This from the California Department of Fish and Wildlife monthly newsletter. Thought it was kind of interesting-Rita
Question: How well can ducks actually see? Can they see color? I know deer see different shades of gray, but what about ducks and geese? (David V.)
Answer: Waterfowl can control the curvature of both the lens and cornea (mammals, including humans, only control the lens). This is basically how birds can see extremely well while flying and while in the act of diving/feeding. In addition, their eyes act independently and they use one at a time to allow for depth-perception since nearly all waterfowl have monocular, not binocular, vision (they can’t stare forward at objects).
Another unique thing about waterfowl is they can see in almost all directions. A few ducks are the exception to the rule, but usually the eye placement allows them to view in many different directions at the same time. Secondly, waterfowl have a very high number of cones (which dictates color vision in humans) which allows them to see sharp images and have color vision where colors are more vivid than humans’ ability. The breadth of color vision is much wider than our own since UV light can be observed by waterfowl (UV light is absorbed by lenses in humans). This allows waterfowl to fly at night or feed in the dark or at low light conditions.