Last Saturday was long-awaited by Pennsylvania hunters who pursue the Ruffed Grouse, our state bird. It’s a fact that grouse numbers are down, here and in other states. Habitat and weather are factors, but is West Nile Virus also hurting their population?

Research is ongoing; early results are worrisome. In addition to the Pennsylvania Game Commission, other research entities include Colorado State University, Guelph University, the Ruffed Grouse Society, multiple other state agencies, and hunters.

Here’s how susceptibility of Ruffed Grouse to West Nile Virus was tested: ten native grouse were inoculated with West Nile Virus. In addition, five vaccinated grouse were inoculated with the virus, and three native grouse were inoculated with a “sham” virus. All the birds were co-housed and the trial lasted 14 days.

Pre and Post antibodies were measured in the birds. Blood was drawn to measure viremia; in addition oral swabs were taken to measure viral shedding. Necropsies were performed and tissues for study.

Of the ten native grouse which were inoculated with West Nile Virus, four were euthanized between days seven and eight due to severe disease signs, including lethargy, weakness and partial paralysis. Post-mortem examination showed severe inflammation of the heart. None of the five vaccinated birds or the three birds inoculated with the “sham” became sick.

Here’s how hunters helped with the research: the Ruffed Grouse Society had an Upland Game Bird Hunt in Pennsylvania in 2014-15, and fresh blood samples were taken from birds that were harvested. Also, research materials were mailed to 600 cooperating hunters during the 2015-16 and 2016-17 hunting seasons.

Results from the 2015-16 season, by region, for positive west nile antibodies found in tested birds: northeast, 2 out of 22; southeast, 2 out of 7; southcentral 1 out of 9; southwest 2 out of 27; northwest 9 out of 36; and northcentral 12 out of 101.

The preliminary findings? Ruffed Grouse are susceptible to experimentally-introduced West Nile Virus. Are the wild birds also susceptible? Those answers aren’t yet known. If wild birds are exposed to the virus and carry antigens, do they then have a reduced longevity and health? Are birds which live in better quality habitats have a lesser chance of exposure to West Nile?

The research continues, with the hope that we will better understand grouse population dynamics and whether or not West Nile Virus will impact the survival of Pennsylvania’s state bird, the Ruffed Grouse.