2025-06-06 オックスフォード大学
A dehorned white rhino mother and calf in the Greater Kruger region. Photo credit: Tim Kuiper.
<関連情報>
- https://www.ox.ac.uk/news/2025-06-06-study-finds-dehorning-rhinos-drastically-reduces-poaching
- https://www.science.org/doi/10.1126/science.ado7490
除角によりサイの密猟が減少 Dehorning reduces rhino poaching
Timothy Kuiper, Sharon Haussmann, Steven Whitfield, Daniel Polakow, […] , and Res Altwegg
Science Published:5 Jun 2025
DOI:https://doi.org/10.1126/science.ado7490
Editor’s summary
Despite much effort and money spent over decades, rhinoceros populations continue to decline because of the market for their horns based on unsubstantiated health claims in some countries. Over time, rhinoceros poaching has become a multimillion-dollar illegal trade, often controlled by multinational criminal organizations. In the face of this crisis, there are many local heroes who dedicate their lives to protecting the few remaining rhinoceroses using an array of approaches, from increased ranger presence to tracking dogs, at a cost of millions of dollars per year. Kuiper et al. looked at the effectiveness of these approaches and found that only one, removal of the poacher’s reward through dehorning, significantly reduced rhinoceros loss. —Sacha Vignieri
Abstract
Across 11 southern African reserves protecting the world’s largest rhino population, we documented the poaching of 1985 rhinos (2017–2023, ~6.5% of the population annually) despite approximately USD 74 million spent on antipoaching. Most investment focused on reactive law enforcement—rangers, tracking dogs, access controls, and detection cameras—which helped achieve >700 poacher arrests. Yet we found no statistical evidence that these interventions reduced poaching (horn demand, wealth inequality, embedded criminal syndicates, and corruption likely combine to drive even high-risk poaching). By contrast, reducing poacher reward through dehorning (2284 rhinos across eight reserves) achieved large (~78%) and abrupt reductions in poaching using 1.2% of the budget. Some poaching of dehorned rhinos continued because poachers targeted horn stumps and regrowth, signaling the need for regular dehorning alongside judicious use of law enforcement.
