Resident breeder, regular passage visitor and winter visitor.
A large (19-23 inches) tern, the Caspian Tern in summer is most easily identified by its gray-tipped wings, black cap, and large orange bill. In winter, the black in this species’ cap is replaced by mottled gray. Male and female Caspian Terns are similar to one another in all seasons. The Caspian Tern inhabits every continent except Antarctica. In North America, this species breeds locally in central Canada, the Great Lakes, along the Gulf coast of the United States, and along the Pacific and Atlantic coasts of the U.S. and Canada. In winter, Caspian Terns may be found in southern California, along the coast of the southeastern U.S., and further south into Mexico and Central America. In the Old World, this species breeds in Eurasia from Eastern Europe east to China, along the coasts of Africa and South Asia, and in Australasia, wintering widely in the tropics. Caspian Terns breed in a variety of habitats, including marshes, estuaries, barrier islands, bays, and lakes, and may be found either in freshwater or in saltwater. In winter, this species utilizes similar habitat types as in summer. Caspian Terns primarily eat fish and small crustaceans. Caspian Terns may be most easily seen standing or walking along the shore or on the beach, where their large size and bright orange bill are most apparent. With the aid of binoculars, it may also be possible to observe this species feeding by diving headfirst into the water. Caspian Terns are most active during the day.
A large (19-23 inches) tern, the Caspian Tern in summer is most easily identified by its gray-tipped wings, black cap, and large orange bill. In winter, the black in this species’ cap is replaced by mottled gray. Male and female Caspian Terns are similar to one another in all seasons. The Caspian Tern inhabits every continent except Antarctica. In North America, this species breeds locally in central Canada, the Great Lakes, along the Gulf coast of the United States, and along the Pacific and Atlantic coasts of the U.S. and Canada. In winter, Caspian Terns may be found in southern California, along the coast of the southeastern U.S., and further south into Mexico and Central America. In the Old World, this species breeds in Eurasia from Eastern Europe east to China, along the coasts of Africa and South Asia, and in Australasia, wintering widely in the tropics. Caspian Terns breed in a variety of habitats, including marshes, estuaries, barrier islands, bays, and lakes, and may be found either in freshwater or in saltwater. In winter, this species utilizes similar habitat types as in summer. Caspian Terns primarily eat fish and small crustaceans. Caspian Terns may be most easily seen standing or walking along the shore or on the beach, where their large size and bright orange bill are most apparent. With the aid of binoculars, it may also be possible to observe this species feeding by diving headfirst into the water. Caspian Terns are most active during the day.
The Caspian tern (Hydroprogne caspia)[2] is a species of tern, with a subcosmopolitan but scattered distribution. Despite its extensive range, it is monotypic of its genus, and has no accepted subspecies.[3] The genus name is from Ancient Greek hudros, "water", and Latin progne, "swallow". The specific caspia is from Latin and, like the English name, refers to the Caspian Sea.[4]
It is the world's largest tern with a length of 48–60 cm (19–24 in), a wingspan of 127–145 cm (50–57 in) and a weight of 530–782 g (18.7–27.6 oz).[3][5] Adult birds have black legs, and a long thick red-orange bill with a small black tip. They have a white head with a black cap and white neck, belly, and tail. The upper wings and back are pale grey; the underwings are pale with dark primary feathers. In-flight, the tail is less forked than other terns, and wingtips are black on the underside.[3] In winter, the black cap is still present (unlike many other terns), but with some white streaking on the forehead. The call is a loud heron-like croak.[6]
Their breeding habitat is large lakes and ocean coasts in North America (including the Great Lakes), and locally in Europe (mainly around the Baltic Sea and Black Sea), Asia, Africa, and Australasia (Australia and New Zealand). North American birds migrate to southern coasts, the West Indies and northernmost South America. European and Asian birds spend the non-breeding season in the Old World tropics. African and Australasian birds are resident or disperse over short distances.[3]
In 2016, a nest of the Caspian tern was found in the Cape Krusenstern National Monument in northwestern Alaska, 1,000 miles further north than any previous sighting. This development was part of a general trend in Alaska of species moving to the north, a tendency ascribed to global warming.[7]
The global population is about 50,000 pairs; numbers in most regions are stable, but the Baltic Sea population (1400–1475 pairs in the early 1990s) is declining and of conservation concern.[3][8]
The Caspian tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
They feed mainly on fish, which they dive for, hovering high over the water and then plunging. They also occasionally eat large insects, the young and eggs of other birds and rodents. They may fly up to 60 km (37 mi) from the breeding colony to catch fish; they often fish on freshwater lakes as well as at sea.[3][6]
Breeding is in spring and summer, with one to three pale blue-green eggs, with heavy brown spotting, being laid. They nest either together in colonies, or singly in mixed colonies of other tern and gull species. The nest is on the ground among gravel and sand, or sometimes on vegetation; incubation lasts for 26–28 days. The chicks are variable in plumage pattern, from pale creamy to darker grey-brown; this variation assists adults in recognizing their own chicks when returning to the colony from feeding trips. Fledging occurs after 35–45 days.[3]
Preparing for takeoff
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Caspian tern in flight
Two Caspian terns in flight
In flight In New Zealand
The Caspian tern (Hydroprogne caspia) is a species of tern, with a subcosmopolitan but scattered distribution. Despite its extensive range, it is monotypic of its genus, and has no accepted subspecies. The genus name is from Ancient Greek hudros, "water", and Latin progne, "swallow". The specific caspia is from Latin and, like the English name, refers to the Caspian Sea.
