Public health and economic benefits of Spotted hyenas Crocuta crocuta in a peri-urban system.
Species that depend on anthropogenic waste for food can remove pathogens that pose health risks to humans and livestock, thereby saving lives and money. Quantifying these benefits is rare, yet can lead to innovative conservation solutions. To assess these benefits, we examined the feeding ecology and population size of peri-urban spotted hyenas Crocuta crocuta in Mekelle, Ethiopia. We integrated these field data into a disease transmission model to predict: (a) the number of anthrax and bovine tuberculosis (bTB) infections arising in humans and livestock from infected carcass waste and (b) the costs associated with treating these infections and losing livestock. We compared these public health and economic outcomes under two scenarios: (a) hyenas are present and (b) the counterfactual, hyenas are absent. We estimated that hyenas annually remove 4.2% (207 tonnes) of the total carcass waste disposed of by residents and businesses in Mekelle. Furthermore, the scavenging behaviour of hyenas annually prevents five infections of anthrax and bTB in humans, and 140 infections in cattle, sheep and goats. This disease control service potentially saves USD 52,165 due to the treatment costs and livestock loss avoided. Synthesis and applications. This human-hyena interaction in Ethiopia is evidence that large carnivores can contribute to human health and economy. To retain these benefits and maintain tolerance of hyenas, we recommend introducing education programmes to promote safe outdoor behaviour around hyenas, training watchdogs to alert residents of hyena presence, constructing bomas to protect livestock from hyena attacks, and preserving the hyenas' access to carcass waste to reduce their dependency on livestock predation. With humans and carnivores coming more frequently into contact, understanding and communicating how these species can benefit humanity will be critical to motivating human-carnivore coexistence worldwide.