The Illinois Department of Natural Resources (IDNR) asks the public to report any large mortality rates among waterbirds during seasonal migrations.
The IDNR attributes recent waterfowl death tolls to highly pathogenic avian influenza (HPAI). According to the release, snow geese found in Randolph County were suspected of carrying the pathogen.

The Illinois Department of Natural Resources (IDNR)
HPAI was first detected in Illinois in March of 2022 in wild Canada geese. IDNR recommends that anyone handling deceased birds thoroughly wash their hands and clothing after disposal, along with wearing rubber gloves and masks.
IDNR also encourages citizens to report mortality events of 5 or more birds at one location. Reports can be made to the local IDNR district wildlife biologist on their website.