Strontium isotope mapping of elephant enamel supports an integrated microsampling-modeling workflow to reconstruct herbivore migrations

Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) in dental tissues are widely used to study animal and human migration. However, questions remain regarding how different biological processes and sampling methods influence measured ⁸⁷Sr/⁸⁶Sr and subsequent interpretations. We present a unique experiment with the known relocation history of a zoo elephant to evaluate the influence of biological turnover, tissue type, and sampling methods. We collected ⁸⁷Sr/⁸⁶Sr data from the elephant's tusk and molar enamel using in-situ laser ablation microsampling, conventional drilling, and micromilling techniques. Our data comparisons show that the innermost enamel best records the primary ⁸⁷Sr/⁸⁶Sr turnover history, while enamel maturation affects outer enamel ⁸⁷Sr/⁸⁶Sr. Conventional drilling and micromilling show attenuated ⁸⁷Sr/⁸⁶Sr records due to enamel maturation and sample averaging. To effectively account for ⁸⁷Sr/⁸⁶Sr signal attenuation due to turnover, we demonstrated a microsampling-modeling workflow using our tusk and enamel data. This recommended workflow can facilitate geospatially explicit interpretations of seasonal migration.