The Master of the Howl is another office wherein the officeholder's duties bind him to caern grounds only during a moot. The main duty of this office is to lead the assembled werewolves in the howls, songs and chants that begin the moot, in such a way that the howls convey the right mood and set the right tone. It's an important role, as it's vital to seeing that moots run as smoothly and unobtrusively as possible; even so, the Master of the Howl isn't often needed between moots.
Although the Galliard is the obvious auspice for this position, any character with sufficient charisma and talent can fill this role. Knowing the Moot Rite is also required.
There aren't many plot hooks specific to the Master of the Howl office. This can be a good thing, though. If an appropriate candidate exists in your pack, but one who has extensive goals outside the caern, this can work as a way of getting him more directly involved with the caern without making him feel crushed by his duties. And if he starts to enjoy the role, all the better.