Common Merganser (Mergus Merganser) Skye Christopher G

Common Merganser (Mergus merganser) Skye Christopher G. Haas

Rogers City, MI © Willie McHale

One of the more familiar sights to canoeists in (Click to view comparison of Atlas I & II) the North Woods is that of Common Distribution Mergansers. Whether it is a female guiding her Common Mergansers have been abundant in brood across a shallow bay, or the same pair of Michigan most likely since pre-settlement times. birds one keeps flushing all day, grunting as Barrows (1912) reported the species as a they fly up around the next bend in the river, common migrant breeding from Saginaw Bay they can be found on many of northern northward throughout the Upper Peninsula. Michigan’s waterways. Largest of Michigan’s MBBA I reported Common Mergansers as breeding waterfowl, this species is primarily a evenly distributed in the UP, but rather localized fish-eater, hunting its prey by sight or tactile in the LP, with concentrations in the Leelanau probing with its long, thin, serrated bill. Peninsula, the Beaver Islands, and north along Holarctic in distribution, it is known as the coast of Lake Michigan to the Mackinac Goosander in Eurasia. In North America, there Straits. There were also a few scattered interior are a variety of nick-names for this bird reports. One breeding record was confirmed in including sawbill, fish duck and sheldrake. A the SLP, at the tip of “the thumb,” in Huron river south of Whitefish Point in Chippewa County. County is named the Sheldrake. In this waterway, the Common Merganser is a regular At a time when so many bird species are in breeder and the likely inspiration for its name. decline, it is encouraging that the Common Its breeding range in North America stretches Merganser has increased, with birds found in from central Alaska eastward, below the tundra 12.5% of all Michigan townships in MBBA II, line to Newfoundland. Common Mergansers arc up from 9% in MBBA I. Also encouraging is a southward into the upper Midwest and the range expansion into the interior of the NLP, Northeast States. In the west, they are common southwards into the SLP. While the majority of residents in the Pacific Northwest States as well birds are still found in the UP and NLP, SLP as the Rocky Mountains south to northern New records increased from 0.6% to 3.5% of Mexico (Mallory and Metz 1999). townships, with breeding confirmed in four

townships. Particularly notable is confirmed nesting on the Wayne/Monroe County line, a breeding location unknown in historic times.

In MBBA I, Common Mergansers were well Nest cavities are usually near water, but can be distributed across the entire UP. However, in found over a half mile from water (Mallory and MBBA II the species was not found as often in Metz 1999). There is typically only one brood the eastern UP as in the western and central per season. Like the Red-breasted Merganser, portions of the peninsula. Whether this is an the Common Merganser is frequently a brood artifact of increased observer effort in the parasite to other merganser and duck species western UP rather than an actual decline in the (Mallory and Metz 1999). Young from multiple east is unknown. Possible declines in the eastern broods often form crèches. UP were noted by Padding (1991), and thought to possibly result from lake acidification, which MBBA II breeding confirmations were is linked to the decline of reproductive success primarily from sightings of females with their in Common Mergansers (McNicol et al. 1987). broods. At least two nests were found during the atlas period, one was in a Pileated Woodpecker Additionally, Dr. Laurence Binford has noted cavity in a large dead ash near Lake Michigan that identification of female Common and Red- (pers. obs.); the other was placed in a chimney- breasted Mergansers are often confused. He like cavity in a mature broken-off yellow birch suggests inland reports of Red-breasted snag. The female entered through the top of the Mergansers are actually records for Common tree and dropped down to the nest. This snag Mergansers (pers. comm.). Until this issue is was located about 6-7 m above the ground, and resolved, the status of these two species in about 6-8 m from a small rapidly flowing creek Michigan may be unknown in interior portions that was a tributary of the Peshekee River, less of the state. than half a mile from the main stem of the river (pers. obs.). Drainage systems are thought to be Breeding Biology of importance to Common Mergansers as One of Michigan’s earliest migrating waterfowl, females will move their broods downstream Common Mergansers follow ice-out north, with from small ponds and creeks to larger rivers, birds arriving in late February and early March, lakes or bays (Mallory and Metz 1999). and numbers peaking by late March in the south, to mid-April in the northern reaches of Abundance and Population Trends the state (McPeek 1994, Chartier et al. 2004). The North American population of Common Nest selection begins within a few weeks after a Mergansers is thought to be stable, although pair arrives at its territory. Nests are usually declines have been noted in Quebec and located in a tree cavity, typically created by a Newfoundland (Mallory and Metz 1999). BBS broken limb or large woodpecker excavation. routes reported a significant increase in the Occasionally nests are placed in a hole in a population from 1960-1994 (Sauer et al. 2008). riverbank, a cliff cave, or hollow log. Nests are Still this species is not well represented by BBS constructed from wood chips, some grasses, and data, and the USFWS combines estimates for all lined with down feathers plucked from the three merganser species, so making a solid female’s breast. Females are known to re-use a estimate of population numbers is not possible. nest site for multiple seasons (Mallory and Metz 1999). An average clutch is 10 eggs; incubation The Michigan population has experienced begins when the last egg is laid and lasts for 28- positive growth since MBBA I. Found in 64 25 days. Hatch dates range from early June to more townships in MBBA II, this species has late July. The young are precocial and the increased both its numbers and range in the female will continue to brood on the nest for 24 state. The species remains in a solid place as to 48 hours, before leading the young to water. both a breeding and wintering species, as well

© 2011 Kalamazoo Nature Center Common Merganser (Mergus merganser) Skye Christopher G. Haas as a common migrant. As recently as January Mallory, M. and K. Metz. 1999. Common 2009, 15,000 Common Mergansers were Merganser (Mergus merganser). In The observed at a wintering site on Saginaw Bay Birds of North America, No. 442 (A. Poole (Wuepper 2009), and can be found in large and F. Gill, eds.). The Birds of North numbers in the winter months over much of the America, Inc., Philadelphia, PA. southern portion of the state. McNicol, D.K., B.E. Bendell, and R.K. Ross. 1987. Studies of the effects of acidification Conservation Needs on aquatic wildlife in Canada: waterfowl As forests continue to mature and provide more and trophic relationships in small lakes in nest sites, Common Mergansers will likely northern Ontario. Canadian Wildlife Service continue to increase in Michigan, even around Occasional Paper No. 62. lakes with human residential and recreational McPeek, G.A., and R.J. Adams (eds.). 1994. development. For a species dependent on The Birds of Michigan. Indiana University aquatic ecosystems, maintaining water quality Press. Bloomington, IN. free of contaminants like dioxins, PCBs, and Padding, P.L. 1991. Common Merganser. In mercury is essential. The threat of metallic Brewer, R., G.A. McPeek, and R.J. Adams sulfide mining and the accompanying by- Jr. (eds.). 1991. The Atlas of Breeding Birds product of polluting acid mine drainage is an of Michigan. Michigan State University important concern, and the most recent potential Press. East Lansing, MI. hazard to our waterways and natural Sauer, J.R., J.E. Hines, and J. Fallon. 2008. communities. As long as there are suitable The North American Breeding Bird Survey, breeding sites available, and waters that remain Results and Analysis 1966-2007. Version both oligotrophic and free of chemical 5.15.2008. USGS Patuxent Wildlife pollutants, the Common Merganser should Research Center. Laurel, MD. continue to thrive in Michigan. Wuepper, J.T. 2008. Michigan Bird Survey: Winter 2007-2008. Michigan Birds and Natural History 15(3):100-123.

Literature Cited

Barrows, W.B. 1912. Michigan Bird Life. Special Bulletin. Michigan Agricultural College. Lansing, MI. Chartier, A.T., A.M. Byrne, and J.T. Wuepper. 2004. Status and Occurrence of Michigan Birds. In Chartier, A.T. and J. Ziarno. 2004. A Birder’s Guide to Michigan. American Birding Association, Inc. Colorado Springs, CO.