Understanding how species respond to human-induced habitat modification is essential for effective conservation and management. Among these modifications, forest chronic disturbance and landscape anthropization are key drivers threatening biodiversity. While these alterations are often associated with biodiversity loss, their effects are not always direct; rather, they frequently operate through indirect pathways, such as changes in vegetation structure. We used the bird community of seasonally dry tropical forest (SDTF) as a model system to evaluate both direct and indirect effects of these habitat modifications on biodiversity. SDTF provide an ideal context for this research, as they are simultaneously impacted by chronic degradation and landscape anthropization. Bird surveys were conducted across 51 point-counts, each visited nine times between February 2018 and March 2019, in Zapotillo, southwestern Ecuador. A total of 11,012 birds from 110 species, 39 families, and 18 orders were recorded. Our results reveal that landscape anthropization was the primary driver, influencing species richness and evenness, while chronic disturbance enhanced taxonomic distinctness. At the feeding guild level, chronic disturbance influenced the guilds in contrasting ways, both directly and indirectly, through changes in vegetation, such as reductions in canopy height and structural complexity. Our results underscore the importance of conserving well-preserved forest patches within heterogeneous mosaic of anthropized landscapes to support greater bird diversity and abundance while maintaining essential ecosystem services of different functional bird feeding guilds. This study underscores the need for tailored management strategies in SDTFs to address increasing anthropogenic pressures and ensure the long-term resilience of these unique ecosystems.

Plant diversity affects both ecosystem functioning and the functional and taxonomic diversity of multiple trophic levels. However, in the literature, it is unclear if this pattern is driven by species richness per se or by the functional diversity or composition (e.g. resource-use strategy) of the community. Here, we use a novel Hawaiian lowland restoration experiment where plots were planted with the same number of plant species (n = 10), but different functional diversities and different resource-use strategies. The different plant combinations created a range of trait values with species placed in trait space according to their life history traits under the fast-slow plant economics spectrum. Because resource quality varied for detritivores, we were able to test how litter mixtures influenced litter decomposition rates and ground-dwelling arthropod taxonomic and functional diversity and abundance at high (predators) and low (detritivores, fungivores) trophic levels. Using Structural Equation Models, we found that plant functional diversity (measured using functional dispersion and Rao's Q indices) but not resource-use strategy increased both litter decomposition rates and low trophic level arthropod richness and functional diversity. Arthropod abundance increased arthropod taxonomic richness at the two trophic levels but decreased functional diversity at the low level. Finally, we also found indirect bottom-up effects of plant functional diversity on arthropod functional diversity at the high trophic level. Our findings demonstrate that interactions between food webs and plant functional diversity jointly shape biodiversity-productivity relationships, emphasizing the need to adopt a multi-trophic perspective when studying biodiversity and ecosystem function relationships and designing restoration strategies.Read the free for this article on the Journal blog.

The impact of cats and dogs on biodiversity has been the focus of intense debate. Here, we review the scientific literature on the impacts themselves and discuss societal perception of cats and dogs from a cultural point of view. This includes varying feelings of fear and appreciation, related to differences in risks posed to people, animal size, difficulty in handling, and behavior. We then analyze existing international rules on the management of cats and dogs, particularly international treaties and European Union legislation. The documented adverse biodiversity impacts of cats appear to be significantly greater than those of dogs, but in many countries dogs are prevented from roaming free, whereas cats are often allowed to roam freely on a massive scale. This appears to run counter to many legal obligations. A mismatch thus appears to exist between science on the one hand and law on the other hand, which may partly be explained by differing social perceptions. The results of our analysis justify a more homogeneous legal treatment for dogs and cats with regard to their freedom of movement, through a tightening of the rules that affect cats.

Animal corpses act as pulses of organic matter (OM) and serve a key zoogeochemical role by providing localized nutrient inputs to soils and thereby contributing to maintaining soil functions and biogeochemical cycles. Among mammals, carnivore carcasses tend to persist longer than those of herbivores due to lower consumption rates from vertebrate scavengers. This, combined with the different composition and size of carnivore and herbivore carcasses, could modify the effects of animal-derived OM input on soil dynamics. We examined changes in soil properties (pH, electrical conductivity [EC], organic carbon, aggregate stability (AS), microbial respiration and enzymatic activities) driven by the deployment of 20 red fox (Vulpes vulpes: mesocarnivore) and 19 aoudad (Ammotragus lervia: herbivore) carcasses. We also monitored their consumption with camera traps and assessed the modulating effect of scavenging patterns and carrion features (size, type: herbivore vs. mesocarnivore). Carrion increased EC, phosphorus availability and microbial activity in the soil, but had little effect on soil organic carbon or pH. These effects were modulated by carcass size, type (fox or aoudad) and its associated consumption by scavengers. Additionally, scavenger richness modulated the effects of carrion on soil AS and phosphatase. Due to lower carcass weight, longer persistence in the environment, and the interactions between vertebrate scavengers and the carcass, soils below mesocarnivore carcasses featured an enhanced increase in biochemical soil properties, suggesting wider changes in soil microbiological communities as compared to herbivore carcasses. Through contrasting scavenger assemblages and consumption patterns, mesocarnivore and herbivore carcasses play distinct yet equally relevant roles in nutrient-limited dryland soils.

Knowledge of which animal clades and dispersal mechanisms contribute to seed dispersal is critical for understanding the ecology and evolution of plant communities. However, a broad understanding is limited by a focus on single clades and mechanisms. Here, we analyzed a Europe-wide multi-clade seed dispersal dataset with interactions among 447 animal species and 1901 plant species via four dispersal mechanisms: endozoochory (ingestion followed by egestion), epizoochory (external attachment), synzoochory (actively carried by vertebrates), and myrmecochory (dispersal by ants). We aimed to (1) characterize the relative importance of animal dispersal clades and biotic dispersal mechanisms; (2) evaluate links among clades and mechanisms; (3) compare dispersal of dry- and fleshy-fruited diaspores; and (4) evaluate the predictive power of seed dispersal syndromes with empirical data on observed dispersal mechanisms. This revealed that endozoochory by birds and mammals encompasses 90% of plant-animal interaction records. Mammal species tend to have more plants depending upon their dispersal services; however, due to the larger diversity of bird species, more plants depend upon the cumulative services of birds (followed by mammals, insects, and reptiles). Plants with fleshy fruits comprise only 15% of all plant species dispersed by animals but had more animal partners per plant species than plants with dry fruits. Fleshy-fruited plant species were more specifically selected by dispersers, while selection of dry-fruited plants depended more on their relative abundance. Different animal clades tend to disperse plant species via different mechanisms. Endozoochory is the most recorded interaction for birds, mammals, and reptiles. Epizoochory is almost exclusively carried out by mammals, with a negligible role of birds, insects, and reptiles. Synzoochory is performed chiefly by ants (via myrmecochory), followed by birds and then mammals. Predicting vector importance by assigning dispersal syndromes based on diaspore traits (including endozoochorous, epizoochorous, synzoochorous, and myrmecochorous syndromes) only moderately predicted empirically observed dispersal mechanisms. Animals disperse many more species than inferred from diaspore traits, including plants with abiotic syndromes and plants without clearly visible morphological traits. Our results suggest that different animal clades perform complementary dispersal services via multiple mechanisms to plant species with fleshy as well as dry fruits.

Many bird species are known to differ in their vocal repertoires between populations across a range of geographic scales. This is generally assumed to be caused by acoustic drift and social learning of small differences in songs among individuals in separate populations. To determine the extent to which vocal repertoire is structured in a highly nomadic species with a low degree of isolation among populations, we characterized the vocalizations of the ‘Apapane (Himatione sanguinea) and described the variations in its songs on a microgeographic scale. ‘Apapane had significant shifts in their songs in both fragmented and non-fragmented forest habitats, with little to no overlap in song meme structure within distances as short as 2 km, despite birds moving freely between areas with distinct songs. Forest fragments had unique song compositions and shared more syllables with closer fragments than with the ones further apart. Furthermore, microgeographic variation was relatively stable at a given recording location even over multiple years. This pattern of song differentiation in a highly mobile species at the microgeographic scale may be a consequence of their ability to learn new vocalizations over their life and of intraspecific mimicry, or “vocal matching” by individuals visiting other populations.

ABSTRACT Recent advances in automated technologies, such as passive acoustic monitoring, provide a powerful framework for surveying bird communities at broad spatial scales. Among the most widely used artificial intelligence tools for automated bird sound recognition is BirdNET, which can identify over 6,000 species worldwide. However, the effects of key user-defined settings, such as species filtering, remain poorly evaluated. Here, we assess how alternative species-filtering strategies influence BirdNET performance in describing bird communities worldwide. We analysed 5,047 minutes of sound recordings from 72 locations worldwide, comprising 1,192 bird species identified by expert ornithologists. We compared three common species-filtering approaches applied in BirdNET workflows to post-process its output: no filtering, spatial filtering (species present all-year at a given location), and spatio-temporal filtering (species present at a given location and week). The unfiltered approach maximised BirdNET species detection (recall) but suffered very low precision (had many misidentifications) and poor overall performance. In contrast, the other two filtering strategies greatly improved precision and overall performance, despite moderate reductions in recall. Among them, spatio-temporal filtering consistently achieved the best performance across most datasets and regions globally. Within this optimal filtering approach, we also evaluated the role of another parameter: occurrence probability thresholds. Intermediate values of this threshold (around 0.05) maximized BirdNET performance in community-level analyses. Our results demonstrate that species filtering is a key but often underappreciated component of BirdNET workflows. We hope our findings may guide future studies in selecting optimal species filters, while emphasising that filtering selection should be guided by study objectives and data context.

Urbanization acts as a selective filter for wildlife, favoring species pre-adapted to urban environments while creating hostile conditions for others. Previous studies have focused on which traits determine success in urban habitats, while little effort has been put into delineating how bird assemblages are spatially structured within the city. We investigated how spatial gradients in anthropogenic and environmental variables shape bird assemblage distributions across Rome, one of Europe’s largest and greenest metropolitan areas, and map their distribution to reveal how community structure shifts along the urbanization gradient. In spring 2024 and 2025, we conducted acoustic monitoring in 102 sites across Rome’s metropolitan area. Detections of 48 species were modeled against landscape variables, synthesized in three principal components reflecting urbanization intensity, forest cover, and isolation. We then used Outlying Mean Index analysis to cluster species with similar habitat use, and identified three distinct assemblages (avoiders, adapters, and exploiters), and mapped their distribution. Our results highlight a spatial turnover of bird compositions along the urbanization gradient, with different degrees of urbanization supporting distinct bird assemblages. avoiders were concentrated in extensive green areas at the city periphery, while adapters were largely distributed in transitional areas at the interface with the urban matrix. exploiters dominated the urban core but were mostly absent from green areas. Varying urban conditions shape distinct bird assemblages, composed of species with similar responses to urbanization and vegetation. Ensuring a permeable urban matrix and integrating greening initiatives within urban cores can contribute to maintaining high diversity, enhance ecosystem services, sustain species persistence, and limit disservices.

Carrion is a ubiquitous resource in both terrestrial and aquatic ecosystems, yet it has long been overlooked in ecological research. Over the past two decades, studies on carrion and the many organisms that exploit it have flourished, revealing not only wide-ranging ecological functions but also significance far beyond ecology. This growing body of knowledge underscores the need for the formal recognition and consolidation of carrion ecology as a distinct ecological discipline. In this review, we begin by outlining the ecological features that make carrion a unique resource, provide practical definitions of scavenger and scavenging to reduce persistent ambiguities, describe carcass decomposition by linking stages with insect succession, and position carrion within a broader scientific context. Building on this foundation, we then pursue three main goals. First, we show how incorporating carrion ecology enriches ecological concepts and paradigms across levels of biological organisation, from individuals to ecosystems. Second, we emphasise how expanding knowledge of carrion ecology informs many disciplines beyond ecology. Third, we present a conceptual framework that integrates the diverse ecological functions of carrion across eco-evolutionary timescales and addresses the structured and dynamic connections among the multiple disciplines concerned with carrion. By underscoring the ecological and interdisciplinary relevance of this resource, our framework not only clarifies the components and flows of the carrion system but also highlights opportunities for novel cross-disciplinary collaborations. As carrion ecology continues to mature as a scientific field, we expect that this review and synthesis will consolidate current knowledge, stimulate innovative research across disciplines, and firmly position carrion ecology within the broader ecological and scientific landscape.

Recent advances in machine learning have accelerated automated species detection across diverse ecological domains, enabling large-scale, non-invasive monitoring of biodiversity. In ornithological research, the combination of passive acoustic monitoring (PAM) and rapidly-developing novel identification tools such as BirdNET—a deep learning–based sound recognition algorithm—offers new opportunities for surveying vocally active bird communities. Here, we present the first worldwide evaluation of BirdNET using 4224 one-minute recordings from 67 sites across all continents annotated by local experts. More specifically, we assessed the capacity of BirdNET to accurately identify individual vocalizations and characterize bird communities based on the automated analysis of passively collected soundscapes. We further analyzed how its performance varies across continents, biomes, species, and minimum confidence thresholds. The proportion of correct BirdNET predictions (precision) was generally high and consistent across continents (range: 0.57–0.71) and biomes (range: 0.55–0.76). In contrast, the proportion of vocalizations successfully detected (recall) was generally lower and more heterogeneous across continents (range: 0.24–0.52) and biomes (range: 0.34–0.72), reflecting differences in species coverage and local ecological context. BirdNET predictive power, as measured by the Precision-Recall Area Under the Curve (PR AUC; higher values indicating better performance), was highest in North America, Oceania, and Europe (range: 0.16–0.23), moderate in Central/South America (0.13), and lowest in Africa and Asia (range: 0.03–0.04). Species-specific analyses revealed substantial heterogeneity in detection accuracy, with optimal confidence thresholds varying widely by species and analytical goal. Our results establish a global reference point for BirdNET reliability and highlight where algorithmic refinement and expanded acoustic sampling are most needed.

Animal carcasses represent localized and temporally discrete pulses of organic matter and nutrients that can substantially influence soil microbial communities and biogeochemical processes. These pulses are especially relevant in naturally nutrient-depleted soils and ecosystems, such as drylands. However, the role and extent to which biotic factors (e.g., scavenger activity, carcass type and vegetation cover) shape these effects remains poorly understood. We analyzed changes in soil microbial community composition and activity induced by carcass decomposition and their modulation by scavengers and vegetation cover in a Mediterranean dryland ecosystem. We experimentally deployed 10 red fox (Vulpes vulpes) and 10 aoudad (Ammotragus lervia) carcasses in Sierra Espuña Regional Park (Murcia, Spain). Soil microbial community composition (PLFA profiles) and activity (basal respiration, microbial biomass carbon and extracellular enzymatic activities) and other physicochemical properties were measured before carcass placement and five months later in carcass-affected soils. Vegetation cover and scavenger consumption monitored using camera traps were assessed for each carcass. Carrion inputs induced marked changes in microbial community structure, characterized by a shift from Gram-positive dominated communities towards higher relative abundance of Gram-negative bacteria, alongside pronounced increases in soil enzymatic activities. These responses were strongly modulated by biotic factors. Scavenger consumption reduced carcass–soil interaction time, limiting nutrient incorporation into soils and dampening microbial responses. Moreover, soils beneath mesocarnivore carcasses exhibited stronger biological responses than those beneath herbivores, likely due to longer carcass persistence and differential scavenging dynamics. Vegetation cover enhanced microbial activity likely by buffering microclimatic conditions and reducing carcass detectability. Our results demonstrate that carrion decomposition acts as a strong driver of soil microbial structure and biogeochemical functioning in Mediterranean drylands, highlighting the integrative role of scavengers and vegetation in regulating zoogeochemical nutrient pathways.

Animal carcasses represent localized nutrient pulses that can influence soil microbial communities and biogeochemical processes, particularly in nutrient-depleted soils. However, how biotic factors (e.g., scavenger activity, carcass type and vegetation cover) shape these belowground effects remains poorly understood. Here, we experimentally assessed changes in soil microbial community structure and activity following carrion decomposition and their modulation by these biotic drivers in a Mediterranean dryland. We deployed 10 red fox (Vulpes vulpes) and 10 aoudad (Ammotragus lervia) carcasses in Sierra Espuna Regional Park (Murcia, Spain) and measured soil microbial community composition (phospholipid fatty acid profiles), activity (basal respiration, microbial biomass carbon and extracellular enzymatic activities) and physicochemical properties before deployment and five months later. Scavenger activity was assessed with camera traps and vegetation cover was recorded for each carcass. Carrion deposition significantly altered soil conditions, decreasing pH (-2.5%) and increasing electrical conductivity (+82.2%) and phosphorus availability (+449.7%). Microbial communities shifted markedly, with Gram-negative bacteria increasing importantly (+246.7%) and Gram-positive groups declining (-28.6%), while total microbial biomass and activity showed limited changes. These responses were strongly modulated by biotic factors: carcasses consumed by more scavenger species showed dampened microbial responses, whereas denser vegetation cover enhanced microbial responses. Carcass type also modulated microbial responses, with mesocarnivore carcasses inducing stronger shifts relative to their mass, likely due to longer persistence and differential scavenging dynamics. Our findings demonstrate that carrion effects on soils depend not only on nutrient inputs but also on large-scale ecological processes regulating carcass persistence. By linking scavenger activity and vegetation structure with microbial responses, our results highlight carrion as a key interface coupling above- and belowground processes, ultimately shaping microbial heterogeneity and regulating zoogeochemical nutrient pathways in dryland ecosystems.

Birds are key ecosystem service providers given the wide range of services in which they are involved, their outstanding mobility and large population sizes. However, we lack a comprehensive framework to evaluate the ecosystem services (ES) provided by bird species at large spatial scales. Here, we introduce ServiBirds, an innovative database meticulously designed to quantify the ES delivered by bird species, using Spain, a species-rich country, as our study model. The database describes the species-level values in 12 different provisioning, supporting/regulating and cultural ES for 378 bird species from 73 families. For each species, the supporting/regulating services were weighted by its field metabolic rate and its population size in Spain, to enable a more precise view of the current role of the species in such services. In addition, birds provide diverse other ES, especially aesthetic, ecotouristic, as pest controllers and as seed dispersers. The most important providers of supporting/ regulating services in Spain included some, such as the Eurasian Magpie Pica pica and the Common Blackbird Turdus merula, that provide several services and specialists, such as the Griffon Vulture Gyps fulvus, that provide a single service. For cultural services, the top species were those, such as the Red-legged Partridge Alectoris rufa, Golden Eagle Aquila chrysaetos or European Goldfinch Carduelis carduelis, that provide multiple services. Our study underlines the important role that birds play in ecosystem conservation and for human wellbeing. Moreover, the proposed framework can be adapted to other regions, and even taxonomic groups. We hope this study acts as a catalyst to better understand and evaluate the ES provided by birds, thereby serving as a tool for bird conservation and ecosystem management.-Sebasti & aacute;n-Gonz & aacute;lez, E., Carri & oacute;n, S., P & eacute;rez-Granados, C., L & oacute;pez-Iborra, G.M., Botella, F., P & eacute;rez, C., Rocher, G., P & eacute;rez-Garc & iacute;a, J.M., Garc & iacute;a-Rodr & iacute;guez, J., S & aacute;nchez-Zapata, J.A. & Orihuela-Torres, A. (2026). Servibirds: Servibirds: Quantitative assessment of the ecosystem services provided by native birds in Spain.

Context Habitat fragmentation reduces connectivity and constrains species movement across landscapes, threatening biodiversity and ecosystem processes. Ecological corridors are widely proposed to maintain functional connectivity, yet evaluating their effectiveness across large and heterogeneous regions remains challenging in landscape ecology. Objectives We assessed functional connectivity across the Araguaia Biodiversity Corridor (ABC), a ~ 3,000 km corridor linking the Amazon and Cerrado biomes in central Brazil. Specifically, we aimed to identify areas of concentrated movement flow and connectivity constraints for jaguars ( Panthera onca ) and evaluate spatial variation in connectivity along the corridor. Methods Connectivity was modeled using omnidirectional circuit theory (Omniscape) based on resistance surfaces derived from land use, infrastructure, and habitat configuration. Resistance values were informed by telemetry from 16 GPS-collared jaguars monitored between 2011 and 2025. Connectivity outputs were integrated with vegetation cover and morphological spatial pattern analysis to classify landscape structure and movement flow. Results Fifteen of the 16 monitored jaguars used the corridor, indicating its importance for regional movement. Connectivity varied strongly along the corridor. The Mid-Araguaia region in the Cerrado biome showed the highest connectivity, whereas the Amazonian midsection exhibited the lowest connectivity and strongest fragmentation. Integrating current flow with vegetation-cover thresholds revealed connectivity strongholds, stepping-stone systems, and movement-constrained zones. Several areas with moderate vegetation cover showed high movement flow, indicating priority targets for restoration. Conclusions Connectivity across the ABC is spatially heterogeneous and influenced by landscape structure and land-use intensity. Combining omnidirectional connectivity modeling with telemetry data provides a framework for identifying conservation and restoration priorities in large ecological corridors.

Under the current global biodiversity crisis, there is a need for automated and noninvasive monitoring techniques that can gather large amounts of data cost-effectively at various ecological scales, from local to large spatial scales. These data can then be analyzed to inform stakeholders and decision-makers. One such technique is passive acoustic monitoring, which is commonly coupled with automatic identification of animal species based on their sound. Automated sound analyses usually require the training of sound detection and identification algorithms. These algorithms are based on annotated acoustic datasets which mark the occurrence of sounds of species inside sound recordings. However, compiling large annotated acoustic datasets is time-consuming and requires experts, and therefore, they normally cover reduced spatial, temporal, and taxonomic scales. This data paper presents WABAD, the World Annotated Bird Acoustic Dataset for passive acoustic monitoring. WABAD is designed to provide the public, the research community, and conservation managers with a novel and globally representative annotated acoustic dataset. This database includes 5047 min of audio files annotated to species-level by local experts with the start and end time and the upper and lower frequencies of each identified bird vocalization in the recordings. The database has a wide taxonomic and spatial coverage, including information on 91,931 vocalizations from 1192 bird species recorded at 72 recording sites in 29 recording locations (mainly countries) and distributed across 13 biomes. WABAD can be used, for example, for developing and/or validating automatic species detection algorithms, answering ecological questions, such as assessing geographical variations on bird vocalizations, or comparing acoustic diversity indices with species-based diversity indices. The dataset is published under a Creative Commons Attribution 4.0 International license that permits redistribution and reuse on the condition that the original work is properly credited.

Seed dispersal is critical for long-term ecosystem resilience. However, excessive compartmentalisation of research into particular disperser guilds (e.g. birds) hampers our understanding of their relative contributions to overall seed dispersal, risking erroneous conclusions and overlooking key information gaps. Here, we evaluate how information about over 11 000 interactions between 1902 plant and 455 animal species in Europe accumulated over 400 years, and estimate information completeness across disperser guilds, plant types, and dispersal mechanisms (endozoochory, epizoochory, synzoochory, and myrmecochory). Information regarding the plants dispersed by each group of animals ranges from 27% to 79% sample coverage, with birds of prey (27%), ants (28%), and rodents (31%) particularly understudied. Most research focussed on fleshy-fruited plants rather than dry-fruited plants, and most on internal dispersal as the mechanism (endozoochory). Interestingly, scientists' perceptions of what are the most neglected disperser guilds do not correlate with our sample coverage estimates, showing an inability of the scientific community to identify information gaps. We urge researchers to bridge research silos and to study overlooked guilds, mechanisms, and plant types. Implementing community-level synthesis studies that integrate data across guilds is essential for accurately predicting ecosystem responses to global change and developing effective conservation strategies.

Predation and scavenging are two faces of carnivory that operate under distinct ecological rules, yet food web research often overlooks this distinction by ignoring scavenging or conflating it with predation. Using an 8-year dataset of mammalian carnivore feeding events from the Maasai Mara (Kenya), we explicitly separated predation and scavenging to compare their network structure. The study system includes a diverse carnivore guild and a broad herbivore prey size spectrum, including megaherbivores (>1 ton). We assessed two network properties (nestedness and modularity), identified species contributions to network structure and examined the relationships between these species-level contributions and body mass, between the number of interaction events per link and prey/carcass body mass, and between consumer and resource body mass. Despite largely involving the same species, the two networks differed markedly: both were nested, but only the predation network was modular, with modules aligned with prey size classes. As expected, body-size asymmetries structured the two networks in contrasting ways: predation was mostly limited to prey of similar or smaller size than the predator, with a sharp decline above the megaherbivore threshold, whereas larger carcasses, especially those of megaherbivores, attracted more scavenger species. The most influential species across metrics and network types was a herbivore, particularly the wildebeest, except for the lion in weighted nestedness within the predation network. These species-level contributions to network structure were unrelated to body mass. Relationships between consumption degree and prey/carcass body mass differed between networks, and predator-prey body mass correlated positively, unlike scavenger-carcass body mass. These asymmetries reveal opposing size-based constraints, with predation being more tightly constrained by body size than scavenging. Although similar patterns have been suggested previously, no study has directly compared both networks within the same system. Overall, our results show that predation and scavenging are complementary, not functionally redundant, components of carnivory food webs. We also propose a scalable framework for cross-ecosystem comparisons of species-level differences in network structure. Distinguishing scavenging from predation is essential to fully reveal the true architecture of food webs and the mechanisms governing energy flow through ecosystems.

Scavenging has been profusely studied in the last decades. However, carrion is more than a direct source of food for scavengers and decomposers, as it may provide many non-scavenging ecological functions. These include the provision of carrion insects to insectivores and hair to nest-building species. However, the patterns of use of these resources are greatly unknown. In this context, carnivore carcasses may represent an outstanding study model because they usually persist in the environment for longer than herbivore carcasses. Here, we used video-trapping to explore the consumption of carrion insects and hair taking at 99 red fox (Vulpes vulpes) carcasses in three areas of southeastern Spain. Carcasses were frequently used for consuming insects and taking hair (7.3 events in total on average per carcass). These non-scavenging behaviors were observed over eight weeks for most carcasses, peaking around the fifth week. Birds were the main users of carcasses, distantly followed by mammals; reptiles were only recorded feeding occasionally on carrion insects. These behaviors were more frequent during spring, when the demand for insects for offspring feeding and hair for nest building is maximized by many vertebrates. Moreover, the community of species exhibiting each of these behaviors was highly organized, as evidenced from their nested structure. We observed co-occurrence of insect consumption and hair taking in a quarter of carcasses, with co-occurrence being mostly due to chance and certain individuals and groups that used some carcasses for both purposes. Overall, non-scavenging uses of fox carcasses by vertebrates in our study area is more frequent than scavenging, which highlights the broad ecological relevance of carnivore carcasses and opens exciting future research avenues.

In scavenging assemblages, the functional traits of scavengers that impact the structure and function of ecological communities are becoming clearer. However, there are multiple terms for influential scavenger species that lack established definitions. As such, we propose a standardized terminology encompassing five functional roles: frequent scavenger, main biomass consumer, and keystone scavenger, as well as apex scavenger and mesoscavenger (defined through ecological roles and hierarchical positions). Furthermore, we identify and describe five key behaviors, and its actors related to competitive and facilitative interactions among scavengers - signaling scavenger, carrion broker, dominant scavenger, carcass cacher, and carrion transporter - which drive species' roles. We unify concepts of scavenger roles to facilitate comparisons among studies on scavenging.