BILLINGS –After extensive testing, Montana Fish, Wildlife & Parks has concluded that the death of a large number of waterfowl on the Bighorn River in February was caused by starvation.
In February, FWP staff collected mallard, geese and shorebird carcasses from Afterbay to about three miles downstream of the Bighorn Fishing Access Site. The carcasses were transported to FWP’s Wildlife Health Lab in Bozeman for Highly Pathogenic Avian Influenza (HPAI) testing. All carcasses tested negative for HPAI.
Following these negative results, the waterfowl carcasses were sent to the U.S. Geological Survey’s National Wildlife Health Center (NWHC) in Wisconsin for further testing and investigation. No evidence of infectious diseases was detected. Emaciation and starvation were the only consistent ailments found in all sampled carcasses.
FWP’s mid-winter waterfowl surveys for the Bighorn River, conducted in early January, showed higher than average waterfowl numbers, which likely led to more competition for the limited food in the area. Early 2025 brought extreme cold temperatures and large amounts of snowfall to the region, making the search for food even more challenging.
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