|
|
Gull-billed Tern
(Gelochelidon nilotica)
: "Long-legged Tern"
Size: 33-42 cm; wing span 75-90 cm
Weight: Race
"macrotarsa": 220-290 g;
race
"affinis": 150-205 g
|
|
 |
Similar species |
|
 |
Physical description |
|
Click here for a physical description
Gull-billed Terns are medium-sized terns. During the
breeding
season they have a black cap, white front
(throat, neck, chest, belly and vent) and grey wings.
The black eyes are surrounded by the black cap, while
the frons (base of the bill) is also black. The stout bill
is black, the short legs and feet are also black.
In eclipse
the cap becomes mostly white, with grey patches
remaining behind the eyes and some mottled black-and-white
remaining at the back of the head.
Juveniles
are mottled grey, with a mottled cap and black eye patches.
 |
Twitcher's tip |
|
Compared to other, similar
terns, the Gull-billed
Tern has the most massive black bill (hence its name).
|
 |
Taxonomy, classification |
|
See Gull-billed
Tern at Wikipedia .
|
 |
Range, habitat, finding this species |
|
Click here for information on habitat
and range
The overall distribution of this species can be assessed, and
specific locations where birds have been spotted can be found,
based on individual sighting reports submitted by birdwatchers to
ebird.org
.
The global distribution of the Gull-billed Tern is available
HERE
.
Gull-billed Terns are a global species, of which there are 6 extant
races.
All races are dispersive after the end of the breeding season, and
those breeding in the northern hemisphere are the most strongly
migratory races.
Nominate race
"nilotica"
have a very extended breeding range, from
Europe and North Africa in the West, through the Middle East and
southern-central Asia to western China and Thailand in the East.
The breeding range of the Asian race "affinis" extends from
parts of Indonesia (Borneo, Sulawesi, Sumatra) through the
Philippines and south-eastern Asia, South and East China up to
Japan in the East.
Race "macrotarsa" breeds
only in Australia.
The three other races, "aranea", "vanrossemi" and "gronvoldi"
are found in various parts of the Americas (for details see, e.g.,
Wikipedia).
The northern races tend to spend the winters farther South, e.g.
in southern America, in Africa, south-eastern Asia and even
New Zealand.
Gull-billed Terns, race
"macrotarsa"
breed only in Australia.
They are most common along the coastline, in particular in QLD
and along the Great Barrier Reef, but also inland, e.g. in the
Murray-Darling Basin and in the Lake Eyre Basin.
Apart from these locations their range is patchy; some may be
found in the central NT and in western WA. After substantial
inland rainfall they can disperse into all areas of the
Australian continent, including the continent's major deserts.
They are rare visitors to the Bass Strait and Tasmania as well.
Occasionally, migratory birds of the Asian race
"affinis"
can be found primarily along the North coast of the Australian
continent.
Gull-billed Terns can be found above
coastal waters,
but also in
tidal flats
and inland, in the shallows of
freshwater lakes,
including
ephemeral lakes and
ephemeral wetlands.
|
 |
Sightings |
|
Click here for sighting information
Race "macrotarsa"
A Gull-billed Tern, race
"macrotarsa",
was first spotted by us at Dangars Lagoon near Uralla, NSW, in
November 2006.
Gull-billed Terns, race
"macrotarsa",
were also spotted by us in the wetlands of Capricorn Resort, Yeppoon,
in July 2009. Special access to the wetlands kindly granted by
the owners of Capricorn Resort is most gratefully acknowledged.
Subsequently, a small number of birds was spotted by us at
Goran Lake, an
ephemeral lake
about 30 km South of Gunnedah, NSW, in April 2011 and again in
April 2012 and December 2012.
In June 2011 Gull-billed Terns, race
"macrotarsa",
were also seen in a
saltmarsh in the
estuary of the
Manning River near Old Bar, NSW.
Several birds were also seen by us on farm
irrigation dams
about 10 km North-West of Moree, NSW, in April 2012.
The contributions to these observations by C. Hayne and A. Lines
are most gratefully acknowledged.
C. Hayne reports that Gull-billed Terns, race
"macrotarsa",
are the most common tern in
the Moree area. They are seen all year round above farm
irrigation dams and all
types of natural wetlands. Sometimes they are seen together with
Whiskered Terns and
Caspian Terns.
Gull-billed Terns, race
"macrotarsa",
were also spotted by us at Lake Altiboulka, in far
western NSW, about 95 km east of Tibooburra, in September 2012.
A Gull-billed Tern, race
"macrotarsa",
was first spotted by us at Narrabri Lake in August
2013.
Gull-billed Terns, race
"macrotarsa",
in non-breeding plumage
were next seen at Barambah Dam, QLD, in June 2017.
M. Eaton reports spotting Gull-billed Terns, race
"macrotarsa",
in non-breeding plumage
at South West Rocks, NSW, in July 2017, and at Old Bar, NSW, in
December 2019. They were also found at Tannum Sands, Gladstone, QLD,
in June 2021. Another was located at Bribie Island, QLD, in August 2021.
In October 2020, a small flock of 10 Gull-billed Terns, race
"macrotarsa",
was found by us at Yarrie Lake, near Wee Waa, NSW.
Race "affinis"
B. Hensen reports spotting Gull-billed Terns, race "affinis", at Lee Point,
Darwin, NT, in August 2013. At the same location in August 2014 we
only found race "macrotarsa".
B. Hensen found another Gull-billed Tern, race "affinis", at Lee Point,
Darwin, NT, in July 2018 and at the Leanyer Sewage Treatment Plant,
Darwin, NT, in November 2018.
|
 |
Photos |
|
Race "macrotarsa"
 |
ADULT |
|
 |
BREEDING |
|
Near-lateral view of an adult Gull-billed Tern in breeding
plumage
(photo courtesy of M. Eaton)
[Bribie Island, QLD, August 2021]
Lateral view of a Gull-billed Tern in breeding
plumage
[Near Old Bar, NSW, June 2011]
Lateral view of Gull-billed Terns in both breeding and non-breeding
plumage, with one
smaller tern which looks, by its bill, to be a
Common Tern
[Lee Point beach, Darwin, NT, August 2014]
Near-frontal view of a Gull-billed Tern in breeding
plumage in flight
[Goran Lake, NSW, April 2012]
Near-frontal view of a Gull-billed Tern in flight, slightly
different angle
[Goran Lake, NSW, April 2012]
Near-lateral view of a Gull-billed Tern in breeding
plumage
in flight (photo courtesy of M. Eaton)
[Near Old Bar, NSW, December 2019]
Lateral view of a Gull-billed Tern in breeding
plumage
in flight
[Near Old Bar, NSW, June 2011]
Lateral view of a Gull-billed Tern in breeding
plumage in flight,
showing the upperwing pattern (left) and underwing pattern (right)
[Goran Lake, NSW, April 2012]
Gull-billed Tern in breeding plumage caught at a somewhat
inconvenient moment...
[Goran Lake, NSW, April 2012]
 |
NON-BREEDING |
|
Gull-billed Tern in non-breeding plumage standing in shallow water;
in this view the eye mask of the non-breeding plumage is clearly visible
[Goran Lake, NSW, April 2011]
Here the same Gull-billed Tern is seen digging something out of the mud
[Goran Lake, NSW, April 2011]
Near-frontal view of a Gull-billed Tern in non-breeding
plumage
banking in flight
[Goran Lake, NSW, September 2012]
Lateral/ventral view of a Gull-billed Tern in non-breeding
plumage in flight
[Goran Lake, NSW, September 2012]
Near-dorsal/ventral view of a Gull-billed Tern in non-breeding
plumage in flight
[Goran Lake, NSW, September 2012]
Near-dorsal/ventral view of a Gull-billed Tern in non-breeding
plumage in flight
[Near Old Bar, NSW, June 2011]
Race "affinis"
 |
ADULT |
|
 |
NON-BREEDING |
|
Near-frontal view of a Gull-billed Tern in non-breeding
plumage;
note the small ear patch
(photo courtesy of B. Hensen)
[Lee Point, Darwin, NT, August 2013]
Near-lateral view of a Gull-billed Tern in non-breeding
plumage
(photo courtesy of B. Hensen)
[Lee Point, Darwin, NT, August 2013]
Near-frontal view of two Gull-billed Tern in non-breeding
plumage
resting on a beach
(photo courtesy of B. Hensen)
[Lee Point, Darwin, NT, August 2013]
Lateral view of several Gull-billed Terns, race "affinis", in
non-breeding plumage,
one of which is taking off, displaying prominently its dark wing
tips (photo courtesy of B. Hensen)
[Leanyer Sewage Treatment Plant, Darwin, NT, November 2018]
Direct comparison of the sizes of two Gull-billed Terns
in non-breeding
plumage resting on a beach: race "macrotarsa",
left, and race "affinis", right - note the difference in
sizes; in the background a Caspian Tern in breeding
plumage
(photo courtesy of B. Hensen)
[Lee Point, Darwin, NT, August 2013]
 |
Food, Diet |
|
As opposed to other terns, Gull-billed Terns feed on crabs, other
crustaceans as well as grasshoppers, dragon flies and other insects
that they take from sand
dunes, sand bars, dry mudflats or the edges of inland
lakes or
dams.
Gull-billed Tern taking a mud crab it has scabbed from a
Bar-tailed
Godwit
(slightly unsharp)
[Near Old Bar, NSW, June 2011]
Here the prey can be seen more clearly
[Near Old Bar, NSW, June 2011]
Gull-billed Tern with its prey
[Lee Point beach, Darwin, NT, August 2014]