Figure 2. Eye of Mallard drake. The combined weight of the two eyes 

 was 3.2 grams. The brain weighed 5.3 grams. 



entirely the same as ours, and science shows no pathway leading to a com- 

 mon understanding. 



The naturalist often assumes that bird and man look upon a landscape 

 that appears alike to both. Yet the world of man and bird cannot be the 

 same ; the bird's eye is structurally different, and its actions, experiences, and 

 visual perspectives are different. The eyes of the duck, goose, and swan 

 are placed on the sides of the head, and by such an arrangement the water- 

 fowl enjoys the advantage of horizon-wide vision. In a glance a duck may 

 see nearly twice as much of the landscape as a man can take in. Among 

 gregarious birds this wide visual field permits each individual to see its 

 companions on all sides, which is of special importance in flock movements. 

 An enemy does not easily approach unseen from behind. The broad view 

 of the landscape is an aid to orientation during travel; in an instant a duck 

 sees where it was a moment earlier, where it is now, and where it is going. 

 Man understands the value of such wide vision when he ventures into 

 strange country; it is characteristic of human beings to turn the head many 

 times in unfamiliar surroundings to examine the region just traversed. 



Though having this advantage of wide vision, the duck lacks the ability 

 possessed by man and the owl to perceive the landscape with stereoscopic 

 solidity; there cannot be the same awareness of depth and distance that is 

 inherent in our own binocular vision. To be sure, the eyes of the waterfowl 

 are set slightly forward so that there is some overlapping of the visual field, 

 hence a narrow binocular span ( Figure 3 ) . In feeding, a duck faces its food 



