Wisconsin wildlife is facing a critical period as late winter conditions test the limits of their resilience. A recent blizzard, dubbed “Iona,” delivered record-breaking snowfall across the state in mid-March, exacerbating the challenges already present for animals preparing for spring. While the storm has passed, the lingering effects – particularly for species already stressed by dwindling food supplies – are a concern for wildlife biologists.
The timing of the blizzard was particularly unfortunate. Non-migratory animals like white-tailed deer and wild turkeys are at their most vulnerable in late winter, having depleted their fat reserves throughout the colder months. Migratory birds, arriving early to take advantage of emerging food sources, found those resources buried under feet of snow. Understanding these seasonal pressures is key to assessing the impact of events like Iona and informing future conservation efforts.
Iona dumped 33.2 inches of snow on Sturgeon Bay, 30.9 inches on Wausau, 27 inches on Appleton, 21.5 inches on Marshfield, 24 inches on Stevens Point, and 16 inches on Oshkosh, all establishing new records, according to the National Weather Service. The National Weather Service provides ongoing updates on weather patterns and records across the country.
The heavy snowfall, coupled with winds exceeding 50 miles per hour in some areas, disrupted travel and closed schools across much of the state on March 16. But the impact extended far beyond human inconvenience. Flocks of sandhill cranes, Canada geese, and smaller birds like fox sparrows, American robins, killdeer, and woodcock, which had begun arriving in Wisconsin, suddenly found their food sources inaccessible.
Assessing the Winter’s Impact
Fortunately, the winter of 2025-26 had been relatively mild throughout February in most of Wisconsin, meaning many animals were in reasonably solid condition when the blizzard struck. Greg Kessler, a wildlife biologist with the Wisconsin Department of Natural Resources (DNR) based in Brule, noted that non-migratory animals appeared to be coping well. “I’ve yet to identify a dead deer or turkey due to starvation, and neither has any of the loggers I’ve talked to,” Kessler said, adding that predation remains a factor, but the deer and turkey populations seem to be holding steady. Kessler, who has been with the DNR for 33 years, conducts regular field work in Douglas County.
The DNR utilizes a metric called the Winter Severity Index (WSI) to gauge the impact of winter conditions on deer populations, particularly in northern Wisconsin. The index assigns points based on the number of days with temperatures below 0°F and the number of days with snow depths exceeding 18 inches. A WSI score below 50 indicates a mild winter, 50-79 is moderate, 80-99 is severe, and over 100 is very severe. More information about the DNR’s deer management program, including the WSI, is available on the agency’s website.
Regional Variations and Long-Term Trends
As of the end of February, most of Wisconsin was experiencing a mild winter according to the WSI. However, portions of northern Wisconsin, including Ashland and Iron counties, were nearing or at a “severe” level. Kessler’s area in Douglas County registered a WSI of 41, but he anticipates that number will increase by 8 or 9 points due to the blizzard and subsequent weather events in March. Despite the increase, he remains optimistic. “Still, things are looking good by historical measures,” he said.
The winter of 2013-14 remains the most severe on record, with a WSI of 143. In contrast, recent years have seen milder winters, with scores of 55 in 2021-22, 69 in 2022-23, 10 in 2023-24, and 32 in 2024-25. These milder conditions have contributed to a growing deer population, reaching a record high of 1.82 million in the DNR’s 2024 post-hunt estimate.
Keith McCaffery, a retired DNR deer biologist, observed about 12 inches of “sagging” snow near his home in Rhinelander on March 20. He expressed cautious optimism, stating, “If this keeps up, and we don’t get hit with something terrible, I expect the deer and other wildlife will be doing just fine.”
The DNR has not received any reports of unusual or mass wildlife deaths following the blizzard. This contrasts with a January storm on the East Coast, where prolonged subfreezing temperatures and frozen ground led to the deaths of over 170 woodcock in Cape May Point, New Jersey, as reported by the Cape May County Herald. The Ruffed Grouse Society/American Woodcock Society documented birds struggling to find food in the frozen conditions.
Looking Ahead
Mark Kakatsch, vice president of the Wisconsin Wildlife Federation, noted seeing flocks of geese flying south after the blizzard, likely seeking more favorable conditions in Illinois. Those that remained faced a few challenging days before temperatures rose and the snow began to melt.
The WSI data will be used by the DNR and its Citizen Deer Advisory Councils in the coming weeks to inform recommendations for antlerless deer quotas and hunting season frameworks for the 2026-27 season.
Trout Season Opens April 4: In a related development, the 2026-27 Wisconsin inland trout harvest season will open on April 4, a month earlier than in previous years. The DNR cites strong trout populations and a desire to provide more fishing opportunities during a traditionally closed season. The change received widespread public support at the 2025 spring hearings. The season will run through October 15. This earlier opening does not apply to inland lakes and ponds, which will still open on the first Saturday in May (May 2 in 2026). Detailed information is available in the Guide to Wisconsin’s 2026-2027 Trout Fishing Regulations.
Wisconsin’s wildlife has demonstrated resilience in the face of challenging winter conditions. Continued monitoring of the WSI and careful management of hunting seasons will be crucial to ensuring the health of these populations in the years to come. The DNR will continue to assess the long-term impacts of the blizzard and adapt its strategies accordingly.
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