Sterna caspia Pallas, 1770, Caspian Sea. Monotypic.
OTHER COMMON NAMES
French: Sterne caspienne; German: Raubseeschwalbe; Spanish: Pagaza Piquirroja.
19–22 in (48–56 cm), 1.3–1.7 lb (574–782 g). Largest tern with stout blood-red bill with some black at tip, slightly forked tail, black undersurface of primaries in flight. Generally black cap; white neck, throat, and belly; light gray mantle. Nonbreeding has forehead and crown whitish with dark spotting. Juvenile is gray above with brown bars, crown mainly white, tail and primaries dark gray.
North America, northeast Europe (Baltic), Africa, Madagascar, central and south Asia, Australia (coastal; sparse inland), New Zealand.
Breeds on sand, shell or rocky islands, occasionally on salt marshes. Winters along coasts and on large inland lakes and reservoirs.
Mainly diurnal, territorial, with relatively small territories for terns.
FEEDING ECOLOGY AND DIET
Feeds mainly on small to medium-sized fish, including young salmon, sometimes the eggs and young of other birds or on carrion. Can take larger fish than most other terns. Forages on freshwater lakes, inland seas, and coastal estuaries. Feeds in small flocks but may feed solitarily and defend space.
Monogamous; both sexes incubate the eggs and care for the young; breeds April to June in Northern Hemisphere, September to December in Southern Hemisphere, and all year in Australia. Densely colonial in most places, may nest solitarily in Europe within colonies of other gulls and terns. Clutch is two to three eggs. Incubation period 26–28 days. Fledging period 35–45 days. Chicks form creches, and there is extended parental care beyond fledging. Most breed at three years of age.
Not threatened. Colonies vulnerable to human disturbance; may abandon. Many populations are vulnerable and have experienced declines. Listed as threatened in Canada, where some colonies are exposed to vandalism and deliberate persecution.
loss due to succession threatens some colonies. Reliance on large fish exposes them to contaminants in regions such as the Great Lakes and elsewhere.
SIGNIFICANCE TO HUMANS
Feathers used for millinery trade in the late 1800s; extensive egging in some places. Viewed as a predator and pest by fish hatcheries, and harrassed or eliminated at breeding colonies in Washington State.
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