Ninja Turtles: high mobility and successful passage through common barriers to movement in a semi-terrestrial freshwater turtle

Abstract

Anthropogenic landscape change due to urbanisation, agriculture and resource extraction inevitably results in linear barriers within the landscape. Artificial linear structures such as roads, fences, levees, and dams limit the movement of some species and further fragment residual habitat. In this study, we investigated the ability of Eastern long-necked turtles (Chelodina longicollis) to cross various terrestrial obstacles commonly encountered in their habitat. We tested two types of fences (chicken wire and exclusion fencing) commonly used in agricultural systems and three sizes of rocks (gravel, gabion, and large boulders) often used for road construction, erosion control, and waterway stabilisation. We examined the success rates of turtles in crossing obstacles, the effect of fatigue on crossing attempts, and the impact of individual boldness on movement behaviour. Turtles displayed high success rates in crossing gravel (85.4%), gabion (86%), boulders (73.3%) and hinged joint exclusion fencing (94.7%). Chicken wire style wire netting had no successful crossings (0%) despite 276 attempts. A significant fatigue effect was observed throughout the experiment, with turtles making an average of 3.94 (± 4.93 SE) fewer attempts at the end of the experiment (day eighteen) as opposed to day one. Bolder turtles were faster at crossing obstacles, however, boldness had no bearing on obstacle-crossing success. These results highlight the need for thoughtful selection of waterway and wetland infrastructure and the fatiguing impact of constant exposure to anthropogenic barriers for wildlife.