Restoring Biodiversity by Lowering Deer Numbers at Shawnee Lookout (Ohio)

Shawnee Lookout is a 607 ha park managed by the Hamilton County Park District near Cincinnati, Ohio. At the very southwest corner of the state and at the confluence of the Great Miami and Ohio Rivers, the site has experienced human occupation for the past 10,000+ years. As the first site in Ohio to be placed on the National Historic Registry, Shawnee Lookout is most famous for its archeological features. A total of 39 separate features have been described, ranging from earthen walls to burial mounds.

Most of the park, however, has been managed as natural areas since the Park District acquired the land in 1967. It became very evident beginning in the mid-1980s that numbers of white-tailed deer (Odocoileus virginianus) in the park were growing larger than the habitat could support. In the woods, a browse line had appeared where the deer had eaten nearly all palatable plants within their reach (Figure 1). Most biologists agree that high deer densities cause significant habitat damage and negative effects on biodiversity (Boucher et al. 2004), but identifying management goals for deer densities is elusive. An appropriate deer density for a habitat will be a complex function of habitat quality, past deer densities, and attributes of the surrounding landscape. After ten years of studying the problem, the Hamilton County Park District began a deer management program in 2003 with the goal of reducing the deer population from an estimated 192 deer per 259 ha to no more than 20 deer per 259 ha in order to prevent significant habitat damage and biodiversity loss (Frankland and Nelson 2003, Horsley et al. 2003, Tilghman 1987). With deer numbers at ten times the target level, we knew the job would not be easy.

For the past seven seasons (2003–2009), existing park employees who have been trained as sharpshooters have removed a total of 755 deer from Shawnee Lookout under permit from the Ohio Department of Natural Resources. All resulting venison was donated to local food pantries to feed the needy. According to most recent infrared aerial surveys in March 2009, the population has been reduced to approximately 35 deer per 259 ha. Although there is still more work to do, we are beginning to see positive signs that this effort is paying off.

Figure 1.

Browsed pines at Miami Whitewater Forest, which is a few kilometers north of Shawnee Lookout Park in Ohio. Vegetation in Shawnee Lookout has been similarly pruned back by deer to create a visually distinctive browse line.

Photo by Denis Conover

Deer exclusion pen research has been conducted in the park since 1994 (Conover 1994–2009), and vascular plant surveys have been conducted throughout the park over the years (Rankin 1988, Conover 2001). Based on several years of deer-exclosure data and vascular plant survey observations throughout the park, it is apparent that several species of native plants are now growing and flowering more vigorously than they were a few years ago at Shawnee Lookout Park. Some of these species include Solomon's seal (Polygonatum biflorum), fire pink (Silene virginica), spiderwort (Tradescantia virginiana), trilliums (Trillium spp.), Guyandotte beauty (Synandra hispidula), and greenbriars (Smilax spp.) (Table 1). In addition, the browse line is not as obvious now as it had been a few years ago.

Because white-tailed deer experience rapid body growth in the first 18 months, one of the best indicators of deer health is body weight of 18-month-old females. In western Ohio, the average eviscerated weight of an 18-month-old doe is 47.3 kilograms based on hunter harvest data (Tonkovich et al. 2004). During the first year of the deer management program (2003), the average weight of an 18-month-old eviscerated doe in the park was 39.7 kg. During the 2008/2009 season, the average was 52.3 kg.

The data show that after seven years of population reduction, the white-tailed deer in Shawnee Lookout Park are regaining their health and that their negative impact on their environment is reduced.