The gyrfalcon is the largest falcon in the world and the most northern diurnal raptor, a swift bird of majestic appearance. It hunts in a variety of ways, but one characteristic, more than any other, its climbing ability - that is, flying straight up at a steep angle, often making only one turn before it has gained ascendancy over its intended prey - made the bird a favourite in times past, especially when hunting for large, high flying quarry. Giraldus Cambrensis (Gerald de Barry), in his book, De Arte Venandi cum Avibus (Art of Falconry), which is assigned to the last part of his life, c....