White-tailed deer can be seen year-round in the Arb. They are a familiar resident of woods and meadows all across the Eastern United States. When one encounters deer in the Arb they seem to gambol off playfully. But come fall, the violence of the rut shatters the illusion of playfulness. Furthermore, the familiar deer is only familiar because of drastic overpopulation that makes it a major management concern for Arb staff.
The shortening days of late September and October bring many changes to the Arb. The vegetation turns from a lush green to a rustic brown, and then the landscape becomes more visible each day as the obstruction of leaves are shed from their hosts in an action known as abscission. Through the winter the trees are empty of leaves, but buds remain, and are a good way to continue to identify trees when they don’t have leaves. All over the Upper and Lower Arb, white-tailed deer take advantage of the food source in the fall, cropping the buds to fuel them through the rut. While trees lose their leaves, deer begin to shed their velvet, a layer of skin covering the antlers. From the time the deer’s antlers begin to bud in April, a process initiated by increasing day length, the vesicle-rich velvet provides the growing antler with oxygen and nutrients. During the summer, when male whitetails are well fed, their antlers can grow as much as half an inch a day. The shortening day-length that causes so many changes in the landscape causes an increase in whitetails’ testosterone levels, which terminates the blood supply to the velvet. The antlers then calcify, and within one or two days, the deer shed their velvet. They have help of course. While out in the Arb, you may be able to find small to medium-sized trees with wide vertical strips of missing bark. Called ‘rubs,’ whitetails use these trees to break the velvet and tear it from the antlers. The antlers are most susceptible to damage as they develop, so male whitetails do not begin to rut until they’ve shed their velvet in late September. The peak of the rutting season is usually in November.
As deer gather for the rut, they can devastate developing plant communities. Areas of the Lower Arb where forest regeneration is underway are especially vulnerable. Each year from Thanksgiving until the end of the year, while students are away, a bow hunt is held in the Arb. The number of deer taken in the Arb each year is quite modest when one considers that 150,000 to 200,000 are taken each year in Minnesota, but the deer catch on to the presence of hunters in the Lower Arb, preventing them from gathering there in high concentrations. Unfortunately, the deer sometimes just take refuge in the Upper Arb, where hunting is not allowed, but restoration efforts are still underway.
– Owen McMurtrey for the Cole Student Naturalists
Add a comment