Thursday, 9:00 AM. 13 degrees, wind W, light. The channel is obscured by lake smoke, and light snow is falling with a current accumulation of 2”. The sky is overcast and the barometer predicts partly cloudy skies.
There are of course many environmental factors that can affect wildlife populations. Snow depth is a strong factor in deer survival, deep snow keeping deer “yarded up” in heavy cover, limiting access to browse and thereby causing starvation and limiting fawn production. It also makes deer more susceptible to predation. Bad weather when fawns are born or are very young limits reproductive success. Overpopulation of any species can damage and limit food supply and increase disease (overpopulation has been a possible factor in chronic wasting disease, which has been limited to the southern portion of the state to this point). Interspecific competition for food can be a factor, but is not in the case of Wisconsin deer, which currently have little competition for their food sources from other animals. Snow depths in recent years seem little changed from the usual in the northern portion of the state, and recent spring weather, although cool, does not seem to have been extreme.
That pretty much leaves predation as the suspect in the decline in the northern deer herd. The 2009 statewide deer season harvest, according to the recent DNR figures, is the lowest in twenty-seven years, and was particularly low in the northern portion of the state. The decline has been rapid, a thirty- percent decline from 2008, which was itself a twenty-percent decline from 2007. Which predators might be most suspect in such a rapid decline? There are quite a few. Since the reintroduction of the timber wolf a few years ago the Wisconsin wolf pack has increased exponentially, the DNR estimating there are now 700 wolves in Wisconsin (given the inability of the DNR to accurately predict the decline of the deer herd, one might wonder at its accuracy in estimating the size of the wolf population, which one might suspect may be even larger than estimated). It is estimated a mature wolf will kill about fifteen adult deer per year, a considerable predatory factor. Less appreciated is the fact that an adult black bear will take on average four fawns a year, and the Wisconsin bear population according to the DNR is approximately 36,000. Bayfield County has the highest population of black bears in the state as evidenced by its annual bear season kill of over 300 animals. One amateur trail camera outside a local bear den allegedly recorded a sow bringing fourteen fawns to its cubs this spring, although this is hearsay. Then there are bobcats, which can bring down an adult deer, as well as coyotes. Coyotes may or may not kill a lot of deer, although they certainly harass them. During the 2008 season I seldom saw deer tracks in the snow that were not covered with coyote tracks. This year, amazingly, I heard no coyotes howling at sunset, and prior years they were absolutely raucous, and I saw few tracks in the snow. Since wolves kill and drive out coyotes in their territories, I am wondering if locally we have had a big increase in the wolf population, although I personally did not see any while hunting. And, although the DNR denies it, there have been a number of pretty creditable reports of cougars in the area again this year.
But, of course, the main predator of deer in Wisconsin is man, and hunting seasons have proliferated to the point where it seems the deer seldom get a chance to rest or recover. The archery season starts early, then there is a youth hunt, the regular gun deer season, a muzzle loader season, and a late doe season. The recent deer seasons have concentrated on the taking of does to reduce herd reproduction, with virtually unlimited doe tags available in many management units. The goal of the DNR has been to drastically reduce the size of the Wisconsin deer herd, and it seems they have been quite successful. Next I will offer some probable reasons for this, and attempt to analyze the current situation.
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