Books I-II of De arte venandi cum avibus, edited by Marcus Welser from a very old, incomplete defective manuscript, which lacked Books III-IV. More than a dissertation on hunting, this work is considered the first zoological treatise written in the critical spirt of modern science, centuries before the scientific revolution. Besides the most detailed exposition of the method of hunting with falcons, the work concerns the anatomy of birds, a description of avian habits, and the excursion of migratory birds. Written during the 1240s by Frederick II, Holy Roman Emperor, who was also an accomplished linguist and scholar, the original manuscript was lost in 1248 at the siege of Parma.

Manuscripts of De arte venandi cum avibus exist in a two-book version at Rome, Vienna, Paris (2x), Geneva and Stuttgart, and in a six-book version at Bologna, Paris, Nantes, Valencia, Rennes, and Oxford. The most famous is an illuminated manuscript commissioned by Manfred, son of Frederick II: a two-column parchment codex of 111 folios ( Vatican, MS. Pal. Lat. 1071). This manuscript of the two book version and is illustrated with brilliantly colored, extraordinarily lifelike, accurate and minute images of birds, their attendants, and the instruments of the art. The manuscript also contains additions made by Manfred, which are all clearly marked in the beginning by notations such as "Rex", "Rex Manfredus" or "addidit Rex".

Facsimile edition of the manuscript: Graz, Austria: Akademische Druck-u. Verlagsanstalt, 1969.  Digital facsimile of the 1596 edition from Google Books at this link. 

English translation of the six-book version of Frederick's work, edited, with numerous appendices, illustrations, and an annotated bibliography of ancient, medieval and modern falconry, by Casey A. Wood and F. Marjorie Fyfe.