Tern (4)
(Other definitions for gull that I've seen before include "Take in" , "Common seabird" , "Rook - bird of the sea" , "Seabird - fool" , "A bird; to deceive" .)
(Other definitions for seagull that I've seen before include "One sitting atop mast perhaps" , "Avian scavenger" , "Marine bird" , "Bird paradoxically fond of landfill sites" , "Main creature" .)