Terns and skuas, while not technically gulls, are often mistaken for them.
Another five-letter word for 'change' is 'alter.'
linen
Short is a five letter word. Another is brief.
Another word for sanctuary is "haven".
Regal.
Solve, reply
troth
grand?
Jolly is another five letter word meaning merry or happy is another.
Agree?
Fancy.
Crook. :D