Supplementary feeding and endoparasites in threatened avian scavengers: Coprologic evidence from red kites in their wintering stronghold

Enhancing monitoring and transboundary collaboration for conserving migratory species under global change: The priority case of the red kite

Calls for urgent action to conserve biodiversity under global change are increasing, and conservation of migratory species in this context poses special challenges. In the last two decades the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has provided a framework for several subsidiary instruments including action plans for migratory bird species, but the effectiveness and transferability of these plans remain unclear. Such laws and policies have been credited with positive outcomes for the conservation of migratory species, but the lack of international coordination and on-ground implementation pose major challenges. While research on migratory populations has received growing attention, considerably less emphasis has been given to integrating ecological information throughout the annual cycle for examining strategies to conserve migratory species at multiple scales in the face of global change. We fill this gap through a case study examining the ecological status and conservation of a migratory raptor and facultative scavenger, the red kite (Milvus milvus), whose current breeding range is limited to Europe and is associated with agricultural landscapes and restricted to the temperate zone. Based on our review, conservation actions have been successful at recovering red kite populations within certain regions. Populations however remain depleted along the southern-most edge of the geographic range where many migratory red kites from northern strongholds overwinter. This led us to a forward-looking and integrated strategy that emphasizes international coordination involving researchers and conservation practitioners to enhance the science-policy-action interface. We identify and explore key issues for conserving the red kite under global change, including enhancing conservation actions within and outside protected areas, recovering depleted populations, accounting for climate change, and transboundary coordination in adaptive conservation and management actions. The integrated conservation strategy is sufficiently general such that it can be adapted to inform conservation of other highly mobile species subject to global change.

Sugar water feeding practices are associated with bird species composition in urban backyards

Feeding backyard birds with sugar water is increasingly popular in urban areas, but it has poorly understood effects on bird assemblages. In New Zealand, ca. 20% of households engaged in feeding wild birds use sugar water, often in an attempt to attract native, nectarivorous birds. Developing best practices for sugar water feeding could be a powerful tool for attracting these species in urban areas. However, it is currently unclear whether these feeders actually support native species, and, if so, which feeding practices are most effective in increasing visitation. We surveyed New Zealanders who provide sugar water to birds about their feeding practices via an online questionnaire. The aim of our research was to understand existing practices and their effect on attracting native species, as well as the motivations and social factors behind urban sugar water bird feeding. Our results show that this practice is popular throughout the country with the majority of households successful in attracting native nectarivorous species to their gardens. Sugar water feeder type had the largest effect on reported species richness at feeders in comparison to other factors (e.g. sugar concentration). Feeders specifically designed for nectarivorous birds, namely the Tui Nectar Feeder™, are more successful at attracting natives in comparison to other commonly used feeder types. Thus, individual householder decisions around feeder use can have important consequences for bird species composition in urban gardens. Future research is needed to understand the consequences of sugar water feeding for bird communities and individual bird health.

Demographic modeling to fine-tune conservation targets: importance of pre-adults for the decline of an endangered raptor

Large, long-lived species with slow life histories and protracted pre-breeding stages are particularly susceptible to declines and extinction, often for unknown causes. Here, we show how demographic modeling of a medium-sized raptor, the Red Kite Milvus milvus, can aid to refocus conservation research and attention on the most likely mechanisms driving its decline. Red Kites' survival and reproduction increased through three sequential stages for 1-2, 3-6, and 7-30 yr of age, mainly corresponding to individuals that are dispersing, attempting to gain a territory, and breeding. As typical of long-lived species, elasticities were highest for adult (≥7 yr old) survival, but this was high, with little scope for improvement. Instead, the declines were driven by an extremely low survival of pre-adults in their first years of life, which weakened the whole demographic system by nullifying the offspring contribution of adults and curtailing their replacement by recruits. For example, 27 pairs were necessary to generate a single prime age adult. Simulation of management scenarios suggested that the decline could be halted most parsimoniously by increasing pre-adult survival to the mean levels recorded for other areas, while only the synergistic, simultaneous improvement of breeding success, adult and pre-adult survival could generate a recovery. We propose three actions to attain such goals through selective supplementary feeding of both breeding and non-breeding individuals, and through mortality improvement by GPS remote-sensing devices employed as surveillance monitoring tools. Our results show how improving demographic models by using real, local vital rates rather than "best guess" vital rates can dramatically improve model realism by refocusing attention on the actual stages and mortality causes in need of manipulation, thus building precious time and resources for conservation management. These results also highlight the frequent key role of pre-adult survival for the management of long-lived species, coherent with the idea of demographic systems as integrated chains only as strong as their weakest link.

Seasonal and spatial occurrence of zoonotic Salmonella serotypes in griffon vultures at farmland environments: Implications in pathogen pollution and ecosystem services and disservices

Livestock production is a large source of microbial, pharmaceutical, and antimicrobial pollution worldwide. Vultures are one group of birds with particularly high exposure to food-borne pathogens due to frequent consumption of infected livestock carcasses. The potential origin and spatial-temporal shedding patterns of livestock-adapted Salmonella serotypes of zoonotic importance were evaluated in adult and nestling Griffon vultures (Gyps fulvus). We specifically assessed the exposure source and subsequent elimination of Salmonella-infected carcasses (ecosystem services) or transmission back to livestock (ecosystem disservices) by vultures, thus contributing respectively to disease mitigation or amplification in natural and farmed environments. The results show a seasonal high occurrence and turnover of a high variety of serotypes, especially swine-adapted ones isolated at high frequency. This suggests that vultures can be reservoirs and long-distance carriers of faecal Salmonella shed in supplementary feeding stations and breeding colonies. Contrary to their conservation purposes, feeding stations can act as Salmonella hotspots and reservoirs. However, a role for vultures in the transmission back to food-producing animals seems impossible because they do not come into contact at indoor farms, while transmission to free-ranging ruminants was not supported by the presence of ruminant-adapted serotypes in the vultures. Therefore, vultures do not promote disservices associated with the re-infection of livestock with Salmonella, but can provide quantitatively important ecosystem services by removing carrion contaminated with these and other zoonotic pathogens potentially affecting their health. Sanitary vigilance of the farms authorised to provide food for avian scavengers should avoid the disposal of swine and poultry carcasses with Salmonella and the antibiotics used to treat it. Extensive free-ranging livestock and their carcasses exploited in the countryside should be a priority for the conservation of vultures and their ecological function as cleaners and disease mitigators.

The Role of Carrion in the Landscapes of Fear and Disgust: A Review and Prospects

Animal behavior is greatly shaped by the ‘landscape of fear’, induced by predation risk, and the equivalent ‘landscape of disgust’, induced by parasitism or infection risk. However, the role that carrion may play in these landscapes of peril has been largely overlooked. Here, we aim to emphasize that animal carcasses likely represent ubiquitous hotspots for both predation and infection risk, thus being an outstanding paradigm of how predation and parasitism pressures can concur in space and time. By conducting a literature review, we highlight the manifold inter- and intra-specific interactions linked to carrion via predation and parasitism risks, which may affect not only scavengers, but also non-scavengers. However, we identified major knowledge gaps, as reviewed articles were highly biased towards fear, terrestrial environments, vertebrates, and behavioral responses. Based on the reviewed literature, we provide a conceptual framework on the main fear- and disgust-based interaction pathways associated with carrion resources. This framework may be used to formulate predictions about how the landscape of fear and disgust around carcasses might influence animals’ individual behavior and ecological processes, from population to ecosystem functioning. We encourage ecologists, evolutionary biologists, epidemiologists, forensic scientists, and conservation biologists to explore the promising research avenues associated with the scary and disgusting facets of carrion. Acknowledging the multiple trophic and non-trophic interactions among dead and live animals, including both herbivores and carnivores, will notably improve our understanding of the overlapping pressures that shape the landscape of fear and disgust.

Anthropogenic Change Alters Ecological Relationships via Interactive Changes in Stress Physiology and Behavior within and among Organisms

Anthropogenic change has well-documented impacts on stress physiology and behavior across diverse taxonomic groups. Within individual organisms, physiological and behavioral traits often covary at proximate and ultimate timescales. In the context of global change, this means that impacts on physiology can have downstream impacts on behavior, and vice versa. Because all organisms interact with members of their own species and other species within their communities, the effects of humans on one organism can impose indirect effects on one or more other organisms, resulting in cascading effects across interaction networks. Human-induced changes in the stress physiology of one species and the downstream impacts on behavior can therefore interact with the physiological and behavioral responses of other organisms to alter emergent ecological phenomena. Here, we highlight three scenarios in which the stress physiology and behavior of individuals on different sides of an ecological relationship are interactively impacted by anthropogenic change. We discuss host-parasite/pathogen dynamics, predator-prey relationships, and beneficial partnerships (mutualisms and cooperation) in this framework, considering cases in which the effect of stressors on each type of network may be attenuated or enhanced by interactive changes in behavior and physiology. These examples shed light on the ways that stressors imposed at the level of one individual can impact ecological relationships to trigger downstream consequences for behavioral and ecological dynamics. Ultimately, changes in stress physiology on one or both sides of an ecological interaction can mediate higher-level population and community changes due in part to their cascading impacts on behavior. This framework may prove useful for anticipating and potentially mitigating previously underappreciated ecological responses to anthropogenic perturbations in a rapidly changing world.

Avian Scavengers as Bioindicators of Antibiotic Resistance due to Livestock Farming Intensification

Industrial food animal production uses huge amounts of antibiotics worldwide. Livestock, their excreta used for manure and meat subproducts not intended for human consumption can all play important roles in the transmission of bacterial resistance to wildlife. Vultures and other scavengers can be directly exposed to active antibiotics ingested while feeding on livestock carcasses. This study evaluates whether bacterial resistance in the red kite (Milvus milvus) differs between two wintering areas selected based on patent differences in farming practices—particularly in the industrial production of food animals (primarily swine and poultry) vs. scarce and declining sheep herding. The results support the hypothesis that intensification in food animal production is associated with increased bacterial multidrug resistance in wildlife. Resistance was positively correlated with time elapsed since the beginning of the commercial application of each antibiotic in human and veterinary medicine, with clear differences depending on farming intensification between areas. Monitoring programs are encouraged to use red kites and other avian scavengers as valuable sentinels of contamination by antibiotics and clinically relevant resistant pathogens from livestock operations of variable intensities. Farms authorized for supplementary feeding of threatened scavengers should avoid supplying carcasses with active antibiotic residues to avoid bacterial resistance in scavenger wildlife.

Supplementary feeding stations for conservation of vultures could be an important source of monophasic Salmonella typhimurium 1,4,[5],12:i:

Vultures are nature's most successful scavengers, feeding on the carcasses of dead animals present in the field. Availability of domestic carrion has been unstable due to rapidly changing agro-grazing economies and increasing sanitary regulations that may require burial or burning of livestock carcasses. Thus, several griffon vulture (Gyps fulvus) recoveries are based on European legislation that guarantees the animals' welfare, avoids intense persecution of the vultures and allows the feeding of threatened wildlife in supplementary feeding stations (SFS). However, in recent years, many studies have speculated on the likelihood that avian scavengers may be infected by feeding on pig carcasses at SFS from intensive livestock. In this context, the present study evaluated whether free-living griffon vultures and pig farms share zoonotic Salmonella strains to test the hypothesis that vulture are infected during consumption of carcasses provided at SFS. Here, the occurrence, serotypes and genomic DNA fingerprinting (phage typing and pulsed-field gel electrophoresis) of isolated strains were carried out in griffon vultures and pig farms authorised to provided carcasses at SFS in Castellón province (eastern Spain). The bacteriological analyses revealed that 21.1% of vultures and 14.5% for pig farms samples tested were Salmonella-positive. Monophasic S. typhimurium 1,4,[5],12:i:- was the most frequently isolated serovar. Comparison of Salmonella strains isolated from vultures and pig farms revealed that monophasic S. typhimurium 1,4,[5],12:i:-, S. Derby and S. Rissen strains were highly genetically homogeneous (similar DNA fingerprint). In conclusion, the current study indicates that free-living griffon vultures and pig farms that provide the carcasses at SFS share several zoonotic Salmonella strains. On this basis, and although transmission could be bidirectional, our result seems to corroborate the pig carcasses-to-vulture transmission and cross-infection at SFS. As an immediate Salmonella control strategy in wild avian scavengers, we suggest the implementation of a programme to guarantee that solely pig carcasses from Salmonella-free farms arrive at SFS.

Culture- and molecular-based detection of swine-adapted Salmonella shed by avian scavengers

Salmonella can play an important role as a disease agent in wildlife, which can then act as carriers and reservoirs of sanitary importance at the livestock-human interface. Transmission from livestock to avian scavengers can occur when these species consume contaminated carcasses and meat remains in supplementary feeding stations and rubbish dumps. We compared the performance of PCR-based detection with conventional culture-based methods to detect Salmonella in the faeces of red kites (Milvus milvus) and griffon vultures (Gyps fulvus) in central Spain. The occurrence of culturable Salmonella was intermediate in red kites (1.9%, n=52) and high in griffon vultures (26.3%, n=99). These proportions were clearly higher with PCR-based detection (13.5% and 40.4%, respectively). Confirmation cultures failed to grow Salmonella in all faecal samples positive by the molecular assay but negative by the initial conventional culture in both scavenger species, indicating the occurrence of false (non-culturable) positives by PCR-based detection. This suggests that the molecular assay is highly sensitive to detecting viable Salmonella in cultures, but also partial genomes and dead or unviable bacteria from past infections or contamination. Thus, the actual occurrence of Salmonella in a particular sampling time period can be underestimated when using only culture detection. The serovars found in the scavenger faeces were among the most frequently isolated in pigs from Spain and other EU countries, especially those generally recognized as swine-adapted monophasic variants of S. Typhimurium. Because the studied species obtain much of their food from pig carcasses, this livestock may be the primary source of Salmonella via direct ingestion of infected carcasses and indirectly via contamination due to the unsanitary conditions found in supplementary feeding stations established for scavenger conservation. Combining culture- and molecular-based detection is encouraged to understand the epidemiology and impact of Salmonella in wildlife populations.

Supplementary feeding as a source of multiresistant Salmonella in endangered Egyptian vultures

Wild birds have repeatedly been highlighted as vectors in the dissemination of livestock and human pathogens. Here, the occurrence, serotypes and antimicrobial resistance of Salmonella were assessed in adult Egyptian vultures (Neophron percnopterus), to test the hypothesis that infection is associated with the consumption of swine carcasses provided at supplementary feeding stations (SFSs). Faeces of year-round resident griffon vultures (Gyps fulvus) were also tested to assess whether infection was acquired in the breeding grounds of both species or in the African wintering quarters of Egyptian vultures. Depending on the shedding rate criteria considered, the occurrence of infection in Egyptian vultures varied between the three consecutive sampling days in a range with a minimum of 23%-41% and a maximum of 64%-92% of individuals (n = 11-14 individuals, 27-39 faeces). The occurrence in the single sampling of griffon vultures was 61% of faeces (n = 18). Vultures mostly fed on pig carcasses, which together with their predominant infection with multiresistant serotypes (mostly the monophasic 4,12:i:- variant resistant to aminopenicillins, aminoglycosides and tetracyclines) typically found in pigs from Spain, strongly supports a carcass-to-vulture transmission and cross-infection routes at SFSs. Efforts are encouraged to avoid discarding carcasses of pigs with Salmonella at SFSs established for the conservation of threatened scavengers. This could contribute to reducing the long-distance transmission of resistant pathogens with an impact on livestock and human health while avoiding infection risk and its effects on wildlife.

Oral mycoses in avian scavengers exposed to antibiotics from livestock farming

The exposure to antimicrobial pharmaceuticals as environmental contaminants can exert direct and indirect detrimental effects on health of wildlife. Fungal infections pose a major threat to domestic, captive-housed wild and free-ranging wild animals worldwide. However, little is known about their role in disease in birds in the wild. Here, we evaluated the incidence of thrush-like lesions in the oral cavity of wild nestling cinereous vultures (Aegypius monachus), griffon vultures (Gyps fulvus), Egyptian vultures (Neophron percnopterus) and golden eagles (Aquila chrysaetos) exposed to veterinary antibiotics via the consumption of medicated livestock carcasses. Lesions, which varied in number, size and location, were more frequent in the cinereous (77.8%, n=9) and griffon vultures (66.7%, n=48) than in the Egyptian vultures (28.6%, n=21) and golden eagles (28.6%, n=7). In all individuals (100%, n=24) of a subsample of the affected nestlings, yeast species were isolated from thrush-like oral lesions and identified using a well-established system based on their carbohydrate assimilation profiles and other complementary tests. Fourteen yeast species from seven genera (Candida, Meyerozyma, Pichia, Yarrowia, Cryptococcus, Rhodotorula and Trichosporon) were isolated from the lesions of the four host species. We found differential infections and effects depending on host age-related exposure or susceptibility to different yeast species across the development of nestling griffon vultures. This unprecedented outbreak of oral mycoses is alarming because of the delicate conservation status of several of the affected species. The role of livestock antibiotics in the transition of yeast species from commensal to opportunistic pathogens should be evaluated in an attempt to avoid the detrimental effects of contamination and disease on host health, as well as on the transmission of fungal emerging pathogens among wildlife populations and species, and their dissemination across livestock and human populations.

Occurrence of veterinary pharmaceuticals in golden eagle nestlings: Unnoticed scavenging on livestock carcasses and other potential exposure routes

Wildlife exposure to pharmaceuticals can occur through contaminated water, and through the excreta and carcasses of medicated livestock, with potential for bioaccumulation and transfer through food webs. We evaluated whether nestling exposure to pharmaceuticals can occur from food delivered to nests in the golden eagle (Aquila chrysaetos), a top predator and facultative scavenger. Despite the fact that diet analysis suggests an apparently low dependence on livestock carcasses reduced to two piglets remains (1.5% of food remains, n=134), a high proportion of nestlings (71%, n=7) showed fluoroquinolone residues in plasma, mostly enrofloxacin, which is exclusively used in veterinary treatments. The occurrence and concentration (54.5±6.6μg·L^-1) of fluoroquinolones in plasma was similar to those found in the nestlings of three vulture species largely dependent on livestock carcasses obtained at supplementary feeding stations, which are managed for the conservation of their populations. Although the number of analysed eaglets is comparatively small, the fact that enrofloxacin was found in all nests sampled in three breeding seasons suggest an exposure to the drugs similar to that of vultures. An underestimation of the role of carrion, especially from small piglets whose consumption may have gone unnoticed, and the predation of semi-domestic prey and generalist prey exploiting carcasses of medicated livestock, can contribute to explaining the unexpectedly high occurrence of these drugs in eaglets.