Large home range scavengers support higher rates of carcass removal

Abstract

Vertebrate scavenger communities vary in species composition across the globe. They include a wide array of species with diverse ecological strategies and life histories that support essential ecosystem functions, such as carrion removal. While previous studies have mostly focussed on how community aspects such as species richness and composition affect carrion consumption rates, it remains unclear whether this important function of scavengers is better explained by the dominance of key functional traits or niche complementarity as a result of a diverse functional representation. Here, we test three competitive hypotheses to assess if carrion consumption in vertebrate scavenger communities depends on: (a) the presence of key dominant traits (functional identity hypothesis), (b) functional diversity that promotes niche complementarity (functional diversity hypothesis) or (c) the accumulation of individuals and species, irrespective of their trait representation (functional equivalence). To explore these hypotheses, we used five study areas in Spain and South Africa, which represent a gradient of scavenger biodiversity, that is, ranging from communities dominated by facultative scavengers, such as generalists and meso‐predators, to those including vultures and large carnivores. Within study areas, traits that characterize obligate scavengers or large carnivores (e.g. mean home range, proportion of social foragers) were positively linked to rapid carrion consumption, while the biomass of functional groups including facultative scavengers were either weakly or negatively associated with carrion consumption. When combining all study areas, higher rates of carrion consumption were related to scavenger communities dominated by species with large home ranges (e.g. Gyps vultures), which was found to be a key trait. In contrast, metrics describing functional diversity (functional dispersion) and functional equivalence (species richness and abundance) had lower predictive power in explaining carrion consumption patterns. Our data support the functional identity hypothesis as a better framework for explaining carrion consumption rates than functional diversity or equivalence. Our findings contribute to understanding the mechanisms sustaining ecosystem functioning in vertebrate communities and reinforce the role of obligate scavengers and large carnivores as keystone species in terrestrial ecosystems.

Biases in the Detection of Intentionally Poisoned Animals: Public Health and Conservation Implications from a Field Experiment

“…Birds like vultures and other raptors might feed on the carcasses of animals that have been previously poisoned. Secondary poisoning may affect mainly birds because of their higher response capacity due to great searching and movement abilities compared to terrestrial animals [38,39]. Our experiment was unable to capture these cascading effects, which could be relevant to fully assess the impact of poisoning along the food web, as previously described for rodenticides [40].…”

Predicted climate‐induced reductions in scavenging in eastern North America

“…It is also possible that carcass presence under warm and wet conditions in the future may lead to an increased disease risk to humans (O'Bryan et al, 2018; Ogada et al, 2012). Attention placed on the conservation of species‐rich scavenger communities, especially vultures that facilitate rapid carcass removal, is therefore likely important to retain the functional role of scavenging in eastern North America (Gutiérrez‐Cánovas et al, 2020; Sebastián‐González et al, 2016). Although a great deal of attention is placed on species extinction risk and distribution changes as a result of changing climate (Chen et al, 2011; Thomas et al, 2004), a reduction in scavenging highlights the impact of climate‐induced adjustments in behavior that could have negative impacts at a large scale in a temperate ecosystem.…”

Phylogenetic affinities and morphology of the Pliocene cathartiform Dryornis pampeanus Moreno & Mercerat

“…Carcass availability is the second (and a strong) limitation on the distribution and home range of scavengers (Tyrberg 80; Gutiérrez‐Cánovas et al . 39). Vizcaíno et al .…”