Agassiz deer survey shows big decline
Deer populations in Agassiz National Wildlife Refuge and surrounding state lands in northwest Minnesota declined dramatically from last winter, results from a recent aerial survey show.
According to Gregg Knutsen, biologist at Agassiz, the aerial survey conducted Monday produced an estimated 600 whitetails, down from 1,460 last year. That breaks down to a density of 5.6 deer per square mile, Knutsen said, far below the refuge’s goal of 15 to 20 deer per square mile.
“We knew from the planning we weren’t seeing many deer, but when you crunch the numbers and see that kind of decline, it’s definitely an eye opener,” he said.
Last year’s winter, which extended into May, likely played a role in the extent of the decline, Knutsen said; many of the deer counted during last year’s survey may have perished before winter finally ended.
“Last year, the winter simply didn’t end,” Knutsen said. “We try to conduct surveys as late as possible while still having good snow cover to capture as much winter mortality as we can.
“Last year, we didn’t capture the full extent of the winter mortality. We came up with an estimate, and winter continued for another two months. We certainly lost deer, so last winter’s estimate was probably a little higher than what we truly saw” going into last fall’s hunting season.
Knutsen said he compared this year’s survey results to the severe winters of 1995-96 and 1996-97, and the trend is similar. During the winter of 1995-96, the survey tallied 1,290 deer, an estimate that plummeted to 455 in the 1996-97 survey.
“You hear a lot of people comparing this winter, severity-wise, to a couple of those winters, so when you look at what happened back then and the conditions we’ve had this winter, it’s not necessarily all that surprising,” he said.
It’s also possible, Knutsen said, that standing corn on private lands west of the refuge and outside of the survey area have attracted deer that can’t be counted. The survey covers 108 square miles of Agassiz refuge and adjacent portions of Eckvoll and Elm Lake wildlife management areas, which the Minnesota Department of Natural Resources manages.
Knutsen said deer densities in the survey area last hit refuge goals in the winter of 2009-10.
“It’s one of those things,” he said. “You get a couple of hard winters and regardless of how you structure a deer season, it’s hard to grow a deer herd.”
Knutsen said he didn’t see any signs of deer mortality during the survey, but the crusted snow conditions that have developed since the recent warm snap are difficult for whitetails.
“Conditions like this with the snow and overall tough conditions on deer create a situation where the wolves are certainly going to be able to take advantage of things, and deer mortality from wolves is higher this year than other years,” he said.
On the plus side, Knutsen said, moose estimates during this year’s survey were stable, following a trend that’s been seen the past five years. This year’s moose estimate was 46, Knutsen said, down from 65 last year; there’s a lot of fluctuation in numbers when the sample size is so small.
“It’s encouraging to see they seem to be maintaining,” he said. “We saw multiple calves this past May, so we’ll see. We’ll continue to try to keep tabs on them and stay abreast on what’s going on.”
They survey also documented a single wolf and a bear hibernating in a den above the ground, Knutsen said.