Loons fall from the sky in Wisconsin; late April cold snap to blame

A mix of cold air and moisture in the Upper Midwest is causing ice to form on the wings of some loons in high altitude flight, leading to reports of the birds crash landing in Wisconsin.

While “loon fallout” hasn’t been reported in Minnesota this season, freezing rain this weekend up north could prove treacherous for the state bird.

The late April cold snap is creating icing conditions for loons as they fly north, following lake ice-outs. The super-cooled water in the atmosphere freezes onto them, making it difficult to stay aloft.

The Raptor Education Group in Antigo, Wis., posted on Facebook Thursday that the atmospheric conditions in northern Wisconsin have caused loons to land in poor conditions — and loons are not built for land.

The group said loons have been seen on the ground across northern and central Wisconsin, including Rice Lake, about two hours from the Twin Cities.

Lori Arent, an assistant director at the Raptor Center at the University of Minnesota, said the cold conditions are similar to when airplanes build up ice on their wings.

“The ice gets so heavy that the birds cannot stay airborne and they fall to the ground, sometimes hard, in unusual places,” Arent said. “Loons need water to take off, so when their wings get iced, they often land in fields and other locations not near water.”

Weather conditions perfectly bad for flight

Loons are likely more susceptible to icing hazards because, unlike most birds, they can’t perch in a tree to wait out a storm. They have to either swim or fly. That’s why they make their nests on shallow platforms they can jump onto and off the water.

Freezing rain and drizzle occurs when warm air intrudes aloft melting snow to rain which can then fall back into a cold layer as super cooled water droplets. Water can remain liquid in this super-cooled state until it touches a cold object and instantly the water molecules lock into ice formation.

Freezing drizzle within a cloud forms when there isn’t enough condensation nuclei formed yet (i.e. snow flakes). This often happens before or after a snowfall, when the air is saturated but below freezing.

Until a burst of snow occurs, which will then collect all that super cooled drizzle, you have suspended frozen water droplets. 

A late-season freezing drizzle or freezing rain event and lake ice-out timing create perfectly bad conditions for loons. Their migration follows open water since they have to have it.

If they fly too far ahead of ice-outs and get caught in conditions favorable for icing, they can get into trouble. 

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