Wildlife advocates say the population has been dropping by 1.4 percent per pair of loons a year over the last 30 years
Loons are a staple on almost every northern lake in Canada. Their unique cries are recognizable by most lake-goers, and the birds are something of a Canadian icon, alongside the beaver and polar bear.
But the bird’s reduced productivity is causing concern.
In a 40-year update of the common loon, released by Birds Canada, it’s stated that loon productivity, meaning the number of young that loons produce, has declined in the last three decades by 1.4 percent per pair of loons every year.
The report said that in the early 1990s, 0.7 offspring were produced per pair every year on average. Now, that number is down to 0.55, and if it drops below 0.48, the population of loons could start to decrease.
“(Loons) live 20 to 30 years often in the wild,” said Doug Tozer, director of water birds and wetlands for Birds Canada. “So you potentially have this big lag time between low chick production and when you actually see your adults nesting out there.”
Tozer said the reason for the lower reproductive rate is unclear.
“The one thing that we’ve come up with, we have concocted this hypothesis that we call the acid mercury climate hypothesis…. When you look at the data at whatever angle, the loons definitely produce fewer chicks on more acidic lakes, and the declines are definitely steeper on the acidic lakes too. It’s not only that they produce fewer, but the declines over time are steeper too.”
Tozer said Birds Canada plans to carry out experiments to see if this hypothesis is the cause, or at least one possible cause.
“We were forming some collaborations with some researchers in the (United States) and we hope to collaborate on using some data to be able to figure out if that avenue is worth further scrutiny or not, if that’s where it’ll give us more justification for going after climate change stuff to help with the issue,” Tozer said.
According to the report, more than 4,000 volunteers collected the data on loons over four decades, on 4,500 lakes across Canada.
“We have all this wonderful data, but we definitely could use more volunteers, especially in places outside of Ontario. The prairie provinces… (British Columbia), Quebec, the Atlantic provinces, we have smaller sample sizes there.”
Darwin Park is a Birds Canada volunteer and the surveyor for Crimson Lake in Alberta.
Park said he uses his kayak to go around the lake and monitors the nesting of the loons. This helps his work as a Birds Canada volunteer.
“At the end of the year, I fill out more formal data sheets, and try and do what I call, normalize the information,” Park said.
He said he hadn’t noticed a decrease in productivity on Crimson Lake, but he said that could be due in part to the health of the lake.
“We don’t have a lot of agricultural drainage, virtually none into the lake,” he said. “So we have a pretty pristine condition.”
However, Park recognized the drop in productivity in general across Canada, and said it’s a cause for concern.
“As I say, (loons are) part of my heart and soul. And it would be a tragedy if something happened not just to our lake, but any lake where it couldn’t or didn’t come back anymore.”