"The question has been asked, - how it is that the number of animal metaphors and similes in Shakespeare's work so greatly exceeds that of any other of his brother dramatists? The answer is to be found mainly in that his deeper study of the problem concerning man's origin and destiny led him thus closely to connect man with his fellow denizens of the earth. " (Emma PHIPSON)
Indeed it is not what Shakespeare says about one bird or another that matters, it is the use he makes of it. Shakespeare never uses a bird for its own sake, always to draw a human parallel.
"The humanists were at first so excited by their discovery of the ancient texts that they had less interest than their medieval predecessors in the direct observation of Nature. Renaissance scholars were strongly attached to a world view in which magic and science were closely intertwined. " (Peter BOWLER)
Shakespeare shared this view, but as a poet and playwright interested in the human condition, and not as a scholar. He gathered in his work much of the scientific knowledge of the time, mingled with folklore, or the fashionable subject of falconry.
Shakespeare has created his own "mythornithology", not that any of the elements he used were new, but he has his own and very effective way of weaving them into metaphorical patterns. Shakespeare using his bird lore, takes us along with him in the various realms of magic, nature and falconry.
Tradition, superstition, and personal response to the beauty of nature enables him to create an atmosphere that places the audience in the mood to react at the fundamental questions of life. Moreover it seems that bird images are at the core of many image clusters that spread into other fields, thus carrying an even more powerful meaning.