MINNEAPOLIS (WCCO) – Weather officials found themselves surprised Wednesday when they learned that the plume they spotted on radar over northern Minnesota turned out not to be a wildfire but lots and lots of ducks.

About 600,000 of them.

The National Weather Service station in Duluth tweeted about the wildfire-waterfowl confusion, explaining that forecasters spotted the suspicious plume Wednesday morning in the Rice Lake National Wildlife Refuge and called officials there to see if they were aware of the situation.

The wildlife officials said they were conducting a waterfowl survey and estimated some 600,000 ducks were flying over the park, located just south of McGregor.

According to the U.S. Geological Survey, all sorts of flying animals, from birds to bats to insects, can appear on radar.