Caspian Tern

Sterna caspia

Order CHARADRIIFORMES - Family LARIDAE - Subfamily Sterninae

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1. Cool Facts
2. Description
3. Similar Species
4. Sound
5. Range
6. Habitat
7. Food
8. Behavior
9. Reproduction
10. Conservation Status
11. Other Names

As large as a big gull, the Caspian Tern is the largest tern in the world. Its large coral red bill makes it one of the most easily identified terns throughout its worldwide range.

Cool Facts

• The oldest known wild Caspian Tern lived to be more than 26 years old. Average life span of Great Lakes Caspian Terns is estimated to be 12 years.

• The Caspian Tern aggressively defends its breeding colony. It will pursue, attack, and chase potential predatory birds, and can cause bloody wounds on the heads of people who invade the colony. The entire colony will take flight, however, when a Bald Eagle flies overhead, exposing the chicks to predation from gulls.

• The largest breeding colony in North America is off the coast of Oregon. Increasing numbers of terns at this site have caused problems with young salmon releases, some of them endangered species. Efforts are being made to move the colony to other areas, away from the fish stocking programs.

• Young Caspian Terns appear to have a difficult time learning to catch fish efficiently. They stay with their parents for long periods of time, and are fed by them even on the wintering grounds. Many young terns do not return to the nesting grounds for several years, remaining instead on the wintering areas.

Description

• Size: 47-54 cm (19-21 in)
• Wingspan: 120-135 cm (47-53 in)
• Weight: 530-782 g (18.71-27.6 ounces)

• Large, gull-like tern.
• Black cap.
• Body white.
• Bill large, thick, and brilliant red with dark tip.

• Silvery gray back and wings.
• White underparts, rump, and tail.
• Primaries dark underneath, show as black patch in flight.
• Black legs and feet.
• Tail short and only slightly notched. Breeding (Alternate) plumage: Black cap extends from bill through eye to back of head. Very short crest on back of head.
  Nonbreeding (Basic) plumage: crown streaked and mottled with black and white, only slightly whiter at forehead.

Sex Differences

Sexes look alike.

Immature

Juvenile has blackish crown, black edging to back feathers.

Similar Species

• Larger and more robust than other terns. Pointed red bill and black cap distinguishes it from gulls.
• Royal Tern thinner with thinner wings, has thinner more pointed orange or orange-red bill, more deeply notched tail, and outside of the breeding season, an extensive white forehead.

Sound

Call a raspy "kowk." Juvenile begging call a high pitched whistling; heard frequently during migration and in winter.

»listen to songs of this species

Range

Summer Range

Breeds in scattered locations across North America, along Pacific Coast, in central Canada, around the Great Lakes, in west-central United States, along the Gulf Coast, and along the Atlantic Coast. Also breeds in Eurasia, Africa, Australia, and New Zealand.

Winter Range

Winters along the Pacific Coast from southern California southward to Guatemala, and along the Atlantic and Gulf coasts from North Carolina westward to Texas, Mexico, and southward to Honduras. Also in West Indies, Panama, and northern South America, as well as Africa, Mediterranean, Indian Ocean, and India.

Habitat

• Breeds in wide variety of habitats along water, such as salt marshes, barrier islands, dredge spoil islands, freshwater lake islands, and river islands.
• During migration and winter found along coastlines, large rivers and lakes. Roosts on islands and isolated spits.

Food

Almost entirely fish; occasionally crayfish and insects.

Behavior

Foraging

Flies over water with bill pointing down; plunges into water to catch fish.

Reproduction

Nest Type

A scrape in ground. Lined often with dried vegetation, small pebbles, broken shells or other debris. May have elaborate rim of sticks. Nesting colonies occur on island beaches, often near colonies of other bird species.

Egg Description

Buff, sparingly marked with dark spots and sometimes large irregular blotches.

Clutch Size

Usually 1-3 eggs.

Condition at Hatching

Eyes open. Covered with down and able to leave nest (usually after several days).

Conservation Status

Numbers increasing across North America: using man-made dredge spoil islands and dikes for breeding. Declining in Europe. It is listed as rare or vulnerable in some areas because of the scattered nature of breeding colonies. Beach nesting areas vulnerable to disturbance and predation.

Other Names

Sterne Caspienne (French)
Charrán caspia, Pagaza Piquirroja (Spanish)

Sources used to construct this page:

Cuthbert, F. J., and L. R. Wires. 1999. Caspian Tern (Sterna caspia). In The Birds of North America, No. 403 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.