Gull-billed Tern
Gelochelidon nilotica
Medium-sized tern with thick black bill. Very pale overall with black cap in breeding plumage. Legs black. Nonbreeding plumage shows dark cheek patch. Found in marshier habitats than most other terns, in the Americas usually near the coast but not on the ocean (though also occasionally seen on beaches and mudflats); in Europe and Asia can also be found in wetlands well away from the coast. Rarely seen in flocks with other terns; often single or in pairs. Feeds on invertebrates and crabs in mud and marshes; often patrols the edges of ponds but does not grab fish from the water like other terns.
Identification
This is a fairly large and powerful tern, similar in size and general appearance to a Sandwich tern, but the short thick gull-like bill, broad wings, long legs and robust body are distinctive. The summer adult has grey upperparts, white underparts, a black cap, strong black bill and black legs. The call is a characteristic ker-wik. It is 33–42 cm (13–17 in) in length and 76–91 cm (30–36 in) in wingspan. Body mass ranges from 150–292 g (5.3–10.3 oz).<p>In winter, the cap is lost, and there is a dark patch through the eye like a Forster's tern or a Mediterranean gull. Juvenile gull-billed terns have a fainter mask, but otherwise look much like winter adults.<p>Juvenile Sandwich terns have a short bill, and are frequently mistaken for gull-billed tern where the latter species is uncommon, such as North Sea coasts.
Taxonomy
The gull-billed tern was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with terns in the genus Sterna and coined the binomial name Sterna nilotica. Gmelin based his description on the "Egyptian tern" that had been described in 1785 by the English ornithologist John Latham in his book A General Synopsis of Birds. Latham had in turn based his own account on that by the Swedish naturalist Fredrik Hasselquist that was published in 1757. The gull-billed tern was moved to the resurrected genus Gelochelidon based on a molecular phylogenetic study published in 2005. The genus had been introduced in 1830 by the German zoologist Alfred Brehm. The genus name combines the Ancient Greek gelaō meaning "to laugh" with khelidōn meaning "swallow". The specific epithet nilotica is from Latin niloticus meaning "of the River Nile".<p>Five subspecies are recognised:
- Scientific name
- Gelochelidon nilotica
- Authority
- (Gmelin, JF, 1789)
- Order
- Charadriiformes
- Family
- Laridae
- Genus
- Gelochelidon
Range and habitat
It breeds in warmer parts of the world in southern Europe, temperate and eastern Asia, both coasts of North America, eastern South America. This bird has a number of geographical races, differing mainly in size and minor plumage details.<p>All forms show a post-breeding dispersal, but the northern breeders are most migratory, wintering south to Africa, the Caribbean and northern South America, southern Asia and New Zealand.<p>The gull-billed tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
- Breeding range
- PAL, AF, OR, NA, MA, SA : widespread inland, sw Europe to ne China; coastal China; coastal w North Atlantic and Caribbean; coastal s California and Mexico; coastal South America and inland nc Argentina
- Non-breeding range
- to subtropical and tropical coasts, rivers and lakes worldwide (except remote is.)
- Migration
- Complete migrants
Behavior
The gull-billed tern breeds in colonies on lakes, marshes and coasts (including bays and earthen levees). It nests in a ground scrape and lays two to five eggs. While widely distributed in freshwater areas in Eurasia, it is associated almost solely with saltwater, coastal areas in North America.<p>This is a somewhat atypical tern, in appearance like a Sterna tern, but with feeding habits more like the Chlidonias marsh terns, black tern and white-winged tern. It does not normally plunge dive for fish like the other white terns, and has a broader diet than most other terns. It largely feeds on insects taken in flight, and also often hunts over wet fields and even in brushy areas, to take amphibians and small mammals. It is also an opportunistic feeder, and has been observed to pick up and feed on dead dragonflies from the road.
Conservation
- Population trend
- declining
Photos
Distribution
Bird Calls
Other Birds
Rufous-breasted Warbling Finch
Poospiza rubecula
Rare and endangered bird found at high elevations in the western Andes of northern and central Peru. Note the black mask and the reddish-orange eyebrows, throat, and breast. Similar to Rufous-browed Hemispingus of the eastern Andes, but eyebrows are shorter and connect over the bill. Young birds mostly lack the mask and eyebrow and are heavily streaked below. Inhabits scrub and stunted woodland.
White-naped Pigeon
Columba albinucha
A dark maroon-gray pigeon with a hind-crown and nape that are white in the male and gray in the female. At close quarters the bill can be seen to have a black base with a red-yellow tip, and the legs are reddish-purple. In flight the tail has pale-tipped corners. A scarce and localized resident found in pairs in the canopy of lowland and sub-montane forest in isolated populations in the Albertine Rift and Cameroon. Vocalizations are poorly documented, but reputed to be similar to those of Rameron Pigeon, which is larger than White-naped with a yellow eye-ring, bill, and feet, white speckling on the wings, and no white on the head.
Sharpe's Starling
Pholia sharpii
Small, distinctive starling with a blue-black back, a white throat, and a buff belly. Except in good light, the upperparts usually look black. The pale eye is always distinctive. Uncommon and local in montane forest. Found in the canopy, in pairs or small flocks; often perches up conspicuously on dead snags and other open perches. The call is a sharp “sveet” and the song is a high-pitched tinkling that is distinctive, but quiet and easily ignored. Separated from similar starlings by its pale throat.
Start Your Bird Watching Journey
Identify a bird outdoors and keep the field guide close for your next observation.