Climate change has an unlikely new ally. In Ethiopia, urban scavengers, such as hyenas and hooded vultures, are preventing over a thousand tonnes of carbon emissions every year, just by eating rotten meat. The findings are reported in Ecological Solutions and Evidence.
Scavenging animals are a common feature of large Ethiopian cities, where they live in the shadows and eat what they can. “Animals like spotted hyenas have adapted to a high-density, urban environment and have become an essential part of the city’s ecosystem,” says Gidey Yirga from the University of Sheffield.
This is true of the country’s second largest city, Mekelle. Every year the 660,000 residents collectively slaughter over a million chickens, goats and sheep for food, then chuck away the leftovers. Two thirds of this organic waste is dumped at roadsides and other open sites, where it decomposes and releases greenhouse gases, such as methane and carbon dioxide, into the atmosphere.
When they feed on food waste, scavengers help to lock this carbon away. To estimate how much of an effect this has on climate change, Gidey and colleagues interviewed 409 randomly selected households then extrapolated their data to the entire city.
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The researchers found that the city generates around 1,240 metric tonnes of meat waste every year – equivalent to the total weight of roughly 31,000 live sheep. Spotted hyenas, stray dogs and African wolves scarf about half of this. Together, the animals prevent the release of an estimated 1,063 metric tonnes of carbon emissions annually and save the waste disposal sector around $100,000 USD per year.
“At a time when cities across the world are struggling with waste and climate goals, we’ve found that scavengers are providing essential ecosystem services while significantly reducing potentially catastrophic sanitation risks,” says Yirga.
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Scavengers don’t tend to be popular. Lots of people don’t like them, because of threats that are real and imagined. In this study however, many interviewees said that they were happy to live alongside the animals peacefully. “Although hyenas are often among the most persecuted species in Africa, in our study area, they are considered ecologically important,” the authors write. “This creates a unique case of co-existence between wildlife and people.”
Now, the researchers hope that this tolerance will spread. If it does, the model could be applied to other Ethiopian cities and African states where organic waste is routinely dumped at road sides.
Top image: spotted hyena at night. Credit: Michael J. Cohen/Getty Images
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