BELLEVILLE, Ill. (AP) — State wildlife officials suspect that bird flu killed at least 300 waterfowl recently found dead at public hunting sites across southern Illinois.

The Illinois Department of Natural Resources said Tuesday the wild birds, mostly snow geese, have been found dead at Baldwin Lake, Pyramid State Recreation Area, Rend Lake and Carlyle Lake.

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The wild birds are believed to have died of avian influenza, the DNR said in a news release. The state agency is asking anyone who sees 20 or more dead birds at one spot to report those birds deaths to a district wildlife biologist, the Belleville News-Democrat reported.

The DNR said hunters should avoid handling any sick or dead birds found in the field, and they should not allow their hunting dogs or pets to eat waterfowl that died from unknown causes.

The wild bird deaths in southern Illinois come several months after highly pathogenic avian influenza was detected in Canada geese in Illinois

The bird flu virus is primarily spread by wild birds as they migrate across the country.

A nationwide bird flu outbreak that has hit mostly chickens and turkeys on commercial farms has already prompted the slaughter of more than 52 million birds at farms in 46 states.