Common Merganser

Mergus merganser
Range Map

The Common Merganser winters over much of the USA, but is resident in the Pacific Northwest and Rocky Mountain zones. Their range is not limited to North America. Rather, they have a global presence, and breed in northern Europe and Asia from the Atlantic to the Pacific oceans.

Rather than building ground nests, the Common Merganser requires cavities in trees to make their nest. Old woodpecker holes can satisfy their needs for egg laying, though they may use recesses and small caves in rocks or holes in mud banks for nesting.

I have several fond memories of meetings with this species. Once, during my 2005 Alaskan adventure, I watched a momma merganser teaching her half-grown brood to catch small eels in the Lutak Inlet, just below the mouth of the Chilkoot River. The young birds weren’t quite ready for Primetime, but all their activity was a treat to watch.

Another indelible memory I carry came from an afternoon along the Madison River in Yellowstone National Park. I stopped on the roadside to enjoy a gathering of Bison with several calves (sometimes called Red Dogs or Little Reds). I noticed a commotion on the water and saw a small group of adult Common Mergansers chasing trout in the river. The river was only a foot or two deep, and I could see how remarkably fast these ducks swim. It seemed to me they swam as fast as the fish in the river. I understand these ducks like to forage in groups by surrounding their prey and give themselves a higher success rate.

Taxonomists recognise three subspecies of Common Merganser:

  • M. m. americanus breed from Alaska east to the Canadian Maritime provinces. They spend winter farther south to southwestern USA and northern Mexico.
  • M. m. merganser breeds from Iceland to Kamchatka, including central Europe, northern China and Japan. They spend winters on Atlantic coasts and from central Europe to Iran, also Korea, Japan and China.
  • M. m. orientalis breeds in central Asia from Afghanistan east through Tibet and the Himalayas to western China. They spend winter from the Indus Valley and Himalayan foothills to southeast China.

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