replacement roost or colony.

Track any handled or relocated animal through the authorised wildlife carer. Record release location, date, condition and follow up outcome.

If breeding birds abandon a site, investigate noise, lighting, access, predators, water level and habitat changes before work continues.

  • Use fixed observation points where practicable.
  • Keep observers outside the approved buffer.
  • Compare counts, behaviour and habitat use over time.
  • Report failed relocation, mortality or repeated disturbance under the project incident process.

After habitat disturbance: 3. Reporting and close out

Prepare a close out report covering survey effort, bird records, colonies, roosts, injuries, mortalities, stop work events, approval conditions and mitigation performance.

Provide maps showing cleared areas, retained habitat, buffers, lighting controls, water management and any replacement habitat.

Notify the regulator, land manager and approval holder of reportable incidents. Retain records for the period required by the approval, permit or SMP.

  • Include photographs before, during and after works.
  • List outstanding actions, responsible people and completion dates.
  • Record whether breeding or roosting habitat was lost, retained, restored or replaced.
  • Use the findings to update the fauna management plan for later project stages.

After habitat disturbance: 4. Incident review and adaptive management

Review every unexpected interaction with Caspian Terns, including collision, oiling, repeated flushing, nest disturbance, water level change and unauthorised entry into a buffer.

Identify the cause and change the work method, timing, access, lighting, plant, buffer or crew training before continuing similar work.

Share lessons with supervisors, spotter catchers, contractors and the approval holder.

  • Check whether the survey timing detected the relevant use period.
  • Check whether the buffer was large enough for the actual terrain and activity.
  • Check whether birds had safe feeding, roosting and escape areas.
  • Close the incident only after corrective actions are verified in the field.

Rehabilitation actions: 1. Restore feeding and roosting habitat

Rehabilitation should restore shallow water, safe shorelines and quiet roosting places rather than simply replace cleared ground. Design the outcome around the local estuary or wetland system, and maintain it through the seasons.

Reinstate natural drainage, tidal exchange and seasonal water levels where these have been altered. Obtain ecological and hydrological advice before changing wetland flows.

Restore shallow clear water, gently graded margins, mudflats, sandy spits and low disturbance islands where these features formed part of the affected habitat.

Retain open sight lines around roosts. Do not plant dense trees or tall vegetation on an exposed sand spit or island used by Caspian Terns unless the ecological design specifically requires it.

Keep rehabilitation areas free of vehicles, dogs, uncontrolled recreation and unnecessary night lighting.

  • Use locally suitable substrates and stable bank treatments.
  • Prevent sediment, concrete washout, fuel and other pollutants from entering water.
  • Reconnect restored habitat to nearby estuaries, rivers, wetlands and feeding areas where practicable.
  • Protect restored sites from trampling and unauthorised access until stable.

Rehabilitation actions: 2. Breeding sites and replacement structures

Caspian Terns do not use nest boxes or bat boxes. Do not install these structures as a substitute for a lost colony.

Where a breeding site has been lost and replacement is justified, design an open artificial nesting site with a qualified seabird ecologist. A suitable concept may involve a predator protected island, gravel or sand platform, or other open site that resembles the local nesting substrate.

Place any artificial nest site away from regular people, vehicle, vessel and predator access, with clear flight paths and nearby shallow feeding water. Obtain all approvals before construction.

Do not attract birds to a replacement site while an existing active colony could be displaced. Use decoys, fencing or other attraction methods only under an approved ecological program.

  • Base the design on local colony habitat, including rocky islands or sand spits where appropriate.
  • Provide a safe buffer and no lighting directed at the site.
  • Inspect the structure for erosion, weeds, predators and human access.
  • Treat any use by Caspian Terns as an active breeding place and apply the relevant protections.

Rehabilitation actions: 3. Weeds, predators and water quality

Control weeds that alter open shorelines, sandbanks, mudflats or wetland flow. Prevent weed spread on machinery, vehicles, vessels, fill and footwear.

Manage food waste and artificial shelter that may attract feral cats, foxes or rats to colonies and roosts. Use methods approved for the site and avoid poisoning or trapping that could harm birds.

Maintain clear water and protect fish habitat. Control sediment, contaminated runoff, fuel, sewage and other pollutants during establishment and maintenance.

Coordinate water management with wetland managers. Avoid sudden drawdown, flooding or isolation of shallow feeding areas during breeding or when dependent young are present.

  • Inspect and clean plant before entering rehabilitation areas.
  • Remove waste at the end of each shift.
  • Map weed infestations and treat them before seed set where practicable.
  • Review predator signs after floods, fires and major construction activity.

Rehabilitation actions: 4. Long term monitoring

Monitor restored sites through wet and dry conditions and across relevant breeding and non breeding periods. Record presence, abundance, feeding, roosting, breeding behaviour and disturbance.

Compare use of the restored site with nearby reference habitat. A successful outcome should include safe access to feeding water and a stable roost or breeding place, not just revegetation cover.

Continue monitoring until the ecologist and approval holder agree that habitat function is stable and management targets have been met.

  • Survey high tide roosts and low tide feeding areas where the site is tidal.
  • Repeat breeding season observations from August to November in south western Australia, and use locally appropriate timing elsewhere.
  • Record water levels, habitat condition, weeds, predators, people, vessels and lighting.
  • Use monitoring results to adjust water management, access controls, predator control and maintenance.

Sources