Non-Lethal Sexing Techniques for Hatchling and Immature Desert Tortoises (Gopherus agassizii)

Abstract

The development of non-lethal techniques for sexing hatchling and immature desert tortoises is critical to population and ecological studies. Two methods for sexing desert tortoises were evaluated with respect to accuracy, efficiency, and suitability to field application. Laparoscopy was found to be 100% accurate and could be used on hatchlings as small as 28 grams total body mass. Plasma testosterone was 98% accurate for juvenile and immature tortoises ranging from 69190 mm straight carapace length. Plasma testosterone is the most suitable methodology for field studies in that only a small blood sample is required for sexing purposes. Laparoscopy is 100% accurate; however, it may require holding the animal for an extended period of time.