ResultsSince 1981 researchers have recovered and identified 1171 animals found dead on the roads of Jonathan Dickinson State Park. The data reveals that some species have far greater chance of becoming roadkill than others and that some species, such as Blue land crabs (Cardisoma guanhumli), tend to overwhelmingly be killed only between the months of July – September (Figure 1). The summer months of July – September have the highest occurrence of road kills in general. (Figure 2). Of the 91 species recorded, 70 species had nine or fewer recorded deaths from 1981 -2015. We considered these 70 species to be minimally affected, and they are therefore not included in the graphs. There were 21 species found to have more than 10 deaths (Figure 3), and the data analysis focused on these species. The Southern Black Racer (Coluber constrictor) was the species with the highest number of roadkill casualties in JDSP, with a total of 141 individuals killed. The data also showed that, snake species in general (n=10) accounted for 41.75% of all road kills shown (Figures 3 and 4). Among those snake species affected is the Corn snake or Red Rat snake (Elaphe guttata), which is a designated species of interest. The data suggests that within Jonathan Dickinson State Park every 2 -3 years Corn snakes experience a spike in Roadkill, further study is needed to possibly answer why. Another species on Florida’s endangered or threatened species list is the Gopher tortoise (Gopherus Polyphemus) of special interest because of its status with the Florida Fish and Wildlife Conservation Commission (FWC). Gopher Tortoises are a state-designated threatened species with 62 recorded deaths due to roadkill since 1981; however, the data shows that 45 of those 62 were killed on US-1, a high-speed highway along the eastern perimeter of Johnathan Dickinson State Park.

IntroductionFor decades the personnel and volunteers at Jonathan Dickinson State Park (JDSP) have been cataloging information about animals killed on the roads within and along the perimeter of the park. The data were collected and analyzed in an effort to help reduce the impacts of roads on the species within the park. In total, researchers recorded the date, time and location of over 1000 animals killed from 1981- 2015. Although some animals could not be identified, researchers were able to identify 91 different species affected by roadkill within Jonathan Dickinson State Park. Previous studies indicate that, in general, roads have negative impacts on species abundance, by increasing mortality rates, decreasing habitat connectivity, reducing habitat size and quality and altering animal behavior, even minor roads can have a significant impact on species mortality rates and animal behavior (Polak et al., 2014). With that in mind, we looked for any information or trends in the data that could help managers mitigate the future impacts of Roadkill on the species residing within the

park.

Methods & Materials

Roadkill data has been recorded in Jonathan Dickinson State Park since 1981 by park staff and visitors.

The data was organized by year and species and then analyzed using Microsoft Excel.

ConclusionsRoadkill is a serious threat to animal populations, and has the potential to drive threatened populations extinct(Cook and Blumstein, 2013). Fortunately there are options when trying to mitigate the impacts of roads on the species which live near them; unfortunately there is no cure-all option. Signs could be posted Just past the Ranger station informing drivers to watch for key species such as the Gopher Tortoise, also in areas where drivers are at greater risk of encountering animals in the road. Driver awareness is likely the most effective tool at the disposal of wildlife managers at JDSP and surely the only option that works equally for all affected species. Fencing roads can be a very effective measure for some species, such as Gopher Tortoise or Raccoon, whereas smaller animals pass right through. Fencing alone also decreases habitat connectivity effectively cutting off gene flow and habitat accessibility for some species. Fencing is also expensive and time consuming for installation and maintenance. Wildlife crossings paired with limited fencing (in the most impacted sections of road) are a good way to help prevent isolating species with fencing alone. Studies have shown fencing roads reduces species mortality rates, increases population persistence and, in combination with wildlife crossings, can facilitate animal movement and genetic flow (Polak et al. 2014). If fencing and wildlife crossing are not appropriately placed to help direct animals to the crossings, habitat fragmentation can be increased, causing unknown impacts on multiple species (Bager and Fauntoura, 2013). Not much can be done to prevent the numerous species of snakes in JDSP from entering the roadways of the park. Fencing the US-1 perimeter would only isolate the species trying to move between JDSP and the Hobe Sound National Wildlife Refuge located directly across US-1 from the park. What we can do to help as drivers, would be to learn from the data and be mindful while driving our vehicles through the park, especially in the summertime when the highest numbers of animals fall victim to the dangers of the road.

References and Acknowledgements

Do Roads Really Kill?Barry Carson, Palm Beach State College, Palm Beach Gardens, FL

Jessica Miles, Department Chair Environmental Science and Technology Program, Palm Beach State College, Palm Beach Gardens, FL

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Seasonal Breakdown of the Top Five Species Impacted as Roadkill

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Fig. 1: Represents the seasonal deaths by roadkill of the five species with the highest number of Road-kills in Jonathan Dickinson State Park since 1981.

Fig. 2: Shows all recorded Road-kills in Jonathan Dickinson State Park since 1981 broken down by season.

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Fig. 3: Shows by scientific name the 21 species most affected by roadkill within Jonathan Dickinson State Park since 1981. * Indicates a species is on the Florida Fish and Wildlife Conservation Commission's Threatened or Endangered Species list.

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Fig. 4: Displays the common names of the 21 most affected species and shows the number of road kills since 1981 within Jonathan Dickinson State Park. * Indicates a species is on the Florida Fish and Wildlife Conservation Commission's Threatened or Endangered Species list.

• Bager, A., and Fontoura, V. (2013). Evaluation of the Effectiveness of a Wildlife Roadkill Mitigation System in Wetland Habitat. Ecological Engineering, 53, 31-38.

• Cook, T. C., and Blumstein, D. T. (2013). The Omnivore’s Dilemma: Diet Explains Variation in Vulnerability to Vehicle Collision Mortality. Biological Conservation, 167, 310-15.

• Polak, T., Rhodes, J., Jones D., and Possingham, H. P. (2014). Optimal Planning for Mitigating the Impacts of Roads on Wildlife. Journal of Applied Ecology, 51.3, 726-34.

• I would like to thank Dr. Jessica Miles at Palm Beach State College and Natasha Warraich at Johnathan Dickinson State Park for contributing their time and expertise throughout the course of this research project.