Hooded Merganser

Appearance

The hooded merganser is a sexually dimorphic species. The female has a brown body, with a white underside and a light brown crest extending from the back of the head. The male has a similar appearance during nonbreeding season. During breeding season, however, the male's plumage changes color: The head, back and neck become black, with white stripes near the chest and tail, and the bird develops a white crest on the back of the head that can be extended to attract mates.

First-winter birds differ from adult females, in having a grey-brown neck and upper parts, and narrower white tertial-edges than adults; all females are dark-eyed whereas in first-winter males, a pale eye is acquired during the winter.

Distribution

Hooded Mergansers have two year-round ranges. One is located in the Eastern United States. It goes from the Gulf Coast to the around the Canadian border and from the Atlantic Coast to around the Mississippi. A smaller year-round range is located in Washington, southern British Columbia, and northern Idaho. The species also breeds from Missouri to southern Canada and from Nova Scotia to eastern North Dakota and Saskatchewan.

Status

Population declines in the past have been linked with large scale deforestation. Because these waterfowl are cavity nesters, they require more mature trees in which suitable nests are likely to be found. Proper timber management today is thought to be increasing available habitat. When managing wooded habitat for cavity nesting ducks, sufficient mature trees should a priority consideration.

As mentioned previously, these ducks do benefit from artificial nest boxes. Nest boxes should be implemented if natural habitat is lacking.

Acid rain and other types of pollution such as run off maybe affecting Hooded Mergansers as well due their high reliance on aquatic forage. More research is necessary to determine if these ducks are being negatively affected by these factors.

Habitat

Most often found in areas with ample amounts of emergent vegetation. Known to occupy smaller bodies of water such as ponds and small estuarine environments. Also found in larger wetlands, impoundments, flooded timber, and rivers. Hooded mergansers prefer fresh water but will inhabit brackish water sites.

Reproduction

Males and females of this species form monogamous pairs and remain together until the female successfully lays her eggs. Breeding occurs anytime between the end of February through June but is dependent upon region. At this time the male leaves the female to incubate and care for their brood. Females will actively seek out cavities in dead trees or artificial nest boxes like those frequently occupied by wood ducks. Cavity selection is generally a site that is 4-15 feet off the ground.

Females will lay a clutch size of 7-15 eggs and begin incubation when the last egg has been laid, indicating a synchronous hatching event. During incubation, the female may lose anywhere from 8% to 16% if her body weight. This will result in all hatchlings being the same size and easier parental care for the female.

Hooded merganser hatchlings are altricial like most waterfowl and will usually leave the nest within 24 hours after they hatch. Once they leave, the young will be fully capable of diving and foraging on their own.

Food

The diet of this small diving duck is typically aquatic insects, fish and aquatic invertebrates. Most studies conducted on their diet show that 44-81% is fish, 22-50% crayfish, and 13-20% aquatic insects. Prey is typically found by sight while diving underwater.