The Ubiquitous Mallard—A Cautionary Tale, by Tina Mitchell

Mallard Batiquitos 

Hardly in need of an introduction, the Mallard is our most familiar, common, and widespread duck, residing almost everywhere in North America at some point during the year.  Tamed since antiquity, Mallards are the progenitors of all races of domestic ducks except the Muscovy.  In fact, while hybridization is common among many waterfowl species, Mallard seems to be particularly promiscuous, hybridizing easily where its range overlaps with American Black Duck, Mottled Duck, American Wigeon, Northern Pintail, Gadwall—as well as city park pond favorites such as the large domestic Long Island and Muscovy Ducks. 

Large, long-billed, and classically shaped, the Mallard is the archetypal duck.  The adult male’s pale body supports his distinctive iridescent green head, bright yellow bill, narrow white neck ring, and plum-colored breast.  (His short, curled tail feathers are an adorable and unique affectation.)  The female is streaky brown overall with a slightly paler head; females can be easily confused with several other similarly drab-looking species of female ducks.  The female’s distinguishing traits include an impudently large brownish olive to orange bill with dark blotches, white tail feathers, and a whitish undertail that contrasts with her otherwise brown body.  In flight, both sexes show a white-bordered, iridescent blue speculum on the wing.

The species’ scientific name (Anas platyrhynchos) reflects its prominent, broad bill—from Latin for “duck” (anas) and Greek for “broad” (platus) and “snout or beak” (rugkhos).  The common name derives from the old French maslard, meaning a wild drake.  And speaking of drakes, a male duck is called a drake; a female, ahen; and the young (no surprise here), ducklings.

We generally classify ducks in two ways, based how they forage in the water.  Dabbling ducks, such as the Mallard, feed on the surface or “tip up,” with their tails in the air and their heads underwater, to grab vegetation below the surface.  Diving ducks such as mergansers and grebes dive and chase food underwater—typically fish and crustaceans—.  During breeding season, Mallards eat mostly animal foods, including insects such as midge larvae, caddisfly larvae, aquatic invertebrates such as snails and freshwater shrimp, and terrestrial worms. The rest of the year, their diet predominantly features aquatic vegetation, seeds from moist-soil plants and cereal crops (e.g., corn, rice, wheat), and acorns. Notice what’s not on that list.  Bread.  Mallards love bread; at ponds they frequent, people often gladly indulge them by tossing bread onto the water.  Mallards can’t really extract needed nutrition from bread; but they fill up on it and then don’t eat anything else that actually does have the nutrition they need.  So please, don’t feed Mallards bread of any kind.  Instead, if the pond you’re visiting allows it, you can offer them lettuce and kale—even the limp, brown-edged leaves that humans don’t like—ripped into small pieces (ducks don’t have teeth!), bird seed, or frozen corn or peas.(Please note that feeding any wildlife is not allowed at the Lagoon.)

Mallards winter as far north as open water allows, retreating to fast-moving streams and coastal bays during freeze-ups.  Pairs generally form in the winter, so migratory Mallards arrive on their breeding grounds ready to breed.  (In San Diego County, where Mallards likely don’t migrate, they still form pairs in the winter months.)  The world  of breeding and nesting waterfowl can be wild and wooly. Conspecific nest parasitism occurs commonly (up to 21% of nests); Redheads, Canvasbacks, Cinnamon Teal, and Northern Pintails also parasitize Mallard nests. Mallards likely start laying early; the first week of March is not rare. Hens lay 1−13 eggs (typically, 8−9); the incubation period is 23−30 days.  Ducklings are precocial, hatching fully covered with down. They usually leave the nest as a group on the morning after hatching, if the weather is decent—13−16 hours after hatching—with the hen leading the way.  Only the hen attends the ducklings. They begin pecking at dark spots and small objects as soon as they leave the nest.  In the first month, ducklings eat mostly animal foods (e.g., invertebrates, small crustaceans, mollusks, fish eggs), catching these morsels on the water’s surface or on land.  By the second month, they feed below the surface—dabbling and tipping up. The female may lead them to different wetlands up to a dozen times a day or travel distances up to ½ mile, emphasizing the importance to Mallards of wetland distribution on their landscapes.  The female watches over the ducklings until they can fly at 52–70 days.

Mallard drakes undergo a rapid, dramatic molt in late summer. During this brief period, they are extremely vulnerable to predators because they can’t fly without flight feathers.  They seem to have evolved to do what the females do for most of the year—merge safely into the wetlands background with drab, streaky brown feathers.  But even in this eclipse plumage, as it’s called, you can differentiate males from females by their bills.  Year-round, females’ bills show blackish splotches while males’ bills show no splotches. So if you spot a flock (or a raft, a term for a group on the water) of drab-looking Mallards in late summer, take a moment to check their bills.  You may find an “imposter” drake or two mingling among the ladies.



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