A detailed examination, from the point of view of an ornithologist, of the pictures of birds in the thirteenth-century manuscript, Vatican, Pal. Lat. 1071, of De arte venandi cum avibus of Frederick II, shows that most of them are not the accurate representations that have generally been claimed. The illustrators, of whom there were probably not less than three, show little knowledge of natural history, and, even when they were drawing birds such as falcons that must have been available to them, they did not observe very closely. They were no better than many of the artists active in England at the same period or earlier, and a comparison indicates that they did not, as has sometimes been suggested, influence the northern illustrators. The number of subjects, though high, is not wide, being confined for the most part to birds that were likely to have been used as quarry in falconry. Few British species illustrated in MS. Pal. Lat. 1071 are not also in at least some English manuscripts, but many in English manuscripts that live also in Italy are absent from De arte.