Risky conclusions regarding shrinking rhino horns

Abstract

Abstract 1. Image-based analyses from an online repository on rhino horns asserted that declines in size over time could be the consequence of poaching and hunting. 2. We provide reflections on whether the sample was representative enough to make generalizations, the study adequately accounted for the main sources of horn-size variation and the statistical methods were adequate to be confident in the results. 3. The sample had a limited representation, most coming from zoo animals. We highlight several sources of variance in horn size that such a sample could not evaluate robustly using linear regressions, both for establishing a proxy for horn size corrected for size of a rhino and assessing trends over time. 4. Nevertheless, horn poaching continues to be the key threat to rhinos. Addressing the underlying drivers of poaching and trafficking are key priorities for responsible public debate, policy making and interventions.