North American Black Duck (Anas rubripes)
by Wanda Gorsuch

Common Names: black mallard, red leg

Black duck populations have been in decline since the 1950’s.  Recent research suggests that mallard populations have been expanding eastward in to black duck breeding habitat.  Mallards interbreed with black ducks as well as competing with them for resources such as food and nesting sites.

Identification

A large dabbling duck, males weighing an average of 1,317 g are slightly larger than females who average 1,090 g. 

Drakes have a blackish-brown body with contrasting pale-grayish, finely streaked head and neck.  They sport a dark crown, nape and an eye stripe.  Speculum is an iridescent bluish-purple bordered with a narrow band of white.

Hens are similar, but paler overall.  They have V shaped markings on their breast in contrast to the U on the males.

It can be easy to confuse black ducks with mallards or black duck X mallard hybrids.  Male black ducks can be distinguished from female mallards by their olive bill (orange and black in mallards).  It is harder to distinguish between male black ducks and male mallards in eclipse plumage as both of them have olive bills.  Male mallards have a distinct cinnamon wash on their breast which is lacking in male black ducks.

Distribution

In breeding season black ducks are found throughout Canada’s eastern provinces, south through the northeastern United States down to the upper Mississippi River.  Winter finds them generally on the Atlantic coast from the Maritime Provinces south to Florida.

Habitat

Freshwater wetlands, brooks lined with speckled alder, lakes, ponds, bogs and salt marshes throughout mixed hardwood and boreal forests are some habitats where black ducks are found in breeding season.  Though black ducks favor freshwater habitat during breeding season, they generally winter in salt water habitats such as salt marshes and tidal areas.

Food

Black ducks eat a wide variety of foods including seeds, roots, tubers, stems and leaves of moist soil and aquatic plants.  Aquatic insects, crustaceans, mollusks and fish, especially in marine areas, also make up part of their diet.  They may also eat grain when available. 

Reproduction

Pairs are formed in the fall and winter, before black ducks arrive at the breeding grounds. 

The female starts building a nest by scraping a bowl in the ground.  Materials such as grass, twigs, leaves, stems, and conifer needles in the vicinity are added to make a nest. 

One egg a day is laid, usually just after sunset.  A hen will lay an average of 9 eggs in total.  Once the last egg is laid the hen will start incubating continuously.  Only females incubate the eggs.  Eggs hatch about 25-26 days after the last egg is laid. 

Ducklings start peeping 30 hours before they hatch.  Hatching takes 3-4 hours.  Once their down is dry, ducklings are led from the nest by the female to a suitable body of water.  They do not return to the nest.

Conservation and Management

The continental population of black ducks is less than half of its historical size.  It is not considered Endangered, but is below the goals set by the North American Waterfowl Management Plan (NAWMP).  Strict harvest regulations have been in place in both Canada and the United States since the mid 1980’s which has helped slow the decline.  In 1986 the Black Duck Joint Venture was formed through NAWMP to help black duck populations.

Sources of Information

Bellrose, F.C.  1976.  Ducks, geese and swans of North America, 2^nd edition. Stackpole Books, Pennsylvania.

Johnsgard, P.A.  1978.  Ducks, geese, and swans of the world. University of Nebraska Press, Nebraska.

Longcore, J.R., D.G. Mcauley, G.R. Hepp and J.M. Rhymer.  2000.  American black duck (Anas rubripes). In The Birds of North America, No. 481 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.