From regional to global patterns in vertebrate scavenger communities subsidized by big game hunting

Abstract

Aim Anthropogenic food subsidies are increasingly present in ecosystems, but their impacts remain poorly understood. Big game hunting is a growing activity that annually subsidizes ecosystems with tonnes of carrion world-wide. By feeding on carrion, scavengers support key ecosystem functions and services, becoming key vectors to transfer the impacts of human-mediated food subsidies across ecosystems. We characterize and compare the structure of vertebrate communities feeding on these subsidies, namely big game hunting remains, at a global scale.Location Global.Methods We collected data from a countrywide field study in Spain and broadened it up to nine regions in four continents by reviewing scientific literature. We analysed the structure of the scavenger communities considering species composition, richness and scavenging frequency.Results Seventy-nine vertebrate species, 19% globally threatened, scavenged food subsidies from big game hunting world-wide. Scavenger richness (2.0-11.0% of vertebrates/region) positively correlated with total vertebrate richness. Although scavenger communities at hunting remains varied among regions, we describe a general structural pattern. Birds and mammals dominate consumption, with birds scavenging twice more frequently than mammals -but more mammal species scavenge compared to birds. Generalists dominate scavenging globally, especially where the presence of obligate scavengers (vultures) and apex predators (e.g. wolves, hyenas, eagles) is low.Main conclusions Anthropogenic food from hunting subsidizes many vertebrate species from different trophic levels and conservation status and thus is expected to affect from populations to ecosystems. Obligate scavengers and apex predators seem to play a key role structuring the scavenger community through top-down mechanisms. The general structure of scavenger communities we describe here provides a benchmark for comparisons of subsidized and non-subsidized communities. More data on the spatio-temporal availability of anthropogenic food subsidies and their consumption by scavengers world-wide are needed to efficiently preserve biodiversity, and the associated ecological functions and services, in increasingly subsidized ecosystems.

Free lunch, may contain lead: scavenging shot small mammals

“…). This corroborates previous work showing that birds, on a global scale, scavenge more often than mammals (Mateo‐Tomás et al ). Raptors scavenged sporadically, possibly indicating that they opportunistically took carcasses when hunting.…”

“…Similar to carcasses from big game hunting, shot ground squirrels and prairies dogs were consumed by a diverse suite of scavengers (Mateo‐Tomás et al , Lafferty et al , Gomo et al ). We observed 14 different species of scavengers across 8 locations in Montana (Table ; Fig.…”

“…In many locations worldwide, humans subsidize scavengers with carcass remains (Mateo‐Tomás et al , Lafferty et al , Gomo et al ). These food subsidies often occur predictably in time and space (e.g., during and following hunting seasons) and have the potential to improve the body condition and overall survival of the scavengers (Haroldson et al , Mateo‐Tomás et al ). Consequently, facultative scavengers may become more prevalent and increase their overall predation on prey (Moleón et al ).…”

Mapping the spatio-temporal risk of lead exposure in apex species for more effective mitigation

“…Griffon vultures feed on carcasses often consumed by many other species, including threatened ones (e.g. Spanish imperial eagle Aquila adalberti) [1,8]. The strong dependence of griffon vultures on human-mediated carcasses from livestock [9] and hunting [8] further enhances its usefulness for monitoring potential exposure to environmental contaminants on humans (e.g.…”

“…Spanish imperial eagle Aquila adalberti) [1,8]. The strong dependence of griffon vultures on human-mediated carcasses from livestock [9] and hunting [8] further enhances its usefulness for monitoring potential exposure to environmental contaminants on humans (e.g. consuming meat from livestock and big game) [10][11][12].…”