Duck eggs have yet to regain the glory they were accustomed to in past generations. Our forefathers and foremothers usually preferred them due to their larger size, loger shelf life, and higher nutritional content - they are richer in Omega-3 fatty acids. Their large albumen (the yellow part) makes them perfect for baking, making pastries and cakes fluffier. People who are allergic to chicken eggs can also often consume duck eggs without any adverse effects.
These ducks only eat what nature provides, and are used as a method of pest control in the rice fields they roam free in.