Adult great skua (Stercorarius skua) being harassed by Arctic terns (Sterna paradisaea) guarding their nest sites, Svalbard, Norway

great skua arctic terns svalbard nesting bird behavior wildlife summer predator seabirds nest defense aerial confrontation natural habitat avian interaction marine environment protection aggression feeding flight migration colony territory breeding coastal nature ecosystem flying instincts challenge encroachment season ornithology research species animal shorebirds conservation land birds sea tundra ecological birdwatching