By Gael Bissell

Have you ever heard a deep rolling frog-like call “pahwawaa… pahwawaa,” or hoarse, raven-like repeated croaks or gacks coming from water birds? These are the rare and odd sounds of the breeding male and female Hooded Merganser (Lophodytes cucullatus), a common yet shy woodland duck of North America. In Georgia, folks call this species the “frog-duck” because of the male’s repeated call that sounds much like the local pickerel frog.

Hooded Mergansers are the smallest member of the North American merganser family (there is a smaller species in Europe known as the Smew). They are closely related to Goldeneyes, Buffleheads, and their larger cousins, the Common and Red-breasted Mergansers. Hooded Mergansers have small, short, but sharp serrated bills that they use to catch and hold small fish, aquatic insects, and their favorite, crayfish. They require clear water for foraging and their eyes have an unusual refractive property that the bird can change under water to help them detect prey. The most unique characteristic of the Hooded Merganser is their distinctive fan-shaped, collapsible crest that can make their heads look oversized and oblong in comparison to their small bodies.

Hooded mergansers winter along the east and west coasts and on large freshwater lakes that don’t tend to freeze in winter. They are less common in the southwest. Breeding takes place in eastern, northern, and some midwestern forested wetlands, both conifer and deciduous. As with Goldeneyes and Buffleheads, they nest in tree cavities, usually on small wooded ponds. The North American population of Hooded Mergansers is considered stable. Management focuses primarily on maintaining availability of nesting snags and trees across their breeding range.

Hooded mergansers migrate through Montana each spring and fall, but we are fortunate that this species nests here in the Flathead on our small forested ponds and lakes. When these birds arrive in small groups in April and May, the males have already transformed from brown nondescript small diving ducks, looking much like the females and juveniles of this species, to magnificent colorful showy birds with impressive, shiny crowns with big white patches. Males typically display to females and other males by expanding their crest and jerking their head back across their back and croaking (as described above). Male Hooded Mergansers also sport black and white striping on their backs, a white chest with two black spurs, and bright cinnamon colored flanks. The striking breeding plumage of the Hooded Merganser, like the colorful male Harlequin duck, is a photographer’s dream.
Females typically court the males by bobbing their tawny reddish heads and eliciting a hoarse gack described above. Females are overall dark gray and brown, cryptic colors important for nesting and raising young. In flight, these small waterfowl have rapid but shallow wing beats that elicit a high distinctive whirring sound. Hooded mergansers can be confused with Buffleheads, who also have white patches on their heads and are similar in size. However, Hooded Mergansers have darker bodies in comparison to the white body of the Bufflehead.

After breeding takes place, male Hooded Mergansers leave the area while the females nest in tree cavities or in Wood Duck houses. The openings are usually between 3-5 inches. Like Wood Ducks, Goldeneyes, and Buffleheads, Hooded Mergansers often lay their eggs in other females’ nests. This “brood parasitism” is different from that of the Brown-headed Cowbird, because these species will only lay eggs in nests of their own species. Female clutches can range from 13 up to 44 eggs as a result of this brood parasitism. The eggs are white but spherical and thick-shelled. The young typically leave their nest cavities within 24 hours of hatching. After these fluffy young drift down from their nests, they may need to walk up to a ½ mile or more with their mother to reach water.

Next spring when you are out bird watching on our wetlands, maybe you will hear the Hooded Mergansers croak like a frog or cack like a crow! Then you can say you’ve heard the only frog-duck in Montana!

By Gael Bissell