MyTern
AUSTRALIA
A pocket guide to the terns of Australia
Caspian Terns, Glenn Ehmke
Contents Introduction ......................................................... 3 General habitat ..................................................... 4 Nesting habitat ..................................................... 5 Chicks ................................................................. 6 Feeding strategies ................................................. 7 Threats ............................................................... 8 Tips for identifying similar-looking terns.................... 9 Species’ profiles .................................................. 10 Terns in flight ..................................................... 28 Monitoring terns...................................................30 Counting techniques ............................................ 32 BirdLife Australia projects ..................................... 38
Introduction This booklet is a field companion for monitoring Australian terns. MyTern contains key information about the habitat, distribution, nesting requirements and identification of terns. Terns are in the subfamily Sterninae and are closely related to gulls, but are smaller, slimmer and longer-tailed. Noddies are very closely related and appear similar to terns (but have a wedge-shaped tail and inverse colouration: light cap and dark body). Twenty species of terns and three species of noddies have been recorded in Australia, including migratory species and vagrants. Most terns hunt fish or arthropods (insects and crustaceans) by diving, skimming the surface of the water, or on the wing. Terns are a significant part of many marine and island ecosystems and are good indicators of ecosystem health, as they are high order predators. Terns are relatively easy to monitor due to their high visibility and they often occur in large groups at breeding and roosting sites. Three species of terns are presently threatened at the state, national and/or international level; these are the Little Tern, Fairy Tern and Roseate Tern. Monitoring of these species is important for identifying threats and population trends to aid their conservation.
Key for species’ profiles bp = breeding plumage nbp = non-breeding plumage juv = juvenile plumage
Note: the size (cm) of each species refers to body length, the images are not drawn to scale, and the distribution maps are based on all species’ records in Australia (from BirdLife Australia Atlas data). 2
Crested Terns, Dean Ingwersen
3
General habitat
Nesting habitat
Terns depend on aquatic and terrestrial environments for their survival. Put simply, they mostly feed offshore or close to water but roost and breed on land. Terns can breed on:
Most terns nest in a shallow depression on the ground in bare sand, soil or mud. Nests may also be among rocks or low plants. They can be sparsely lined with plant matter, feathers, stones and shells. Some species also surround their nest with debris and vegetation. Plants used for nesting include seaweed, saltbush, beach daisy and pigface.
• • • • • • •
ocean beaches (above the high tide mark) cliffs rocky flats sand dunes estuarine foreshores islands freshwater inland wetlands
Terns tend to nest in exposed and open areas to look out for danger, and they mostly nest near water. Outside their breeding colonies, terns can be found in roosts, which are a congregation of all ages and reproductive conditions. Terns can roost on beaches, sand banks, spits and islets. Depending on the species, foraging occurs over pelagic waters (pelagic species like Bridled and Sooty Terns have long wings for foraging in these areas), coastal waters, in estuaries, shoals, tidal lagoons, freshwater lakes, mudflats, flooded ricefields and pastures.
More unusual nest placement occurs in some species: Whiskered Terns nest on a raft of vegetation (floating or moored); White Terns and noddies build their nests in trees and low bushes.
Little Tern nest, Charles Dove
Sooty Tern on nest, Andrew Silcocks
Most species produce a single clutch per season (1–4 eggs) during spring and summer. Both sexes incubate the eggs (for ~30 days) and care for their young. Tern eggs are generally grey-brown and speckled to blend in with their surroundings. Among species, eggs range in size from a 20-cent coin to a chicken egg. Some species occasionally nest solitarily, but most nest in small colonies (5–200; e.g. Fairy Tern), whilst others nest in large colonies, sometimes in the thousands (e.g. Crested Tern). Black-naped Tern, Nicole Andrews
Fairy Tern, Dean Ingwersen
Gull-billed Terns, Charles Dove
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5
Chicks
Feeding strategies
Tern chicks are semi-precocial: born well developed, feathered and with their eyes open. The downy chicks are grey, brownblack or buff in colour and mottled to camouflage with their surroundings. For most tern species, chicks rely entirely on their parents to provide food and shelter for the first four weeks. After that they are almost fully grown and can fly and forage independently. During the chick phase, parents take turns foraging and feeding the chicks, either at the nest or close to the nesting area. Older chicks may gather in loose groups called crèches; this behaviour is typical for species such as the Crested Tern.
Hover and plunge: Most tern species hover (at 2–15m) over the water, with their body horizontal and bill pointing down, and then plunge to capture their prey (sometimes submerging completely). This is done over shallow coastal waters, just beyond the surf zone, over pelagic waters, or near rocks, reefs and submerged seagrass beds. Some species might also hover and dive to take prey over wetlands and marshlands.
Little Tern, Charles Dove
Dipping: Some species dip in flight to capture their prey over the water or just below its surface. This strategy can also be used over mud flats or cultivated fields. White-fronted Tern, Charles Dove
Stages of Little Tern development. Top left: The clutch hatches over a 24 hour period. In the first image, one chick has hatched hours earlier and is dry and fluffy, while the second egg has a crack appearing. Top right: The second chick is still wet following hatching, and the third egg is yet to hatch. Bottom left: A young, flightless chick is calling for food, awaiting its parent’s return. Bottom right: A chick close to fledging. Photos by Charles Dove. 6
Aerial hawking: Some species, such as the Whiskered Tern or White-winged Black Tern, can feed by aerial hawking (feeding on the wing).
Whiskered Tern, Andrew Silcocks
7
Threats
Tips for identifying similar-looking terns
•
• Sturdy bill, all yellow Little Tern Fairy Tern • Thicker white line on (bp) Breeding upper edge of folded plumage (bp)
• Long thin bill, yellow with black tip • The black eye line reaches the bill
Fairy Tern • Paler upperparts Non-breeding • Wing tips only slightly darker than plumage rest of wing (all (nbp)
Little Tern (nbp)
• Darker carpal bar* • Cap more receded • Dark wing tips, noticeable in flight (all seasons)
Australian Gull-billed Tern
• Continuous elongated black eye mark • White cap streaked black • Paler upperparts • Heavier bill • Stand taller, longer legs
Common Gull-billed Tern
• Broken black eye mark • Approximately 20% smaller • Looks similar to macrotarsa when breeding, but only in breeding plumage March/April
• Slightly heavier bill • Less distinct eye mark, finishing at eye line
Whitewinged Black Tern (nbp)
• • • • •
Disturbance of breeding colonies leading to abandonment of eggs and chicks Rubbish on land or in the water can cause entanglements, be ingested or attract predators Predation of adults, chicks and eggs by feral and domestic cats and dogs, foxes and rats Predation of eggs and chicks by native Silver Gulls, crows, ravens and pelicans, often as a result of human disturbance to nesting birds Habitat loss from coastal development, invasive plants and sea-level rise Depletion of prey through overfishing, habitat loss, climate change and/or poor water quality Fairy Terns, Bill Betts
Recreation vs. Procreation! Tern nesting sites may look like any old stretch of beach to us, but they are often located strategically: close to feeding grounds and protected from the prevailing weather conditions. When their nesting sites overlap with popular recreation areas, the terns cannot simply move to a new location to nest. Human disturbance is a major cause of desertion and failure at some tern colonies; parent birds will flee the nest and expose their eggs and chicks to predators, and eggs may also be crushed by people or recreational vehicles. For humans to coexist with tern colonies, we may have to adjust where and when we swim, walk, exercise dogs, picnic, drive off-road vehicles or birdwatch for a short period of the year - a simple solution that could save our seabirds from extinction. 8
primaries* • Bulkier
seasons)
(macrotarsa) eclipse
Whiskered Tern (nbp)
(affinis) eclipse
• Distinct black ‘headphone’ mark behind eye (comes below eye line) • Paler rump • Lighter and buoyant in flight • Slightly smaller
• Thicker white line on Common Whitefronted Tern upper edge of folded Tern (nbp) primaries* (nbp)
• Shorter bill • Greyer upperparts • Smaller
Black-naped • Bigger and bulkier Tern (bp and • Paler upperparts • Tail longer and nbp)
Little Tern (nbp)
• Black eye line finishes in square patch (not point) • Fine dark mottling on crown
• Yellow bill Crested Tern (bp and • Bigger in size nbp)
• Orange-yellow bill Lesser Crested Tern (bp and nbp)
• Longer more deeply forked tail
deeply forked
*Note – Carpal bar = contrasting band on upperwing. Primaries = primary feathers, ‘fingertip’ feathers, the longest on a bird’s wing. 9
Fairy Tern Sternula nereis (22–24cm)
Little Tern Sternula albifrons (20–23cm)
IUCN Vulnerable
Endangered (NSW, Tas, Qld) Black cap extends from bill to nape
Pale outer primaries
Crown mostly white and mottled black
bp
Mainly white with pale grey back and upperwings
Dark crown Black eye-line extends to bill
bp
Yellow bill with black tip
Receded cap
Orange-yellow bill, lacks black tip
Black bill Dull yellow legs
nbp
nbp
Distribution: Found along the WA coastline, east to Tas and Vic. Most common in WA and rare in NSW, NT and Qld. Movements poorly known, appears to be partly migratory. The Tas and south-west Australian populations are migratory, but in Vic and SA, they appear not to move regularly. Also has a subspecies found on Coral Sea islands.
Distribution: In northern Australia from Shark Bay, WA, to the Gulf of Carpentaria, and along the east coast to Tas and farther west to the Coorong. Migratory, after breeding approximately 90% of the population move to Asia in their non-breeding plumage. Little Terns also breed in Japan, which can result in mixed flocks in breeding and non-breeding plumage.
Habitat and prey: Found on coastal beaches, inshore and offshore islands, sheltered inlets, sewage farms, estuaries and lagoons. It favours both fresh and saline wetlands. Feeds almost entirely on fish.
Habitat and prey: Mainly coastal, found on beaches, sheltered inlets, estuaries, lakes, sewage farms, lagoons and river mouths. Feeds on small fish, insects, crustaceans and other invertebrates.
Breeding behaviour: Nests above high water mark on sheltered beaches, spits, banks and ridges. Breeds in small colonies. Sometimes interbreeds with Little Terns where range overlaps.
Breeding behaviour: Breeds on sand spits, banks, ridges or islets in sheltered coastal environments, also on sandy ocean beaches.
Breeding season: September–February. 10
Breeding season: September –January, might differ slightly in northern Australia. 11
Roseate Tern Sterna dougallii (35–40cm) IUCN Least Concern
Black cap extending down neck
Tail streamers are white
bp
Black-naped Tern Sterna sumatrana (30–32cm) Diagnostic narrow black band from eye to nape
Long, narrow, black and red bill
bp
Slender build Deeply forked tail in flight
Darker bill later in breeding season Long, red legs
White forehead
Black crescent on ear coverts
nbp Darker legs in immature birds nbp
Dark tail in immature birds
Red legs in nonbreeding adults
Distribution: West, north and north-east coasts from southwest WA to south-east Qld. Breeds mostly along the coasts of WA and Qld.
Distribution: Mostly found in north-east Australia near the Torres Strait, Great Barrier Reef and Coral Sea, also breeds within this region.
Habitat and prey: Blue water seas, often near offshore coral or continental islands. Rarely inshore or near mainland, only if nesting on islands nearby. Not often seen in large flocks, and can roost with other terns. Mostly eats fish.
Habitat and prey: Associated with offshore sand cays, coral cays or rocky islands. Forage inshore near coral reefs, but forages more at sea outside of the breeding season. Feeds entirely on fish.
Breeding behaviour: Breeds on offshore islands, cays and banks, mainly on sand, coral or rocks. Nests in small to large colonies.
Breeding behaviour: Breeds on beaches or coral cays or islands in narrow strip just above the high tide mark. Mostly nests in small colonies.
Breeding season: November–August.
Breeding season: August–March.
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13
Common Tern Sterna hirundo (32–37cm)
White-fronted Tern Sterna striata (35-43cm) White front
Black crown extends from bill to nape
bp Thick white line on upper edge of folded primaries
Mostly white with grey back and wings
bp
Black cap does not extend as far, leaving white forehead
Dirty white crown White forehead
Deeply forked tail in flight
Legs mottled red and black
Black bill
nbp
nbp Black legs Black legs
Distribution: A regular non-breeding visitor to Australia; numerous on the north and east coasts of Australia, but rare in the far south-west. Habitat and prey: Mainly coastal and found in offshore waters, ocean beaches, estuaries and large lakes. Occasionally seen in freshwater swamps and brackish and saline lakes. Mainly eats fish, but also aquatic insects and crustaceans. Breeding behaviour: This species does not breed in Australia.
Distribution: Distributed along the south-east coast of Australia, from southern Qld to Tas and west to SA, mostly as a winter visitor. Mostly breeds in NZ and Tas (Flinders Island and Cape Barren Island). Approximately 90% of Australian records are of birds in their first year. Habitat and prey: Occurs in coastal seas and exposed rocky coasts and forages mostly on fish. Breeding behaviour: Nests in colonies with hundreds or thousands of breeding pairs, frequently in association with other tern species. Colonies can be on islets, reefs, cliffs, sand dunes and beaches. Breeding season: October–February.
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15
Whiskered Tern Chlidonias hybrida (26–27cm) Short, slightly forked tail in flight (looks square compared to other terns)
Black crown
White-winged Black Tern
Chlidonias leucopterus (22–24cm)
Red bill (and legs)
Black body
bp
bp
Short bill
Grey wings
Streaked crown
nbp
White underparts
White cheeks and neck Dark, grey underparts White forehead
Blackish legs (and bill)
nbp Grey back and tail
Black ear-phone shape behind the eye
Off-white underwings and underparts
Distribution: Scattered and widespread in most regions of mainland Australia, except for the arid zones. Migratory and nomadic. Breeding is most numerous in the south-east interior. Habitat and prey: Shallow freshwater wetlands and swamps, brackish and saline lakes, sewage farms, irrigated croplands and large dams. Mainly eat small fish, amphibians, crustaceans and insects. Breeding behaviour: Breeds in loose colonies in large inland swamps and marshes. Breeding season: September– December, but can be erratic.
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Distribution: Found in coastal and sub-coastal areas of Tas, and north, east, and south-east mainland Australia. Breeds in northern Eurasia, and is a non-breeding summer migrant to Australia. Habitat and prey: Found mostly in coastal or sub-coastal wetlands, including tidal estuaries, lagoons, grassy swamps, and sewage ponds. Feeds on insects, spiders and fish. Breeding behaviour: Does not breed in Australia, but many birds acquire their breeding plumage before departing for Eurasia.
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Sooty Tern Onychoprion fuscatus (40–46cm) White forehead patch finishes above eye
Bridled Tern Onychoprion anaethetus (36–42cm)
White streaks through black cap bp
bp Black upperparts and white underparts
White band extending over eye
Brownish-grey upperparts
Shorter tail streamers
Stout bill nbp
Tail deeply forked (in flight) with long streamers
Dark legs
Distribution: Mainly found in tropical seas off WA and Qld, where they nest on islands and reefs, with sporadic sightings on coasts in south-west and south-east Australia. Habitat and prey: Offshore and pelagic zones of tropical waters, rarely inshore. Forages at sea and mostly eats cephalopods, crustaceans and fish. Breeding behaviour: Nests on vegetated coral cays and offshore islands and stacks. Can nest in very large colonies. Breeding season: September– January and April–October in Qld.
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Long legs
Distribution: Mainly found on coasts of WA, NT and Qld. Habitat and prey: Offshore in tropical and subtropical seas, often well away from land, over pelagic waters. Forages in open seas and mostly eats fish. Breeding Behaviour: Breeds on offshore coral cays, rocky islands and rock stacks. Nests are usually concealed in crevices or caves or among or under rocks. Nests in small to large groups. Breeding season: October-March.
19
Common Noddy Anous stolidus (40–45cm) bp Dull white cap
Black Noddy Anous minutus (35–40cm)
Thin white line from base of bill to rear of eye
White cap bp Sooty black plumage (underwing similar colour to body)
Dark brown plumage (underwing lighter than body) Long stout bill, slightly curved
Long wedgeshaped tail in flight
Slender, straight bill
More clearly defined white cap in juvenile birds
Duller and mottled cap in juvenile birds
juv
juv
Distribution: Mainly off coast of Qld, but also north-west WA and Pilbara coast.
Distribution: Mostly off north-east and east coasts of Qld, also found off coast of northern WA and NSW.
Habitat and prey: During non-breeding season, mostly found in pelagic waters. Mostly eats fish, but also squid, molluscs, insects and even Pandanus fruit.
Habitat and prey: Wooded tropical or subtropical islands and surrounding seas. Feeds mainly on fish, squid and crustaceans.
Breeding behaviour: Breeds on or near rocky islands or coral cays. Often breeds on or among clumps of grass or herbs. Breeding season: Varies greatly; can breed annually or twice a year, in spring to early summer and autumn. 20
Breeding behaviour: Mostly breeds in tall, sheltered trees. Often in large colonies (tens of thousands). Breeding season: October–March, peaking in November and December.
21
Crested Tern Thalasseus bergii (43–48cm) Black cap and crest
Long deeply forked tail in flight
Lesser Crested Tern Thalasseus bengalensis (37–42cm)
Black cap and crest
bp
bp
Yellow bill
Grey upperparts
Grey upperparts and white underparts
Long orange bill
White forehead and forecrown
White forehead merging to black spotting on crown nbp nbp White underparts
Distribution: There are few stretches of the Australian coastline where the Crested Tern cannot be seen.
Distribution: Widespread along northern coasts and most breeding colonies occur in eastern Qld.
Habitat and prey: Found on exposed ocean beaches or sheltered embayments, such as bays, harbours, inlets, estuaries and lagoons. Mainly eats fish and occasionally prawns and squid.
Habitat and prey: Prefers sand and coral cays, especially those with <25% vegetation cover. Mostly forages in inshore waters, rarely seen at open sea. Mostly eats fish.
Breeding behaviour: Breeds in large groups of sometimes over 1000 individuals. Breed on islands, cays and banks of sand, shells, coral or rock.
Breeding behaviour: Breeds in open areas, including beaches, low lying sandbanks and coral cays. Nests in small to large colonies. Breeding season: October–May.
Breeding season: October– December. 22
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Australian Gull-billed Tern
Common Gull-billed Tern
Gelochelidon nilotica macrotarsa (35–38cm) Black crown extends from bill to nape Grey back and wings
Gelochelidon nilotica affinis (33-42cm)
bp Head mainly white with streaked brownishgrey crown
White cap with no streaks
Grey back and upper wings Eye mark is broken with two narrowly joined black spots
Stout black bill
nbp
White body
nbp
Long black legs This species has been split into two subspecies: Australian Gull-billed Tern and Common Gull-billed Tern. They might be separated into two full species in the future.
Distribution: Breeds in Australia, common and widespread in mainland Australia, but a vagrant in Tas. Winters mainly in the north. Habitat and prey: Found in freshwater swamps, brackish and salt lakes, beaches and estuarine mudflats, irrigated croplands and grasslands. Diet includes fish, reptiles, amphibians, crustaceans, small mammals and insects. Breeding behaviour: Generally nests in colonies on small islands in a lake or marsh. Breeding season: Flexible breeding season, depending on location and influenced by rainfall, thus can be seen in breeding plumage in all months. Mostly October–December. 24
Distribution: Breeds in south-east Asia. A non-breeding visitor in Australia, mostly seen during summer. Found in north-western Australia and as a visitor to the northern coast of Qld, infrequently recorded in northern NT. Habitat and prey: Along coastlines, feeds over mudflats during low tide. Diet similar to subspecies macrotarsa. Breeding behaviour: This subspecies does not breed in Australia and is mostly seen in non-breeding plumage (the same time subspecies macrotarsa is in breeding plumage, but there is some overlap). Might be seen in breeding plumage in March or April (just before its northwards migration). 25
Caspian Tern Hydroprogne caspia (50–56cm) Black crown from bill to nape Finely streaked white crown
Rare and vagrant terns and noddies Arctic tern Sterna paradisaea (28-39cm) Rare vagrant found mostly in the southern parts of Australia, migrates from the Arctic to the Antarctic each year (a journey of up to 80,000km).
bp
Grey upperparts
bp
Dark red bill
Deeply forked tail in flight
Grey upperwings
Distinctive large red bill
nbp
White underparts nbp
Short legs
Lesser Noddy Anous tenuirostris (30-35cm) Occurs on the Houtman Islands and Ashmore Reef, WA. Smaller than Common Noddy
Short, wedgeshaped tail in flight
Distribution: Common and widespread (though seldom in large numbers). Mainly sedentary but numbers fluctuate seasonally in many areas, including Tas. Habitat and prey: Usually found near the coast, in wetlands, on coastal and inland beaches and sheltered estuaries. Can live equally well in fresh water and saline environments. Feeds almost entirely on fish. Breeding behaviour: Breeds on low islands, cays, spits, banks, ridges and beaches. Breeds in scattered single pairs or dense colonies. Breeding season: October– December, might differ slightly in northern Australia. 26
Grey Ternlet Procelstema cerulea (25-30cm) Rare vagrant on the east coast.
Greyish-black plumage
Large, dark eye
A small, pale noddy
Wedge-shaped tail in flight
White Tern Gygis alba (28-33cm) Rare vagrant on the east coast.
Large, dark eye
A small, white tern
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Terns in flight
Black Noddy
Little
Fairy
Black-naped
Lesser Noddy
Common Noddy
Common
Roseate
Lesser Crested
Crested
White-fronted Caspian
Whiskered
Gull-billed
White-winged
White Arctic
Sooty 28
Bridled
Grey Ternlet 29
Monitoring terns Monitoring is essential to detect, interpret and report changes in tern populations. It provides us with information to ensure tern numbers remain healthy and so we can act to reduce the impacts of threats to their survival. However, monitoring is more than just counting birds - it needs to be coordinated, consistent and carried out in a way to minimise disturbance. Nesting terns are particularly vulnerable to human impacts, so it is vital that you check with BirdLife Australia before getting involved in any tern monitoring (see pages 38-39 for details about the different monitoring projects). BirdLife Australia works with relevant authorities and under the appropriate ethics, research and access permits to carry out monitoring programs. We therefore require our volunteers to be registered and inducted. Breeding birds should not be monitored or approached without the appropriate permits.
•
Include species relevant to the variable of interest (e.g. focus on a flagship species or a key threat that needs to be mitigated)
•
Reported into a shared database, such as Birdlife Australia’s Beach-nesting Birds portal or the Shorebirds 2020 portal (see pages 38-39)
Threat Monitoring For birds that nest on the coast, it is essential to understand the threats that operate at their breeding sites. Threat monitoring enables us to determine the health of breeding sites and to act to mitigate threats. Beach-nesting Bird Project volunteers, for example, undertake threat assessments every time they visit a site (see page 38). Thanks to these data, we can quantify threats (e.g. the rate of visitation by dogs to a site), inform local land management and improve beach user behaviour. The Important Bird and Biodiversity Areas (IBA) Program has a growing network of IBA Guardians who also carry out annual ‘IBA Easter Health-checks’, which record threats to birds and their habitats. This enables us to identify appropriate management actions.
Caroline Wilson
Monitoring needs to meet a few basic requirements; a well structured monitoring program should be: •
Safe for you and for the birds that you monitor
•
Regular in time and space
•
Repeatable by using standardised techniques
•
Accurate in species identification and number of birds
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Grainne Maguire
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Counting techniques
Counting tips:
Counting terns requires practice and patience! Below we introduce some techniques for achieving accurate counts.
•
Be prepared by making a visit to the site before the count, so you know what to expect. Decide on whether you need a scope, the number of counters required and where to set up your vantage point(s)
•
As you arrive at a roost, estimate the total number of birds
•
Briefly scan the flock, pick out and count the rare species and get an idea of general flock composition (i.e. if there are multiple species)
•
Keep in mind that some birds may be hard to spot because they are hidden behind another bird
•
For multiple species counts: if you have several counters, each person can focus on one or two species; easily identifiable species (e.g. Silver Gulls) for new counters and harder ones (e.g. Roseate and Common Terns) for experts. Multiple species often sort themselves by size; determine where each group sits or get an estimate of the ratio of each species (e.g. 20% Little Terns amongst the Crested Terns)
•
For big flocks: estimate the number of birds in blocks of 10, 50 or 100 (see page 37). Also remember, if a site contains ≥20,000 waterbirds (of any species) it meets Ramsar site criteria
•
Handheld mechanical counters can be a useful tool
•
Some roost sites lend themselves to high resolution photography which may help with counts and identification
•
Report zero counts: they provide valuable data
•
Practise counting in everyday life (e.g. number of Silver Gulls outside the fish and chip shop, people on the bus or at a football match) or try the count game at birdlife.org.au/ projects/shorebirds-2020/educational-material
•
For counting flying birds: the same principles for roosting birds apply, only faster!
Counting roosting or flying terns Firstly, every count requires information on location, date, time and observers. Time of year: Anytime, but mostly outside of the breeding season (March – August). During the breeding season, counts of nesting terns will be more meaningful (page 34). Time of day: Counts during the day (e.g. 8:00-16:00) are better than those at dusk or dawn, as birds are often out feeding during these periods. Practical consideration such as good light and concentration of birds in a single roost are also important. Site selection: Any area where terns congregate regularly (e.g. islands or spits at the open sea, inshore waters, estuaries, river mouths, lagoons or freshwater lakes, beaches, sheltered inlets, sewage farms, dams or other human-made structures). Please ensure appropriate permissions or landholder agreement are in place before visiting a site.
Whiskered Terns, John Barkla
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33
Counting nesting terns
Counting tips:
Note: This is a highly sensitive activity and only approved monitoring programs can be undertaken.
•
Firstly, keep a safe distance (at least 60–100m) and count from one or more vantage points (using binoculars or a scope) that allow viewing of the whole nesting colony – if your presence is causing the colony to be unsettled, increase your distance
As with monitoring or observing roosting or flying terns, record information on location, date, time and observers. Also record coordinates of the colony location for future reference.
•
Time of year: Throughout the breeding season (mainly September – March). Ideally, a count should be done when birds are nesting, but before eggs have hatched.
Avoid hot or very cold days, and if on the beach, avoid times of high tide
•
Time of day: In the morning, when non-breeding birds are more likely to be absent from the colony.
Keep in mind that terns can nest among (or close to) other tern species or seabirds, so take care accessing the area and be aware of other birds around you
•
Count all observed incubating adults (see count diagram on page 37)
•
If the colony is large, count nests in groups of 50 or 100 as for roosting or flying terns
•
Use photos from vantage points (in uneven or rocky areas)
•
If counting after the incubation period (be very vigilant of disturbance at this time), record number of all age classes (chicks, juveniles, fledglings) and ratio of hatched to unhatched nests if visible
•
Record presence or evidence (i.e. footprints) of predators or any other threats (human disturbance, litter)
•
Record the presence of any site protection (e.g. signs or fencing). If you think a site needs protection, remember you will need land manager approval and seek advice from BirdLife Australia on best practice site protection
Site selection: Areas associated with coastal tidal flats, beaches, inland wetlands, rocky flats, cliffs and islands (see page 5 and species’ profiles for more information).
Crested Terns, Dan Weller
Caroline Wilson
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35
Estimating numbers
Caution! Birds within nesting colonies will take flight when people are closer than 60–100m. Flight initiation distances vary among species and also at sites, depending on the exposure the birds have had to people. Also, some tern species will mob together and attack a potential predator or intruder, including humans.
The diagrams below illustrate how to quickly estimate tern numbers. For flying birds, start counting from the direction the birds are flying to, circle X birds in an area of typical density and copy this circle across the whole flock. Count the number of ‘copies’ made for your total estimate. The technique for roosting or nesting terns is very similar, count a block of birds and copy this block across the whole colony. For mixed flocks repeat this procedure for each species.
Estimating flying terns: Estimated count: 7 circles of ~5 = ~35 birds
Grainne Maguire
Estimating roosting or nesting terns: Sooty Terns and Common Noddies, Dean Ingwersen
36
Estimated count: 4 rectangles of ~10 = ~40 birds
37
BirdLife Australia projects
Shorebirds 2020
Beach-nesting Birds
The Shorebirds 2020 program coordinates the national shorebird population monitoring in Australia. We need your help to conduct annual counts at key shorebird areas so we can detect national population trends. We also work to discover and mitigate the factors behind local and national population declines.
The Beach-nesting Birds Project focuses on the monitoring and conservation of beachnesting shorebirds across Australia, including Hooded Plovers, Beach Stone-curlews, Red-capped Plovers and Pied Oystercatchers. Their highly Hooded Plover and chicks, Glenn Ehmke camouflaged eggs and chicks, and vulnerable nest placement, make these birds highly susceptible to breeding failure, particularly on busy beaches over summer. We work to raise awareness about the birds that depend on beaches for survival.
birdlife.org.au/shorebirds2020
Curlew Sandpiper, Dean Ingwersen
IBA
We train volunteers (using strict protocols, needed to work with these vulnerable species) to participate in monitoring and nest site protection. Our online portal assists with site specific data collection, mainly for sites used for breeding and flocking. Together with a team of community volunteers and coastal land managers, we have successfully increased the breeding success of the threatened Hooded Plover and seen its return to historically occupied beaches! In the coming years, we hope to extend this project to beachnesting seabirds, which are facing similar threats.
Important Bird and Biodiversity Areas (IBAs) are Key Biodiversity Areas and sites of global bird conservation importance. BirdLife Australia’s IBA Program has many dedicated volunteers (IBA Guardians) and we are keen for you to join our network. Guardians collect data on birds, threats and conservation actions in the annual IBA Easter Health-checks. These local experts look after IBAs and contribute to their protection.
birdlife.org.au/beach and portal.mybeachbird.com.au/
birdlife.org.au/iba
BirdLife Australia Branches BirdLife Australia has local branches throughout Australia; they provide an opportunity for communities to participate in local activities, including research and conservation projects. Many branches carry out long-term monitoring programs, some of which focus on terns and other waterbirds. To learn more, see: birdlife.org.au/who-we-are/branches-and-locations 38
Threatened Bird Network If you are interested in volunteering with other threatened bird research and conservation projects contact the Threatened Bird Network at
[email protected]
Colin Wilson
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Whiskered Terns, Andrew Silcocks
Prepared by: Caroline Wilson Leeann Reaney Golo Maurer Grainne Maguire Nick Bradsworth Tern illustrations by Jeff Davies and Nicolas Day. This work is copyright. Reproduction in whole or part may only occur with the written permission of BirdLife Australia. ISBN: 978-0-9873140-4-8
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