Hooded Merganser Life History

Habitat

Habitat Lakes and PondsHooded Mergansers breed in forested wetlands throughout the eastern half of North America and the Pacific Northwest, and may also nest in treeless wetlands where people have put up nest boxes. They are most common in forests around the Great Lakes. Their habitat ranges from spruce-fir forest in the Northwest to pine-hardwood forest and cottonwood-elder riparian forest in the Midwest, to oak-cypress-tupelo forest in the Southeast. Families of newly hatched ducklings forage in shallow water such as marshes, small lakes, ponds, beaver wetlands, swamps, and forested rivers—and rest on exposed rocks, logs, or sandbars. They winter in these habitats as well as on shallow freshwater and brackish bays, estuaries, and tidal creeks, where they often concentrate along the edge of ice. During migration they stop in a wider range of habitats, including open waters of rivers and lakes, brackish coastal bays, tidal creeks, and seasonally flooded forest.Back to top

Food

Food FishHooded Mergansers eat small fish, aquatic insects, crustaceans (especially crayfish), amphibians, vegetation, and mollusks—their diet is broader than in other mergansers, which eat fish almost exclusively. Hooded Mergansers dive in clear, shallow forest ponds, rivers, and streams and locate prey by sight, with eyes that are specially adapted to seeing underwater. They propel themselves with their feet and use their slender, serrated bills to grasp their prey. Ducklings can dive for food right after leaving the nest, at one day old, though their dives are short and shallow during their first week. They also feed by swimming with just their heads underwater.Back to top

Nesting

Nest Placement

Nest CavityThe female chooses the nest site, and may start scouting for next year’s tree cavity at the end of each breeding season. Nest cavities can be in live or dead trees and are usually close to water. Cavities are typically 10–50 feet off the ground, up to about 90 feet. Hooded Mergansers nest readily in boxes, preferring those with wood shavings or nest material from previous uses. They prefer cavities with 3–5 inch openings.

Nest Description

The female makes a shallow bowl in the material already present in the cavity, gradually adding down from her belly after she starts laying eggs.

Nesting Facts
Clutch Size:5-13 eggs
Number of Broods:1 brood
Egg Length:1.7-2.4 in (4.3-6.2 cm)
Egg Width:1.5-2.1 in (3.9-5.4 cm)
Incubation Period:26-41 days
Nestling Period:1 day
Egg Description:White, nearly spherical, and unusually thick shelled.
Condition at Hatching:Well-developed and downy, with brown backs, yellowish or reddish cheeks, white underparts, and grayish spots on wings and tail.
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Behavior

Behavior Surface DiveUnlike dabbling ducks, Hooded Mergansers swim low in the water. Their legs are far back on their bodies, which helps in diving but makes them awkward on land. They take flight by running across the water, flying with fast wingbeats and never gliding until they are about to land (by skidding to a stop on the water). Hooded Mergansers are usually in pairs or small groups of up to 40 birds. They court in groups of one or more females and several males. The males raise their crests, expanding the white patch, often while shaking their heads. Their most elaborate display is head-throwing, in which they jerk their heads backwards to touch their backs, with crests raised, while giving a froglike croak. Females court by bobbing their heads and giving a hoarse gack. Once a female begins incubating eggs her mate abandons her, and it’s not known if they reunite the following season. Incubating females may use a broken-wing display to protect eggs or nestlings from raccoons, mink, black rat snakes, black bears, pine martens, European Starlings, Northern Flickers, Red-headed Woodpeckers, and Red-bellied Woodpeckers. Back to top

Conservation

Conservation Low ConcernHooded Mergansers are fairly common and their populations are stable and possibly increased between 1966 and 2015, according to the North American Breeding Bird Survey. The species rates a 9 out of 20 on the Continental Concern Score. Hooded Merganser are not on the 2016 State of North America's Birds Watch List. These elegant little ducks are found in many parts of the U.S. in Canada throughout the year. In the early twentieth century, Hooded Mergansers were overhunted, but hunting pressure has declined markedly since then: hunters take about 95,000 Hooded Mergansers per year in the U.S., out of roughly 15 million ducks shot each year. Even before the twentieth century, humans cleared and altered many forests where Hooded Mergansers nest, in the process reducing or displacing breeding birds from regions of their original range. As with all birds that nest in tree holes, dead trees are important habitat components and landowners can improve Hooded Merganser habitat by leaving dead trees standing on their property. In addition, Hooded Mergansers take readily to nest boxes of the appropriate size, and programs in Missouri, Maine, Iowa, and Oregon have helped local populations increase.Back to top

Backyard Tips

If you live near the appropriate habitat for mergansers, consider putting up a nest box to attract a breeding pair. Make sure you put it up well before breeding season. Attach a guard to keep predators from raiding eggs and young. If your box does not have nest material from a previous resident, you can add wood shavings to entice a new resident. Find out more about nest boxes on our Attract Birds pages. You'll find plans for building a nest box of the appropriate size on our All About Birdhouses site.

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Credits

Dugger, Bruce D., Katie M. Dugger and Leigh H. Fredrickson. 2009. Hooded Merganser (Lophodytes cucullatus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

Lutmerding, J. A. and A. S. Love. Longevity records of North American birds. Version 2015.2. Patuxent Wildlife Research Center, Bird Banding Laboratory 2015.

Raftovich, R. V., K. A. Wilkins, S. S. Williams and H. L. Spriggs. 2012a. Migratory bird hunting activity and harvest during the 2010 and 2011 hunting seasons. Laurel: US Fish and Wildlife Service.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski, Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley guide to birds, second edition. Alfred A. Knopf, New York, USA.

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