Captain Wedderburn sees a beautiful girl and says to his servant that if it was not against the law he would kidnap her. She tells him she is on her father's land, it will soon be supper time, and she will not go with him. He seizes her anyway and takes her to his lodgings. There is a battle of wits with riddles and questions but it ends in a happy marriage.
John Mowat says the ladies might think the song a bit vulgar but there's nothing in it.
According to Medieval bestiaries, the dove had no gall bladder, hence no bile, hence its gentleness.

Card image is used courtesy of the James Madison Carpenter Collection, American Folklife Center, Library of Congress.