Study underway on birds and wind towers

Jane Howard

Finding sources of energy that are good for the environment and good for the economy sounds like a win-win endeavor. TheCook County Local Energy Project (CCLEP) has been attempting to do just that by pursuing the development of several types of renewable energy: solar, biomass, and wind. Toward that end, it has sought the findings of Ph.D. candidate Anna Peterson, who was hired by Hawk Ridge Bird Observatory and the University of Minnesota-Duluth’s Natural Resources Research Institute to conduct a study that could affect the potential of wind power along Lake Superior’s North Shore. Peterson, a student of wildlife conservation at the University of Minnesota, has identified one of the critical elements in the equation: migrating birds.

Peterson met with a group of Cook County citizens in October to present her findings so far. At that meeting were CCLEP volunteers along with representatives from Friends of Superior National at Lutsen (interested in attracting bird watchers to the golf course and possibly using wind power to charge golf carts) and Lutsen Mountains (interested in developing wind power at the ski hill).

Surprising findings

Peterson’s goal was to find out how many birds migrate through the North Shore corridor, what paths they take, and where they stop to rest along the way. So far, she has found one big surprise: the numbers of raptors and songbirds traveling within about a mile of the shore are in the hundreds of thousands to millions. The Hawk Ridge Bird Observatory calls it “a massive movement that has been previously underestimated.”

The study started out with a focus on raptors, but as it unfolded, it expanded, because the volunteers gathering data were finding that songbirds (“passerines”) outnumbered raptors 30, 40, or 50 to one. Over 100 species have been identified, some on the decline and/or the Minnesota Department of Natural Resources’ list of “Bird Species of Greatest Conservation Need.” Some of the birds weigh no more than half an ounce.

The study’s hours of observation have been expanded to sunrise when the songbirds start to fly. Raptors don’t usually fly until two hours after sunrise when they can catch warmer air currents, Peterson said.

Peterson told the group that the Sawtooth Mountain ridgelines act as giant funnels, pulling in birds from hundreds of miles away. Once they get here, they try to avoid flying too far out on the water, creating a bird superhighway of sorts between Lake Superior and the second ridgeline within one to six miles of the shore.

“Most of these birds are babies,” Peterson said. “They’ve just hatched. They don’t know what’s going on.” Some of them have been blown east as they try to fly south, and they end up coming southwest down the North Shore.

Migration hazards

Not all the birds make it to warmer climates. A big storm this fall left thousands of birds dead in Lake Superior. Local fishermen called about the devastation, Peterson said, “and they were pretty distraught about it.”

Most of the birds fly within 100- 500 meters of the forest canopy, Peterson reported, right in the paths of communication towers, wind turbines, and large buildings.

Another hazard for birds is light from lighthouses and buildings at night or during foggy conditions. Songbirds sometimes travel at night, and birds in general are attracted to lights, Peterson said. Birds will circle a halo of light and either run into each other, hit the beacon, or fall from exhaustion.

Birder Jeremy Ridlbauer said that this was a problem after the September 11, 2001 attack on the Twin Towers in New York City. After consulting with the Audubon Society, officials turned beacons off every 20 minutes to allow birds to escape the area.

The good news for both the birds and potential wind development is this, Peterson said: “The birds are not randomly distributed. There are patterns to where they fly.” They tend to fly either parallel to shore or directly inward, along ridgelines and valleys. Songbirds fly mostly along the shoreline, and raptors follow either the shoreline or the ridgelines. “The closer you are go shore,” Peterson said, “the more birds you’re going to see.”

Some of the birds are heading to Central or South America, and some will stop within the borders of the U.S. Some will stay in Cook County “if they can,” said Peterson. “Weather plays a major role in all of this.”

Wind turbines and other obstacles

Peterson shared her concerns about the effect of wind turbines on birds, saying that the U.S. Fish and Wildlife Service advises against wind towers in migration corridors. Rotating blades around a central light would have the worst effect, she said. In areas where “wind farms” have rows of turbines, the towers act like fences—birds will not fly past a line of turbines and mate with the birds on the other side. One solution would be to install lower towers with air traffic warning lights that blink on and off, Peterson said.

Along with wind turbines come storage buildings, power lines, and roads, which can also fragment bird habitats. Peterson even considers homes a problem for birds: “There’s issues up in the air and there’s issues on the ground,” she said, “—even if it’s your house.”

A bird’s migration is a “pretty significant” part of its lifespan, Peterson said, when it tends to congregate in certain areas with others of its species. In Europe, wind towers are turned off at certain times to decrease their effect on migrating birds. Most of the bird migration along Lake Superior’s North Shore takes place between August and November. The birds don’t come back this way in the spring, Peterson said.

Where to go from here

Comparing the effect of one type of energy source with another could be complicated. What is the effect of fossil fuel on bird mortality? How much could solar power be used in place of wind power in the Arrowhead region?

Peterson said a lot more research could be done. She would like to be able to use radar to study where birds are moving 24 hours a day and the effects of weather on migration patterns. “If we know these two elements of the North Shore bird migration,” she wrote in a summary of her findings so far, “we can properly site communication towers and wind turbines, as well as predict when turbine blades should be shut off.”

“Our budget this year is $50,000,” she told the group, “and all we do is count birds.”

“The better we know this migration event,” Peterson said in her summary, “the better equipped we will be to properly site wind turbines and communication towers.”

Peterson’s study was begun in 2008 with funding from the Minnesota DNR Lake Superior Coastal Program and the U.S. Fish and Wildlife Service. Peterson expects to complete a report of the findings by December 2011 and a set of conservation guidelines by March 2012. An overview of the project can be found at http://www.

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