An outbreak of disease has killed hundreds of deer in Southeastern Wisconsin just as hunters have begun to take to the forests and fields for the state’s celebrated deer season.
The Wisconsin Department of Natural Resources suspects that epizootic hemorrhagic disease (EHD) has killed at least 1,200 deer in Wisconsin as of Tuesday, including more than 900 in Washington County. The body count is enough to make it the largest such outbreak in Wisconsin history.
EHD is a fairly uncommon illness to see here. The virus that causes it is spread through a species of midge (aka noseeum), a small, semi-aquatic fly that thrives in hot, humid climates more common in Southern and Western states. EHD has shown up in the Midwest sporadically, though, including six smaller outbreaks in Wisconsin since 2002. According to Steffen Peterson, a DNR senior wildlife biologist for Washington and Ozaukee counties, Wisconsin is just within this midge’s northernmost range. The disease does not spread from deer to deer, and people are not affected by it.
The first deer to test positive were found near Richfield and West Bend, near bodies of water. EHD causes major internal bleeding and a high fever. The carcasses of deer killed by the virus are often found in or near water, as the animals die attempting to cool their body temperature.
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Impact on the Hunt
Wisconsin’s archery and crossbow deer hunting seasons opened Saturday, so how will this major die-off impact the harvest? Well, unless you’re within a 20-mile radius of Washington County’s outbreak, it probably won’t.
“Certainly folks that hunt in this core area are likely going to experience something, reduced numbers in the woods,” Peterson says. “They may not see the deer that they’re used to seeing while they’re out in their tree stand.”
The DNR is not adjusting any of its hunting rules this season due to the outbreak, unless a major emergency happens.
And the herd, at least in Washington County, is well positioned to rebound from the outbreak. The county’s deer population has increased 42% over the last five years, jumping to about 16,000. The county’s deer advisory committee has agreed that population reduction is necessary to maintain balance and reduce urban nuisances – car crashes, crop and property damage, etc. – and that has not changed since the outbreak.
The DNR’s “data crunchers in Madison” have determined that a neutral harvest – the amount of antlerless or female deer that need to be killed to level off the population – is about 3,700 a year, Peterson says. Washington County averages about 2,000 antlerless kills a year.
The deer population across Wisconsin is incredibly robust and will likely rebound quickly after this outbreak, Peterson says. The DNR wildlife health team is working directly with states that handle a higher number of yearly EHD outbreaks, and even populations nearly decimated by the virus tend to bounce back – and with increased immunity to the virus. We may even see ecological benefits from this natural culling of the herd.
“It’s certainly not how you’d want to see population controlled – it’s a pretty devastating disease,” Peterson says. But, “ecologically speaking, [we] actually may see some benefits. Forest regeneration [is] really challenging in this part of the state.” A decline in the deer population will make it easier for plants to fully regrow.
Looking Ahead
The good news is that EHD is only transmittable from midge to deer. While not much is known about how the virus works or how it’s spread, we do know that when an infected deer dies, the virus dies with it. Unlike chronic wasting disease, a degenerative disease of the brain caused by a prion that has caused widespread concern in Wisconsin, EHD does not spread among deer. There is no risk to humans, and the venison of a deer infected with EHD is safe to eat.
And this outbreak’s clock is ticking: Midges are killed by a hard frost.
Will EHD in Wisconsin become the new normal? Peterson says that remains to be seen. Climate change, causing increasing temperatures and humidity in the state, may create the perfect habitat for the midge, leading to more frequent outbreaks of EHD. Peterson says he’s hoping for an early freeze to choke the virus out before it continues to spread through the state, but he remains optimistic overall and for this year’s hunt.
“I had a conversation today where an individual said, ‘Well, it’s not a reason to hang up your gun or hang up your bow. You can still get out in the woods,'” Peterson says. “Don’t get discouraged. I fully expect a quick rebound, given how robust our herd is in this part of the state.”
If you find a deer you suspect has died of EHD, or witness a live animal exhibiting strange behavior (infected deer often froth at the mouth and lose movement of their hind legs), call the Wildlife Switchboard at 608-267-0866 or email DNRWildlifeSwitchboard@wisconsin.gov to leave a report. The DNR asks for reports to include the date of observation, number of deer involved, body condition of the deer or carcass, exact location and your contact information for further questioning. Click here for more information from the DNR about the current outbreak.
