I realize this is an old topic, but I was reading up on the Falconer archetype and stumbled across it. A consensus seems to have been established in this discussion that the player could not choose a raven as their bird companion because it is not a "bird of prey." This is incorrect.
The book explicitly states that the bird may be either a bird of prey or a scavenger, and lists vultures as an example. Ravens are also scavengers, and would absolutely qualify as a large bird (again, not size category but rather large in comparison to other birds). There's no reason to state that you could not elect to have a raven animal companion using the Bird stats from the CRB.