You can’t walk into a gift shop in northern Wisconsin without seeing the dark red eyes and black-and-white mottled backs of buds emblazoned on postcards, magnets and T-shirts.
The common loon is a symbol of the Northwoods, its mourning call conjuring up images of warm summer days away from the hustle and bustle of everyday life.
But real-life birds may be at risk, according to a recent study.
Wisconsin’s loon population has declined 22% over the past three decades. The study shows that the decline is likely due to lakes becoming less clear from climate change and land use.
Walter Piper, a behavioral ecologist at Chapman University in Orange, California, and an author of the study, said that reproductive success — or the ability of a loon to have a chick that lives to have its own offspring — is in Wisconsin. It’s only a matter of time until there are bigger declines, Piper said.
“I’m on pins and needles every year,” he said.
Here’s how climate change and land use are affecting the Northwoods’ prized bird.
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Flowers need cool and clean water with natural banks
Common loons breed in freshwater lakes from Alaska to most of Canada, including parts of a number of other US states, such as Wisconsin, Minnesota, and Michigan, which are the southern tip of their range.
Gulls overwinter on the Atlantic and Pacific coasts and then return to freshwater lakes in the Great Lakes Northwoods to breed and raise their young.
The bird needs clear, cold water lakes to nest, said Tom Prestby Wisconsin Conservation Manager at Audubon Great Lakes. Loons are visual hunters and rely on their underwater vision to dive and catch fish, he said.
Flowers also need natural banks near water to nest, Prestby said. That’s because hummingbirds have webbed feet that are more like flippers, he said, so they can’t walk across the ground like other birds do.
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Young and older birds are dying at alarming rates
Piper and other scientists working on the Loon Project began monitoring breeding pairs of loons in 1993. In all, they track 110 breeding pairs in Oneida, Lincoln and Vilas counties.
Piper’s previous work with the project shows that life for the little birds in northern Wisconsin is getting tougher.
According to their 2020 study, over the past three decades, there has been a sharp decline in the ability of chickens to produce chicks. Both young and older birds are dying at higher rates than previously recorded.
One of the most dramatic declines is the survival of young mushrooms that have not yet begun to reproduce, known as floaters.
In the 1990s, about half of the waders that migrated to the coast for the winter would return to northern Wisconsin in the summer to claim territory, Piper said, referring to the time as the “roaring ’90s.”
Now, only about 16% return, he said.
Flowers usually produce a brood of chicks a year with one or two eggs. But Piper said two-bird broods are becoming rarer.
And the birds that survive are on average 11% lighter than they were 30 years ago, putting their survival at risk.
Why are the little birds getting lighter?
Piper and his colleagues wanted to see what is contributing to this overall population decline. So in their latest study, they wanted to understand if the birds were getting enough food.
The team examined water clarity for 127 lakes in the northern part of the state from 1995 to 2021, using satellite imagery. They compared satellite data with measurements taken directly from the lake to ensure the images were accurate.
Piper said they focused on water purity in July because that is the most critical month for the chicks’ growth since they hatch in June.
They found that there is a very close correlation between water clarity and chicken weight, Piper said.
The most likely reason for this is that adults can’t find food as well in darker waters to feed themselves and their raptors, Piper said.
Why are lakes getting darker?
The lakes are more turbid in rainy years, not because of the rain itself, but because of what flows into the lakes, Piper said.
For example, heavy rain can wash sediments into lakes, as well as nutrients, such as nitrogen and phosphorus from fertilizers, that can promote algal blooms.
As climate change brings heavier and more frequent rainfall to northern Wisconsin, that’s likely to get worse over time, he said.
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Will alien populations continue to decline in the Northwoods?
Scientists also began monitoring another population in Crow Wing and Cass counties in central Minnesota in 2021.
Although it’s still early days, Piper believes loons in Minnesota are heading in the same direction as those in Wisconsin.
Prestby is concerned that heavier rain events with climate change will not only make the lakes less clear, but that they will remove the natural shores that the animals need – and even wash their eggs if the weather is right. right.
One of his biggest concerns is that climate change could shift their range north and the prized bird may no longer spend its summer in Wisconsin.
“Nobody knows when or if, but it’s certainly a possibility that one day we won’t be in their breeding range anymore,” Prestby said.
“That would be a very, very sad day.”
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Caitlin Looby is an America Report staff member who writes about the environment and the Great Lakes. Contact him at clooby@gannett.com or follow him at X@caitlooby. Please consider supporting the journalism that informs our democracy with a tax-deductible gift to this reporting effort atjsonline.com/RFA or by checking The GroundTruth Project with the subject line Sentinel Campaign Report in the Journal of America Milwaukee. Address: The GroundTruth Project, Lockbox Services, 9450 SW Gemini Dr, PMB 46837, Beaverton, Oregon 97008-7105.
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