What the Turtles Taught Us: Improving Migratory Outcomes for Eastern Long-Necked Turtles Across Conservation Fences

Abstract

In Australia, conservation fences are widely used to enclose threatened native species in an area while excluding European Red Foxes (Vulpes vulpes) and Cats (Felis catus) that threaten them. However, conservation fences can have unintended negative consequences on other species within their vicinity, interrupting movement patterns and causing mortality via entrapment. A key component of conservation fence design should be the inclusion of structures to allow the transit of species negatively affected by fences, while maintaining an effective barrier to threats. In this study, we designed and tested a method to allow the movement of Eastern Long-necked Turtles (Chelodina longicollis) through a ‘turtle tunnel’ under a conservation fence. This Australian freshwater turtle periodically migrates over land in response to changing weather conditions, wet-dry cycles of wetlands, to nest, and to seek habitat and food resources. We tested the ability of wild-caught Eastern Long-necked Turtles to enter and traverse turtle tunnels in pen trials. We found that Turtles were able to navigate the turtle tunnels as intended, with 100% of individuals entering tunnels and 44% successfully traversing the tunnels during the timed trial. These results were used to inform the placement of nine turtle tunnels along a new conservation fence at Booderee National Park, Jervis Bay Territory, Australia. We monitored installed turtle tunnels at Jervis Bay for 6 months using a combination of camera traps and observational data collected during daily fence line checks. We found further evidence for the use of tunnels by Eastern Long-necked Turtles and found that Foxes did not attempt to traverse tunnels. From our findings, we suggest that turtle tunnels be considered in the construction of conservation fences where they intersect with known areas of freshwater turtle migrations, but that further research is required to assess the long-term effectiveness of the design as a wildlife transit device.