Introduction

The Hooded Merganser is the smallest of three North American mergansers and the only one restricted to this continent. Breeding throughout a wide area in the forested east and northwest where suitable nest cavities enhance adequate brood habitat, it is most common in the Great Lakes region. Favorite winter habitats include forested freshwater wetlands, brackish estuaries, and tidal creeks. Unlike other mergansers which feed almost exclusively on fish, Hooded Mergansers have a more diverse diet, diving and capturing small fish, aquatic insects, and crustaceans, particularly crayfish, with the aid of eyes well-adapted to underwater vision.

Because of this species’s secretive nature and dispersed population, little is known about its biology relative to other waterfowl species, despite its ready use of nest boxes. Taxonomically intermediate between goldeneyes (Bucephala sp.) and mergansers in the genus Mergus, the Hooded Merganser shares many courtship behaviors and vocalizations with these species. Female Hoodeds first breed at two years of age and lay unusual, almost spherically shaped eggs with disproportionately thick shells. Like other waterfowl that nest in holes, this species commonly lays its eggs in the nests of conspecifics and other cavity-nesting ducks.

There is no reliable information on population size or status of this duck, although historically populations suffered from deforestation, hunting, and perhaps pesticides. Current evidence suggests populations are stable and possibly increasing in some areas, even though large segments of the breeding population are vulnerable to the effects of acid rain.