Wildlife - Deer Information
A Retrospective on Hunting Deer Over Bait in South Carolina - Can Baiting Negatively Affect Hunter Success and Deer Harvest Rates?
Baiting has the potential to unnaturally increase the survival of individual deer and when used in extreme amounts, baiting has been demonstrated to cause unnaturally high local deer populations due to increased survival and reproduction (Figure 1).2 Artificially high deer numbers is contrary to the goals of SCDNR’s deer management program and is not in the best 4 interest of the state’s natural resources nor the general public.
Figure 1. Relationship between deer population density and the amount of bait or supplemental feed that is provided. Note that as more food is available deer numbers increase.
Referring to the survey data the following example can be used to demonstrate how the magnitude of baiting may have affected deer density in the coastal plain. This example simply estimates the number of deer required to consume the amount of feed (corn) that is being provided to the landscape by hunters.
If we assume that the average deer needs approximately 2,000 calories per day and that one pound of corn has approximately 1,600 calories then we can deduce that the average deer needs 1.25 pounds of corn per day to meet its requirements. Survey results indicate that 43 pounds of feed are available per square mile per day, therefore, this would support approximately 35 deer/mi2. Although this is a relatively high deer density, there are regions of South Carolina that naturally support this number of animals without adverse affects.
However, deer would not restrict their diet only to feed that is being provided by hunters. Although corn is high in energy (carbohydrates) it is low in protein and other essential vitamins and minerals and should not be considered a complete feed. In fact, a study examining deer use of supplemental and natural feed in the Coastal Plain found that only about 50 percent of the diet was composed of feed (corn) with no statistical difference in deer sex, age, or month of sampling.3 Therefore, the amount of feed being supplied by hunters would theoretically support approximately 70 deer/mi2. With few exceptions, this population density should be considered extremely high and unnatural in South Carolina. Without supplementation this population density should result in poor biological characteristics (reproduction, body weights, antler characteristics, etc.) and there is no evidence that is the case in the Coastal Plain. This analysis begs the question, "Are we unnaturally 'propping-up' the deer population in the Coastal Plain?"
Research has demonstrated that baiting can change natural movements, distribution, and behavior of wildlife, including deer.4 It has been documented that changes in deer movements and behavior related to baiting lead to increased levels of nocturnal activity by deer and that younger animals are most susceptible to being seen/harvested during legal hunting hours.5
With increasing technology and decreasing cost, many hunters are now using trail cameras to monitor deer activity on the property they hunt. For obvious reasons, these cameras are typically located over bait sites. Although observations by cameras is high, hunters are learning that deer frequent bait sites much more at night than in the daytime. Data collected on one study site in the Coastal Plain yielded visitation rates of 25:1 night versus day (Figure 2, C. Ruth unpublished data). This data set includes approximately 30,000 observations and it was collected outside of the hunting season when deer should be exhibiting natural behaviors. If deer movements and behavior are being modified by bait, what impact could this nocturnal use of bait be having on hunters’ ability to efficiently harvest deer?
Figure 2. Visitation to supplemental feeding sites by deer monitored in South Carolina.
Also, as the availability of bait increases and ultimately moves towards supplemental feeding, there can be increased physical condition of deer at the local level (Figure 3).6 As body condition increases, deer become more selective as to what and when they eat and they can spend less time feeding (Figure 4). Both of these factors, increased selectivity of foraging and decreased time spent foraging, reduce deer movements. Anything that decreases deer movements makes the animals less available to hunters and negatively impacts hunter success and deer harvest rates.
Data is available from the Coastal Plain that illustrates the relationship between supplemental feed and deer condition, as well as, the relationship between deer condition and hunter success.7 Body weights and hunter effort data were collected from over 300 deer on each of two study areas located approximately 20 miles apart, in the same physiographic region, and on the same river system. One site is a public Wildlife Management Area (WMA) where baiting/feeding is prohibited and the other site is private land with a history of baiting/supplemental feeding. Neither area utilized selective harvest strategies and overall harvest pressure could be considered very high.
Results indicated that deer in 9 of 10 sex/age classes had significantly greater body weights from the area with a history of feeding compared to the area where feeding was prohibited. That is not to say that deer from the WMA were in poor condition, but rather, the deer from the area where feeding took place weighed more than would be expected naturally. On the other hand, it required nearly 3 times as much effort to harvest a deer on the area were feeding took place (3.37 man-days/deer) compared to the area where it did not (1.16 man-days/deer). Again, this data demonstrates the positive relationship between feeding and deer body condition and the negative relationship between body condition and hunter success. Deer in better condition can be more selective in their feeding activities and in doing so they can more easily avoid hunters.
Figures 3 and 4. Physical condition of deer will increases as the availability of bait increases towards supplemental feeding and as deer condition increases deer movements decrease which decreases the success of hunters.
Changes in deer movements and distribution can increase the probability of spreading diseases and parasites because animals are concentrated at bait sites where they repeatedly come in contact with one another.8 In 1994 bovine tuberculosis (TB) was detected in deer in an area of Michigan. It was determined that high concentrations of deer around bait sites were a primary factor in maintaining and increasing the prevalence of the disease. Similarly, chronic wasting disease (CWD) has emerged as the most significant disease threat that North America's deer and elk populations have ever faced. The disease is similar to mad cow disease that was so devastating to Europe's livestock industry. CWD has been diagnosed in 22 states and two Canadian provinces, however, it has not been detected in any Southeastern states in the vicinity of South Carolina.
Each of these diseases pose a significant risk to South Carolina because of the potential negative impacts it could have upon the deer resource, the deer hunting tradition, and the State's economy (200 million dollars in annual retail sales related to deer hunting). Due to changes in deer movements, their congregations and behavior, baiting presents a major hurdle in managing these diseases. As was the case in Michigan with TB, states that have detected CWD and allow baiting have been forced to take immediate steps to address the issue.
Deer are normally selective browsers with feeding activities occurring widely over their home range. However, due to changes in movements associated with bait, deer concentrate their foraging activities around the baited area and research has documented that the habitat around artificial feeding locations can be negatively impacted due to this concentrated foraging.9 The unnatural movements and congregations of deer associated with bait sites may suppress the ability of plants to regenerate which can change plant species composition and ultimately affect the entire local ecosystem.10
The inferior quality of typical deer bait (corn) is also a concern since it is being consumed by many species of wildlife including deer. Although the effects of certain feed contaminants are documented in livestock, the effects are not well known in wildlife. Research conducted by the Southeastern Cooperative Wildlife Disease Study at the University of Georgia indicates that aflatoxin, one contaminant of concern, has been found at "above acceptable" levels for animal feed in approximately 50 percent of deer bait sites sampled in South Carolina.11 Although deer appear to be somewhat resistant to low levels of aflatoxin, it is documented that birds and monogastric mammals are more susceptible than ruminants.12 Therefore, the effects on these "non-target" species are a concern. (Note: the national incident in 2005 with contaminated pet food and mortalities in dogs was related to aflatoxin).
Finally, the baiting of deer may artificially increase, or at least concentrate, the local population of turkey and quail nest predators such as raccoons, opossums, foxes, etc.13 These animals may affect local turkey and quail nest success and/or contribute to pathogens contaminating such a site.