A novel technique for monitoring reproductive endocrine patterns in Temminck’s pangolins, using scales as hormone matrix

Abstract

Currently, pangolins are the most trafficked wild mammals in the world, but due to their elusive nature, they are critically understudied. Thus, in addition to acquiring basic knowledge, there is an increased need for advanced forensic tools to aid with enforcement against wildlife criminals. Temminck’s pangolin (Smutsia temminckii) is the only species occurring in southern Africa and as research has focussed on their general ecology, little is known about their physiology. Hormones are key drivers of physiological processes and can be quantified in a variety of matrices. Keratin-based materials, like hair and feathers, have become increasingly popular matrix choices, especially where the use of other sampling matrices is comparatively difficult. Pangolins are morphologically unique mammals that are covered in keratinous scales, which are one of the main reasons why they are extensively traded. These scales and other pangolin body parts are used in various traditional medicine practices across Africa and Asia. The present study aimed to examine the suitability of scales as a hormone matrix for monitoring reproductive endocrine patterns in Temminck’s pangolins. A protocol was developed to enzymatically digest the scales before hormone extraction and measure progestagen and androgen metabolite concentrations in the resulting suspension. Results showed that reproductive steroid metabolite concentrations are measurable in scales, while sample mass should be taken into consideration when doing comparisons. However, steroid metabolite concentration was not scale section or body region specific. Once a reliable hormone extraction protocol was established, sex-related differences in progestagen and androgen metabolite concentrations were investigated. Although concentrations were not significantly different between sexes, individuals clustered into a male and a female group. Furthermore, a juvenile and sub-adult male overlapped with females, possibly indicating later sexual maturity in males. Results also indicated that a ratio of scale progestagen to scale androgen metabolite concentrations was most accurate for sex prediction of the scales. Therefore, Temminck’s pangolin scales are a suitable hormone matrix and scale hormone ratios show promise as a sex identification tool, particularly applicable in forensic investigations to assist law enforcement.