Abstract
Hibernation is a crucial aspect of the life history of freshwater turtles inhabiting temperate regions. Therefore, understanding their hibernation habitat selection is essential for the targeted conservation of turtle species and their habitats. The Chinese softshell turtle (Pelodiscus sinensis), a medium-sized freshwater turtle, is widely distributed in China; however, populations are rapidly declining, and threatened by habitat destruction, overfishing, and water pollution. Little is known regarding this species' habitat selection during the winter months. In 2020-2022, we equipped 22 P. sinensis with radio transmitters (VHF), and we successfully relocated 13 turtles, 11 of which were buried in submerged substrates and 2 buried in terrestrial soil for hibernation. In aquatic habitats, turtles preferred ponded areas formed during the dry period of the Yellow River with low water velocity and less anthropogenic disturbance. However, we found little evidence for the selection of dissolved oxygen levels. In terrestrial habitats, turtles are buried under densely vegetated soils with their dorsal carapace approximately 5 cm beneath the surface, allowing respiration through a protruded neck. Terrestrial hibernacula were close to the water, maintained more than 30% humidity throughout the winter, and were effectively protected against freezing. To the best of our knowledge, this is the first formal report of the behavior of terrestrial hibernation in softshell turtles. Our results suggest that P. sinensis has selectivity toward hibernation habitats with specific microenvironmental characteristics, indicating that protection of the characterized habitats provided in this study is important for the future conservation of this threatened softshell turtle species.