MINNEAPOLIS — Tests on more than 750 ducks shot by Minnesota hunters this fall have turned up no signs of the kind of bird flu that devastated the Midwest poultry industry earlier this year, according to data released by the Department of Natural Resources Thursday.

Wildlife agencies are testing wild waterfowl to see if ducks and geese flying south for the winter are carrying highly pathogenic forms of avian influenza such as H5N2, which could provide an early warning if the disease returns. Scientists believe that wild birds, primarily ducks, are the main carriers of the dangerous H5 bird flu viruses that began showing up in North America last November.

Wild waterfowl don’t normally get sick from these viruses, but they’re deadly to domestic poultry. Bird flu cost producers more than 48 million chickens and turkeys before the outbreak ended with the onset of warm weather in June. Minnesota and Iowa were by far the hardest hit states.

DNR wildlife research manager Lou Cornicelli said none of the 753 Minnesota duck samples tested so far came back positive for highly pathogenic flu strains. About 19 to 21 percent tested positive for low pathogenic bird flu, which isn’t considered a threat.