It’s a haunting sound synonymous with nightfall in the summer when an eerie calm spreads over glassy wetlands and cottage country lake surfaces across Canada.
But the trembling call of the common loon may be getting less common amid “substantial” North American declines, new research suggests — with Prairie and Atlantic populations suffering among the steepest losses.
“The most alarming thing is the extent of this decline,” said Matthew Fuirst, an ecologist with Birds Canada and one of the authors of a study published Thursday in the journal FACETS.
Canada is home to 94 per cent of the global common loon population, with an estimated 254,000 breeding couples (half a million individuals) that migrate north to make the next generation every spring.
The iconic species, a minted representation of which many Canadians routinely carry around in their pockets and purses, has faced threats before — from DDT to lead-based fishing tackle and mercury poisoning.
Former CBC reporter Howard Sommerville explores how DDT threatened Canadian loon eggs in this 1971 story from the CBC archives.
Now, the latest team of nearly two dozen collaborators from Canada and the U.S. cite climate change among a list of possible drivers for declines in loon chicks.
The study analyzes loon breeding data from 3,421 lakes the past three or so decades, half of which came from thousands of volunteer observations as part of the long-running citizen science effort, the Canadian Lakes Loon Survey.
There were “significant declines” in how many chicks were observed in that time in a majority of regions.
The researchers looked at nearly 46,000 breeding loon pairs documented on given lakes where eggs or newborn chicks were recorded, but where no six-week-old chicks were recorded. This was the benchmark they defined as loon chick productivity rate.
The study suggests a 40 per cent average drop in loon chick productivity in 10 of 12 study areas — including in B.C. and Ontario — over the past three or so decades.
Loon chick productivity sank even more starkly by 65 per cent across Alberta, Saskatchewan and Manitoba since the early 1990s. Meanwhile, Canada’s East Coast saw a 74 per cent reduction, according to researchers.
Quebec and the state of Maine were the only regions where chick productivity seemed more or less stable.
A common loon range map that appeared in the new FACETS journal article documenting loon declines in North America. (FACETS journal)
The team notes that while the loon chick population isn’t the only measure of how healthy or stable the population is, the long-term declines could “signal looming population declines” in the Prairies, Ontario, Atlantic Canada and in New York, Massachusetts and New Hampshire.
“This study design is very strong, and frankly, I consider the results that they are presenting here as being alarming,” said Nicola Koper, dean of the faculty of environment at University of Northern British Columbia, who was not part of the study.
Koper is co-author of Best Places to Bird in the Prairies and she was professor of conservation biology for nearly two decades at the University of Manitoba before moving on to UNBC.
She said the losses are dramatic on their own, but the fact they’ve happened over only three decades is startling.
“Some [readers] will be 30 years old, and so if they think back to whether they feel like they saw more loons with babies when they were younger, the chances are that that’s accurate, that they have themselves observed this change,” said Koper.
Climate change behind declines
The research team says the cause of the declines may vary depending on the region and that unknown is something they’re digging into now, said Fuirst.
But in all cases the losses are propelled by human activity.
“Human development and the development of shorelines, the environmental contaminants from climate change is another threat we’re experiencing, ” said Fuirst.
“As climate change influences weather patterns, the rain which is acidic makes the lake more acidic and thus reducing the amount of fish that are available for those loons.”
A common loon baby rests on its parent’s back in northwestern Ontario in July 2026. (Bryce Hoye/CBC)
Warmer temperatures associated with climate change have also brought more rain and storm events to loon habitat.
That could be destroying low-lying loon nests or drowning eggs during flood events when waters rise or are disturbed from violent wave action, said Koper.
Recent research from the U.S. Midwest has also made a connection between poor loon health and lower water clarity, which can arise from sediment running into lakes as a result of more frequent rains.
That makes it harder for loons to see and hunt their minnow, crayfish and other prey in the water, said Fuirst.
“It’s this domino effect of climate change basically down to water quality,” he said.
The study pooled together Alberta, Saskatchewan and Manitoba data into a single Prairie category because there wasn’t enough data to analyze loon numbers confidently in each of those regions on their own.
Koper said that may be more a reflection of how many of the many lakes in the Prairies are inaccessible to volunteers or otherwise unpopulated.
Fuirst said anglers should opt for lead-free, less-toxic tackle options, boaters should avoid disturbing loons and cottagers should ensure shorelines remain as natural as possible.
“The everyday person can take several actions to help steward lakes and the loons that they rely on,” he said.
Koper encourages people concerned by the findings to take action and get involved in citizen science projects like the Canadian Lakes Loon Survey and “advocate with … politicians about the importance of climate change and how it’s impacting our wildlife and our lives.”
