Hyenas are frequently vilified and often feared. Hemingway once described the hyena as a stinking, foul devourer of the dead, with jaws that crack the bones the lion leaves.
But a new study concludes that spotted hyena scavenging provides significant public health and economic benefits to the African cities they roam.
In a study conducted in and around the Ethiopian city of Mekelle, home to 310,000 people and 120,000 livestock animals, a University of Michigan conservation ecologist and two colleagues found that spotted hyenas annually remove 207 tons of animal carcass waste.
Mekelle is the capital of northern Ethiopia’s Tigray region. The carcasses of livestock animals that are slaughtered for food there, or that die naturally, are often dumped at the local landfill or on roadsides, where hyenas feed on the waste. The researchers wanted to know whether hyenas—by removing this waste from the environment—might also prevent pathogens from jumping into people and livestock.
They determined that hyena scavenging annually prevents five infections of anthrax and bovine tuberculosis in Mekelle residents and 140 infections in cattle, sheep and goats. This disease-control service potentially saves the city $52,000 annually in treatment costs and livestock losses avoided.
The study, published online Sept. 26 in the Journal of Applied Ecology, is the first to quantify the public health and economic benefits of scavenging by spotted hyenas.