Test results are in from the first year of a multi-state study on West Nile virus in ruffed grouse in Minnesota, Michigan and Wisconsin. These first-year results are showing that, while the virus is present in the region, exposed grouse can survive.
In 273 samples from
grouse that hunters harvested in Minnesota during 2018, 34 samples (12.5
percent) had antibodies consistent with West Nile virus exposure that
were either confirmed in 10 samples (3.7 percent) or likely in 24
samples (8.8 percent). The tests did not find the presence of virus in
any of the ruffed grouse hearts, meaning the birds were not sick when
In Wisconsin, West Nile virus exposure was detected in
68 of 235 (29 percent) ruffed grouse blood samples with exposure to the
virus either confirmed in 44 (19 percent) or likely in 24 (10 percent),
and two grouse had virus present in their hearts. In Michigan, West
Nile virus exposure was detected in 28 of 213 (13 percent) ruffed grouse
blood samples with exposure to the virus either confirmed in nine (4
percent) or likely in 19 (9 percent), with four having virus present in
“The study tells us that some birds that have been
exposed to West Nile virus are surviving – both juvenile and adults –
and they are not sick when harvested in the fall,” said Charlotte Roy,
grouse project leader with the Minnesota Department of Natural
Resources. “But this study does not tell us about birds that may have
died from the disease over the summer.”
Research in other states
points to good grouse habitat as one factor that can produce birds in
better condition and better able to survive stressors like West Nile
The DNR had asked grouse hunters to collect two types of
samples to help determine if the birds were exposed to the virus: a
blood sample to determine if the grouse had developed an immune response
to the virus, and the heart 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.
Hunters who submitted samples in 2018 will be mailed a letter this fall
notifying them of the test results of the birds they submitted.
you to all hunters who contributed samples last year, as well as
hunters who are submitting samples this season,” Roy said.
collection is continuing during the 2019 grouse hunting season. Ruffed
grouse hunters can voluntarily submit samples if they are willing to
collect blood on filter paper strips within 30 minutes of harvest,
hearts, and a few feathers for sex and age determination, and are
willing to provide harvest location information.
Sample collection kits have been available for pickup at DNR area wildlife offices
within the ruffed grouse range since Labor Day on a first-come
first-serve basis. Due to strong interest by hunters, many offices are
already out of kits, so hunters should call ahead before stopping.
Read the full MN DNR article