BGSU research draws a connection between songbirds' migration patterns and Lake Erie islands

When tiny songbirds begin their trek from the tropics of South and Central America to the northern United States and Canada each spring, they rely on the setting sun, the stars, moon, and the earth’s gravitational pull to guide them. 

Scientists have long known the birds, some so small they would fit in the palm of a hand, use these natural navigational tools. 

But on Lake Erie, these birds also appear to be using the topography of the Lake Erie Islands to help their navigation, new research from an on-going study by Bowling Green State University  researchers indicates. 

As they prepare to navigate across or around Lake Erie, some birds stay close to the shoreline and avoid flying directly across the lake. Large numbers, however, fly parallel to the island archipelago - South Bass Island, Middle Bass Island and Kelleys Island in U.S. waters and Pelee Island in Canadian waters - preliminary results from the study by BGSU Distinguished Research Professor Verner Bingman, Ph.D., and graduate student Murphy Harrington indicate. 

This indicates these birds, including warblers, thrushes, orioles, and sparrows, take the islands and other land features into account when determining their flight path.

“It shows that these birds are not just passively migrating,” Bingman says. “They’re attending to the topography that they’re flying over. They can exploit that topography in many ways depending on factors.

“They’re really decision makers. They display remarkably clever flexibility in how they are able to use the topography, sun, moon, and stars.”

Bingman and Harrington wanted to examine whether the birds use the islands as stopover sites to avoid shifting winds and storms - as well as rest and refuel, which bird banding research has indicated - before continuing the rest of their journey over the lake. Their study is funded through the Ohio Sea Grant College Program at Ohio State University. 

How the study worked

Harrington, who is working on her master’s degree in ecology in conservation biology, set up an infrared camera on Middle Bass Island in fall 2022 during the birds’ migration south, in spring 2023 for northern migration and again this fall. She started at the East Point Nature Preserve pier but then moved to an open area near the house where she was staying on the island due to wind and waves at the pier.

She also set up a control site in Bowling Green, where field researchers observed the birds migrating there. The cameras picked up thousands of birds passing through the camera’s range through signals generated by their body heat.

Harrington and the BGSU field researchers watched the cameras at night, about a half hour after sunset. 

“The evidence is somewhat equivocal, somewhat uncertain because we haven’t carried out the wind analyses yet that are critical to this,” Bingman says. “There certainly is an indication, not confirmed, that the birds are exploit the island archipelago to minimize drift and to compensate for their bearings.”

Once the wind analyses and final data from this fall are available, Harrington and Bingman will complete a final report with their findings. 

How can the study help birds and nature?

By better understanding the migration patterns of birds around the island archipelago, the more information scientists and decision-makers will have about important habitat in the area. 

“I think in terms of conservation, the greater utility of the kind of research we’re doing, there certainly are on-going conversations about wind turbines on Lake Erie,” Bingman says. “Those are of considerable potential impact to these birds. Wind turbines are not good for migratory birds, but wind turbines might be inevitable for clean energy.”

He emphasizes that he, Harrington, and their fellow researchers are not in the position to make polity and take a stand. They hope to offer information to those who make these decisions.

“Where do you put them?” he says of the wind turbines. “That’s where this research could be fundamental. It could influence developers to keep the turbines away from the islands.”

Regardless, the research emphasizes the importance of the Lake Erie coastal areas and the islands to bird migration.

“To me, it’s a logical inevitability that any habitat you can preserve on the islands is going to help migratory birds,” he says. 

The research also highlights the ecological significance of the Lake Erie Islands, Harrington says. 

“It was important to me to know that I was able to do a project that was going to bring more attention to that area,” she says. “On top of whatever comes out of this study, I hope it encourages more people to observe what is going on on those islands.”

She worked with the Lake Erie Islands Conservancy, whose members supported her work, found her a place to stay and even invited her over for dinners while she was there. When she couldn’t find a ride back to the mainland, one of the residents flew her across the lake. 

She also watched Tom Bartlett, Cleveland Museum of Natural History Department of Ornithology research associate and bird bander for the U.S. Geological Survey and North American Banding Council, band birds at his banding station on Middle Bass. His information is also critical to migration research. 

“It’s a small group of people and they manage to do so much good on those islands and raise a lot of awareness,” Harrington says. “The number of people going out there is increasing. They’re really doing their best to keep people informed about why the islands are important ecologically.”