Development of surveillance techniques for juvenile Red Eared Slider Turtles

Abstract

The red eared slider turtle (REST, Trachemys scripta elegans) is one of the most traded reptiles in the world and represents a significant biosecurity threat when established outside its native range. Over the past 20 years there have been several REST detections in Australia. In Queensland, significant surveillance and control efforts have been undertaken to manage a population of REST north of Brisbane since they were first detected in 2004. However, despite low genetic diversity and evidence of egg laying in captured females, no juvenile REST have been detected or captured at this site. Artificial basking platforms have been successfully used to monitor adult turtles, but not juveniles. Reports suggest that juvenile turtles prefer to aquatically bask in shallow, warmer waters rather than terrestrially like adults. To develop a method for detecting juveniles, a platform with a semi-submerged base was designed, tested, and deployed at a site with a reported breeding REST population in Fairfield, Sydney. The pilot trial detected REST with a carapace size between 100 - 150mm, and all basking occurred at night. Trials continue to further refine the platform design, extend the length of monitoring, and compare detections between paired adult and juvenile platforms. In addition, the inclusion of a hydrophone (acoustic monitoring device) underneath the platforms is being investigated as an alternative or complementary method of monitoring. Detection of REST within a water body, for surveillance and demonstrating proof-of-freedom, is critical to mitigate the negative impacts of REST on native turtles and other species. The development and refinement of surveillance techniques to detect both juvenile and adult turtles will support management or eradication efforts through detection of breeding populations of REST.