Diving for dinner: the common merganser

Kayaking on a nearby lake during the first week of November, I spotted an unusual shape floating on the water’s surface. It turned out to be a dead female merganser, floating dorsal side up. When I turned the bird over to check for any obvious cause for her demise, I found a four-inch fishing plug ensnared in her bill and one foot. This unfortunate duck likely spotted the lure underwater, either as it was being retrieved, or on the lake bottom. The merganser mistook the lure for a small fish and grabbed it with her bill, getting her bill hooked. Once on the surface, she used her foot in an effort to free the lure, only to catch her foot on another treble hook, and drowned.

The common merganser (Mergus merganser) is a diving duck that can be found in the area year round. They are a migrating species, and some lakes in the area now have some visiting birds from the north. Mergansers can be spotted along the river all year long and breed here.

The merganser is primarily a fish eater. It will take small fish while diving, then surface and swallow its prey whole. If the fish is somewhat larger, the merganser can stretch the side of its mouth to accommodate the prey. The bill is equipped with small teeth to grab fish and other small live prey. When they dive for dinner, they can stay underwater for up to a minute, but 20 to 30 seconds is their usual dive time.