Urbanization and an expanding human population have led to a large degree of habitat destruction and fragmentation. These, in turn, reduce biodiversity and wildlife population sizes on a global scale. Transportation infrastructure, such as roads and railways, are some of the largest contributors to habitat fragmentation. Roads are well-established to negatively impact wildlife, but some studies suggest a potential use in habitat connectivity by functioning as wildlife corridors to connect distant populations. Railways are similarly known to impact wildlife by increasing mortality rates as well as provide unique risks such as electrocution and entrapment when compared to roads. However, the influence of railways on the movement and behavior of most taxa remains understudied. Here, I used Gopher Tortoises (Gopherus polyphemus) at the John F. Kennedy Space Center as a model system to (1) determine whether roadsides are or could be used as a wildlife corridor to connect distant habitats and (2) evaluate the impacts of railways on tortoise movement and behavior while providing management implications for both roads and railways. To examine the use of roadsides as wildlife corridors, I tracked the movement of individuals found along roadsides using radio-telemetry to determine if tortoises used the roadsides to move between inland and coastal habitat. In addition, I compared home range sizes of tortoises along roads to those of inland and coastal habitats to examine differences in spatial use patterns with regards to roads. I translocated tortoises from distant habitats into the roadside corridors to determine whether they would use the roadsides as a connective route to return to their original capture location. Overall, I determined that roadsides do not function as movement pathways, as even translocated tortoises remained along roads throughout the duration of the study. Instead, roads appear to function as long-term residential areas and potentially suitable habitat. I suggest management of roadsides to reduce mortality and further studies to examine the potential of roadsides acting as ecological traps. To study the impact of railways on tortoise movement and behavior I first used radio-telemetry to track the movement of tortoises found less than 100 m from railways. I simulated movement by using 1000 correlated random walks per tortoise to determine if the number of observed crossing events were significantly less than what would be expected by chance. Second, I measured behavior via continuous focal sampling for one hour to determine railway crossing ability and test for behavioral differences associated with the familiarity of the railways using a principal component analysis. Lastly, I tested if trenches dug underneath the rails could be used as a management strategy to alleviate the impact of railways on tortoises. I found that tortoises are unlikely to cross the railways and the number of observed crossing events were significantly less than what we would expect by chance. Additionally, familiarity with the railway did not have any influence on a tortoise's ability to cross nor their behavior. Trenches were frequently used to move from one side of the railway to the other and are, therefore, a valid management strategy to alleviate the impacts railways have on tortoise mortality, movement, and behavior. Overall, I conclude that transportation infrastructure and the expanding human population have immense impacts on wildlife, especially on turtles and tortoises. I recommend further research continue to identify unique management strategies as well as alternative barriers that may play a large role in a species' decline.
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Master of Science (M.S.)
College of Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Rautsaw, Rhett, "The paths less traveled: Movement of Gopher Tortoises along roads and railways" (2017). Electronic Theses and Dissertations. 5705.