Sterna hirundo - Common Tern
Feather characters. Barbules are from short until medium length (0.7-1.1 mm). Pigmentation varies in different body feathers, it is absent or concentrated in nodes and parts of internodes (less than 50%). Slightly thickened nodes (16-24 per mm) are equally distributed along the entire length of barbules, only slightly decreasing in size towards distal end. Villi are absent and internodes are straight. Minute prongs may be present along the entire length of barbules, on both sides of the pennulum. These prongs are unequally distributed, and many nodal structures without prongs may be found.
Field characters. Size 35 cm. Weight 120 g (103-145) (Dunning, 1993). Most common tern. A slender bird with a black cap and a deeply forked tail. Bill red with a black tip, legs red. Upperwings and back are grey. Outer 4-6 primaries are darker than rest of upperwing, forming a diamond-shaped pattern. The underside of the primaries are tipped dark, forming a somewhat sloppy line, in contrast to that of Arctic Tern (Sterna paradisaea, not included in BRIS). Wings are less translucent than in the latter; in favourable light conditions a translucent wing panel can be seen, formed by the inner four primaries. Juvenile has a dusky cap, a dark reddish bill, brownish grey upperpart markings and a dark shoulder bar.
Voice. Usually noisy. Loud, rasping 'crie-eeer', fast 'kirri-kirri' and fast kikkikkkik'.
Distribution. Summer visitor. Common near water; locally common breeding bird. Map: see MapIt.
Habitat. Both coastal and inland near large water bodies. Breeds in small or huge colonies in short vegetated areas, like coastal dunes, (salt) marshes, and meadows. Usually coastal outside breeding season.
Food. Fish and crustaceans.