Urban scavengers as providers of ecosystem services: Waste management and carbon reduction in a rapidly urbanizing African City

1. Scavengers, such as spotted hyenas (Crocuta crocuta), African wolves (Canis lupaster), hooded vultures (Necrosyrtes monachus) and stray dogs (Canis lupus familiaris), are crucial for waste management in urban ecosystems, particularly in areas with poor waste management and sanitation.

2. This study quantifies their economic and carbon capture services by comparing the cost of their waste disposal with alternatives and estimating the CO2 emissions avoided by consuming organic waste.

3. Through semi-structured interviews with 409 households in Mekelle, Ethiopia, we estimated the annual disposal of meat and organic waste and explored residents' perceptions of the ecosystem services.

4. Our results showed that approximately 1,058,200 animals (chickens, sheep and goats) were slaughtered annually at home, which is equivalent to 3286 animals per square kilometre. This generates approximately 1240.6 metric tons of meat waste (3.85 tons per square kilometre).

5. Scavenging of this meat waste could prevent an estimated 1063.34 metric tons of carbon emissions annually, which corresponds to an economic value of approximately $99,507. Furthermore, 32,656 metric tons of other organic food waste are produced each year (101.4 tons per square kilometre), which is sufficient to sustain an estimated population of 3051 spotted hyenas in Mekelle.

6. Predators/scavengers in our study area process approximately 5026 metric tons of organic waste annually, providing a waste disposal offset valued at around $100,510 per year. Spotted hyenas are the primary contributors, processing 4455 metric tons of human-generated organic waste, which translates to a value of approximately $89,100 annually. Stray dogs follow, processing 519 metric tons, valued at $10,380 per year, while African wolves process 51.5 metric tons, contributing a value of $1030 annually.

7. In conclusion, the main predators/scavengers in our study area provide essential urban ecosystem services, from waste management to CO2 emissions reduction. These species are highly specialized in the consumption of organic waste, and residents recognize the benefits they provide in waste removal, further highlighting the potential for beneficial co-existence between wildlife and humans.

8. Practical implication: Future research should explore diverse urban settings to understand how religious practices, cultural differences, and urbanization influence waste generation and human–wildlife interactions.