An outbreak of epizootic hemorrhagic disease, or EHD, has hit white-tailed deer populations hard in
some areas of Montana this hunting season. The disease, which
causes fever, organ failure and internal hemorrhaging, has
contributed to massive die-offs of deer in the central and eastern
portions of the state.
“This year we have heard reports of lots of dead deer in regions
four, five, six and seven,” said Ray Mulé, a wildlife manager for
Montana, Fish, Wildlife & Parks in Billings. “I would say we
have seen die-offs in some areas that are at 50 percent or higher.
When we start seeing those kinds of numbers, it is a severe
outbreak.”
EHD is a virus transmitted to
white-tailed deer by biting gnats. This year’s wet spring and late
fall created excellent conditions for large numbers of the tiny
insects to hatch and linger late into the season.
Mulé said the intensity of the outbreak has varied depending on
area. He said the number of deer dying in a particular location
could be due to environmental factors or the density of the deer
population.
“EHD is not spread deer to deer, so you see more die-off in
areas that have more deer to start with,” Mulé said.
Neil Anderson, FWP Region 3 wildlife
lab supervisor, said EHD has not impacted
white-tailed deer populations in southwest Montana.
“Usually we don’t find EHD out here
for some odd reason,” Anderson said. “It gets to the Rocky Mountain
Front and it doesn’t seem to come any further. I think there is
evidence of the midges around, but something environmentally may
cause the virus not to do that well or the midges aren’t very good
at transmitting.”
EHD is a seasonal disease that occurs
mostly during late summer and early fall, but this season’s late
freezing temperatures helped carry the outbreak well into October.
The disease dissipates with the onset of freezing temperatures that
kill off the gnats.
Once a white-tailed deer is infected with the virus, the animal
has little chance of survival. Mulé said up to 90 percent of
white-tailed deer infected by the virus die. The virus incubates
for seven to 10 days. Once it matures it typically results in death
within 24 hours.
Hunters headed east may discover carcasses of dead deer near
water and around riparian habitats. The animals may move to water
to drink in response to depletion in body fluids caused by
hemorrhaging. White-tailed deer infected with the virus have also
been found immersed in water, perhaps in an effort to control
fever.
Mulé said the virus is not transmissible to humans. He said
eating venison or handling game meat from white-tailed deer
infected with EHD is not a danger. Mulé
said the virus may be transmissible to mule deer, elk and antelope,
but those species have a much greater resistance to the virus.
“Unfortunately, there really isn’t anything we can do to combat
EHD,” Mulé said. “The disease is
widespread across the whole United States. When it erupts, you know
it is going to erupt. You just have to ride it out.”
On a positive note, Mulé said white-tailed deer are a prolific
species. Even though they might take a huge population hit this
season, they tend to rebound rapidly.
The EHD outbreak has been particularly
tough on a region of the state already beleaguered by a harsh
winter and widespread flooding which hit antelope and mule deer
populations hard. In some hunting districts, antelope numbers are
down 70 percent from 2010 estimates.
In response, FWP dramatically
decreased the number of tags available in some districts to give
those species time to recover.
Despite the setbacks, Mulé said hunters are still heading east
to fill their tags.
“People that come out here are typically hunting multiple
species,” Mulé said. “If there are lower numbers of mule deer and
antelope and the white-tail on top of it, people might think twice,
but we haven’t heard from people saying they aren’t coming.”
