Ecological impacts of SR 200 on the Ross Prairie ecosystem
Ross Prairie is a 6,500-ha conservation area in SW Marion County, Florida. It serves as an important regional habitat node connecting the Ocala National Forest to the Withlacoochee and Goethe State Forests. SR 200 is a major two-lane state highway that bisects the reserve. Rapid growth and development have recently necessitated the need to widen the road to four lanes. A comprehensive approach that employed several methods was used to determine the current and potential impacts of SR 200. These methods included road-kill and track surveys, mark-recapture and telemetry studies, and GIS analysis. Each method was used to evaluate road impacts on different taxa. The study was conducted from May 2002 to December 2004. Results of the road-kill surveys included 759 individuals from 57 identifiable species. The majority were anurans followed by meso-mammals. Locations of significant numbers or rare species of road-kills by taxa were identified. A total of 537 sets of whitetail deer, 481 sets of carnivore, and 474 sets of snake tracks were recorded. Hotspots were identified for snake, white-tail deer, and carnivore tracks. A total of 1,777 herpetiles were captured in right-of-way drift fence traps. Southern leopard frogs and Florida gopher frogs were most abundant. Individuals of several species of snakes, frogs, and lizards were recorded crossing the road in the two sandhill crossing sections, and moving to/from the Ross Prairie wetland basin. Of 342 small mammals captured, one cotton mouse was recorded crossing the road; only six small mammals were found as road-kills. The road likely is a significant barrier to small mammal movement. Average home range of 18 gopher tortoises monitored adjacent to the road was 3.14 ha. Only three attempted crossings of SR 200 were recorded, two were successful, and one resulted in death. For gopher tortoise, the road is a semi-permeable barrier. Home range of the 13 eastern indigo snakes monitored averaged 127.6 ha. No road crossings were recorded; they seemed to use the road as a home range boundary. Because of road-kills, there is documented evidence that road crossings are attempted. Only 5 bobcats, 2 coyotes, and 1 gray fox were captured and used in the carnivore telemetry study. Yet observations, track, and scat evidence suggest that a significantly higher number of these animals were present in the Ross Prairie area. Average home range size was 13.67 km2 for bobcats. Most radio-collared felids avoided SR 200 or used the road as a home range boundary, whereas the radio-collared canids commonly crossed major roads. To improve habitat connectivity and eliminate road mortality we recommended installing four box culverts in the upland sandhill areas, bridges at each wetland/upland ecotone, and a series of five culverts within the wetland basin adjoined by a herpetile exclusion wall. Between all these structures we suggested 2-m barrier fencing with herpetile-excluding mesh at the base of the fence.