LANSING, Mich. (AP) — Michigan officials are asking hunters who pursue ruffed grouse to submit some of the birds for West Nile virus testing.

The state Department of Natural Resources is cooperating with Minnesota and Wisconsin on a study of how the Great Lakes region’s ruffed grouse are being exposed to the illness.

Scientists have documented a rise in the number of the birds testing positive. Twelve in Michigan were found to be infected in 2017, although the DNR says there’s no evidence that the state’s overall population is in peril.

A recent study found that the virus may have contributed to population declines in areas of Pennsylvania with lower-quality or scarce habitat.

Michigan collected more than 200 grouse for the study last year from the Upper Peninsula and the northern Lower Peninsula.