It appears there’s an answer to why ruffed grouse numbers have dropped in many areas of the state, but the solution may not be easy to obtain.
Recent results from a Pennsylvania Game Commission study revealed that Pennsylvania’s state bird has declined, particularly from 2000-2004, and has yet to recover.
During the same time frame, something has increased.
West Nile virus first surfaced in the state in 2000 and two years later, it was found in all 67 counties. I remember when the virus began to turn up throughout the state and it was often found in birds. State agencies encouraged anyone who discovered a dead bird, particularly crows and blue jays, to let them know as those two species were heavily impacted by WNV.
At the time, Luzerne County even maintained a flock of Rhode Island Red hens at various mosquito “hot spots” to monitor for the appearance of the virus.
When it came to watching for and even finding the virus, birds were the canary in the coal mine.
And for good reason.
Acting on the correlation between the appearance of West Nile virus and the decline of grouse populations, the PGC embarked on an ambitious plan to determine if the disease was actually the cause for the decline of grouse.
To do that, the agency needed grouse that were never exposed to mosquitoes or the virus. There was only one source: unhatched eggs.
We all know how hard it can be to find grouse in the woods, but finding a nest with eggs is even more difficult. The PGC enlisted the help of its staff in the field and hunters, and six nests with eggs were discovered.
The eggs were collected and transported to a facility in Idaho where they could be hatched and raised in a quarantined environment. Eighteen chicks made it into the study, and 10 were inoculated with the virus, five received a vaccine and later inoculated and three were placed with the other chicks to see if West Nile could be passed from bird-to-bird.
Now, it was time to wait for a few crucial answers.
Could grouse become infected with the virus? If so, was it deadly? And was it serious enough to force a population to decline statewide?
According to the PGC, four of the 10 chicks inoculated with the virus became ill within eight days. The other six survived for the entire two-week study, but four of them had severe internal lesions.
Eight of the 10 infected birds were impacted by the virus to the point that researchers believed it was doubtful they would have survived.
There was an answer.
West Nile virus kills ruffed grouse.
But what percentage of the population has been impacted by the virus?
Last year, the PGC tested 204 blood samples collected from grouse harvested by hunters, and 13 percent turned up positive for West Nile virus. Since these grouse were killed by hunters and not the disease, it still remains to be seen just how fatal the virus is to the wild population.
Still, the Game Commission is considering options to aid grouse populations, including reducing the harvest.
The impact of West Nile virus on grouse is not an easy problem to solve. Grouse numbers are down, the number of grouse hunters is down and throwing a deadly disease into the mix makes for a questionable future for the species. The PGC will collect more blood samples from hunter-harvested grouse this season and work with other states on possible management options.
Perhaps the West Nile issue is just one that we’ll have to live with when it comes to ruffed grouse. At the very least, we’ll have to keep our fingers crossed that it’s an issue our state bird can live with as well.