There’s a group of white-tailed deer (Odocoileus virginianus, Cervidae) that frequently forage in a field behind my house in southeast Michigan. I normally count 12-20 individuals in the group, but over the last few weeks their number has been increasing. The other day I noticed the herd is now at 42 individuals, by far the largest I’ve seen it in the last eight years. 36 deer can be seen in the following short video clip. Six others were behind the tree at the beginning of the video.
My camera’s video capabilities are limited, and this shot isn’t zoomed in as far as I would like. I did take a few stills using a slightly better zoom:
The group seems to be composed of does and yearlings of both sexes, though bucks could be present. Bucks shed their antlers following the fall mating season (the rut), and now it’s nearly impossible to differentiate them from females at this distance. Family groups tend to be led by females, but I suspect males could also be taking advantage of the food and cover here.
The group isn’t growing because of new births; fawns won’t be born for several more months. It seems that more individuals are simply coming together for the foraging opportunities in the corn and soybean stubble and the relative safety of nearby trees.
The Michigan Department of Natural Resources states that groups are usually “up to 25 deer,” so 42 animals seems like an uncommonly large congregation. A DNR report from 2006 showed a 15-year increasing trend in deer numbers in the county. At that time the county population was estimated at 20,800 animals, roughly double what it was in the early 1990s. The size of this group may suggest that the county population has continued to grow since 2006, perhaps exceeding the DNR target density of 22 to 26 deer per square mile. This could warrant a change in population management.
While they’re beautiful animals, proper population management is essential for both the welfare of the deer and the safety of people. Food could become scarce if the deer exceed the carrying capacity, leading to starvation. High deer density also fosters the spread of diseases like bovine tuberculosis and chronic wasting disease. Populations left unchecked could result in mass suffering and sudden population crashes from disease outbreaks. In addition, the approximately 20,000 deer in our county lead to about 800 vehicle collisions annually. This is bad news for deer and people alike. If the local population has indeed continued to increase, it’s possible the Michigan DNR will modify its management plan for the next few years. They may increase the number of deer hunting permits in order to keep populations in check.