Details
Mergus merganser
The common merganser is a long-bodied fish-eating duck of northern rivers and lakes. Its saw-edged bill grips fish as it dives by day.
Map: Ecoregions 2017 © RESOLVE (CC BY 4.0) · Natural Earth (PD)
It uses clear rivers, lakes, reservoirs, and wooded waters in the Palearctic and Nearctic. Breeding sites include tree cavities and nest boxes near water.
Length is 58-72 cm and weight 900-2100 g. Males have a glossy green-black head and white body; females have a chestnut head and grey body, with a narrow red serrated bill.
Diurnal birds form loose groups outside the breeding season. They swim low on the surface, then dive in pursuit of prey.
A carnivore, it feeds mainly on fish, along with aquatic insects and crustaceans. Serrations on the bill help hold slippery prey.
Females lay eggs in tree holes, rock cavities, or nest boxes and lead ducklings to water after hatching. The young soon swim and catch small aquatic animals.
It is listed as Least Concern. Clean fish-rich waters and available nesting cavities are important habitat features.
