Super-scavengers: Vertebrates outperform invertebrates and microbes at removing carrion from a tropical forest

Scavenging by vertebrates is an important ecosystem service as they are known to remove carrion more efficiently than other taxa. How long would carrion persist bereft of vertebrate scavengers? Our study addresses this question in a forested landscape, by comparing carrion utilization by vertebrate scavengers, invertebrates, and microbes (decomposers). To understand carrion removal, we used experimental placement of chicken carcasses in a dry deciduous forest near Panna Tiger Reserve, Madhya Pradesh, India. Carcasses were placed under different treatment conditions (vertebrate scavenging, invertebrate scavenging, microbial decomposition and control to account for moisture loss), by experimentally excluding other scavengers. The daily rate of carcass utilization and proportion of carrion biomass remaining differed between treatments. Vertebrates consumed carcasses at the highest rates, removing 83% of carcass biomass in one day (CI 95%), followed by invertebrates (7.3%) and microbes (3.9%). Additionally, desiccation accounted for another 3.6% weight loss per day. The study showed drastic differences in carrion removal rates between taxa, indicating the irreplaceable role of vertebrates in the scavenging community of tropical forests, without whom carcasses would persist over prolonged periods. Our results support earlier studies that found overwhelming influence of vertebrate scavengers on carrion removal compared to other scavenging guilds.