Animalia Life

Sterna hirundo
SUBFAMILY
Sterninae
TAXONOMY
Sterna hirundo Linneaus, 1758, Sweden. Four subspecies usually are recognized.
OTHER COMMON NAMES
French: Sterne pierregarin; German: FluЯseeschwalbe: Spanish: Charrбn Comъn.
PHYSICAL CHARACTERISTICS
12.6–15.4 in (32–39 cm), 0.2–0.3 lb (100–130 g). Typical small tern with black cap; white neck, throat, and belly; and gray back and upperwings. Breast sometimes suffused with pink at start of breeding cycle. Bill red with black tip in breeding season. Outer five primaries have dark outer webs. Nonbreeding adult has white forehead, crown black with white streaks. Juvenile is gray above barred with dark gray or brown. Black carpals distinctive in juvenal and non-breeding adult plumages.
DISTRIBUTION
Breeds in north temperate to subarctic zones in North America, Europe, and Asia, winters along coasts of Central and South America, both coasts of Africa, in coastal India and around coastal islands of Pacific (including around Australia).
HABITAT
Breeds in coastal and inland areas on sandy barrier beaches, in vegetated inter-dune areas, on rocky, sandy, or shell islands, on piers, and on seacliffs. Winters on coastal estuaries and up large rivers. Adapted to nesting on piers and other artificial sites and to feeding on jetties and piers.
BEHAVIOR
Diurnal; territorial during breeding season.
FEEDING ECOLOGY AND DIET
Feeds mainly on small fish obtained by plunge-diving. May also eat crustaceans, insects, and fish offal. Feeds in dense flocks in ocean, often with other terns and over predatory fish that force bait fish to the surface. Near colony, some common terns engage in piracy (both of conspecifics and other terns).
REPRODUCTIVE BIOLOGY
Lays mainly May through June. Usually colonial, although it may nest solitarily or in very small, loose colonies. Often nests with other terns or skimmers, frequently near vegetation for protection from weather or predators. Both sexes defend territory, incubate the eggs, and care for chicks. Lays three eggs. Incubation period 22–28 days. Fledging period 24–28 days, with extended parental care. Few breed at two years, most at three years.
CONSERVATION STATUS
Not threatened. Extensively impacted by millinery trade in late 1800s; often whole birds were used on hats. Some colonies still exposed to egging, and birds are eaten in some places. Coastal colonies vulnerable to development, and foraging birds exposed to contaminants and oil pollution. Also vulnerable to increases in predators associated with humans (dogs, cats, foxes, raccoons) and to tidal flooding.
SIGNIFICANCE TO HUMANS
Once heavily egged, and still egged by humans for food in many places. Often used by fishermen to indicate schools of predatory fish and to indicate presence of land.

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