West Nile virus survey in Michigan ruffed grouse shows strong survival rates

Second-year results from the multistate West Nile virus in ruffed grouse study show similar results to the previous year, that while the virus is present in the Great Lakes region, grouse exposed to the virus can survive.

In coordination with Michigan, Minnesota and Wisconsin natural resource departments, ruffed grouse hunters provided more than 700 samples for virus exposure and infection analysis. Blood samples were analyzed for antibodies that would indicate if the bird had been exposed to WNV. Heart tissue was tested for the presence of the virus.

During the 2019 season, Michigan hunters submitted 281 samples from four study areas in the Upper and northern Lower peninsulas. Of these, 20 (7%) tested positive for exposure, with antibodies to West Nile virus confirmed in seven (2%) birds and likely in 13 (5%). One juvenile male from Iron County tested positive for the presence of viral material in its heart. Polymerase Chain Reaction results for 35 samples are still pending. These results could impact the percentage of birds positive for the presence of viral material in their hearts. When final results are available, they can be found on the WNV FAQ sheet.

In Wisconsin, 37 (20%) of the 188 samples were positive for antibodies consistent with virus exposure, with exposure being confirmed in 17 (9%) and likely in 20 (11%). The virus was not found in heart tissue from any of the Wisconsin samples.
In Minnesota, 39 (12.3%) of the 317 samples were positive for antibodies consistent with exposure. Exposure was detected in three (0.9%) and likely in 36 (11.4%). The virus was not found in heart tissue from any of the Minnesota samples.
A study from Pennsylvania suggested that birds produced in areas of high-quality habitat are better equipped to survive stressors like West Nile virus. An accessible overview of the Pennsylvania study is available in this Young Forest Project article from November 2016.

“Forested areas with different stages of succession provide optimal habitat and health for grouse,” said Al Stewart, upland game bird specialist with the Michigan Department of Natural Resources. “Birds that live in high-quality habitats are likely to have stronger immune responses to diseases and other pressures. Creating and maintaining these areas are crucial to the success of our grouse population.”

Hunters who provided email contact information with their 2019 samples will be notified of their results this fall.

“We appreciate all of the time and effort made by the state’s grouse hunters to provide samples for this study,” said Julie Melotti, a laboratory technician with the Michigan DNR’s Wildlife Disease Lab. “We would not have been able to achieve this level of sampling without their help.”

Due to current budgetary limitations, funding for the continuation of this study through 2020 is under consideration. Further information on WNV in ruffed grouse can be found on the Michigan DNR’s WNV and Ruffed Grouse FAQ sheet.