1938 deer exclosures

 

During the 1930s,’40s, and early ‘50s there was considerable interest in the impact of deer browsing on tree and shrub growth. Rampant logging and numerous large wildfires earlier in the century had created nearly ideal deer habitat. Also, very mild winters during much of that time also contributed to major deer population increases. According to some old hunters, it was not a matter of if you bagged a deer; but which deer did you want?

In order to evaluate browsing pressure, numerous fenced deer exclosures were constructed (some were also fenced to keep out snowshoe hare). Typically, they were about 10 yards by 10 yards square and fenced to 8 feet high. These permitted early wildlife biologists to measure how much new browse growth was produced each year and how much was removed by browsing through the winter. Other studies at some of these sites involved how much of each year’s new growth could be removed year after year and the plant survive. One such study here found mountain maple (an abundant and preferred deer food) withstood seven years of 100 percent removal with only 1 of 9 plants dying.

Many of these exclosures were built in (at least) northeastern Minnesota, northern Wisconsin, and the Upper Peninsula of Michigan. At least five were located here in Cook County. There is/was one in a cedar stand on Leveaux Mountain and four in the Jonvik Deer Yard (a heavily used deer wintering area along the North Shore that extends from Cascade River almost to the Caribou Trail.

When I took the D.N.R. Wildlife Manager position at Grand Marais in 1969, The Regional Wildlife Supervisor in Grand Rapids gave me a map marked with the approximate locations of these exclosures. All were quite easy to find except the one marked “1938”. I spent at least two days searching that large cedar stand before finding it. I could not see it until I was only a few feet away. Then I marked a path (following deer trails) until I got to a location I recognized.

One day in the very early 1970s I noticed an elderly fellow looking at the shrubs by an exclosure near Hwy 61 and Spruce Creek. It turned out to be Larry Krefting, one of the early wildlife biologists who had been involved with the exclosure studies in all three of the states mentioned above. He was retired but still actively studying conditions at exclosures. I learned a lot from him beyond what had been written about the studies.

A few years later, a professor I knew from Lakehead University in Thunder Bay asked about bringing down a class of students to see what a classic example of a deer yard looked like. They did not have large deer yards there and he felt the students should experience being in one. That spring Larry and I took them to a couple of the exclosures where Larry talked about the early history of the studies, and I covered the more recent activities and deer studies. Young folks don’t want to just stand around listening (I don’t either). Therefore, we took them on a bit of a hike through the deer yard and farther up the hill to the 1938 exclosure.

In 1938, a North-South oriented rectangular area about 10 yards by 30 yards (or more) was clear-cut in the cedar stand. A standard 10-yard by 10-yard square deer and hare proof exclosure was erected in the middle one-third; that left a similar size unfenced area to both the north and south of the exclosure. This site gave the students a very clear example of what heavy browsing pressure can do over about a 35-year period. There were a few small spruce and balsam scattered through the two unfenced areas and several small stems of browse (all very heavily browsed). The fenced area was very crowded with 20- to 30-foot-tall deciduous trees and shrubs; only a couple of very shade-stunted conifers were in it.

For about the next 25 years, a class of Lakehead University students got the same tour each spring. Unfortunately, Larry passed away after the first several years, so I took over presenting the historical information too. As time passed, plant succession progressed within the exclosure. Gradually many of the deciduous trees and shrubs were replaced with spruce, balsam, and some cedar. The unfenced areas contained more small conifers and the older conifers in them had become taller.

As should be expected, time took its toll on the exclosure posts and fencing. In 1991, Dave Ingebrigtsen (D.N.R. Wildlife Habitat Specialist) took on the task of renewing the structure with new posts and fencing. Rather than risk damaging the vegetation (both inside and outside of the exclosure) by removing the 53-year-old material, the new materials were installed right against the existing exclosure.

I had not been to the site since I retired in 2000; so, in the spring of 2021 I returned to it, accompanied by Shawn Perich and Nancy Hansen (D.N.R. Area Wildlife Manager at Two Harbors). Not only did I want to visit one of my favorite spots again, but I also felt there should be more people who know where it is and how to find it.

The now 30-year-old materials are still in very good condition. The exclosure now contains mostly conifer trees (including a number of cedars) with only a few deciduous stems left. The areas outside of the exclosure now have quite a few conifer trees of various sizes. There are a few more deciduous browse stems, but they are heavily browsed even though the current deer population is very low. It is still a very good example of what deer browsing can do when there is too little browse available, or the population is too high.

As we get older, I think it is quite common for one to recall fond memories of the past. As I stood there, I realized that I also knew some of those Canadian students during their professional careers and they, too, are now retired.