As freezing air swept into the Upper Midwest this past week, juvenile Common Loons recently tagged with tracking devices began their first migrations to the warm Gulf of Mexico.
By Monday, November 17, eight young loons from the Midwest had reached the Gulf of Mexico; eight more were en route to southern wintering areas.
Scientists from the U.S. Geological Survey and other agencies captured and radio-marked the birds on lakes in Minnesota and Wisconsin during the last two weeks of August. The researchers are studying the challenges the birds face during their first two years of life, when they are most vulnerable.
You can follow the birds’ movements on the website of the USGS Upper Midwest Environmental Sciences Center.
“Midwest loons are susceptible to avian botulism in the Great Lakes and pollution found in U.S. waters during migration and while overwintering,” says Kevin Kenow, USGS lead scientist for the study. “Resource managers need information on the iconic birds’ first critical years to develop effective conservation strategies.”
Researchers say Common Loons are bioindicators, or living gauges of ecosystem health, in the Great Lakes states. About 93 percent of adult loons survive year to year, but only about 50 percent of young birds reach the age of three.
“Satellite-transmitter and geolocator-tag technologies help us learn more about the movements, habitat use, and causes of mortality of young loons and ultimately about the health of the overall food web,” Kenow says.
The tracking devices record daily location, temperature, light levels, and pressure data used to log the birds’ foraging depths.
Previous band-recovery data suggests that some loons remain on Gulf coast wintering grounds year-round for two years while others may fly north up the Atlantic coast during summers.