Gull-billed Tern
Gull-billed Tern
Gelochelidon nilotica
At a Glance
Besides the thick bill that gives it its name, this tern has a relatively stocky build and broad wings. Typically seen in leisurely flight over marshes, hawking for insects in the air or swooping down to take prey from the water or the ground; unlike typical terns, rarely dives into water for fish. On the ground, walks better than most terns. Widespread in warmer parts of the world, but local in North America, mainly in southeast. Generally found only in small numbers.
All bird guide text and rangemaps adapted from Lives of North American Birds by Kenn Kaufman© 1996, used by permission of Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Category
Gull-like Birds, Gulls and Terns
IUCN Status
Least Concern
Habitat
Coasts and Shorelines, Fields, Meadows, and Grasslands, Saltwater Wetlands
Region
California, Florida, Mid Atlantic, New England, Southeast, Texas
Behavior
Direct Flight, Swooping
Population
190.000
Range & Identification
Migration & Range Maps
Mainly a summer resident in California and on Atlantic Coast; some remain through winter on Gulf Coast.
Description
13-15" (33-38 cm). Thick black bill, relatively long legs, overall pale look. In flight, looks broad-winged and buoyant. Summer adult has black cap, but young and winter adults very white-headed. Compare to Forster's and other terns; Gull-billed catches many insects in midair rather than plunging into water for fish.
Size
About the size of a Crow
Color
Black, Gray, White
Wing Shape
Long, Pointed, Swept, Tapered
Tail Shape
Forked, Notched, Square-tipped
Songs and Calls
Rasping katy-did, similar to sound made by that insect.
Call Pattern
Flat, Undulating
Call Type
Raucous
Habitat
Salt marshes, fields, coastal bays. Restricted to seacoast in North America (except in Florida and at Salton Sea, California), but does most foraging over marshes, pastures, farmland, and other open country just inland from coast. Nests mostly on beaches, islands. Reportedly used to nest more often in salt marshes, abandoned those sites because of human persecution.
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Behavior
Eggs
2-3, sometimes 1-4. Pale buff, spotted with dark brown. Incubation is by both parents (although female may do more), 22-23 days.
Young
Leave nest a few days after hatching, move to dense plant cover if nearby. Both parents bring food for young. Age at first flight 4-5 weeks. Young may remain with parents 3 months or more, beginning southward migration with them.
Feeding Behavior
Forages by flying slowly into wind, dipping to surface of land or water to pick up items, or by catching flying insects in the air. Sometimes forages while walking on ground; rarely plunges into water.
Diet
Mostly insects. Feeds on a wide variety of insects, caught on ground, in air, or at surface of water; also spiders, crabs, shrimp, mollusks, earthworms, marine worms, small fish, lizards, frogs, toads, rodents, small birds.
Nesting
Colonial breeder. Colonies usually small, not as densely packed as those of many terns. Has some aerial displays, but much of courtship display takes place on ground, involving elaborate posturing, bill-pointing, male feeding female. Nest site is on open ground, sometimes on gravel roof. Nest (built by both sexes) is shallow depression, often with rim of soil, addition of some plant material and debris.
Conservation
Conservation Status
Evidently far less numerous on the Atlantic Coast today than it was historically. Human disturbance and loss of nesting sites among likely causes. Has begun nesting on rooftops in some Gulf Coast areas. Colonized southern California, apparently from western Mexico, beginning to nest at Salton Sea in 1920s and at San Diego in 1980s.
Climate Threats Facing the Gull-billed Tern
Choose a temperature scenario below to see which threats will affect this species as warming increases. The same climate change-driven threats that put birds at risk will affect other wildlife and people, too.