Last week while exploring in Boundary County I came across a handsome pair of ducks that I didn’t recognize. After taking a few pictures of them I consulted my Birds of Idaho field guide and learned they were Hooded Mergansers. I discovered that Hooded Mergansers are found from southeastern Alaska, central British Columbia and southwestern Alberta to Oregon, Washington, Idaho and northwestern Montana.
Male hooded mergansers have a large white crest surrounded by black. The top of the head, neck and back are all black, and the chest, breast and belly are white. Wavy black lines can be seen on the tawny sides and flanks. The rump and tail are dark brown. The long, narrow, serrated bill is black. The iris is bright yellow and the legs and feet are dull yellow.
The female hooded mergansers have a gray-brown head and neck with a reddish-brown crest. Gray pervades their neck, chest, sides and flanks, and brownish-black dominates their back, rump and tail. The upper bill is black-edged with orange and the lower bill is yellow. The legs and feet are greenish in color and the iris is brown.
Unlike 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 backward to touch their backs, with crests raised, while giving a froglike croak. Females court by bobbing their heads and giving a hoarse quack. Once a female begins incubating eggs her mate abandons her. Incubating females often use a broken-wing display to protect eggs or nestlings.
Hooded Mergansers eat small fish, aquatic insects, crustaceans (especially crayfish), amphibians and vegetation. 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.
The 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.
The female makes a shallow bowl in the material already present in the nest cavity, gradually adding down from her belly after she starts laying eggs. The clutch size is 5-13 eggs without markings and they only have one brood per year.
The white patch on the male’s cheeks is to scare off predators and to warn away rivals, which he raises when alarmed. The average lifespan of the Hooded Merganser is 11-12 years in the wild.
I hope to see them again in the spring after their ducklings hatch.
Enjoy the outdoors in Boundary County.