This picture shows a backlit flower, or is it a common tern diving for a fish? The common tern (Sterna hirundo) is a seabird of the tern family Sternidae. Like most terns, this species feeds by plunge-diving for fish, either in the sea or in freshwater, but molluscs, crustaceans and other invertebrate prey may form a significant part of the diet in some other areas. The common tern has a circumpolar distribution, breeding in temperate and subarctic regions of Europe, Asia and North America. It is strongly migratory, wintering in coastal tropical and subtropical regions. Breeding in a wider range of habitats, the common tern nests on any flat, poorly vegetated surface close to water, including beaches and islands, and it readily adapts to artificial substrates such as floating rafts. In The Netherlands the common tern is a breeding bird of man made landscapes such as Agricultural grasslands and flat rooftops of buildings as well. The nest may be a bare scrape in sand or gravel, but it is often lined or edged with whatever debris is available. Up to three eggs may be laid, their dull colours and blotchy patterns providing camouflage on the open beach. Incubation is by both sexes, and the eggs hatch in around 21–22 days, longer if the colony is disturbed by predators. Eggs and young are vulnerable to predation by mammals such as rats and American Mink, and large birds including gulls, owls and herons.