Birds of the Hackensack:

Ruddy Duck

By Ivan Kossak

If you were to see a Ruddy duck (Oxyura jamaicensis) in winter you might wonder how it gets its name.  A relatively small and chunky duck averaging 15 inches long (as compared to a Mallard’s 23 inches), the Ruddy duck is a rather drab, mottled brown across the back with a lighter mottling along the flanks and breast.  A white cheek and dark cap complete a somewhat uninspiring winter ensemble.  However, when spring approaches, the male Ruddy takes on its namesake bright, rusty look about the body while his bill turns bright blue.  The female (as is the case with most birds) retains much the same look in breeding season as in winter.  This allows her to be inconspicuous on the nest.  The Ruddy duck is the only member of a group of ducks known as stiff-tails to regularly occur in North America.  These ducks use their long, spiky tails as rudders as they dive in search of food.  The Ruddy duck’s diet is varied, consisting of marsh weeds, algae, crustaceans, insects and insect larvae.

Ruddy ducks are typically silent.  However, when males are displaying, they will make sounds that have been variously described as “bubbling” or “clucking” by beating his breast with his bill creating bubbles in the water.  Ruddy ducks typically nest in freshwater marshes, but have also been known to breed in brackish marshes as well.  Although fairly common in winter, Ruddies rarely nest in New Jersey.  In past years, Ruddy ducks bred regularly at Kearny Marsh and have been found nesting in recent years in Kingsland Creek in the Meadowlands.  DeKorte Park is one of the best places in New Jersey to see male Ruddy ducks in their bright, breeding plumage.

Ruddies have been known to be nest parasites, laying eggs in the nests of various other waterfowl.  And if this habit did not make them unwelcome enough in certain avian circles, the Ruddy duck is also the subject of substantial controversy in Europe.  Historically, the Ruddy duck was confined to North America.  However, in the 1940s they were introduced into Britain, rapidly colonizing much of Europe.  There has even been a concerted effort on the part of some Europeans to eradicate Ruddy ducks from European waters.  Ruddies have superior diving abilities compared to their European cousins and are seen as threatening the White-headed duck of Spain with extinction: a reminder that alien invasive species from our own area are just as great a threat to biodiversity in other areas of the world as their counterparts from other parts of the world are here.