What metaphors are used in The Trumpet of the Swan by E. B. White?

The concept of Trumpeter Swans is metaphorical in itself. The reference results in number of metaphorical images throughout the story that link sound as a comparison:

“if you had been sitting by the pond on that first warm day of spring, suddenly, toward the end of the afternoon, you would have heard a stirring sound high above you in the air—a sound like the sound of trumpets.”