Successfully Determining the Sex of Adult Varanus mertensi (Reptilia: Varanidae) Using a Combination of Both Hemipenile Eversion and the Ratio of Androgens:Estradiol in Plasma

: In remote field localities, given limited access to specialized equipment, determining the sex of captured adult varanid lizards before release can be problematic. Determining the sex of the tropical semiaquatic Varanus mertensi, a species with significant tail musculature, is difficult using traditional hand‐pressure‐induced hemipenile eversion. As an alternative, we propose an extended technique for identifying the sex of adult V. mertensi. We recommend using a combination of the traditional field‐based hemipenile eversion technique and a measurement of the ratio of androgens to estradiol in plasma samples taken from field‐captured animals.