Bird GuideGulls and TernsGull-billed Tern

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.
Category
Gull-like Birds, Gulls and Terns
Conservation
Low 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, About the size of a Robin
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.

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.

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.

Climate Vulnerability

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 Map

Audubon’s scientists have used 140 million bird observations and sophisticated climate models to project how climate change will affect the range of the Gull-billed Tern. Learn even more in our Audubon’s Survival By Degrees project.

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.

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