3-Mercapto-3-methyl-1-butanol, a component of leopard urine, repels leopards and spotted hyaenas and protects livestock from leopard attacks; a series of case studies

Abstract Mammals’ semiochemicals could provide tools to control pests, deter unwanted behaviours, enhance the survival of imperilled species, and improve the productivity and welfare of domestic animals, but because producing facsimile copies of whole odours is unrealistic in terms of technical challenge and cost, the real-world application of mammals’ chemical signals depends on mammals responding to simple subsets of the components of their social odours. Experiments in multiple locations in southern Africa have shown that the odour of 3-mercapto-3-methyl-1-butanol (3M3MB), a component of leopard urine, can protect livestock from leopards, and repel spotted hyaenas. Camera-trapping for four-months at an overnight enclosure (known locally as a kraal), on a cattle ranch in Botswana, with no 3M3MB being released, yielded seven records of leopards and seven of spotted hyaenas, and one calf was killed by a leopard. Over the following 4.5 months, with 3M3MB being released, there were no records of leopards, one record of spotted hyaenas, and no losses of calves. At another ranch, after three leopards entered through a gate during a one-month control period, 3M3MB was deployed at increasing release rates, and the number of leopard records decreased to zero as the release rate increased, but then rose again after five months of continuous use. On the same ranch, when sheep and goats were fitted with collars emitting 3M3MB, losses to leopards declined from seven per month to zero for the five months that the collars were in operation. On a third Botswana ranch, leopards killed 0.6 calves per month when no 3M3MB was present and 0.2 calves per month when 3M3MB was released. The value of the livestock saved was approximately six times the cost of the repellent. At Shangani, in Zimbabwe, camera traps captured images of two leopards just outside shade-cloth kraals where 3M3MB was being released, but no livestock were attacked despite the shade cloth fence providing no physical barrier. On the same ranch, a leopard killed 4 calves in 5 days at a traditional thorn-branch kraal, 3M3MB and camera traps were deployed for the following month, during which no leopard images were captured nor calves killed. After the 3M3MB was removed, 2 calves were killed within 10 days. 3M3MB deterred spotted hyaenas from crossing a veterinary cordon fence in Botswana, and its efficacy rose with release rate.