Tracking sparrows and warblers across Lake Erie

A: Indigo bunting

B: White-throated sparrow

C: Blackpoll warbler

D: Canada warbler

 

By Kate Habrel

Researchers have discovered that more sparrows and warblers fly northeast to Canada in spring by island-hopping across western Lake Erie than those that fly over open water in the lake’s center.

Such flight patterns are increasingly important to know as various groups consider building off-shore wind farms on the lake, energy experts say..Ohio’s wind energy project, Icebreaker, recently received a $40 million grant from the U.S. Department of Energy to place six wind turbines 8 to 10 miles off Cleveland’s coast – in the path of some migrating birds. Construction is scheduled to begin in 2018.

While wind turbines produce clean energy, they may disrupt the flights of migratory birds. Knowing where and when they cross can minimize disruptions and avoid bird casualties.

A new study found that more birds, especially sparrows, fly over water near a chain of islands in the western side of the lake. This suggests that when sparrows decide to cross Lake Erie, they’re more likely to use the islands than fly directly over it on a route that lacks stopping points..

“That can hopefully guide the placement and operation of those wind farms,” said David Gesicki, a doctoral candidate in the department of biological sciences at Bowling Green State University, and lead author of the study. “As a scientist, that’s something we really hope we can push more and more toward.”

Birds in the study were more likely to cross over land than over water. Sparrows, the study suggested, were more likely than warblers to attempt an open water crossing. Warblers were equally likely to go directly over the lake or follow the coast.

These songbirds migrate from their winter locations in the U.S. Gulf Coast and Mexico. Lake Erie is an important stop on their journey northeast.

“They reach the Great Lakes, and they basically need to make a decision: Do we cross the lake or do we try to take a detour?” said Verner Bingman, a professor at Bowling Green State University in Ohio.

That choice is partially influenced by the location of Lake Erie’s islands. An archipelago stretches across the western side of the lake from Sandusky Bay in Ohio to Pelee Island in Canada.

It’s not easy to figure out such flyways. Researchers measured the birds’ night flight calls to see which species and species groups went where. Each species has a unique call that can be analyzed with computer software.

Gesicki collected the data in spring of 2012 and 2013. He  recorded calls from along Ohio’s Lake Erie coast, the Cleveland Water Intake platform and West Sister Island.

“With the audio recorders, we get a sense of where some species are dropping out and just refusing to cross,” Gesicki said. “A computer screen has really allowed us to see these tiny calls that are fractions of a second long.”

Thanks to these calls, Gesicki found a large number of white-throated sparrows crossing the lake at West Sister Island. The number of birds crossing over water there was higher than the number going over land.

West Sister Island might provide a convenient stepping stone for white-throated sparrows across Lake Erie. Further study is needed determine if that is the case.

“I don’t really have an explanation for that, but it’s really quite a striking finding,” Bingman said. “It might’ve been a one-time occurrence, but it was just peculiar.”