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.

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The progressive lost of natural wetlands as a consequence of human activities has lead to the use of new habitats by the species linked to water presence. In Southeast Spain, thousands of irrigation ponds have been lately constructed to store water for agriculture and are used by waterbirds as an alternative habitat. For this study, breeding and wintering waterbirds were counted in a subset of irrigation ponds between 2002 and 2007. Breeding communities were more abundant than wintering communities, but they presented a similar richness and diversity. The ponds were selected by waterbirds according to their characteristics, and breeding communities were more selective than wintering communities. Our results enhance the importance of pond size (area), connectivity (distance to the nearest wetland) and habitat quality (resource offer and construction material) in the pond selection process. The presence and design of these impoundments could be playing a crucial role for some waterbirds species. Therefore, the long-term information provided here can be useful for establishing management strategies for these artificial wetlands.

Global warming due to human-induced increments in atmospheric concentrations of greenhouse gases (GHG) is one of the most debated topics among environmentalists and politicians worldwide. In this paper we assess a novel source of GHG emissions emerged following a controversial policy decision. After the outbreak of bovine spongiform encephalopathy in Europe, the sanitary regulation required that livestock carcasses were collected from farms and transformed or destroyed in authorised plants, contradicting not only the obligations of member states to conserve scavenger species but also generating unprecedented GHG emission. However, how much of this emission could be prevented in the return to traditional and natural scenario in which scavengers freely remove livestock carcasses is largely unknown. Here we show that, in Spain (home of 95% of European vultures), supplanting the natural removal of dead extensive livestock by scavengers with carcass collection and transport to intermediate and processing plants meant the emission of 77,344 metric tons of CO2 eq. to the atmosphere per year, in addition to annual payments of ca. $50 million to insurance companies. Thus, replacing the ecosystem services provided by scavengers has not only conservation costs, but also important and unnecessary environmental and economic costs.

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.