by Theresa Ciraolo
The Common Merganser, as the name implies, is a common bird. However, their status as common is not a downfall for these adaptive, beautiful animals. In fact, since they are frequently spotted in the F
lathead V alley, the Common Merganser was the first bird I encountered in Glacier National Park. I had just moved here in late April, winter still firmly in place in the valley, and I decided my first introduction to this environment would be the Rocky Point trail on the shores of Lake McDonald. So many people travel to this area to spot the large charismatic animals like grizzly bears or a large moose grazing in the brush. This was my first time in Montana and, unsurprisingly, I was just like the hoard of tourists eager for a glimpse of the large, exciting animals. However, after walking to the beach near Fish Creek Campground, touching the glacial water of Lake McDonald for the first time, I looked up just in time to see a beautiful bird emerge out from beneath the water approximately two hundred feet away. Trying to get a good look at it before it dove and disappeared under the water again, I found that each dive brought it a little bit closer. I spotted the bird’s vibrant rusted red head, with what looked like a mohawk of feathers on top, and grayish body and quickly pulled up the Merlin Bird ID app. I finally identified that bird as a female Common Merganser, the first animal I would see in Glacier National Park and the first bird to mark my summer of birding and exploring the Northern Rockies.
Common Mergansers (Mergus merganser) are part of the Anatidae family which consist of ducks, geese, and swans. They are found throughout the majority of Montana and throughout most of the United States in northern habitats. In fact, the Flathead Valley is an ideal place to spot these ducks due to the valley being a year-round habitat for them. These birds are found on the coast and in the interior of North America. In fact, the migration patterns of Common Mergansers are different for coastal vs. interior birds. Interior birds tend to migrate farther, apart from populations that stay in their habitat yearlong like the birds we find here in the Flathead Valley.
Are you intrigued enough by the Common Merganser to go out and try to spot one? If you are, seek out where they reside in freshwater rivers or lakes, like Lake McDonald, in your area. These birds’ nest in large tree cavities in mature forests nestled near a water source. The females can lay an average of ten eggs that they incubate without the help of the male. Hatchlings are out of the nest only a day after birth and are capable of flight about two months after hatching. The females tend to them for several weeks, however, the young feed themselves. Therefore, the young birds may survive even if they are abandoned early on in life. The Common Merganser is a sexually dimorphic bird. This means there is a systematic difference in form between the male and female. This can include size, color, markings or even behaviors. For the Common Merganser, the males of this species tend to be bigger in size and weight. The male ducks can be approximately 60 to 70 cm in length and approximately 3.7 lbs. However, the female ducks are slightly smaller at approximately 54 to 68 cm in length and approximately 2.7 lbs. It is sometimes hard for the untrained eye to tell the difference between birds on the water based on size, but the Common Merganser makes it quite easy for experienced and beginner bird watchers alike because of the drastic differences in female color and markings compared to the males. Males have striking deep green heads, paper-white underbellies plus sides and black backs; females, on the other hand, have gray bodies, a white chest, and a rusted cinnamon-colored head with feathery crests at the top. Common Mergansers have narrow, serrated red beaks with hooked tips that they use for skilled fish catching. In fact, their bills are a unique adaptation that is different from the flat, rounded bills of many other species of ducks which allows them to specialize in catching and eating fish. Other than a wide variety of fish, the Common Merganser can also be seen feeding on mussels, shrimp, salamanders, and sometimes even small mammals.
s populations are steady at an estimated global breeding population of 1.9 million individuals. However, climate change has already affected their habitat range, with increased temperatures in the spring endangering young in the nest and increased recurrence of fire preventing their habitats from recovering. The Common Merganser is an important species at the top of the aquatic food chain; therefore, we can use their population’s health as an indicator to measure our surrounding environment’s health and learn from our common neighbor.