Gryphon of the Hidden Realm

This is a long, classic fantasy book, in the tradition of Tolkien, CS Lewis and David Eddings, set in a different world.
Female gryphons are disappearing, abducted by the evil elves, the rulers of the Nomoi Empire. Hwedolyn must find out what is happening to them. He meets partisans, men, and must question ancient lore if he is to survive.
The story begins when a young orphan boy, a serving hand at the tavern high in the mountains, knows that every new moon, a barrel of mead is left out on the plateau, and in the morning it is gone and two goats are left as payment. Who or what is it that collects the mead on this, the darkest night of the month? He decides to stay awake one night and see what manner of monster it is.
In this, the second book in the Gryphonomicon Gryphon Dragon Histories, the story of Hwedolyn the gryphon and Gwendolyn his eyrie-mate continues.
Note - this is Book 2. All three books in this series are available in the "Robert Denethon Fantasy and Alternate History Collection."