By: Nora Sirbaugh
In seeking to better understand the problems related to our deer population, the best place to begin is by understanding the deer.
Our whitetail deer, odocoileus virginianus, is one of 30 known subspecies of whitetail deer. Herds of whitetail initially were purchased and imported in the early 20th century to bolster the local population, which had diminished to a mere 200.
In late May and early June, there is an uptick in deer-vehicle collisions. This is because young does are driven from family groups and are on the move while mature does stake claims to "birthing territories" and give birth and nurture fawns.
First-time mothers tend to have single fawns, but mature does are very likely to have twins. Generally, yearling does do not breed, but it is estimated 60 percent of 7-month-old doe fawns do breed because they "make weight" due to a rich diet.
Within hours of giving birth, a doe will remove herself from the area where she has put her fawn in order to prevent her own body odor from attracting predators. When humans approach fawns, the doe remains hidden.
Although they are alone, those fawns are not orphans. Don’t touch them! Don’t pick them up! Leave them be! Fawns are the most vulnerable generation of the deer, and, locally, the most likely predators are coyote and bear.
May is a time of abundant vegetation. Deer feed ravenously, replacing weight lost over the winter. By June, vegetation peaks, and deer feed on farm crops and forbs (broad-leaved plants), which they prefer to grasses, hence, their invasion of gardens rich in such plants.
There are some 650 known plants deer will eat. Not all are of equal nutritional value. Deer also get their water from these plants when dew and succulent new growth supply sufficient moisture.
In July and August, deer will retreat to the safety of the forest, seeking ponds and lakes, which are major openings in the tree canopy, allowing the sun to produce food. In addition, water plants are rich in the needed proteins deer seek.
"Edge" is one of the most important features of the deer habitat. This is where forest meets open areas – wherever sunlight can get to the earth, allowing new growth that, when leafed out, you will not be able to see through. That is, unless you have too many deer.
Too many deer destroy this edge and allow us to look into the forest. It does not matter what the number of deer is. When you can stand in a field and can look into a forest, there are too many deer. The destruction of the edge reduces or eliminates the populations of song and game birds and small mammals dependent on such cover for their own survival.
It is not just the destruction of the rainforests of South and Central America that threaten the songbird populations, but the elimination of the understory in the northern climates by deer.
By August, the last antler growth is complete in the bucks. Fawns are weaned. Deer seek out food rich in nitrogen, like alfalfa, clover, peas – all farm crops.
In spring, the deer ate the corn, but now they do their worst damage to the farm crops because most of the natural vegetation has matured and its food value has dropped.
By September, this feeding frenzy is severe as the deer need to bulk up for the lean months of winter. Each deer needs about 8 pounds of vegetation per 100 pounds of weight a day. Bucks weigh 200 to 300 pounds; does 150 to 250 pounds.
Their favorite food of choice at this time is acorns, rich in much-needed protein. If food is scarce, the fat buildup will continue at the expense of restricted body growth. That fat is there despite inadequate food and comes at the expense of smaller body size and, in the case of bucks, smaller antler size.
In the fall, bucks and does, which have lived apart all through summer, come together to share food supplies.
October begins mating season, and the bucks rub trees. This is primarily to work off aggression and strengthen neck muscles. It is known they deliberately entangle antlers in small saplings, then rip them from the ground. They also scrape areas to mark territories and begin traveling singly to do so.
Now the second uptick of traffic accidents in late October/November occurs as these amorous males are on the move. Dominant males have the largest antlers and bodies. Mating is over by early December, and since antlers are sexual weapons used for dominance, they are shed.
An ideal winter habitat is low and swampy with a good stand of white cedars, a nutritious food in short supply because of overbrowsing.
The most important feature is vegetation thick enough to break the force of the wind, which deer cannot stand. However, there is little of such habitat left.
The deer still need about 3 pounds of nutrition per 100 pounds of weight. Many deer are found dead of starvation by the end of winter with stomachs full of indigestible large twigs. Fawns die first because even the most caring does drive fawns away when it comes down to survival.
Many pregnant does will give birth to underweight fawns that eventually will die.
Yet despite all these difficulties, deer continue to increase in population with devastating effect to our landscapes and to the deer themselves. To learn more about deer, I highly recommend Leonard Lee Rue III’s "Way of the Whitetail."
Nora Sirbaugh is a certified master gardener of Mercer County and a member of the Hopewell Township Environmental Commission.