– The National Weath­er Service’s local ra­dar lit up a­gain Thurs­day morn­ing, but this time me­teor­olo­gists knew what was afowl.

Last week, weath­er ex­perts were brief­ly alarmed by ra­dar ac­tiv­i­ty over Rice Lake National Wild­life Refuge that looked like it could be a wild­fire. It turned out to be 600,000 ducks that had been dis­turbed by a team of wa­ter­fowl sur­vey­ors on the lake.

Thurs­day, ref­uge staff con­ducted an­oth­er sur­vey — and this time called the Weath­er Serv­ice to give folks there a heads-up. Workers count­ed more than 900,000 ducks, the Weath­er Serv­ice said.

Based on the ra­dar image, “the sky had to be pret­ty much just com­plete­ly filled with ducks,” said Bryan Ho­well, a me­te­or­ol­o­gist.

It’s not un­u­su­al to see birds or in­sects on the ra­dar, Ho­well said, but the tim­ing of the ac­tiv­i­ty was sus­pi­cious when it first caught me­teor­olo­gists’ eyes.

“U­su­al­ly when we see birds on the ra­dar, it’s right around sun­rise, when they’re leav­ing their nests,” Ho­well said. The ducks that time took flight around 10 a.m.

He add­ed that the ref­uge man­ag­er told the Weath­er Serv­ice that ducks come to the lake in large num­bers each year to feast on its wild rice.

This year, Ho­well said he was told a vast ma­jor­i­ty of the birds on the lake are ring-necked ducks, which dive for food. Higher wa­ter lev­els in Rice Lake mean fewer mal­lards are mak­ing it a stop on their trips south for the win­ter.