The Nesting Cycle of a Mallard

1. Courtship begins as early as November and continues through the winter, as males vie for females’ attention. Once a pair bond forms, the male and female will stay together through spring migration and during the nest-building and egg-laying stages, but the male departs when incubation begins.

2. The female alone builds a nest, on the ground, often far from water. She begins by roughly shaping a cup, arranging dried grasses and other material around the edge. The nest is often under a small shrub or grass tussock, sometimes using grasses to form a canopy. The site and the materials are carefully selected to camouflage the nest. When egg laying begins, the female still spends her time mostly with the male on a nearby pond or marsh, and only returns to the nest quickly and quietly about once a day to lay an egg. During most of this time the nest is unattended, and the female does little to defend it. After incubation begins, the female lines the nest with downy feathers plucked from her breast, and continues to add plant material and down to the nest throughout incubation.

3. Once the clutch is complete—containing, on average, ten eggs—the female begins to incubate, sitting on the eggs to warm them. She sits roughly twenty-three hours a day for about twenty-eight days, relying on camouflage, stealth, and luck to avoid detection. When incubation begins and the female is spending all of her time on the nest, the male’s responsibilities are over; he travels, often hundreds of miles, to a food-rich wetland, where he will stay for the summer.

4. The embryos all begin to develop inside the eggs when they are triggered by the warmth of incubation, so even though the eggs were laid over many days, they will all hatch within a few hours. The young start peeping and clicking inside the eggs about twenty-four hours before hatching, and this may help synchronize hatching. It is usually just a few hours from the time the first egg hatches until the entire family is ready to leave the nest together in search of good feeding areas.

5. Soon after hatching, the precocial chicks are mostly self-sufficient—able to walk, swim, and find their own food—and the female leads them away from the nest. The ducklings still depend on the adult female for warmth, and in colder climates require regular and nightly brooding for up to three weeks. The adult also provides critical vigilance and guidance to find good feeding areas and avoid predators. At this stage the ducklings are extremely vulnerable, and many are taken by predators: foxes, cats, hawks, gulls, crows, predatory fish such as largemouth bass and pike, snapping turtles, and even bullfrogs.

6. These young Mallards are about thirty days old, past the most vulnerable period but still weeks from flying. If they survive the gauntlet of predators and other hazards, the ducklings grow quickly, and when they are about sixty days old their wing feathers are fully developed and they are able to fly. Within a few months they will be essentially indistinguishable from older ducks, and are able to breed the following spring.

Survival

A nesting attempt has only a 15 percent chance of fledging any young. Once hatched, fewer than half of all ducklings survive the first two weeks, and only about a third of those survive the next six weeks to fledging. Incubation is the most dangerous phase for the adult female, as she spends almost all of her time sitting on the eggs, relying on camouflage to avoid predators. In several studies, up to 30 percent of adult females did not survive the four weeks of incubation.