The use of strontium isotopes ( ⁸⁷ Sr/ ⁸⁶ Sr) to determine the geographic assignment based on keratin values of shed skins of green pythons ( <i>Morelia viridis</i> ) as an effective tool against wildlife crime

Abstract The green tree python is quite a favorite pet for sale on the international market. The species is therefore protected by the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). Since the illegal poaching of large numbers of specimens in the wild might lead to the detriment of native populations, and wildlife breeding farms were found to be serving as conduits to funnel wild-caught green tree pythons out of Indonesia, a forensic tool to distinguish wild-caught from captive-bred specimens could support the enforcement of CITES protections. To disrupt the illegal trade of green tree pythons, we have developed an effective tool to distinguish the animals supposedly bred in captivity from those caught in the wild, based on the strontium isotope composition in conjunction with trace element data. Like in human hair, 87 Sr/ 86 Sr values seem to vary according to the relative contribution of endogenous and exogenous sources. Thus, we infer that if there is enough sustainable strontium available for the analysis, it might be possible to use the 87 Sr/ 86 Sr values in parallel with trace elements to distinguish wild-originated specimens from the in captivity-bred ones. Indeed, our pilot study on the shed skins of animals where the geographic origin was either the Czech Republic or Indonesia, confirms that shed skins can be effectively used for further forensic Sr radiogenic isotope analyses.