New research from Birds Canada suggests the loon population in the Sudbury area is in a state of decline.
The data is contained in the report "The Legacy of Regional Industrial Activity: Is Loon Productivity Still Negatively Affected by Acid Rain?" It says the number of chicks being hatched yearly is lower than levels needed to maintain the population of Ontario's official bird.
Doug Tozer is director of Waterbirds and Wetlands at Birds Canada and co-author of the report. Drawing on data collected by volunteers in the Canadian Lakes Loon Survey, as well as research out of Wisconsin by researcher Rob Alvo, Tozer says the reasons for the decline in chicks are complicated.
"Long story short, those two data sets tell us that loons are producing far fewer chicks now than they did in the 1980s, about two-thirds the number of chicks now compared to then," Tozer said.
While adult populations have remained fairly steady, the bulk of the decline in chicks, he noticed, appears to be on more acidic lakes. Acid rain may be a contributing factor in raising the level of acidity in the water.
"Many of us thought we had solved the acid rain problems," Tozer said. "The emissions causing acid rain in Sudbury, had been cut by over 90 per cent, and we've done a good job on this and there's been lots of other signs of recovery."
The Canadian Wildlife Federation said although Ontario's official bird is not yet endangered, it's important to monitor the population.
"Shoreline developments continue to destroy nesting sites, and recreational activities can seriously disrupt both adults and chicks," the group says on its website. "Studies show that acid rain kills fish and other sources of food in lakes. So, in very acidic waters, loon chicks can starve."
The Nature Conservancy of Canada is also working with groups in other parts of Canada to protect loon habitats. Support for the Daphne Ogilvie Nature Reserve in B.C. and Abraham Lake in Nova Scotia have made it possible for the common loon to thrive in those locations.
So what gives?
"Unfortunately, we don't really know why that is. And that's the real mystery to be solved here," Tozer said.
A major conference on loon populations — the Northeastern Loon Study Working Group — came up with a hypothesis that Tozer said is "worth pursuing."
"We call it the acid mercury climate hypothesis," he said. "It works like this: There's a lot of mercury pollution out there in our lakes. It got there via fossil fuel emissions similar to the acid rain story.
"And we wonder if climate change ... is causing more and more of that mercury to get into food chains and make its way up to loons," said Tozer.
"As we know from lots of other research, when mercury gets into loons, they basically become bad parents, so to speak, and produce fewer chicks."
Despite the idea being floated around in research fields, Tozer said he still hopes mercury levels in the food chain aren't the big "smoking gun" behind the decline.
"If it is, we're in big trouble, because the acid in the mercury pollution is already out there and we can't get it back, and climate change is coming on like gangbusters.
"If we're right, loons won't do well at the end of this story,"