by Carl Strang
Today I share my dossier on one of our most familiar birds, the mallard duck. This is one case in which my initial entry in the 1980’s was large enough that it remains the bulk of the file.
Adult male mallard
Widespread, common marsh bird, also frequenting suburban ponds, lakes and streams. Singles and pairs occasionally appeared in western Alaska, but the mallard was not a common species there.
Adult female mallard and ducklings
Courtship begins in September in Illinois and Pennsylvania, as drakes come out of eclipse, but (at least in northeast Illinois) may not peak until January. The male has a large variety of courtship displays, generally preceded by preliminary shakings of the head from side to side, tail shaking, and lifting and shaking the entire front half of the body (the last seems to represent a higher intensity). The most common of the male’s displays is the Grunt Whistle, beginning with lifting the front half of the body (note similarity to the most intense form of the Preliminary Shake). While the body is lifted the neck is arched forward and down, and the tip of the bill is used to flick out an arch of water drops. As this happens the bird emits a high-pitched peeping sound. Frequently several males Grunt Whistle together, and in fact courtship displays generally occur when several males plus at least one female are close together on the water.
Mallard Preliminary Shake
Down-Up is another display, in which the male lowers the front of his body into the water while lifting the tail end. The bill points down as the bird dips, then it is pointed upward. This is an especially beautiful display when several males, facing one another, bow simultaneously.
In Head-Up-Tail-Up, the body is contracted while the neck stretches upward (bill kept level). This always ends with a bout of Nod-Swimming, with the bird swimming rapidly low in the water, neck stretched low and forward, pumping slightly as the bird swims.
Sometimes several courtship displays may be performed simultaneously. Here, the two males on the left are performing the Down-Up display, the one on the far right is performing a Grunt-Whistle, and the one just left of him appears to be in a Head-Up-Tail-Up.
Males and females can be seen together more and more in pairs as winter and spring pass. The female continues to test the drake with Inciting, a display in which she mechanically waves her bill back and forth to point toward another nearby mallard. The male commonly responds by chasing that bird away. Rarely and inexplicably, drakes perform the Inciting motion.
Female mallard performing the Inciting display.
Copulation begins usually with the male performing an exaggerated vertical pumping of his neck with the bill held parallel to the water surface. If the female is receptive, she identically pumps her head. After the two have done this together a few seconds, the male swims behind her, then climbs onto her back. Head pumpings cease as the male achieves a grip on the back of the hen’s upper neck with his bill. She sinks low in the water, he swings his tail around to the side of hers as she pulls hers out of the way, and genital contact is made. Post-copulatory displays are bathing motions by the female and Nod-Swimming by the drake.
The presence of a male with the brood may be a sign that these birds have some domestic mallard in their ancestry.
Pairs appear on land in mid-spring, usually with the female leading the search for a nest site. The nest is built of grasses mixed with down. Generally one pale blue-green egg is laid per day until the 8-13 egg clutch is complete, then the female incubates the eggs and usually raises the young alone. After the ducklings hatch and dry, they follow the hen on an early-morning trek to water, sometimes a mile or more distant. On 8JE86 I saw a drake with a female and large downy ducklings on land, an exception to the rule that males stay away from broods which females raise alone. This was in DuPage County, where ducks are unusually dense because of artificial feeding, and there is considerable domestic mallard in the gene pool. Single failed-nest females sometimes become injured from rape attacks by multiple males. Possibly this male was insuring against the loss of the brood. Young ducklings are distinguished from those of wood ducks by a dark line between the eye and bill, and a darker yellow base color.
Female incubating a nest
General vocalizations include peeps of ducklings, loud call of adult females (series of quacks, first one long and successive ones shorter), and a chuckling continuous call occasionally performed by flocked birds on the water. Mallards winter in DuPage County. Occasional large flocks spent the early winter in the center of Lake Maxinkuckee in Indiana, flying out to harvested corn fields to feed. Mallards feed on the surface of water or tip up to take food from the bottom.
Occasionally an incubating duck leaves the nest for a time. When she does so, she covers it with the mixture of down and grass for camouflage.
Once a hen had a nest in my fenced-in yard in Warrenville, but abandoned before incubation was complete.
Mallard eggs are a pale green in color.
19AP99. Mallard nest at Willowbrook under a columbine, against east wall of garage/bird nursery building (was gone, abandoned or destroyed, by 30AP).
14MY99. Mallard female with 7 young ducklings in stream at Willowbrook.
17SE99. Some mallards at Willowbrook appear to be in eclipse plumage, or perhaps young are molting into their first adult plumage.
29OC00. McKee Marsh. A green-headed male with a group of black ducks has a very dark gray body, no curly tail feathers, and no white neck band, apparently a hybrid.
4MY09. Mallard male with female and duckling chased away another male that showed interest in the female.
Mallard ducklings approaching maturity
23NO09. Mayslake. A dozen mallards were diving for food in May’s Lake, coming up with aquatic vegetation after being completely under water 3-5 seconds. A pied-billed grebe was with them, also diving.