The Wisconsin of Department of Natural Resources this week released its chronic wasting disease sampling numbers, which paint a picture of a slow-growing plague, and scary-high prevalence rates in some counties.
The spread of CWD is an old story in Wisconsin, and it’s one that many deer hunters tend to tune out. After all, the DNR’s harvest numbers and the overall deer population estimates both look great (more on this in a minute). However, a deeper dive into county-level data shows what could be the start of a troubling trend.
Here’s a quick look at some of the key numbers from Wisconsin:
- 75 percent of counties in the state have had positive CWD detections
- 17,399 deer were sampled in 2024
- 1,786 samples tested positive
- 89 percent of positive tests came from the Southern Farmland Zone
- The Southern Farmland Zone had an overall prevalence rate of 20.6 percent
- Richland, Sauk, and Iowa counties have the highest prevalence, with up to 50 percent of adult bucks testing positive in some areas
The Good News
Despite the spread of CWD, deer hunting in Wisconsin is still pretty great. As Milwaukee Journal Sentinel writer Paul A. Smith reported, last season 13 counties hit their highest buck harvest numbers since the 1980s.
Badger State hunters tagged 321,844 deer last season, which is an 8 percent increase from the previous season.
And even with all of the concerns over wolves and tough hunting in some northern parts of the state, the DNR estimates that the statewide deer population is 1.825 million, which is the highest in recent history.
It would be easy to look at these rosy numbers and conclude that CWD doesn’t have much of an impact on deer hunting. The disease has been spreading through the state for decades. And yet, overall, there’s still plenty of deer, good hunting opportunities, long seasons, and big bucks.
The Bad News
The story gets a lot gloomier, however, when you focus on counties in the Southern Farmland Zone, where CWD has higher prevalence rates.
The five counties with the highest prevalence rates all saw significant harvest declines in 2024 compared to their five-year average. The most stark example was Iowa County, which saw a 25 percent decline in buck harvest and a 30 percent decline in doe harvest. That county had a prevalence rate of 25 percent.
| County | CWD Prevalence Rate (%) 2024 | Buck Harvest vs 5-year Average | Doe Harvest vs 5-year Average |
| Richland | 33.3 | -14.2% | -9.9% |
| Green | 30.6 | -9.5% | -16.8% |
| Sauk | 26.8 | -6.3% | -21.1% |
| Lafayette | 26.2 | -21.7% | -9.8% |
| Iowa | 25.2 | -25.5% | -30.0% |
| Columbia | 21.7 | 2.3% | 7.0% |
| Grant | 21.6 | -5.8% | -10.8% |
| Rock | 19.9 | 6.1% | 8.2% |
| Dane | 17.2 | -9.9% | 4.3% |
| Walworth | 12.9 | 11.5% | 30.7% |
| Crawford | 11.1 | 7.3% | 3.1% |
| Vernon | 9.8 | 1.30% | 8.0% |
| Kenosha | 8.3 | -2.1% | -3.0% |
| Jefferson | 7.0 | 21.2% | 10.7% |
| Dodge | 2.4 | 31.6% | 11.7% |
| Racine | 2.2 | 3.3% | 40.8% |
| Waukesha | 1.9 | 0.9% | -9.8% |
| Washington | 0.1 | 13.8% | 3.6% |
| Milwaukee | 0.00 | -4% | -70.0% |
| Ozaukee | 0.00 | 4.20% | 10.9% |
Since chronic wasting disease is almost always fatal to the deer it infects, it’s possible that the disease is the reason hunters in those counties are starting to see a decline in harvests. Recent research from the DNR shows that CWD likely negatively impacts survival rates. Researchers studied wild collared deer that were infected with CWD and non-infected deer going back to 2017.
Their study found that “adult does that were infected with CWD had half the annual survival rate of healthy deer, at 41 percent compared to 83 percent, respectively. For adult males or bucks, the survival rate was far lower among infected deer at 17 percent compared to 69 percent,” according to reporting by Wisconsin Public Radio.
What’s scary for hunters in the rest of the state — and any state that is struggling to contain CWD — is that prevalence rates can grow quickly. For the most part, those top five counties have seen CWD prevalence rates double in the last 10 years.
As any good logician, or skeptical Wisconsin deer hunter will tell you, however, correlation does not imply causation. It’s impossible to say for certain that the harvest declines are caused by CWD.
For example, because Wisconsin does not have county-level hunter participation data, we don’t know if hunters are moving out of these high-prevalence areas. After all, who would want to hunt in an area where there’s a 30 percent chance that the deer you shoot is infected with CWD — and up to 50 percent if you’re targeting mature bucks.
Read Next: Would Banning Doe Harvests Help Save Northwoods Deer Hunting?
What This Means for Hunters
CWD is getting worse in Wisconsin, but not every county needs to suffer the same fate as Richland or Iowa.
“Although we have detected CWD in new areas of the state in recent years, many of these areas are at a low prevalence rate, and opportunities still remain to slow the spread and growth of the disease statewide,” Erin Larson, DNR deer herd health specialist, said in the agency’s press release.
In other words, hunters need to embrace the idea that we might need to harvest more deer in certain areas in order to keep herds healthy overall.
Plus, the state’s 15-year CWD management plan will expire this year, according to WPR. This means that state wildlife managers and hunters will get another crack at managing deer herds to prevent the spread of this disease. I hope we find the resolve, and the resources, to do it.
Read the full article here
