High above the southern French village of Duilhac, Patrice Potier and his son Simon are standing in the ruins of the Peyrepertuse castle, narrating a feast for the eyes. As 2,000 spectators watch, nearly a dozen birds of prey are swooping up and down the cliffside, disappearing from view only to return and land on an outstretched arm. This 13th-century castle, built more than 2,500 feet above the ground below, is perfectly positioned for such a spectacle. Two winds intersect here, and no matter which one is blowing on any…
