At a Glance

The largest of the terns, larger than many gulls. Cosmopolitan, nesting on five continents. In North America, it is common along both coasts and locally inland, mainly around large bodies of water. Noted for its long adolescence, with the young dependent on their parents for many months; even in late winter, many an adult Caspian is trailed by a begging youngster from the previous nesting season.
Category
Gull-like Birds, Gulls and Terns
Conservation
Low Concern
Habitat
Coasts and Shorelines, Lakes, Ponds, and Rivers, Saltwater Wetlands
Region
Alaska and The North, California, Eastern Canada, Florida, Great Lakes, Mid Atlantic, New England, Northwest, Plains, Rocky Mountains, Southeast, Southwest, Texas, Western Canada
Behavior
Direct Flight, Soaring
Population
530.000

Range & Identification

Migration & Range Maps

Inland breeders move to coast and southward for winter. Some winter south to West Indies, northern South America.

Description

19-23" (48-58 cm). Large size, thick red bill; short crest gives square-headed look. Forehead is clouded with streaks in winter and on immatures (not clear white as on many Royal Terns). In flight, shows blackish underside of wingtips.
Size
About the size of a Crow, About the size of a Mallard or Herring Gull
Color
Black, Gray, Orange, Red, White
Wing Shape
Broad, Long, Pointed, Tapered
Tail Shape
Notched, Short, Square-tipped

Songs and Calls

Low harsh kraa. Also a shorter kow.
Call Pattern
Flat, Simple
Call Type
Raucous

Habitat

Large lakes, coastal waters, beaches, bays. Found on both fresh and salt water, favoring protected waters such as bays, lagoons, rivers, lakes, not usually foraging over open sea. Inland, more likely on large lakes than on small ponds. Nests on open ground on islands, coasts.

Behavior

Eggs

1-3, rarely 4 or 5. Pale buff, spotted with brown or black. Incubation is by both parents (female may do more), 20-22 days. Young: May leave nest a few days after hatching, move to nearby shore. If colony is undisturbed, young may remain at nest until ready to fly. Both parents bring food for young. Age at first flight about 30-35 days; young may remain with parents as long as 8 months.

Young

May leave nest a few days after hatching, move to nearby shore. If colony is undisturbed, young may remain at nest until ready to fly. Both parents bring food for young. Age at first flight about 30-35 days; young may remain with parents as long as 8 months.

Feeding Behavior

When foraging flies high over water, hovers, then plunges to catch fish below surface. Less often flies low, dips down to catch prey at water's surface. May steal food from other birds.

Diet

Mostly fish. Often concentrates on a few abundant fish species in a given locale (for example, shiner perch on California coast, alewife on Great Lakes). Also eats insects, sometimes eggs or young of other birds.

Nesting

First breeds at age of 3 years. Nests in colonies, sometimes in isolated pairs. Male may fly low over colony carrying fish; female follows. On ground, courtship feeding (male feeds female). Nest site is on bare ground, among driftwood or debris, perhaps sometimes on floating mats of dead vegetation. Nest (built by both sexes) is shallow depression, sometimes with rim or lining of debris.

Climate Vulnerability

Conservation Status

Overall population probably stable, perhaps increasing slightly; range has expanded recently to include southern Alaska.

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 Caspian Tern. Learn even more in our Audubon’s Survival By Degrees project.

Climate Threats Facing the Caspian 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.