White-tailed deer (Odocoileus virginianus) were reported to be quite abundant when white settlers arrived in Iowa in the early 1800's. Although the clearing and cultivating of land for agriculture may have initially improved the suitability of the landscape for deer, uncontrolled exploitation for food and hides rapidly reduced deer numbers. By 1880 deer were rarely sighted in much of the state and in 1898 the deer season was legally closed. By this time deer had been virtually eliminated from all parts of the state.
Reestablishment of Deer
Reestablishment of deer into the state can be traced to escapes and releases from captive herds and translocation and natural immigration from deer herds in surrounding states. A conservative estimate of the population in 1936 placed statewide numbers at between 500 and 700 animals. This small herd grew steadily. By 1950 deer were reported in most counties and the statewide estimate topped 10,000. Concentrations in some areas were beginning to cause problems by damaging agricultural crops. In response to these problems the first modern deer season was held in December of 1953 and 4,000 deer were killed. Currently, the deer herd is estimated to be about 200,000 after the hunting season, and harvests have approached 100,000 in recent years.
Although deer are normally associated with forested areas, deer will utilize many different types of habitat as long as the area provides adequate cover. Examples of these types of areas include brushy draws and fencelines, marshes, and grassy areas like those provided by the federal Conservation Reserve Program (CRP). Standing corn also provides ideal habitat for part of the year since it provides food, cover and easy travel lanes. Deer utilize almost all plants for food at one time or another during the year. Deer feeding habits can best be described as being erratically selective as deer will sample many plants while feeding but often utilize a single source of food for the majority of their diet.
Deer Do Well in Iowa
The white-tail's ability to thrive in Iowa is likely the result of an abundant, reliable food source and a winter climate where snow depths rarely exceed 12" for a prolonged length of time. These factors combine to allow deer to come through the "winter bottleneck" in excellent condition. The excellent nutrition also enables deer to have high reproductive rates. Many deer in Iowa have a single fawn their first year and 2 fawns each subsequent year. Deer in the wild can probably maintain these high reproductive rates until they are 10 years old. Past research in Iowa has found that 8 to 12% of adult does have 3 fawns.
Another reason that deer do so well in Iowa is that they are very mobile. Although many deer stay near the area where they were born, a significant number leave and travel to new areas before establishing a core area. These core areas may change seasonally with deer shifting between wintering areas and breeding areas. These movements allow deer to fill voids left open due to deaths and easily pioneer into new areas when habitat is suitable. High rates of movement occur during 2 periods of the year. The first is in the spring when deer move to their fawning areas. Many of last years fawns are forced to find areas of their own at this time. The second period is in the fall during the breeding season. The breeding season begins in mid-October and runs through mid-January, although the peak of activity occurs during the first 3 weeks of November.
Careful management of deer populations by man has also played a crucial role in allowing deer numbers to return to the levels enjoyed today. Management consists of carefully regulating the harvest since hunting provides the only major source of mortality for deer today. Unchecked, Iowa's deer herd could grow at a rate of 20% to 40% each year. At this rate, deer numbers would double in as few as 3 years. With Iowa's abundant agricultual crops providing food, densities could potentially reach 100 or more deer per square mile before natural regulatory mechanisms would begin to affect deer health and slow the rate of growth. Deer numbers this high would cause economic hardship to Iowa's landowners as well as alter the natural vegetative community. Maintaining a deer population in balance with the wants and needs of the people in the state is a difficult task, but hunting is the only viable management option to achieve this goal.
For more information:
White-tailed Deer, Life History