Thieving Ducks

     Every winter over the years in southeastern Pennsylvania and northeastern Maryland, I have regularly been seeing little groups of gadwall ducks and American wigeon ducks, often together and sometimes mixed with mallard ducks on sluggish creeks and ponds.  Gadwalls and wigeons form only small groups in this area in winter because the northeast coast of the United States is on the fringe of both their wintering grounds. 
     Gadwalls and wigeons have much in common, including being abundant, medium-sized ducks, nesting on the ground mostly around prairie ponds, grassy wetlands and marshes in western and northwestern North America, for the most part, and wintering in Mexico, the southern United States and up the Atlantic Coast to New England.
     Gadwalls and wigeons are both almost wholly vegetarians.  Like mallards, they "tip-up" in shallow water to use their shovel-like beaks to pull up aquatic vegetation from the bottoms of impoundments and sluggish creeks.  Those kinds of ducks are called dabblers.  And wintering gadwalls and wigeon feed on grain and the green shoots of grass and winter rye on land, like mallards, black ducks, Canada geese, snow geese and tundra swans do.  
     Adult gadwall drakes are elegant in a quiet way.  Their body feathering is mostly gray, but they have brown heads and black rears.  Female gadwalls resemble mallard hens, but are more petite.  And both genders have a white patch of feathers on each wing. 
     Gadwalls nest as a single species in northern Eurasia and North America.  Perhaps they have spread around the northern hemisphere in relatively recent years, which didn't give them enough time to become different species because of geographic isolation. 
     Drake American wigeons are handsome with pinkish-brown body plumage, black rears, and an iridescent green patch through each eye and down the back of the neck.  Male wigeons also have white crowns and foreheads, and a large white patch on each wing that is mostly visible when they fly.  Hens also have those white wing patches. 
     American wigeons only live in North America.  But they have a counterpart species that dwells solely in Eurasia.  Maybe these two species were once one, but over time, and isolation from each other, they developed into two kinds of ducks.
     One last interesting and entertaining characteristic wintering gadwalls and American wigeons have in common is their habit of congregating among American coots and diving ducks floating on the surface of water.  Coots and diving ducks dive under water to the bottoms of slow waterways and impoundments to dredge up aquatic plants.  These diving water birds must swim to the surface to swallow that vegetation, but some of them are robbed by waiting gadwalls and wigeons that see them surfacing and quickly take some of that food right from the coots' and divers' bills, obliging them to work harder to make a living.  But it is entertaining to see the thieving gadwalls and wigeons snatch food from the coots and diving ducks.      
     Gadwalls and American wigeons are adaptable, attractive and common kinds of ducks in North America.  They share several habits, including and most notably, their trait of stealing food from the bills of other water birds as soon as they surface from under water.  Most species of life on Earth are resilient, which allows them to live indefinitely on this planet of constant changes and new opportunities.