Wisconsin's loons are declining, project examines if the same is happening in Minnesota

A scientist who documented a decline in Wisconsin’s common loon population has expanded his research to Crow Wing County in north-central Minnesota.

Walter Piper, a biology professor at Chapman University in southern California, hopes to get a better idea if what’s plaguing Wisconsin’s loons — possibly biting black flies that drive them off the nest — also could be affecting Minnesota’s beloved state bird.

Piper’s research has found that Wisconsin’s adult loon population has fallen an estimated 22 percent in the last 25 years. In addition, loon chicks are smaller and the survival rate of young loons is lower.

“I worry that the same thing might be going on in Minnesota,” he said.

Piper partnered with the National Loon Center to expand his research project into Minnesota. The nonprofit plans to build a research and education center in Crosslake in 2024.

“We're hoping to use our study population here in the Whitefish chain and the surrounding lakes to get an understanding and sort of extrapolate to the larger population of loons in Minnesota,” said Natasha Bartolotta, the National Loon Center’s communications and outreach coordinator.

Last summer, Piper’s team attached identification bands to the legs of about 78 loons around the Whitefish Chain of Lakes, about 25 miles north of Brainerd. Their goal is to band more than 100 pairs in all. 

Some loons on the chain were previously banded as part of study by the U.S. Geological Survey, which ran from 2015 to 2017.

Over the next several weeks, the team will revisit the loons' territories to find out whether the birds survived and returned this summer.

Just after dawn one morning last week at a public landing, Piper and three interns loaded a motorboat with binoculars, data log books and personal flotation devices.

The landing on Cross Lake is at a popular recreational area with frequent boat traffic. It doesn't seem like an ideal spot for loons to build a nest. 

But nearby, tucked into a patch of cattails on the edge of a marshy island, the team made its first find of the day: A loon half hidden in the reeds, sitting on a nest. Its mate was lingering nearby, which Piper called a good sign.

“They have a pretty good nest site here, even though it's right in the middle of all this human activity,” he said. 

Once the research team spots a loon, they try to get close enough to tell whether it's been banded and to identify the band's colored markings. They use a GPS device to record the loon's exact location, and document any behaviors, like preening, foot waggling or calling.

On the busy Whitefish chain, loons have learned to coexist with humans, which makes it easier for the research team to observe them.

“It's really human development and the fact that they see humans all the time allows us to do our work,” Piper said. “I guess there's an irony there. Humans are a threat, but also they allow us to get close enough to monitor the population.”

With much of the lakes’ shoreline developed with houses and cabins, loons will build a nest in a small patch of cattails, or on a human-made floating platform, if one’s available. 

Finding a loon on a nest is a good sign. By this time of year, male and female loons should be taking turns incubating the eggs.

But too frequently, Piper said, the loons abandon their nests, driven away by ferocious biting black flies. He recalled one loon they spotted a few days earlier, its head covered by the pests.

"It was diving to try to get rid of the black flies. The black flies were clinging to the loon even when it was going underwater,” Piper said. “That was a male that just could not stay on the nest. So that nest is very much in doubt."

The black fly problem has gotten worse over the past decade or so, as warmer temperatures and heavier rainfalls linked to climate change have boosted their reproduction, Piper said. 

He believes it's a key reason why the number of loons in Wisconsin has fallen an estimated 22 percent over the last quarter century. And he wants to know if the same thing is happening to Minnesota's loons. 

Once the team has finished banding its study population, it will include about three percent of Minnesota’s total loon population, which stretches throughout much of the state, Piper said.

“This is just giving us one snapshot,” he said. “But the comparison between Wisconsin and Minnesota is helpful, because it really does give us a sense of the regional population in the Upper Midwest and how it's doing. If both Wisconsin and Minnesota are declining, that suggests that we have a larger pattern than just a local problem.”

On popular lakes, it might seem like boat traffic would be the biggest threat to loon survival. But while boats do occasionally strike and kill a loon, Piper doesn't think they are a major influence.

"My gut feeling is that at a population level, that's not going to wipe them out,” he said. “If anything wipes them out, it's going to be something else that's hurting them."

Along with black flies, there could be other factors affecting loons. In Wisconsin, lakes are getting less clear, due to heavier rainfalls and polluted runoff from fertilized lawns and urban areas, Piper said. That affects loons’ ability to spot their prey underwater.

It will take time for the research project to yield results. After three to five years of tracking the banded loons in north-central Minnesota, Piper hopes to have enough data to calculate adult survival rates, a critical number in the species’ success.

“I can't wait until we get enough birds banded to be able to get some data that will tell us whether adults are surviving at a high enough rate, and then chicks are being produced at high enough rate, to sustain the population,” he said.

Then, researchers will plug the data into population models to estimate whether the loons are increasing in number, stable or declining. 

If the data show loons are struggling, there are things people can do, Piper said, such as building artificial nesting platforms that boost reproductive success, or working to improve lake clarity.

“My hope is that we can learn what's going on and take some steps to try to help loons,” he said.