Common Merganser
(Mergus merganser)

Overview

Summary

© Jukka Jantunen (flickr.com/photos/jukka_jantunen)
For additional photos and vocalizations, visit Dendroica. (Link opens in a new window.)

The Common Merganser is the largest and the most abundant species of the three merganser species found in Canada. It breeds across Canada, wherever trees are large enough to support suitable nesting cavities. The national population is thought to have remained relatively stable since the 1970s. However the population size and trends for mergansers are not reliably known because aerial surveys of breeding birds do not differentiate among the three different species of merganser. This species has been identified as a priority for conservation and/or stewardship in one or more Bird Conservation Region Strategies in Canada.

Designations

Population status

Population estimate

Distribution maps

• BirdLife International / NatureServe

Migration strategy, occurrence

Responsibility for conservation of world population

Conservation and management

The most important factor limiting population size and breeding distribution of the Common Merganser is probably the availability of suitable nesting cavities; while fish availability can also play a role locally. In recently or historically logged regions, forestry practices may have reduced availability of cavities for nesting. Lake acidification and associated declines in fish populations might have also reduced food availability and overall habitat quality in some regions (Pearce et al. 2015). Due to their trophic level, Common Mergansers are vulnerable to contaminants (e.g. mercury, lead), and may be useful as a bioindicator for fish-bearing streams and lakes (Sea Duck Joint Venture Management Board 2008). Overall, mergansers are not heavily harvested by hunters. In Canada, they are hunted predominantly in the Atlantic Provinces, Quebec and Ontario.

Bird conservation region strategies

Environment and Climate Change Canada and partners have developed Bird Conservation Region Strategies in each of Canada’s Bird Conservation Regions (BCRs). In these strategies, selected species are identified as priorities for one or more of the following reasons:

• conservation concerns (i.e., species vulnerable due to population size, distribution, population trend, abundance, or threats)
• stewardship responsibilities (i.e., species that typify the regional avifauna or have a large proportion of their range or population in the sub-region)
• management concerns (i.e., species that require ongoing management because of their socio-economic importance as game species, or because of their impacts on other species or habitats)
• other concerns (i.e., species deemed a priority by regional experts for other reasons than those listed above or because they are listed as species at risk or concern at the provincial level)

Select any of the sub-regions below to view the BCR strategy for additional details.

References

• Canadian Wildlife Service Waterfowl Committee. 2014. Population Status of Migratory Game Birds in Canada: November 2014. CWS Migratory Birds Regulatory Report Number 44. Canadian Wildlife Service Waterfowl Committee. 2014. Population Status of Migratory Game Birds in Canada: November 2014. CWS Migratory Birds Regulatory Report Number 44. (Link)
• Pearce, J., M. Mallory and K. Metz. 2015. Common Merganser (Mergus merganser), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York. Pearce, J., M. Mallory and K. Metz. 2015. Common Merganser (Mergus merganser), The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York. (Link)
• Sea Duck Joint Venture Management Board. 2008. Sea Duck Joint Venture Strategic Plan 2008–2012. USFWS, Anchorage and Canadian Wildlife Service, Sackville. 95 pp. Sea Duck Joint Venture Management Board. 2008. Sea Duck Joint Venture Strategic Plan 2008–2012. USFWS, Anchorage and Canadian Wildlife Service, Sackville. 95 pp. (Link)