West Nile Virus in ruffed grouse is worth studying
Well, you knew I had to cover this “West Nile Virus found in ruffed grouse” thing sooner or later. The results are in for the 235 or 238 (depending where you get your info from) ruffed grouse tested from the 2018 season in Wisconsin, and 29 percent tested positive for WNV. These are expected findings in a state that has had blue jays and crows showing up dead from the virus since 2004. So finding WNV in our grouse population shouldn’t have surprised anyone.
The findings of 29 percent is higher than in neighboring Minnesota or Michigan, but that number not only includes birds that were deemed confirmed to have the virus, which is only 19 percent. It also includes the birds tested that were not confirmed to have the virus but that had the WNV antibodies or were likely to have the disease. That 19 percent is closer to the reported 13 percent for Michigan and 12 percent of Minnesota birds.
But we are splitting hairs here. The number may be a true 29 percent for Wisconsin. The percentage of birds clinically infected at the time of death was very low, and what affected the grouse population in 2017 was the worst nesting and brooding conditions of my lifetime – over 40 years of hunting grouse.
What is important is that someone in the DNR is studying this. That should have happened as soon as Pennsylvania even hinted that they were wondering if WNV was affecting their grouse population. And, I hate to say it, but it is almost as if the state has either underestimated the economic impact ruffed grouse hunting brings to Wisconsin or took that impact for granted.
It’s almost like the state took the population of ruffed grouse for granted just like managers in Indiana and several other states have, which is why Wisconsin has lots of hunters from Indiana heading to Wisconsin to hunt grouse and Indiana has now listed grouse as threatened.
Ruffed grouse can be seen as a bellwether species for the overall health and quality of the habitat. Just like pheasants are for grassland habitats. They are often considered a species of the young forest and they do thrive with healthy percentages of regenerating forest, generally considered to be 20 to 30 percent. But they need forest of all ages, including older mature trees, especially the male aspen tree for budding to survive the winter. The better the grouse population, the better the overall habitat for deer, wolves, bear, fur bearers, and songbirds. Some deer hunting organizations in Minnesota have started to figure this out.
The good news is that results already demonstrate that some grouse survive exposure to WNV and are not sick when harvested in the fall. The birds that are resistant to the virus will rebuild populations by genetically passing on the resistance, but quality habitat in quantity is still required.
WNV is spread by an infected mosquito biting an animal or bird species that is susceptible to the virus. The studies sanctioned by Pennsylvania suggest that turkeys are not anywhere as susceptible to WNV as grouse. Blue jays, crows, and horses are susceptible. Humans can be infected with WNV from mosquitoes. There is no evidence that WNV can be spread by handling dead birds or by consuming properly cooked game.
WNV infects the heart, brain, and spinal cord of infected animals. Grouse will often lose weight and have what appears to be underdeveloped breast muscles when infected.
Five-hundred self-sampling kits were distributed to grouse hunters statewide with assistance from the Ruffed Grouse Society, the Wisconsin Conservation Congress, and the WDNR this fall. Similar coalitions in Minnesota and Michigan did the same. The idea is to gain a much better ideas of the effect WNV has on the Great Lake States ruffed grouse population.
Most ruffed grouse live less than two years because any creature that eats meat on land loves to eat ruffed grouse. Their purpose in life is to turn truly fibrous and odd sources of protein into delicious white breast meat. Their short life spans, cyclical population, jumpy disposition, and the effects of spring weather make studying the grouse population challenging. And their secretive nature means that if grouse are succumbing to WNV in later summer they are not going to be found before one of the multiple predators that eat them do.
It comes back to “It’s the habitat stupid.”
Wishing you a happy, safe, and prosperous New Year!
CHUCK K OLAR LOCAL OUTDOORSMAN