Common MerganserMergus merganserWhere and when to see them

The Common Merganser is a large, fish-eating duck found across northern North America, Europe, and Asia. It is well suited to life on rivers, using strong swimming and diving abilities to pursue prey underwater. Along the Columbia River system, it occurs on the main river, tributaries, and connected lakes and reservoirs. Its narrow bill has toothlike serrations that help hold slippery fish. In Europe, the species is also widely known as the Goosander.

Size

54–71 cm long; wingspan 86–97 cm.

Weight

Approximately 0.9–2.1 kg.

Lifespan

Can live more than 13 years in the wild.

Status

Least Concern (IUCN).

Common Mergansers often swim with their faces submerged while searching for fish before diving. They propel themselves underwater with their feet and may surface some distance from where they disappeared. Outside the breeding season, they frequently gather in flocks, especially where fish are abundant. Breeding pairs become more dispersed as females seek suitable nest cavities near water. Nests are usually in tree hollows, although rock cavities and nest boxes are also used. The female incubates the eggs and leads the ducklings to water soon after they hatch. Young feed themselves, while the female provides guidance and protection. Migratory movements vary by region, with many birds moving to ice-free waters for winter.

• Its serrated bill gives it the nickname "sawbill."
• Ducklings jump from the nest cavity before they can fly.
• Females sometimes lay eggs in another female's nest.
• Large groups of ducklings may form when broods mix.

Wildlife opportunities depend on the river reach, water levels and species. River-specific viewing months have not been confirmed; general species seasons are not a local sighting forecast.

Common Mergansers favor rivers and lakes where fish are accessible, often in clear water. During breeding, they are closely associated with wooded shorelines that provide large trees with nesting cavities. The Columbia River basin offers suitable habitat along forested tributaries, broad river reaches, and reservoirs. In winter, birds also use larger open waters and may occur in estuaries and sheltered coastal areas. Undisturbed shorelines, islands, and exposed rocks provide places to rest and preen.

Fish make up most of the adult diet. Prey varies with local availability and includes a range of small freshwater fish. Common Mergansers also take aquatic invertebrates and occasionally amphibians or other small animals. Newly hatched ducklings initially eat many aquatic insects before shifting increasingly toward fish.

Common name

Common Merganser

Scientific name

Mergus merganser

Animal group

Birds

Size

54–71 cm long; wingspan 86–97 cm.

Weight

Approximately 0.9–2.1 kg.

Lifespan

Can live more than 13 years in the wild.

Status

Least Concern (IUCN).

Identification

A breeding male has a dark green head, a red bill, a black back, and a mostly white body that may show a faint salmon tint. Females and immature birds have gray bodies, reddish-brown heads with shaggy crests, and a sharply defined white chin patch. Both sexes have a long, narrow bill with a hooked tip and red to orange-red legs. Compared with the Red-breasted Merganser, females usually show a cleaner boundary between the brown head and pale neck, while breeding males lack the other species' mottled reddish breast.