Experimental evaluation of the use of trenches by chelonians on railways

• Trenches allowed the sliders to exit rails. • Tortoises presented high trench avoidance behavior. • Tortoises are more likely to be trapped between rails than sliders. • Trench is a simple and inexpensive mitigation for railway entrapment. Railways can act as traps for chelonians that can become trapped between the rails and end up dying. Trenches between railroad ties are a potential measure to prevent chelonian entrapment, although they have been tested only as a connectivity mitigation. In Brazil, railway companies have reported chelonian fatalities, even in places with minimal or no train traffic. Here, we aimed to evaluate the use of two trench types to prevent chelonian entrapment by allowing animals to escape under the rails. We used experimental arenas to test escape success and trench avoidance in individuals of red-footed tortoise ( Chelonoidis carbonarius ) and black-bellied slider ( Trachemys dorbigni ), species with contrasting habitat and movement capacities. Sliders made significantly more use of the type 2 trench as an exit route out of the tracks when compared to tortoises. The latter species did not frequently use either trench type and also showed higher avoidance of them. These findings indicate that trench use for escape may depend on species-specific behaviors and morphology, which emphasizes the importance of evaluating mitigation measures for each target species. Furthermore, trenches may serve as a dual function to prevent entrapment if installed on both sides of level crossings: as an escape route, allowing species to exit the rails, or as barriers, guiding them back to a safer previous location. This measure offers potential benefits for conservation, and further research is needed to provide valuable evidence for broader application with various species and habitats.