Help us identify this odd bird with floppy head feathers from Gesner’s Historia Animalium, Liber III.
Gesner_historiae_v3_1585_800_watermark
Books, Health and History
The New York Academy of Medicine
Books, Health and History 
Could it be Numida meleagris, the Guinea hen which arrived in Portugal and England in the first part of the 16th century. It looks like more a raptor so this is a ¨wild¨ (turkey) guess. It seems to be the bird which gave Turkey its name.
The bird has been identified as the Madagascar Serpent Eagle. But speaking of guinea hens and turkeys, the turkey in our Gesner is labeled “poulle d’Inde.” It is not included in the blog post, but here is the image: https://twitter.com/NYAMHistory/status/538044619276443648 Thanks for the comment!
Could it be an osprey?
Thank you for the suggestion – another reader has identified it as the Madagascar Serpent Eagle.