CWD Setting Deadly Records in Wisconsin’s Best Deer Habitats

   Alice Roosevelt, the sharp-tongued eldest daughter of Theodore Roosevelt, famously said, “If you can’t say something good about someone, sit right here by me.”

   Would Alice have invited us to sit beside her to badmouth chronic wasting disease? Probably not. Few people do.

   Even so, Wisconsin’s 2025 deer seasons proved we still can’t wish away CWD. The Department of Natural Resources found a record 2,022 CWD cases in a record 41 counties for a record detection rate of 11.2%, up from 10.3% in 2024 and 7.7% in 2021.

   The DNR learned all that by testing 18,046 hunter-killed deer the past 4½ months, which was the hunting community’s best sampling effort since submitting 18,917 in 2020. In contrast, because of lawmaker-suppressed sampling from 2009 to 2017, hunters those years submitted less than 10,000 samples annually.

   Still, those 18,046 samples came from only 5.3% of the 338,685 deer registered during 2025’s hunts. The news grows worse for Wisconsin’s top 12 CWD counties, where the combined CWD infection rate rose from 22% in 2024 to 23.6% in 2025. Their individual CWD rates were Richland, 36%; Sauk, 33%; Lafayette, 31%; Columbia, 27%; Green, 27%; Iowa, 23.5%; Grant, 21%; Dane, 20%; Juneau, 16%; Vernon, 14%; Adams, 13%; and Crawford, 13%.

     When Doug Duren, far left, organized this late-season hunt in January 2009 on his family’s Richland County farm, the county’s CWD infection rate was less than 1%. Its infection rate passed 10% in 2017, 20% in 2021, and 30% in 2023. It stands at 36% after the 2025 deer seasons.     — Patrick Durkin photo

   Tests in 2025 also found CWD in wild deer for the first time in Clark and La Crosses counties, boosting Wisconsin’s CWD-infected counties to 51, or 71% of its 72 counties. Since documenting its first three CWD cases in February 2002, Wisconsin has confirmed 16,383 cases in wild deer.

   Wisconsin documented all those sick deer even though testing has been fully voluntary since 2012. As a result, over 70% of hunters have never submitted a deer for testing. When asked why they forsake the free tests, hunters often shrug and say, “Ignorance is bliss.”

   But willful ignorance doesn’t slow CWD any better than wishful thinking. Consider Iowa County, a few miles west of Madison: Just over half (53%) of its 767 square miles is deer habitat, and yet it has generated 4,720 (29%) of Wisconsin’s CWD cases. And now its herd is declining.

   In 1995, Iowa County’s gun-hunters killed a record 4,738 bucks. But during the November 2024 nine-day season, they killed 916 bucks, an 81% decline. That’s also 51 fewer than their forebears shot in November 1971 when bagging 967.

   Yes, 53 years had passed since Iowa County’s gun-hunters last killed less than 1,000 bucks. They fared even worse during the November 2025 gun season, shooting 894 antlered bucks. The last time they shot less than 900 bucks was 1970 — 55 years ago — when they killed 878.

   That’s no fluke. A year ago, after a decade-long study involving 1,250 GPS-collared deer in northern Iowa County, the DNR documented that CWD kills more female deer in highly infected areas than hunters kill with bullets and arrows. The study found that once CWD infects at least 29% of an area’s female deer — which is the case for much of Iowa, Sauk, Richland and western Dane counties — more deer die annually than reproduction can replace.

   Still, deer haven’t vanished in those counties, partly because their numbers grew artificially high after 2011. After that season, DNR biologists estimated the herds in Dane, Sauk, Iowa and Richland counties averaged 16,740 deer following nearly a decade of aggressive efforts to reduce the herd and slow CWD. The 2011 CWD rates were 4.6% for Dane, 8.6% for Iowa, 3.2% for Sauk, and 1.5% for Richland.

   Infection rates likely would have been even lower, if not for political interference. After the 2006 deer season, Rep. Scott Gunderson, R-Waterford, then chairman of the Assembly’s Natural Resources Committee, called CWD-control efforts a “boondoggle.” He then slashed the DNR’s CWD budget and testing programs in 2007, and forced the agency to start backing off on earn-a-buck rules and October antlerless-only gun-hunts.

   Next, in 2011, then-state Sen. Tom Tiffany, R-Minocqua, pushed through legislation that outlawed earn-a-buck and ended gun-deer hunting before November’s nine-day season.

   Deer herds and CWD soon boomed. By 2020, deer numbers in those four counties rose 92%, on average, to 32,139 deer; and their respective CWD rates hit 17% in Dane, 29% in Iowa, 26% in Sauk and 19.6% in Richland.

   Deer numbers in Dane, Iowa, Sauk and Richland counties then fell 13% by 2024 to 28,035, on average. Those counties’ 2024 CWD rates were 17% in Dane, 25% in Iowa, and 33% in Sauk and Richland.

   What were those rates before politicians slashed CWD funding and monkey-wrenched the deer-management program? CWD rates from 2002 to 2011 varied between 1.1% and 4.6% in Dane, 1.3% and 8.6% in Iowa, 0.1% and 3.2% in Sauk, and 0.15% and 1.5% in Richland.

   And after DNR Cathy Stepp made “passive management” agency policy in 2014, the DNR could only take notes as CWD spread faster than ever. Richland County now leads the state with a 36% infection rate. And with 81% of its landscape defined as “deer range,” Richland County features perhaps Wisconsin’s most fertile, deer-rich, heavily wooded habitats.

   Based on CWD trends in that region, once detection rates hit 4.5% to 5.5%, CWD will infect 10% of deer within three to four more years and 20% after another three to four years. It’s unlikely CWD will behave differently in much of Grant, Vernon, Crawford, Juneau, Adams, Marquette, Monroe, Buffalo, Trempealeau and even La Crosse counties the next decade. Deer habitat covers at least 67% of all those counties’ landscapes.

   Folks are watching Buffalo County closely, given its No. 1 rank in the Boone and Crockett Club’s record book with 165 typical and nontypical white-tailed deer. CWD was first documented there in 2022 when four of 238 deer tested positive, or 1.7%. The rate dipped to 0.9% when hunters tested 420 deer in 2023, but jumped to 2.5% in 2024, and then 4% in 2025 when 16 of 393 deer tested positive.

   Realize, too, that if 4% of the 5,789 deer killed last fall in Buffalo County had CWD, its hunters took home roughly 240 sick deer. Likewise, even though only one of 154 deer (0.6%) tested in La Crosse County had CWD, roughly 23 of its 3,886 deer killed by hunters last fall also carried it.

   Yes, CWD spreads and infects at different rates based on soil quality, deer densities, woodland cover, human development, agricultural practices, and the habits and travels of individual deer. Therefore, parts of Dane, Iowa, Sauk and Richland counties still produce big bucks every year. But CWD will keep reducing those herds and their older deer.

   Just ask Mike Purnell, who owns 700 acres in Richland County with his brother Lloyd. Their four properties seemed CWD-free 20 years ago, but eight of the 14 bucks (57%) they shot in 2025 had CWD. “Deer numbers are way down, and big bucks are nonexistent,” Mike Purnell said. “It’s a new world because of CWD.”

   And just imagine how things will look after another 24 years of CWD.