The recent deer rut of November is now over, with the majority of does being impregnated by bucks. Does are in heat for 24 hours, and, if not impregnated, will not be receptive for another lunar month (28 days) (seasonally polyestrous from October to January). The main breeding is in November (some reach estrus in October, with non-mated females achieving estrus again in November and a possible final third time in December. They will stay with the does (who form winter herds) over the first winter before males disperse in the spring, with some female fawns staying with the mother for two years.
The next three months will be tough for the animals of the forests, especially the deer. With the fall acorn crop already consumed, deer will spend their days in search of overlooked acorns, grasses, mushrooms, grapes, sumac, barberries, foliage buds and other available foods. All of these winter sources of food are poor in nutrition. Basically, the deer will be losing weight throughout the season. Surprisingly, providing corn at feeding stations in winter may not provide much added nutrition due to the low level of bacteria in their guts that enable the breakdown of foods for the deer. In fact, the low bacteria level in spring can prevent deer from getting adequate nutritional value from newly available food, thus predisposing them to starvation in a time of plenty.
Deer deal with winter by putting on body fat in the fall, reducing their metabolic rate, producing a heavy winter coat, and moving to “deer yards”. Their winter coat hairs are tubular, stiff and brittle, trapping more air in their coats for additional insulation. For this reason, the pelts float and have been used historically for life preservers (versus summer coats, which will not float). Winter herds may number up to 150 individuals, centering around areas of food abundance called “yards”. These yards, better called “deer wintering areas”, are not cleared areas, but rather areas with numerous overlapping paths, sloping south or west, with considerable vegetation, especially coniferous vegetation. In such circumstances, leadership is matriarchal (different from dominance, which is always the largest male). Even though it appears to be one large group of deer, they are actually a concentration of groups of either bucks or does and their offspring. In studies within the Shenandoah National Park, winter group size ranged from one to 28, with a mean of 3.4. Herding allows pathways to remain open and to enable more individual protection from predators.
The picture for deer in the Big Meadows area of the SNP is always a case of staggering overpopulation, stress, starvation, disease outbreak and vegetational impact. Pennsylvania studies have shown that deer densities of 20 deer per square mile resulted in a significant decrease in species richness and abundance of woody plants, herbaceous plants and bird species. Compare that to the density of over 200 deer per square mile in the Big Meadows area, and you can imagine the tremendous impact on the deer, songbirds, and vegetation of that region. Deer have been estimated to consume 4 – 6 pounds of vegetation per 100 pounds of body weight per day (deer average from 100 to 250 pounds). This means approximately 200 pounds of vegetation are eaten each day in the Big Meadows area!
Deer have more than just their own fecundity working against them. In addition to a burgeoning bear population, coyotes have established a significant population in the Park and surrounding environs. (In fact, that great Appalachian Mammals website; www.bobpickett.org, notes coyotes are found in every county of PA, MD, VA, WV and NC.) Recent analysis in Virginia has verified an approximate 29% annual growth rate in its coyote population. Over 9200 were harvested in VA in the 2005-6 winter season.
In a fawn survival study in Centre County Pennsylvania during 2000-2001, 218 fawns were radioed and followed with telemetry equipment. Of these fawns, predators killed 22 percent, the leading source of mortality. Of the fawns killed by predators, most were killed by coyotes (49%) and bears (43%). Nearly 50% of all mortality occurred during the month of June, with 18 percent and 16 percent in July and August, while the fawn were still small.
Studies in Texas have shown that the coyote’s diet consists of 70% fawns during June and July. Sheep predation by coyotes is known to drop drastically when fawns are born around the first of June.
It can be said that where deer populations are abundant, coyote predation may benefit deer health by reducing the deer herd and providing more nutrients for the remaining deer. However, coyote predation also has the potential to have significant negative effects on deer herds. Coyote predation in the high mountain areas of West Virginia with lower deer populations and severe winters is likely to have more effect on the deer herd than in areas with higher deer populations.
Bill McShea, the mammal biologist with Smithsonian Institution’s Conservation Research Center in Front Royal, (who has also honchoed our AT mammal survey) has been overseeing a study of immunocontraception, or using a vaccine to prompt the animal's immune system to prevent conception. Since 2003 he has been testing a Canadian PZP-derived drug called SpayVac, which costs $110 per dose but may last a deer's lifetime.
Unfortunately, Bill acknowledges even reliable contraceptives cannot, by themselves, solve the problem. Before the SpayVac tests began in 2003, McShea had 232 deer culled from his 850-acre CRC experimental area, leaving about 50 deer behind. Now the population in that area is growing, despite contraceptives, because new deer are immigrating to the property.
There is yet one new issue that will have an unknown impact on our white-tailed deer population. Chronic wasting disease (CWD) is a neurological disease of deer and elk in North America. The disease is thought to be caused by abnormal, proteinaceous particles called prions that slowly attack the brain of infected deer and elk, causing the animals to progressively become emaciated, display abnormal behavior and invariably results in the death of the infected animal. There is no known treatment for CWD. CWD belongs to a family of diseases which includes mad cow disease. It has now been found in 13 deer in Hampshire County, WV. Although it has not been found in VA, PA, NC or MD, much effort is being expended by each state monitoring harvested deer for this predominantly western disease, first identified in 1967 in Colorado. The good news is this will certainly throw a monkey wrench into the grandiose plans of the Rocky Mountain Elk Foundation to re-introduce elk into all of the eastern United States for the hunting pleasure of their members.