Caspian Tern

The Caspian Tern is the largest tern species on Earth, rivaling many gulls in bulk, with a thick, dagger-like coral-red to orange-red bill that is unmistakable even at a distance. Adults have a black cap, pale gray upperparts, white underparts, and black legs, giving them a powerful, almost gull-like silhouette compared to the more delicate build of smaller terns.

In flight, the wings show dusky, darker underside to the outer primaries, and the tail is only shallowly forked, unlike the deeply forked tails of many smaller terns. Its size, heavy bill, and harsh voice make it one of the more distinctive and easily recognized terns worldwide.

Found on every continent except Antarctica, the Caspian Tern nests colonially, often alongside other terns and gulls, on sandy or gravelly islands in lakes, rivers, and coastal waters.

Key field marks

• Massive size, largest tern in the world
• Thick, coral-red to orange-red bill with a dark tip
• Black cap and black legs
• Only shallowly forked tail
• Dark underside to the outer primaries in flight

Similar species

• Royal Tern: smaller and slimmer with a thinner orange bill lacking the dark tip, and a shaggier crest.
• Elegant Tern: notably smaller with a long, slender, drooping orange bill.
• Gulls: superficially similar in bulk but lack the tern's pointed bill and plunge-diving behavior.

Habitat

Uses a wide variety of large waterbodies including ocean coastlines, estuaries, large lakes, and major rivers, nesting on open sandy, gravelly, or shelly islands and beaches.

Range and migration

One of the most widely distributed terns, breeding on every continent except Antarctica, including North America, Europe, Asia, Africa, and Australia. Northern populations are migratory, wintering along warmer coasts, while some populations in milder climates are largely resident.

Behavior

Caspian Terns are powerful, direct fliers, often seen patrolling over water before plunge-diving for fish, and are notably aggressive in defending nesting colonies against intruders and predators.

Voice

Gives a loud, harsh, crow-like "kraa-uh" call, quite unlike the higher, sharper calls of smaller terns.

Feeding

Feeds almost exclusively on fish, caught by hovering briefly and then plunge-diving from the air into the water.

Nesting and breeding

Nests colonially, often alongside other terns and gulls, on open ground with little vegetation on islands and beaches. Clutches typically contain one to three eggs, incubated by both parents for about three weeks.