Three U.S. Fish & Wildlife biologists are spending several days setting up a radar system on Dave and Cathi Williams’ farm that will track the migration of birds and bats that come across, or along, the shore of Lake Superior. The Twin Cities trio will come back periodically to check the equipment and data over the next month. From L-R: Nathan Rathburn, Kevin Heist and Mike Wells.
Even though it was cloudy, a callous cold creasing our light coats and the feel of stilted rain in the air, the birds didn’t seem to notice and were singing gloriously at Dave and Cathi Williams’ farm last Tuesday morning.
Down in the slowly greening field, about 75 yards to the right of the big pond as you face Lake Superior, were three U.S. Fish & Wildlife Services workers installing Merlin, a sizeable avian radar system. After a day or two of adjustments, Merlin will stay put in the Williams’ field for a month or so, said Nathan Rathburn, one of the three U.S. Fish & Wildlife Service biologists assigned to this project.
“Merlin operates 24-7,” said Rathburn. “Merlin gives us data on the migration of birds and bats in the spring and fall as they fly across or around the Great Lakes. This radar’s partner is in Ashland, Wisconsin.”
Both of these mobile radar units have been stationed around the shorelines of the Great Lakes each spring and fall since 2011. Rathburn said the data from the radar will be combined with current and historical bird surveys, banding data, weather data, NEXRAD radar, and information collected from acoustic and ultrasonic monitors to give the U.S.F.W.S. a much clearer picture of bird and bat migration.
Small bird and bats, weighing as little as 15 grams, can be traced by Merlin’s radar.
Interrupting the radar can be storms or clouds of insects, said Rathburn, adding, “We remove that clutter from the data to get a clear picture of the migration.”
Besides radar, Merlin and his twin in Ashland are equipped with a weather station and acoustic monitors.
The monitors pick up and record the songs of birds and ultrasonic sounds bats make as they make their long spring and fall journeys.
Rathburn said each bird and bat make distinctive sounds that can be distinguished between species. Acoustic monitors are active from dusk to 2.5 hours after dawn. The weather station collects wind and speed direction, rain, humidity and barometric pressure, he said.
Information gathered about birds and bats is shared with the United States Forest Service, the Minnesota Department of Natural Resources, the University of Minnesota and the U.S. Geological Survey.
Collected information from 2011 to now shows that migration occurs in pulses. Just after sunset during migration season birds and bats start to really move, with peak flight occurring about midnight, then declining just before dawn.
The radar unit on the Williams’ farm is the last one to be placed this spring. “This is the last area on the Great Lakes to monitor,” noted Rathburn.
Information gathered will be used to formulate guidelines for where and when wind turbines can operate with minimum risk of harming migrating birds and bats.
As the need for renewable energy increases, the demand for energy produced in an environmentally friendly way will be more in demand.
This project also hopes to show areas around the Great Lakes that have high concentrations of migrant bird and bat populations. This may include stopover habitat where birds and bats eat and rest before continuing migration as well as areas along the lakeshore that concentrate the migrant populations.
Every couple of weeks Rathburn, Kevin Heist and Mike Wells will return to the Williams’ farm to check the battery life and the fuel needed to power the equipment. The data gathered by Merlin can be delivered to their Bloomington, Minnesota office remotely, but when the biologists are back in the county they will examine it here.
Great Lakes Restoration Initiative
The Great Lakes Restoration Initiative began as a project designed to help find the best ways to protect and restore the most extensive system of fresh surface water in the world – the Great Lakes.
The GLRI sprung from the Great Lakes Regional Collaboration Strategy; GLRI answered a challenge presented by the governors of the Great Lakes states. Since 2010 the multi-agency GLRI has provided funding to 16 federal organizations to strategically target the biggest threats to the Great Lakes ecosystem and to accelerate progress toward achieving long-term goals. The bird and bat migration study is just one of the many and varied projects undertaken by the GLRI.
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