From Leslie McInenly

Deer Notes – April 9, 2014

Comment on population goals in southeastern Minnesota

Deer population goal setting in southeastern Minnesota (permit areas 341-349) is almost complete. From April 8 to April 20, 2014, we are seeking your comment on deer population goals recommended by the goal setting advisory team.

Advisory team members listened to public comment at two public meetings and reviewed input collected on questionnaires and through email/mail communication. Additional information considered included hunter and landowner surveys, population and harvest trends, and factors important in deer population management.

To review information and provide comment on the team-recommended goals, visit the Deer Management webpage.

Deer data and the website

The 2013 deer harvest report is now available on the Deer Management Webpage, under the “Resources & Links” tab. During the course of the next year, much of the background data and reports that have been posted to the “Deer Hunting” web page will migrate over to this “Resources & Links” tab.

Anticipated deer population goal-setting plans through 2016

As shown in the map, goals will be revisited for permit areas along the north shore, in north central and east central Minnesota in 2015 (five goal setting blocks) and in six goal setting blocks running from northwestern Minnesota to south central Minnesota during 2016. As planned, management strategies will be implemented to manage populations toward revised goals statewide by fall 2016.

DNR will start collecting information on public desires via mail surveys this year. In addition to this formal process, you can contact us at any time to share your perspectives on deer management.

Winter Severity Index (WSI) and deer management

Winter 2013-2014 has turned out to be a doozie for a considerable portion of the state. As of this writing, nearly all of northeastern Minnesota has been classified as having experienced “severe” winter conditions for white-tailed deer, with the winter severity index (WSI) having reached 180 by April 2, 2014. Some areas have exceeded the WSI level recorded during the tough winter of 1995-1996.

The WSI is a general measure of winter conditions based on the premise that prolonged cold temperatures and deep snow can reduce overwinter survival for deer. In Minnesota, the WSI is calculated by accumulating a point for each day with an ambient temperature less than or equal to 0 degrees Fahrenheit and an additional point for each day with a snow depth greater or equal to 15 inches.

What does this mean for deer and our deer management? Long-term DNR research has demonstrated the relationship between WSI and deer survival. In our research, increasing WSI, and specifically snow depth, had a significant decreasing effect on deer survival. In adult females, the average winter mortality over a 15 year period was less than 10%, but it ranged from 2-30% depending on winter severity. It is important to note that despite similar winter conditions in 1995-96 and 1996-97, the second severe winter had much lower over winter mortality (29% versus 9% observed in the study). This was likely related to lower competition for food, initial mortality of the more vulnerable deer, and the strong condition of non-lactating does entering the second winter. This means that the same WSI value in different years may have a different impact on the population. As with many ecological relationships, it’s complicated.

That said, those winters had a significant impact on the population. However, through fairly restrictive harvest and a few moderate winters (as well as the high reproductive potential deer have), the population and resulting harvest rebounded in just a few years. In 2014, we anticipate taking a similar, conservative harvest approach in areas hardest hit by this winter. DNR staff will be reviewing population and harvest trends and making season management decisions over the next couple of months. Information on our plans for season management will be available this summer.