Year One Results are In for West Nile Virus Ruffed Grouse Monitoring Project
Ruffed grouse harvested in Michigan, Minnesota and Wisconsin during the 2018 hunting season were sent to the Southeastern Cooperative Wildlife Disease Study in Athens, Georgia, to be analyzed.
Now, results are back from the lab with our first year of data in this three-year project. The ruffed grouse West Nile virus surveillance project is a collaboration between the Wisconsin, Minnesota and Michigan DNRs to better understand WNV in our region.
Wisconsin Results
Hunter-submitted samples underwent two types of testing to help us determine if the birds were exposed to West Nile:
- A blood test to determine if the grouse had developed an immune response to the virus and
- A heart test to look for traces of viral genetic material.
As in humans, ruffed grouse can build up antibodies in an immune response to viruses they encounter. Even when the body fights off an illness, these antibodies are left behind in the blood.
Results from the blood samples indicate that 68 (29%) of the Wisconsin-submitted samples had confirmed antibodies to WNV either confirmed (44 or 19%) or likely (24 or 10%).
Results also showed that two (0.9%) of the 235 grouse had evidence of the virus present in their hearts, but as both of these birds had also developed antibodies to the virus (from the accompanying blood test), the results do not directly indicate that these two birds were sick at the time of harvest.
These findings indicate that while ruffed grouse are being exposed to WNV, there are birds that are surviving and clearing the virus from their bodies.
These numbers aren't representative of the whole grouse population, and we can't yet determine what the exposure rate of ruffed grouse to WNV is in Wisconsin.
The study may help identify future research needs in Wisconsin, such as a potential survival study to investigate sources of mortality, with WNV being one of many stressors examined.