Molecular sexing is a viable alternative to probing for determining sex in the imperiled Louisiana Pine Snake (Pituophis ruthveni)

Determining sex is critical for demographic monitoring of endangered species, but this task can be particularly challenging in reptiles that are sexually monomorphic. Conventional sexing methods are invasive, often inaccurate, can cause injury, and, for sexually immature individuals, equivocal. Molecular approaches have been established as viable alternatives but have not been compared with conventional methods. Here we compare the performance of cloacal probing with a molecular genetic approach to determine sex in Louisiana Pine Snakes. This highly endangered species is rare, cryptic, and largely fossorial, presenting particular difficulties for assessing their population status. Molecular assays produced unambiguous sex assignments for all individuals, whereas probing recovered an incorrect or unidentified sex 28% of the time. These results reveal that molecular sexing outperforms probing for determining sex in Louisiana Pine Snakes, suggesting management programs for other snakes of conservation concern could benefit by incorporating similar genetic approaches.