CHICAGO (AP) — Scott Judd trained his camera lens on the white dot in the distance. As he moved up the Lake Michigan shoreline, the speck on a breakwater came into view and took his breath away: it was a snowy owl, thousands of miles from its Arctic home.

"It was an amazing sight," said Judd, a Chicago IT consultant. "It's almost like they're from another world. They captivate people in a way that other birds don't."

The large white raptors have descended on the Great Lakes region and northeastern U.S. in huge numbers in recent weeks, hanging out at airports, in farm fields, on light poles and...