Nocturnal basking in freshwater turtles: A global assessment

Diurnal basking (“sunning”) is common in many ectotherms and generally thought to be a behavioural mechanism for thermoregulation. Recent studies have reported the occurrence of nocturnal few distantly-related species freshwater turtles, but true extent this behaviour unknown, it may underreported due sampling biases (e.g., not surveying turtles at night). Therefore, we initiated global, collaborative effort systematically document quantify activity (diurnal nocturnal) across wide range turtle locations. We conducted camera trap or manual surveys North America, Caribbean, Europe, Asia, Africa, Seychelles, Australia. collected 873,111 trail photographs (25,273 hrs search effort) obtained data on 29 from seven families. Nocturnal was documented 13 species, representing six families (Chelidae, Emydidae, Geoemydidae, Kinosternidae, Pelomedusidae, Trionychidae), including representatives Central Trinidad Tobago, restricted tropical sub-tropical locations, suggesting that environmental temperature plays role behaviour. However, primary factors driving are yet determined vary geographically by species. The frequency duration varied among seasons, events were often substantially longer than diurnal events. This first study widespread basking, our results suggest common, although overlooked, aspect species’ ecology.