Whooper swan (cygnus cygnus) feeding at water surface, martin mere, uk

uk surface horizontals swan vertebrates water migrate waterbird birds martin animals hunters sociable horizontal monogamous wildlife carnivorous nature predator waterbirds migrates aves predation feeding zoology aquatic social whooper bird carnivore migratory vertebrate meat predators mere cygnus migrating swans water anatidae anseriformes monogamy hunter fauna cygnus animal