Anthropogenic Food Research Articles

Importance of predictable anthropogenic food subsidies for an opportunistic gull inhabiting urban ecosystems

The provision of predictable anthropogenic food subsidies (PAFS) to urban wildlife has been recognized as an important trophic input in urban ecosystems. However, there is a lack of agreement about the benefits and harms of urban PAFS for avian species. While there are many studies about the impact of PAFS on birds, little information is available about the potential importance of PAFS on the ecology of urban gulls. In the present study, we aimed to evaluate the importance of human PAFS for the urban population of the yellow-legged gull (Larus michahellis) in the city of Barcelona, northeastern Spain. This opportunistic seabird is considered a pest species in urban areas. Specifically, by conducting a visual census in a location where PAFS were provided every week year-round, we examined the total number and age structure of gulls using this PAFS station. We identified the presence of yellow-legged gulls with some physical anomalies using the PAFS station. The results of this study suggest that PAFS may be an important artificial resource for urban yellow-legged gulls inhabiting Barcelona, used by either breeders or non-breeders, and also used by handicapped individuals. Based on these results, we suggest the regulation of this activity as a complement to other measures focused on the reduction of available food resources present in urban areas to manage this problematic species.

Ingestion of anthropogenic materials by yellow-legged gulls (Larus michahellis) in natural, urban, and landfill sites along Portugal in relation to diet composition.

Pollution is a global concern, increasing rapidly throughout marine and terrestrial ecosystems, and affecting many species. Urbanization enhances waste production, leading to the opening of landfills that constitute a spatially and temporally predictable food source for opportunistic species. Several species of gulls are known to exploit and breed in urban areas, taking advantage of accessible and diverse food resources. The exploitation of anthropogenic food subsidies at sea (e.g. fishery discards), urban sites, and landfills leads to debris ingestion by gulls with potential negative effects. Here we characterize anthropogenic debris ingested by yellow-legged gulls (Larus michahellis) along Portugal, by analysing the content of pellets collected in (1) natural and urban breeding locations, and in (2) urban and landfill resting sites, to assess seasonal patterns in the ingestion of anthropogenic debris. We also relate diet with the presence of anthropogenic debris. Debris materials were found in 28.8% of pellets from breeding locations (natural and urban) and in 89.7% of pellets from resting sites (urban and landfill). Gulls from the most urbanized breeding location exhibited higher levels of ingested materials during the entire breeding cycle, however, gulls from a natural breeding site also ingested high levels of debris during the pre-breeding season. At resting sites, small seasonal differences were detected in the number and mass of debris items ingested, which were both higher during spring and summer. Gulls that typically fed on pelagic fish had significantly less sheet and fragment plastics in their pellets. The presence of certain debris categories in gull pellets was positively related to the presence of some prey items, suggesting that gulls may accidentally ingest debris while foraging at multiple habitats. The quantity of anthropogenic materials ingested by gulls from urban locations and landfills indicates a need for improved waste management.

Geographical differences in sex-specific foraging behaviour and diet during the breeding season in the opportunistic Kelp Gull (Larus dominicanus)

Sexual segregation in feeding strategies has been widely reported in seabirds. Most seabirds occupy wide breeding distributional ranges, and dissimilar ecological settings may result in distinct environmental pressures on males and females leading to geographical differences in sexual segregation. Using GPS loggers and stable isotope analysis of whole blood (δ15N, δ13C), we assessed the occurrence of sexual differences in Kelp Gull (Larus dominicanus) foraging trip parameters, habitat use, isotopic niche and diet during the incubation period at three breeding locations in Argentina characterized by different foraging contexts. At Islote Arroyo Jabali Este, sexual differences were found in trip parameters and habitat use mainly associated with a significantly higher use by males of a refuse dump as foraging site. However, their isotopic niches were similar with both sexes consuming mostly recreational fish waste, suggesting it was mainly obtained by males at the dump and by females at shoreline areas used by fishers. At Punta Tombo, there were no sex differences in trip parameters nor in the main prey consumed consisting of fishery discards, although females used more shoreline areas and males presented a significantly larger isotopic niche width. In contrast, at Isla Vernaci Este, males and females showed similar trip parameters, habitat use, and isotopic niche width and diet composition. Results show geographical differences in the degree of sexual segregation, which may result from differences in the availability of local food resources, particularly anthropogenic food subsidies.

Successful neighbour: Interactions of the generalist carnivore red fox with dogs, wolves and humans for continued survival in dynamic anthropogenic landscapes

Dens are crucial for the survival of all canids; however, for meso-carnivores such as Southeast Asian red foxes, denning is of greater importance as they utilize dens throughout the year for protection, resting and breeding. Red fox is known for its adaptability to dynamic anthropogenic changes and is the most widespread and successful wild terrestrial carnivore. With an ever-growing human population, choice of space for wild animals is limited and such adaptability is important for species survival. Food resource availability also plays an important role in choosing den sites. In this study we examined den site selection, den characteristics, seasonal diet variation of red fox and their diet-niche overlap with dog and wolf. Intensive surveys in search of fox dens were conducted across two study sites Chiktan and Changthang, India. Fox dens were found on mountain slopes where human disturbances were minimal. They also chose den sites closer to human settlements, water and road as compared to random points, which are risky and may expose pups to humans, but provide the advantage of procuring anthropogenic food subsidies. In Changthang, foxes preferred to den at a greater distance from human settlements as compared to Chiktan. The foxes of Chiktan showed a large diet overlap with dogs. While humans and wolves may act as facilitators providing additional food to red fox, dogs were the major competitors. The present research is of broad significance, given the increasing presence of human settlements within original animal ranges, even in remote harsh environments like the Trans-Himalaya.

Restricted human activities shift the foraging strategies of feral pigeons (Columba livia) and three other commensal bird species

Invasive species are a growing concern with increasing global connectivity. Feral pigeons (Columba livia) are widespread and invasive, thus their effective control is of keen international interest. The COVID-19 pandemic has offered an unprecedented opportunity to investigate the impact of a nation-wide Circuit Breaker (restricted human activities) in Singapore on first, the abundance of the feral pigeons and three urban commensals—the Javan myna (Acridotheres javanicus), common myna (A. tristis), and house crow (Corvus splendens) in different food source types; and second, the activity budgets of feral pigeons. A significant and progressive decline in feral pigeon abundance was observed in open food centres and feeding hotspots after the Circuit Breaker was implemented. While the house crow and common myna were less affected, the Javan myna abundance increased moderately at refuse collection centres during the Circuit Breaker and decreased significantly in green spaces after the Circuit Breaker. Changes in food abundance could also predict changes in feral pigeon abundance and its effect was greatest in feeding hotspots. A greater proportion of feral pigeons was observed foraging and moving with a smaller proportion seen resting with probable consequences on their reproductive capacity. Our study also cautions against drawing inferences on biological responses due to similar social restrictions without careful consideration of other ecological factors, like average flock size and time of the day, which also affected the proportion of pigeons foraging on natural versus anthropogenic food. In summary, our results advocate a food limitation approach to control the feral pigeon populations.

Potentially negative ecological consequences of animal redistribution on beaches during COVID-19 lockdown

Significant changes in the intensity or distribution of human activities, like during the 2020 COVID-19 lockdowns, can cause rapid changes to the diversity, distribution and abundance of animals. These changes are usually viewed as positive for ecosystems. Here, we mapped the abundance and habitat associations of coastal vertebrates along approximately 50 km of ocean beaches on the Sunshine Coast in eastern Australia using baited trail cameras before (April–June 2018 and 2019) and during the April–May 2020 COVID-19 lockdown. Many Torresian crows (Corvus orru) occur in urban areas where they scavenge for human-derived food. When this food source collapsed during the COVID-19 lockdown, Torresian crows moved to beaches where we recorded a 6-fold increase in abundance. Torresian crows principally moved to beaches with greater extent of remnant vegetation and larger average tree height. Because anthropogenic food sources would be less abundant on these more natural beaches, rapid changes in the abundance of these aggressive feeders on beaches could result in Torresian crows 1) outcompeting scavengers like large raptors for naturally occurring carrion, 2) consuming insects, crustaceans and other small animals (like small mammals and reptiles) along more natural coastlines, causing potentially significant changes to animal assemblage structure along beaches, and 3) depredating eggs and hatchlings from nests of other birds. Our results highlight that the ecological effects of changes to human pressures are nuanced, depending strongly on the functional role and behaviour of species and the landscape attributes in which they interact with the broader assemblages and ecosystem.

Effects of seed-rich habitat provision on territory density, home range and breeding performance of European Turtle Doves Streptopelia turtur

SummaryConservation measures providing food-rich habitats through agri-environment schemes (AES) have the potential to affect the demography and local abundance of species limited by food availability. The European Turtle Dove Streptopelia turtur is one of Europe’s fastest declining birds, with breeding season dietary changes coincident with a reduction in reproductive output suggesting food limitation during breeding. In this study we provided seed-rich habitats at six intervention sites over a 4-year period and tested for impacts of the intervention on breeding success, ranging behaviour and the local abundance of territorial turtle doves. Nesting success and chick biometrics were unrelated to the local availability of seed-rich habitat or to the proximity of intervention plots. Nestling weight was higher close to human habitation consistent with an influence of anthropogenic supplementary food provision. Small home ranges were associated with a high proportion of non-farmed habitats, while large home ranges were more likely to contain seed-rich habitat suggesting that breeding doves were willing to travel further to utilize such habitat where available. Extensively managed grassland and intervention plot fields were selected by foraging turtle doves. A slower temporal decline in the abundance of breeding males on intervention sites probably reflects enhanced habitat suitability during territory settlement. Refining techniques to deliver sources of sown, natural, and supplementary seed that are plentiful, accessible, and parasite-free is likely to be crucial for the conservation of turtle doves.

The importance of marine resources in the diet of urban gulls

The availability of anthropogenic food subsidies has promoted an increase in generalist opportunistic gull species, which currently breed and forage on predictable anthropogenic resources (e.g. landfills). Here we investigated whether marine resources are still important to urban-dwelling gulls. We studied 4 natural and 2 urban yellow-legged gull Larus michahellis colonies and compared (1) diet composition (through pellet analysis) and (2) isotopic niches of adults and chicks, (3) diet delivered to chicks of different ages, and (4) fatty acid (FA) composition of fledglings, in order to assess diet composition, diversity and quality, and the relevance of marine prey for natural and urban gull populations. Adult urban gulls consumed considerably lower proportions of marine prey when compared to gulls from natural colonies; however, they fed their younger chicks (<20 d old) mostly with fish, representing 61-80% of their chick food deliveries. Refuse items were mostly delivered to chicks older than 20 d. Overall, urban isotopic niches were not completely distinct from those of natural colonies, in some cases sharing ca. 50% of their niche space. Fledglings from the most urbanized colony presented overall higher FA concentrations and diversity, but they were lacking some omega-3 FAs relevant to their physiology. Our results highlight the importance of marine resources in the diet of urban gulls, particularly during early chick rearing, the relevance of food sources in the area around the breeding colonies and the fact that urban gulls benefit from year-round reliable anthropogenic food resources.

An altered microbiome in urban coyotes mediates relationships between anthropogenic diet and poor health

Generalist species able to exploit anthropogenic food sources are becoming increasingly common in urban environments. Coyotes (Canis latrans) are one such urban generalist that now resides in cities across North America, where diseased or unhealthy coyotes are frequently reported in cases of human-wildlife conflict. Coyote health and fitness may be related to habitat use and diet via the gut microbiome, which has far-reaching effects on animal nutrition and physiology. In this study, we used stomach contents, stable isotope analysis, 16S rRNA gene amplicon sequencing, and measures of body condition to identify relationships among habitat use, diet, fecal microbiome composition, and health in urban and rural coyotes. Three distinct relationships emerged: (1) Urban coyotes consumed more anthropogenic food, which was associated with increased microbiome diversity, higher abundances of Streptococcus and Enterococcus, and poorer average body condition. (2) Conversely, rural coyotes harbored microbiomes rich in Fusobacteria, Sutterella, and Anaerobiospirillum, which were associated with protein-rich diets and improved body condition. (3) Diets rich in anthropogenic food were associated with increased abundances of Erysipelotrichiaceae, Lachnospiraceae, and Coriobacteriaceae, which correlated with larger spleens in urban coyotes. Urban coyotes also had an increased prevalence of the zoonotic parasite Echinococcus multilocularis, but there were no detectable connections between parasite infection and microbiome composition. Our results demonstrate how the consumption of carbohydrate-rich anthropogenic food by urban coyotes alters the microbiome to negatively affect body condition, with potential relationships to parasite susceptibility and conflict-prone behavior.

Urban gulls adapt foraging schedule to human‐activity patterns

Numerous animals are able to adapt to temporal patterns in natural food availability, but whether species living in relatively novel environments such as cities can adapt to anthropogenic activity cycles is less well understood. We aimed to assess the extent to which urban gulls have adapted their foraging schedule to anthropogenic food source fluctuations related to human activity by combining field observations at three distinct urban feeding grounds (park, school and waste centre) with global positioning system (GPS) tracking data of gulls visiting similar types of feeding grounds throughout the same city. We found that the birds’ foraging patterns closely matched the timing of school breaks and the opening and closing times of the waste centre, but gull activity in the park appeared to correspond to the availability of natural food sources. Overall, this suggests that gulls may have the behavioural flexibility to adapt their foraging behaviour to human time schedules when beneficial and that this trait could potentially enable them to thrive in cities.

Predicting human-carnivore conflict at the urban-wildland interface

A major threat to mammalian carnivores is death due to human conflict, including carnivore use of anthropogenic food sources, predation of livestock, or car accidents. To reduce conflicts, it is critical to target proactive mitigations using reliable evidence on where conflict is likely to occur. We tested hypotheses about the importance of anthropogenic and environmental predictors in explaining the timing and distribution of human conflict with black bears (Ursus americanus) and cougars (Puma concolor) in a North American hotspot of human-carnivore conflict. Using reported conflict locations and spatial data in use-availability models, we estimated and mapped the probability of conflict for both species, including seasonally for bears, between 2011 and 2017. We found conflict increased for both species along the urban-wildland interface. Conflict with black bears was present in all seasons and increased with intermediate human density (i.e. suburban neighbourhoods). However, in autumn, bear conflict was more common in agricultural areas. Conversely, cougar conflict was primarily in rural areas, as their main attractant was livestock. We recommend targeting areas and times of expected conflict with proactive mitigations, such as bear-resistant garbage bins in communities adjacent to forests, electric fences that deter both carnivore species, and elimination of rural food attractants in autumn.

A review of ecological factors promoting road use by mammals

Abstract Roads have numerous negative impacts for mammals, but may also serve as attractants due to altered vegetation or provisioning of resources. We reviewed the use of roads and their associated features by mammals, in order to understand the ecological factors contributing to road use. We documented 129 studies that recorded road use by 116 mammalian species, spanning 15 orders and 35 families, in six continents. Carnivora was the most common order (40 species, 34% of all 116 species), followed by Artiodactyla (24 species, 20%) and Rodentia (21 species, 18%). The species were placed in the IUCN categories Least Concern (88 species, 76% of all 116 species), Vulnerable (11 species, 9%), Near Threatened (9 species, 8%), Endangered (6 species, 5%), and Critically Endangered (2 species, 2%). We assigned road use to five ecological categories, reflecting the reason for it, with subcategories where appropriate: (1) communication; (2) foraging (subcategories: anthropogenic food, herbivory, predation, salt, scavenging, water); (3) movement (subcategories: bridges, environmental alterations, habitat connectivity); (4) refuge (subcategories: avoidance, burrowing and denning, cover, roosting); and (5) thermoregulation. Foraging, movement, and refuge were the most common uses. Roads provide a variety of resources to mammals, but road use is highly dynamic in time and space. We suggest that the use of roads by mammals is extensive, both geographically and taxonomically. Road use is likely to influence mammalian ecology while contributing to the risk of collisions with vehicles.

The Diet of Foxes and the Availability of Anthropogenic Food on Prince Edward Island, Canada

It has been postulated that red foxes (Vulpesvulpes) inhabiting Prince Edward Island National Park (Canada) make very little use of natural food sources and that anthropogenic food play an integral part in their diet. The use of anthropogenic food sources has also been associated with an increased number of fatal fox vehicle-collisions in the park. The main goal of this study was to examine the composition of the diet of foxes inhabiting Prince Edward Island National Park and to compare this diet with foxes found in other areas of the island. In particular, we examined the importance of anthropogenic food items in foxes inhabiting the national park. We analyzed 38 stomachs from foxes killed by trappers or vehiclesduring late fall and early winter within and outside the national park. Our results showed that rodents and vegetation were the most common food items present in fox stomachs whether the animals were obtained from within or outside the park. Values of coefficient of variation of food items found in fox stomachs indicated a great diversity in diet composition. However, only six stomachs contained anthropogenic food items. Stomachs of foxes killed by vehicles contained twice the amount of anthropogenic food items than those that were collected from trappers. Overall, our findings indicate that anthropogenic food items are only a minor component in the diet of foxes occurring within the park, at least during the period of time examined in this study. Future studies should examine diet composition during other seasons when the quantity and quality of anthropogenic food sources is different.

Using community science data to investigate urban Coyotes (Canis latrans) in Atlanta, Georgia, USA

ABSTRACT Coyote activity was investigated in Atlanta, Georgia from 2015 to 2018 using publicly collected data. More than 500 reports were received annually (1,672 total) and analysis revealed bias toward areas of higher income and education. Human-coyote encounters, defined as an interaction at close range, were rare (196; 12% of observations), but 124 of those reports (63%) indicated the presence of pets nearby. Coyotes were less likely to be observed in areas of high human population density, farmland, and managed clearing, and more likely to be seen in riparian wetlands and areas of low-density development (e.g., parks, golf courses, large-lot homes). Coyote sightings are now relatively common in Atlanta and their presence is generally benign. However, negative coyote interactions do occur and pets should be kept under close supervision and coyote access to anthropogenic food resources prevented. This study demonstrates the effectiveness of using community science to understand urban coyotes.

Implications of bacterial, viral and mycotic microorganisms in vultures for wildlife conservation, ecosystem services and public health

The effects that microorganisms (bacteria, viruses and fungi) have on their hosts remain unexplored for most vulture species. This is especially relevant for vultures, as their diet consists of carcasses in various stages of decomposition, which are breeding grounds for potentially pathogenic microorganisms. Here we review current knowledge of bacterial, viral and mycotic microorganisms present in wild vultures. We consider their potential to cause disease in vultures and whether this poses any population‐level threats. Furthermore, we address the question of whether vultures may act as disease spreaders or mitigators. We found 76 articles concerning bacterial, viral and mycotic microorganisms present in 13 vulture species, 57 evaluating bacteria, 13 evaluating viruses and six evaluating mycotic microorganisms. These studies come from all continents where vultures are present, but mainly from Europe and North America, and the most studied species was the Griffon Vulture Gyps fulvus. We found that vultures are colonized by zoonotic pathogens, and even host‐specific human pathogens. Some recorded bacteria showed multi‐antibiotic resistance, especially those that can be associated with anthropogenic food subsides such as supplementary feeding stations. We found evidence that vulture health can be affected by some microorganisms, producing a wide array of clinical alterations that have the potential to influence mortality risk and fitness. We did not find clear scientific evidence that vultures play an epidemiological role spreading microorganisms to humans and other species. However, there is evidence that vultures could prevent the spread of infectious diseases through their removal of decomposing organic material. The evaluation of vulture exposure to microorganisms is of fundamental importance to design better conservation policies for this threatened group, which may serve a key role as ecosystem cleaners.

Patterns of Feeding by Householders Affect Activity of Hedgehogs (Erinaceus europaeus) during the Hibernation Period.

Simple SummaryUrban areas are thought to represent a stronghold habitat for the West European hedgehog population in the UK. However, little is known about hibernation patterns in residential areas and if overwinter activity is influenced by any ”urban-associated” factors. We monitored hedgehog activity in gardens during the winter hibernation period of 2017–2018 using weekly presence/absence surveys. Hedgehogs were more likely to be present in gardens where householders had provided food in previous seasons or where food was supplied more regularly in a given season. Such relationships could have positive or negative effects on the survival or condition of hedgehogs across the hibernation period. Consequently, further research is needed to identify the effects of supplementary feeding on hibernation biology to help inform conservation guidelines for householders.West European hedgehogs (Erinaceus europaeus) are likely to encounter unusual ecological features in urban habitats, such as anthropogenic food sources and artificial refugia. Quantifying how these affect hedgehog behaviour is vital for informing conservation guidelines for householders. We monitored hedgehog presence/absence in gardens in the town of Reading, UK, over the winter of 2017–2018 using a volunteer-based footprint tunnel survey, and collected data on garden characteristics, supplementary feeding (SF) habits, and local environmental conditions. Over a 20-week survey period, hedgehog presence was lowest between January and March. Occupancy analysis indicated that SF significantly affected hedgehog presence/absence before, during, and after hibernation. The number of nesting opportunities available in gardens, average temperatures, and daylength were also supported as important factors at different stages. In particular, our results suggest that SF could act to increase levels of activity during the winter when hedgehogs should be hibernating. Stimulating increased activity at this sensitive time could push hedgehogs into a net energy deficit or, conversely, help some individuals survive which might not otherwise do so. Therefore, further research is necessary to determine whether patterns of feeding by householders have a positive or negative effect on hedgehog populations during the hibernation period.

Individual dietary specialization in a generalist predator: A stable isotope analysis of urban and rural red foxes.

Some carnivores are known to survive well in urban habitats, yet the underlying behavioral tactics are poorly understood. One likely explanation for the success in urban habitats might be that carnivores are generalist consumers. However, urban populations of carnivores could as well consist of specialist feeders. Here, we compared the isotopic specialization of red foxes in urban and rural environments, using both a population and an individual level perspective. We measured stable isotope ratios in increments of red fox whiskers and potential food sources. Our results reveal that red foxes have a broad isotopic dietary niche and a large variation in resource use. Despite this large variation, we found significant differences between the variance of the urban and rural population for δ13C as well as δ15N values, suggesting a habitat‐specific foraging behavior. Although urban regions are more heterogeneous regarding land cover (based on the Shannon index) than rural regions, the dietary range of urban foxes was smaller compared with that of rural conspecifics. Moreover, the higher δ13C values and lower δ15N values of urban foxes suggest a relatively high input of anthropogenic food sources. The diet of most individuals remained largely constant over a longer period. The low intraindividual variability of urban and rural red foxes suggests a relatively constant proportion of food items consumed by individuals. Urban and rural foxes utilized a small proportion of the potentially available isotopic dietary niche as indicated by the low within‐individual variation compared to the between‐individual variation. We conclude that generalist fox populations consist of individual food specialists in urban and rural populations at least over those periods covered by our study.

The Andaman day gecko paradox: an ancient endemic without pronounced phylogeographic structure

The Andaman day gecko (Phelsuma andamanensis) is endemic to the Andaman Archipelago, located ~ 6000 km away from Madagascar where the genus Phelsuma likely evolved. We complemented existing phylogenetic data with additional markers to show that this species consistently branches off early in the evolution of the genus Phelsuma, and this early origin led us to hypothesize that island populations within the Andaman Archipelago could have further diversified. We sampled the Andaman day gecko from all major islands in the Andamans, developed new microsatellite markers and amplified mitochondrial markers to study population diversification. We detected high allelic diversity in microsatellites, but surprisingly poor geographical structuring. This study demonstrates that the Andaman day gecko has a panmictic population (K = 1), but with weak signals for two clusters that we name ‘North’ (North Andaman, Middle Andaman, Interview, Baratang, Neil, and Long Islands) and ‘South’ (Havelock, South Andaman, Little Andaman Islands). The mitochondrial COI gene uncovered wide haplotype sharing across islands with the presence of several private haplotypes (except for the Little Andaman Island, which only had an exclusive private haplotype) signalling ongoing admixture. This species differs from two other Andaman endemic geckos for which we provide comparative mitochondrial data, where haplotypes show a distinct phylogeographic structure. Testing population history scenarios for the Andaman day gecko using Approximate Bayesian Computation (ABC) supports two possible scenarios but fails to tease apart whether admixture or divergence produced the two weak clusters. Both scenarios agree that admixture and/or divergence prior to the onset of the last glacial maximum shaped the genetic diversity and structure detected in this study. ABC supports population expansion, possibly explained by anthropogenic food subsidies via plantations of cash crops, potentially coupled with human mediated dispersal resulting in the observed panmictic population. The Andaman day gecko may thus be a rare example of an island endemic reptile benefiting from habitat modification and increased movement in its native range.

Effects of an anthropogenic diet on indicators of physiological challenge and immunity of white ibis nestlings raised in captivity.

When wildlife forage and/or live in urban habitats, they often experience a shift in resource availability and dietary quality. Some species even use human handouts, such as bread, as well as human refuse, as a large part of their new diets; yet the influences of this nutritional shift on health and survival remain unclear. American white ibises are increasingly being seen in urban areas in Florida; they collect handouts, such as bread and other food items, from humans in parks, and are also found foraging on anthropogenic sources in trash heaps. We hypothesized that the consumption of these new anthropogenic food sources may trigger increases in indicators of physiological challenge and dampen immune responses. We tested this experimentally by raising 20 white ibis nestlings in captivity, and exposing 10 to a simulated anthropogenic diet (including the addition of white bread and a reduction in seafood content) while maintaining 10 on a diet similar to what ibises consume in more natural environments. We then tested two indicators of physiological challenge (corticosterone and heat shock protein 70), assessed innate immunity in these birds via bactericidal assays and an in vitro carbon clearance assay, and adaptive immunity using a phytohemagglutinin skin test. The anthropogenic diet depressed the development of the ability to kill Salmonella paratyphi in culture. Our results suggest that consuming an anthropogenic diet may be detrimental in terms of the ability to battle a pathogenic bacterial species, but there was little effect on indicators of physiological challenge and other immunological measures.

Red fox viromes in urban and rural landscapes.

The Red fox (Vulpes vulpes) has established large populations in Australia’s urban and rural areas since its introduction following European settlement. The cryptic and highly adaptable nature of foxes allows them to invade cities and live among humans whilst remaining largely unnoticed. Urban living and access to anthropogenic food resources also influence fox ecology. Urban foxes grow larger, live at higher densities, and are more social than their rural counterparts. These ecological changes in urban red foxes are likely to impact the pathogens that they harbour, and foxes could pose a disease risk to humans and other species that share these urban spaces. To investigate this possibility, we used a meta-transcriptomic approach to characterise the virome of urban and rural foxes across the Greater Sydney region in Australia. Urban and rural foxes differed significantly in virome composition, with rural foxes harbouring a greater abundance of viruses compared to their urban counterparts. We identified ten potentially novel vertebrate-associated viruses in both urban and rural foxes, some of which are related to viruses associated with disease in domestic species and humans. These included members of the Astroviridae, Picobirnaviridae, Hepeviridae, and Picornaviridae as well as rabbit haemorrhagic disease virus-2. This study sheds light on the viruses carried by urban and rural foxes and emphasises the need for greater genomic surveillance of foxes and other invasive species at the human–wildlife interface.