Birds of America was first published as a series during 1827-1838 and is the result of more than 14 years of field observation and drawings by John James Audubon (1785-1851) who was a naturalist, painter and ornithologist.
Audubon's birds were drawn from real models. He would first find and shoot the bird using fine shot and then use wire to position the bird into a natural pose. This is different from the common method of many ornithologists who would prepare and stuff the body into a rigid pose. When working on a large specimen, for example an eagle, he would spend up to four 15 hour days preparing it, studying it and sketching it. The birds were drawn life-size and this is the reason some of the birds appear to be in a contorted pose as he struggled to fit the bird on the page!