September 6, 2006
The Colorado Division of Wildlife (DOW) has confirmed that four
greater sage grouse found dead in northwest Colorado died from
West Nile Virus.
"It wasn't a surprise because scientifically we were aware that
grouse are susceptible to West Nile Virus," said DOW sage grouse
researcher Tony Apa. "The virus had been discovered in other
states, but up until now the grouse in Colorado have been fairly
lucky."
Previously, only one other greater sage grouse in Colorado was a
confirmed victim of the virus. That bird was found dead in 2004 in
the Eagle South Routt population.
Apa and his team of researchers are studying sage grouse in the
Danforth Hills, Cold Springs Mountain, and Axial Basin areas of
Moffat County. There currently are 160 radio collared birds in the
study areas. Researchers found four carcasses in July and August
that were sent to the DOW wildlife health laboratory in Fort
Collins. Three additional carcasses were too decomposed to be
submitted for testing. Two recently discovered carcasses are in
route to the lab for testing. Nearly 150 additional greater and
Gunnison sage grouse are radio collared in other populations and
are being monitored intensively, to detect any unusual
mortalities.
West Nile Virus has also been discovered in recent years in
greater sage grouse populations in Montana, Wyoming, Idaho,
Oregon, Utah, and Alberta.
According to the Center for Disease Control, West Nile Virus is a
flavivirus commonly found in Africa, West Asia, and the Middle
East. It is closely related to St. Louis encephalitis virus which
is also found in the United States. The virus can infect humans,
birds, mosquitoes, horses and some other mammals. The virus is
most frequently found in birds from the corvid family, such as
crows and jays, but can also occur in raptors (owls, hawks,
eagles, etc.) and members of the grouse family. West Nile studies
in crows found significant localized mortality with 100% of
infected birds dying in the year of infection; however, more broad
regional studies and studies on other species are still being
conducted.
"We are still studying how West Nile Virus might impact grouse
populations," Apa explains. "One study has found some grouse may
be resistant to the virus, however studies on captive grouse
exposed to the virus have seen significant mortality rates."
Colorado's dusky grouse (also known as blue grouse) season is
currently underway and a limited greater sage grouse season begins
Saturday, Sept. 9 in some parts of Colorado. Hunters should check
the 2006 Colorado Small Game brochure for details on seasons.
According to Dr. Ken Gershman, Chief of the Communicable Disease
Program at the Colorado Department of Public Health and
Environment, there is no evidence that people can become infected
with WNV from eating infected wild game meat.
"Because of their outdoor exposure, game hunters may be at risk if
they are bitten by mosquitoes in areas with West Nile virus
activity," added Gershman. "If hunters anticipate being exposed to
mosquitoes, they should apply insect repellent to clothing and
skin, according to label instructions, to prevent mosquito bites."
Hunters are advised to use standard precautions when harvesting
birds and all wild animals. Hunters should not harvest or touch
animals that appear sick. Hunters should wear gloves when handling
and cleaning animals to prevent exposure of blood to bare skin.
Hands should be cleaned thoroughly upon completing cleaning of
game and hunters should not smoke, drink or eat while handling
game. All game meat should be cooked thoroughly. The Centers for
Disease Control reports that cooking meat to at least 165 degrees
will kill the virus.
Hunters who find greater sage grouse, blue grouse or raptor
carcasses that are in good condition can assist the DOW by
collecting the carcass for testing. Hunters should only collect
the carcass if they are wearing rubber gloves and have a sealable
plastic bag in which to place the carcass. Carcasses should be
frozen and delivered to the nearest DOW office.
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