
Photo: Bob Shettler
![]() Breeding evidence |
![]() Probability of observation |
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Click on plot to view table of mean abundance
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Number of squares
Long-term BBS trends
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Mean abundance (number of birds detected per 5 min. point count) and percentage of squares occupied by region Bird Conservation Regions [abund. plot]
[%squares plot]
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Characteristics and Range During spring break-up Red-breasted Mergansers perform their striking courting rituals as they appear on our rivers and along the ice-free edges of the larger lakes or the Hudson Bay coast. Several males may do neck-stretches and then dip their breasts down in the water to impress the females. These mergansers are somewhat smaller and more slender than Common Mergansers, with bushy crests and particularly long, thin red bills. Males have dark green heads, black-and-white upperparts, reddish-brown breasts, and greyish flanks. Females are largely grey with pale brown, crested heads. Identification is usually straightforward during the breeding season, but can be difficult at other times of the year. The Red-breasted Merganser breeds in boreal forest and tundra regions across the Northern Hemisphere, and is absent as a breeder only from the northernmost islands in the Canadian Arctic. The southern range limit is delineated by a line from the southern Yukon through the Great Lakes to the Maritimes. North American breeders winter along both coasts as far south as Mexico and on the Great Lakes (Craik et al. 2015).
Distribution, Abundance, and Habitat Red-breasted Mergansers were widely distributed through the northern two-thirds of the province, with southernmost occurrences east of Lake Winnipeg. The southern range limit is difficult to define but there were numerous probable breeding records as far south as Aikens Lake (51.2°N). Breeding was confirmed in adjacent Ontario south to the Vermilion Bay area around 49.8°N (Craik 2007). Red-breasted Mergansers were particularly prominent in the Arctic Plains & Mountains, with 100% of surveyed squares being occupied, making it the most widespread duck species there. Other heavily occupied areas include Wapusk National Park, the immediate vicinity of Churchill, several of the larger northern lakes, and the region around Lynn Lake. Overall occupancy declined southward to 27% in the Taiga Shield & Hudson Plains and 8% in the Boreal Softwood Shield (mostly northern portions), with marginal occurrence in the northern Boreal Taiga Plains. Jehl (2004) remarked how little solid evidence there was for breeding of this common species in the Churchill region. Indeed, breeding was confirmed in only nine atlas squares, which can be attributed to the species being a late breeder, after most fieldwork had been completed, and nests being difficult to find (Craik et al. 2015). In addition, reports of nesting concentrations on islands in Lake Winnipegosis may suggest a preference for island-nesting in our region (The Birds of Manitoba). Red-breasted Mergansers inhabit coastal bays, large lakes, and rivers, where they dive for small fish, their main prey. They show a preference for narrow channels, with islets or spits, projecting rocks, and grassy banks. Nests are usually located within 25 m of the water (Snow and Perrins 1998).
Trends, Conservation, and Recommendations Although it is legal to hunt mergansers, being fish-eaters they are not popular with hunters. They may, however, be shot by anglers and fish-farmers who accuse diving ducks of depleting fish stocks. Other threats include entanglement in fish nets, dam construction, deforestation and water pollution (BirdLife International 2018b). This species is poorly surveyed by the BBS and there are no significant trends for Manitoba or Canada. Research on the impact the species has on fish stocks and possible mitigation is recommended (BirdLife International 2018b).
Recommended citation: Koes, R. F. 2018. Red-breasted Merganser in Artuso, C., A. R. Couturier, K. D. De Smet, R. F. Koes, D. Lepage, J. McCracken, R. D. Mooi, and P. Taylor (eds.). The Atlas of the Breeding Birds of Manitoba, 2010-2014. Bird Studies Canada. Winnipeg, Manitoba http://www.birdatlas.mb.ca/accounts/speciesaccount.jsp?sp=RBME&lang=en [14 Feb 2025]
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