Data from: Puma predation subsidizes an obligate scavenger in the high Andes

The ungulate–carnivore–vulture complex is a key trophic module of many terrestrial ecosystems, but one that is globally under threat. Few have explored cross-species dependencies in this module, and the degree to which vultures rely on trophic facilitation by apex carnivores is rarely known and almost never quantified. We investigated the importance of puma Puma concolor predation on its native camelid prey, vicuñas Vicugna vicugna and guanacos Lama guanicoe, in food provisioning for Andean condors Vultur gryphus in the high Andes of north-western Argentina. We evaluated the origin of wild food sources through carcass surveys. We quantified condor feeding habits via foraging observations and through the analysis of pellet contents and stable isotopes from moulted feathers. Of the 102 fresh camelid carcasses we monitored nearly all (94%) resulted from puma predation, and the majority (85%) of camelid carcasses used by condors were killed by pumas. Camelids represented 88% of the prey items identified from 183 condor pellets, and isotopic analyses of moulted feathers from 86 individuals identified via multilocus genotyping revealed that camelids and livestock were the most important prey items, representing 45–58% and 23–38% of condor assimilated biomass, respectively. Synthesis and applications. Our results show that puma predation plays a key role in the foraging ecology of Andean condors, and highlight the importance of predatory processes that make carrion available to scavengers. We contend that targeting the conservation of ungulate–carnivore–vulture modules, rather than a species-specific approach, will be a more effective strategy to ensure the long-term persistence of Andean condors and other obligate scavengers

Data from: Monitoring vultures in the 21st century: the need for standardized protocols

This article calls on scientists, managers and organizations focused on vulture conservation to promote and use standardized monitoring programs based on sampling of molted feathers

Baited Stations

Details of camera trap pictures taken at 8 baited stations in San Guillermo National Park (Argentina), including species registered, total number of Andean condors, their age (Adult, Juvenile, Subadult, Age indet.) and sex (Female, male and Sex Indet.)

Stable isotope data

Uncorrected δ13C and δ15N stable isotope signature of Andean condor molted feathers and hair of potential relevant terrestrial food sources

Limited sexual segregation in a dimorphic avian scavenger, the Andean condor

Sexual segregation is widely reported among sexually dimorphic species and generally attributed to intraspecific competition. Prey diversity and human activities can reinforce niche segregation by increasing resource heterogeneity. Here, we explored trophic and spatial sexual segregation in the only avian scavenger that exhibits pronounced sexual size dimorphism (up to 50% difference in body mass) and a highly despotic social system, the Andean condor (Vultur gryphus). We predicted that larger and dominant males would exclude smaller and subordinate females from high-quality resources, leading to sexual segregation particularly in human-dominated landscapes showing increased prey diversity. We compared resource use between females and males across six sites in Argentina featuring a range of prey diversity via stable isotopes analysis of molted feathers (n=141 individuals). We then focused on two sites featuring contrasting levels of prey diversity and quanti-fied assimilated diet via stable isotopes and space use via GPS monitoring (n=23 and 12 tagged individuals). We found no clear differences in isotopic niche space, individual variation in isotopic signature, or assimilated diet between females and males. However, there were differences in foraging locations between sexes, with females apparently using areas of fewer food resources more frequently than males. Local conditions defined the dynamics of fine-scale sexual differences in foraging sites; yet, unpredictable and ephemeral carrion resources likely prevent segregation by sexes at the landscape scale. Our study highlights complex dynamics of sexual segregation in vultures and the relevancy of analyses under multiple spatial–temporal scales to explore segregation in social species.This study was supported by Conservation Research and Education Opportunities International (CREOI), Hawk Mountain Sanctuary, the Rufford Foundation, the Department of Forest and Wildlife Ecology at the University of Wisconsin-Madison, The National Agency of Scientific and Technological Promotion of Argentina (PICT 0725-2014 and 2016-0354 BID), and Fundación BBVA (project BIOCON-08-126).Peer reviewe

Functional traits driving species role in the structure of terrestrial vertebrate scavenger networks

Species assemblages often have a non-random nested organization, which in vertebrate scavenger (carrion-consuming) assemblages is thought to be driven by facilitation in competitive environments. However, not all scavenger species play the same role in maintaining assemblage structure, as some species are obligate scavengers (i.e., vultures) and others are facultative, scavenging opportunistically. We used a database with 177 vertebrate scavenger species from 53 assemblages in 22 countries across five continents to identify which functional traits of scavenger species are key to maintaining the scavenging network structure. We used network analyses to relate ten traits hypothesized to affect assemblage structure with the ‘role’ of each species in the scavenging assemblage in which it appeared. We characterized the role of a species in terms of both the proportion of monitored carcasses on which that species scavenged, or scavenging breadth (i.e., the species ‘normalized degree’), and the role of that species in the nested structure of the assemblage (i.e., the species ‘paired nested degree’), thus identifying possible facilitative interactions among species. We found that species with high olfactory acuity, social foragers, and obligate scavengers had the widest scavenging breadth. We also found that social foragers had a large paired nested degree in scavenger assemblages, probably because their presence is easier to detect by other species to signal carcass occurrence. Our study highlights differences in the functional roles of scavenger species and can be used to identify key species for targeted conservation to maintain the ecological function of scavenger assemblages

Identifying conservation priority areas for the Andean condor in southern South America

Mobile species face an array of human threats across political boundaries, and their protection relies on identifying and prioritizing areas for conservation. Large avian scavengers are one of the widest ranging and most threatened species globally, and efforts to preserve them have come to the forefront of wildlife management. Vultures require access to functionally distinct habitats for roosting, foraging and flying, yet behavior-specific habitat modelling has been overlooked in management planning. Herein, we developed a spatial prioritization model for the threatened Andean condor (Vultur gryphus) that integrates activity-specific habitat selection across heterogeneous landscapes. We tracked 35 individuals in two regions of Argentina and Chile differing in topography and vegetation composition, and analyzed how landscape covariates influence where condors roost, forage and fly, while accounting for individual differences. We found that individuals responded differently to environmental covariates during each behavior, and identified regional differences for some covariates dependent on behavioral state. We also found important individual differences in habitat selection between birds inhabiting each region. We combined these results into an ensemble spatial prioritization model, and found that most areas of high priority for Andean condor conservation are not under protection. The strategic implementation of conservation measures in these priority areas could have important implications for the recovery of this species. Our study illustrates the value of integrating behavioral- and individual-specific habitat analyses into spatial conservation planning, and points to opportunities for effective management of threatened vultures.Fil: Perrig, Paula Leticia. University of Wisconsin; Estados UnidosFil: Lambertucci, Sergio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Cruz, Jennyffer. University of Wisconsin; Estados UnidosFil: Alarcón, Pablo Angel Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Plaza, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Middleton, Arthur. University of California at Berkeley; Estados UnidosFil: Blanco, Guillermo. Consejo Superior de Investigaciones Científicas. Museo Nacional de Ciencias Naturales; EspañaFil: Sánchez Zapata, José. Universidad de Miguel Hernández; EspañaFil: Donázar, José. Consejo Superior de Investigaciones Científicas. Estación Biológica de Doñana; EspañaFil: Pauli, Jonathan Nicholas. University of Wisconsin; Estados Unido

Functional traits driving species role in the structure of terrestrial vertebrate scavenger networks

Species assemblages often have a non-random nested organization, which in vertebrate scavenger (carrion-consuming) assemblages is thought to be driven by facilitation in competitive environments. However, not all scavenger species play the same role in maintaining assemblage structure, as some species are obligate scavengers (i.e., vultures) and others are facultative, scavenging opportunistically. We used a database with 177 vertebrate scavenger species from 53 assemblages in 22 countries across five continents to identify which functional traits of scavenger species are key to maintaining the scavenging network structure. We used network analyses to relate ten traits hypothesized to affect assemblage structure with the “role” of each species in the scavenging assemblage in which it appeared. We characterized the role of a species in terms of both the proportion of monitored carcasses on which that species scavenged, or scavenging breadth (i.e., the species “normalized degree”), and the role of that species in the nested structure of the assemblage (i.e., the species “paired nested degree”), therefore identifying possible facilitative interactions among species. We found that species with high olfactory acuity, social foragers, and obligate scavengers had the widest scavenging breadth. We also found that social foragers had a large paired nested degree in scavenger assemblages, probably because their presence is easier to detect by other species to signal carcass occurrence. Our study highlights differences in the functional roles of scavenger species and can be used to identify key species for targeted conservation to maintain the ecological function of scavenger assemblage