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Gull-billed Tern

Did you know?

The Gull-billed Tern rarely occurs over the ocean, being an inland species over most continents except Antarctica.

Calls
Varied; common calls include a loud metallic 'gaa-gaa-gaa', a soft nasal 'kek-kek' and a stuttered 'kerrrr'.
Facts and Figures
Research Species: 
No
Minimum Size: 
35cm
Maximum Size: 
38cm
Average size: 
36cm
Average weight: 
230g
Breeding season: 
October to December or when flooding occurs.
Clutch Size: 
One to four, usually two or three.
Incubation: 
23 days
Nestling Period: 
35 days
Conservation Status
Federal: 
Secure
NSW: 
Secure
NT: 
Secure
QLD: 
Secure
SA: 
Secure
TAS: 
Not present
VIC: 
Endangered
WA: 
Secure
Associated Plants
Plants associated with this species
Samphire
grass and reeds; used as nesting material.
Basic Information
Scientific Name: 
Gelochelidon nilotica
Featured bird groups: 
Seabirds
Atlas Number: 
111
What does it look like?
Description: 

The Gull-billed Tern is entirely white, except for a black crown from bill to nape, a grey back and upper wings and darker flight feathers. The iris is dark brown, bill and legs black. The sexes are similar. In non-breeding plumage, the head is mainly white, the crown streaked brownish-grey and the ear coverts are dull black. Immature birds are similar to non-breeding adults. Juveniles are similar to immature birds, but the shoulders are mottled grey and brown. The common name relates to the thicker, shorter bill of this tern, closer in shape to that of a gull.

Similar species: 

Gull-billed Terns resemble Crested Terns, S. bergii, and Silver Gulls,Larus novaehollandiae, but the short stout black gull-like bill, black head with no crest and long legs are diagnostic.

Where does it live?
Distribution: 

The Gull-billed Tern occurs on all continents except Antarctica.

Habitat: 

Gull-billed Terns are found in freshwater swamps, brackish and salt lakes, beaches and estuarine mudflats, floodwaters, sewage farms, irrigated croplands and grasslands. They are only rarely found over the ocean.

Seasonal movements: 

The Gull-billed Tern is nomadic or migratory. Although essentially an inland species, outside breeding season it shows a distinct preference for saltmarshes and lagoons near the coast. Movements are not fully understood but it is common and widespread in south-eastern Australia, and only a vagrant in Tasmania. It winters mainly in the north and substantial numbers migrate to New Guinea and perhaps Indonesia.

What does it do?
Feeding: 

The diet of the Gull-billed Tern is extremely varied, consisting mainly of small fish, reptiles, amphibians, crustaceans, small mammals, insects and their larvae. When fishing, the Gull-billed Tern fans out its tail and with wings outstretched and flapping occasionally, glides swiftly down to the surface of the water. It tilts its head downwards so that its bill is nearly vertical and only the tip touches the water. After seizing its prey the bird gains height rapidly and continues its slow hawk-like flight. It does not dive or settle on the water.

Breeding: 

The breeding season of the Gull-billed Tern is flexible, depending on location. Generally the terns choose to nest in colonies on high, dry ground on small permanent or temporary islands in a lake or marsh. There are few breeding reports north of about 25° S. The nests are shallow depressions scraped in sand or mud, lined with some vegetation. Both sexes incubate the eggs.

References: 
Field guide to Australian Birds.
Field guide to the birds of Australia, 6th Edition
Reader's Digest Complete Book of Australian Birds
The Shorebirds of Australia.
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