Scavenging in the Anthropocene: Human impact drives vertebrate scavenger species richness at a global scale

Abstract

© 2019 John Wiley & Sons Ltd Understanding the distribution of biodiversity across the Earth is one of the most challenging questions in biology. Much research has been directed at explaining the species latitudinal pattern showing that communities are richer in tropical areas; however, despite decades of research, a general consensus has not yet emerged. In addition, global biodiversity patterns are being rapidly altered by human activities. Here, we aim to describe large-scale patterns of species richness and diversity in terrestrial vertebrate scavenger (carrion-consuming) assemblages, which provide key ecosystem functions and services. We used a worldwide dataset comprising 43 sites, where vertebrate scavenger assemblages were identified using 2,485 carcasses monitored between 1991 and 2018. First, we evaluated how scavenger richness (number of species) and diversity (Shannon diversity index) varied among seasons (cold vs. warm, wet vs. dry). Then, we studied the potential effects of human impact and a set of macroecological variables related to climatic conditions on the scavenger assemblages. Vertebrate scavenger richness ranged from species-poor to species rich assemblages (4–30 species). Both scavenger richness and diversity also showed some seasonal variation. However, in general, climatic variables did not drive latitudinal patterns, as scavenger richness and diversity were not affected by temperature or rainfall. Rainfall seasonality slightly increased the number of species in the community, but its effect was weak. Instead, the human impact index included in our study was the main predictor of scavenger richness. Scavenger assemblages in highly human-impacted areas sustained the smallest number of scavenger species, suggesting human activity may be overriding other macroecological processes in shaping scavenger communities. Our results highlight the effect of human impact at a global scale. As species-rich assemblages tend to be more functional, we warn about possible reductions in ecosystem functions and the services provided by scavengers in human-dominated landscapes in the Anthropocene.

Relationships between the distribution of wildlife and livestock diversity

“…To characterize human disturbance of natural systems, we used the terrestrial Human Footprint for 2009 (Venter et al, 2018). This source of data has often been used to analyse the influence of human activities on biodiversity (Garnett et al, 2018; Sebastián‐González et al, 2019). We z ‐scored all variables to facilitate the comparison across models (Schielzeth, 2010).…”

Scavenging and carcass caching behavior by European wildcat (Felis silvestris)

“…Scavenging, where organisms from microbes to vertebrates compete to consume ephemeral carrion, is an important ecological process (Sebastián‐González et al, 2019; Wilmers, Stahler, Crabtree, Smith, & Getz, 2003). Scavengers provide functions in ecosystems and to humanity by removing decaying carrion and potentially harmful pathogens, as well as stabilizing food webs (Ćirović, Penezić, & Krofel, 2016; Sebastián‐González et al, 2020; Wilson & Wolkovich, 2011).…”

Predicted climate‐induced reductions in scavenging in eastern North America

“…Global change (i.e., changing climate and increasing human impact) may alter important ecological interactions (Sebastián‐González et al, 2019). It is suggested that vertebrate scavenger species richness is strongly negatively affected by humans (Sebastián‐González et al, 2019).…”

“…Global change (i.e., changing climate and increasing human impact) may alter important ecological interactions (Sebastián‐González et al, 2019). It is suggested that vertebrate scavenger species richness is strongly negatively affected by humans (Sebastián‐González et al, 2019). In some environmental settings, higher human population density can reduce scavenger richness and diversity due to habitat fragmentation and fatality from conflict or road deaths (Crooks et al, 2011; Hagen et al, 2012; McKinney, 2008; Planillo et al, 2018; Sebastián‐González et al, 2019; Treves & Karanth, 2003).…”