Considering Minnesota’s wolf population survey, fall youth deer hunting, and a nifty trail cam image
The state’s latest wolf population estimate got me thinking about that always compelling statistical concept know as “margin of error.”
Last week, the Minnesota DNR issued a press release explaining that the state had 2,655 wolves during the 2017-2018 winter. Because the survey’s margin of error was plus or minus about 700 wolves, that makes the latest estimate statistically unchanged from the previous winter’s estimate of approximately 2,856 wolves, according to the DNR.
Now, by my math, 700 wolves represents a fairly substantial 26.3 percent margin of error. We’re certainly not trying to land a rocket on the moon here, or estimate the outcome of the fall midterms, or even balance the Drieslein family checkbook, but 26 percent strikes me as surprisingly large.
From 30,000 feet, the difference between a 15 or 26 percent margin of error doesn’t affect management much. Truth be told, if we’re short 700 wolves, well, we’re still well above the statewide goal. (Minnesota has a wolf population minimum goal of at least 1,600 wolves, and it’s also well above the federal recovery goal of 1,251 to 1,400 wolves.) And if we’re over 700, well, we have U.S. Department of Agriculture Wildlife Services eliminating problem wolves, and frankly, it makes all the more case for a statewide management hunt.
So over- or underestimating the number of wolves in Minnesota by 26 percent won’t prevent the sun from rising tomorrow. That didn’t stop the wolf protectionist group Howling For Wolves last week from issuing a release highly critical of the DNR’s population estimate methodology.
But that margin of error number still got me thinking: What’s the margin of error for important game species like moose and white-tailed deer? An entire recreational economy depends on white-tailed deer hunting, and I hope the number for that species is lower than 26 percent.
I chatted with Lou Cornicelli, DNR wildlife research manager, about that question. With wolves, the DNR does not conduct a traditional aerial survey for estimating the population. The agency does track radio-collared wolves and estimates their pack sizes and territories, and it uses that data to extrapolate a winter wolf range population size.
Estimating wildlife populations is difficult, Cornicelli said, because animals are spread across a huge area, and they move frequently. It’s certainly possible to lower margin of error, but survey (or polling) costs increase exponentially as you approach zero margin of error – a statistical impossibility.
“You can refine the error, but it ends up costing a lot more,” Cornicelli said. “Do you want to double the cost to increase precision by some amount, say 5 or 10 percent, when at end of the day, if we have plus or minus 400 or 700 wolves, it doesn’t really change how we manage the species?”
With white-tailed deer, the agency shoots for a 20-percent margin of error within its 128 permit areas, which it estimates numbers via aerial survey across the transition zone of the state. Harvest, winter severity, and other research-derived estimators factor into the population model. The DNR doesn’t have a strict statewide estimate, though it’s probably around 1 million deer, Cornicelli said. The Office of Legislative Auditor 2016 report on deer population management breaks it down in detail if you’re interested (Page 19).
By the way, the DNR remains optimistic about deer hunting in Minnesota this fall, which already is underway. Reminder that hunters in portions of southeastern Minnesota can once again harvest antlerless deer in an early antlerless-only season from Thursday, Oct. 18, to Sunday, Oct. 21, in deer permit areas 346, 348, 349 and 603 in Fillmore, Houston, Olmsted and Winona counties, according to the DNR. The early antlerless season coincides with the four-day special youth deer season. Find more information at mndnr.gov/hunting/deer.
And another by the way: My dad, Robert L. Drieslein, of rural Winona County, sent me this image of a white-tailed buck that one of his trail cameras picked up over the weekend. Dad wondered if the buck was suffering from a hernia. I asked co-workers and Cornicelli what they thought. Minnesota Outdoor News Editor Tim Spielman said he’s seen deer around his north country yard a time or two with what appear to be fatty deposits hanging from their neck or underbelly. Cornicelli didn’t rule out hernia but wondered if it might be a good old pus-filled sack. “You see those quite a bit, but they’re usually up towards the brisket,” he said via email.