Anthropogenic Items Research Articles

Prevalence and source of entanglements in Cape fur seals (Arctocephalus pusillus pusillus) in South Africa

Global pollution is increasing, and marine mammals are commonly affected by marine debris. This study combined data from multiple sources to help understand the prevalence, characteristics and demographic profile of Cape fur seals (Arctocephalus pusillus pusillus) entangled in anthropogenic items. Overall, 383 cases of entanglement in seals were identified with a regional prevalence for South Africa of 0.12 %, i.e., just over one in every thousand animals. Fishing materials were the primary cause of entanglements (70 %), with most entanglements observed on adults (n = 249, 65 %), particularly adult females (n = 95, 66 % of all sex-determined entangled seals). This study highlights the need for correct disposal of waste, particularly that derived from the fishing industry to mitigate the impact of marine pollution on the welfare and conservation of marine fauna in South Africa.

Spatio‐temporal differences in the diet and trophic ecology of Kelp Gulls (Larus dominicanus) in South Africa

Opportunistic species, including some gulls (Laridae), can benefit from urbanization and increased anthropogenic food resources. Knowledge of the level of exploitation of anthropogenic resources by gulls is crucial to understand how changes in food availability might affect their populations, which in turn may impact other species. The Kelp Gull Larus dominicanus is widely distributed in the southern hemisphere and consumes a wide variety of resources, from waste in landfills to seabirds. We assessed if proximity to landfills influenced the diet and trophic ecology of Kelp Gull incubating adults and chicks using a combination of conventional diet sampling (stomach contents, regurgitated pellets), and carbon and nitrogen stable isotope analysis of blood plasma in seven colonies over two consecutive years in South Africa. Kelp Gulls consumed a variety of resources, including marine (e.g. fish), coastal (e.g. molluscs), terrestrial natural (e.g. insects, mammals), or terrestrial anthropogenic (e.g. chicken, bread) items. Inter‐annual differences were most apparent among gulls breeding next to a seabird colony, whereas gulls breeding at other colonies were more consistent in diet and trophic ecology. At most colonies, chicks were fed more natural and higher trophic level food items than were consumed by incubating adults. Overall, distance to landfill did not strongly affect the diet and trophic ecology and our results suggest that the Kelp Gull's broad feeding ecology allows it to buffer changes in food availability by switching among food resources. However, such dietary changes triggered by human actions may impact other species, including threatened seabirds.

Microfibers in the Diet of a Highly Aerial Bird, the Common Swift Apus apus.

Microplastic pollution is a pervasive global issue affecting various ecosystems. Despite the escalating production and well-documented contamination in both aquatic and terrestrial environments, the research focused on airborne microplastics and their interaction with terrestrial birds remains limited. In this study, we collected fecal sacs from Common swifts (Apus apus) to investigate their diet and to evaluate the potential ingestion of microplastics by both adults and nestlings. The diet was mainly composed of Hymenoptera and Coleoptera and did not differ among sexes and age classes. The 33% of nestlings' and 52% of adults' fecal sacs contained anthropogenic items, the totality of which was in the shape form of fibers. The 19.4% of the anthropogenic items were chemically characterized as microplastics, either polyethylene terephthalate (PET; two microfibers) or cellophane (four microfibers). Airborne anthropogenic items, including microplastic, might be passively ingested during the Common swift aerial feeding. In addition, our findings suggest that these ingested microparticles have the potential to be transferred to the offspring through food. While further research is essential to elucidate the pathways of microplastic ingestion, our results reinforce the evidence of the transfer of anthropogenic items from the atmosphere to the biota.

Urbanization does not increase "object curiosity" in vervet monkeys, but semi-urban individuals selectively explore food-related anthropogenic items.

Urban environments expose animals to abundant anthropogenic materials and foods that facilitate foraging innovations in species with opportunistic diets and high behavioral flexibility. Neophilia and exploration tendency are believed to be important behavioral traits for animals thriving in urban environments. Vervet monkeys (Chlorocebus pygerythrus) are one of few primate species that have successfully adapted to urban environments, thus making them an ideal species to study these traits. Using a within-species cross-habitat approach, we compared neophilia and exploration of novel objects (jointly referred to as "object curiosity") between semi-urban, wild, and captive monkeys to shed light on the cognitive traits facilitating urban living. To measure "object curiosity," we exposed monkeys to various types of novel stimuli and compared their approaches and explorative behavior. Our results revealed differences in the number of approaches and explorative behavior toward novel stimuli between the habitat types considered. Captive vervet monkeys were significantly more explorative than both semi- urban and wild troops, suggesting that positive experiences with humans and lack of predation, rather than exposure to human materials per se, influence object curiosity. Across habitats, juvenile males were the most explorative age-sex class. This is likely due to males being the dispersing sex and juveniles being more motivated to learn about their environment. Additionally, we found that items potentially associated with human food, elicited stronger explorative responses in semi-urban monkeys than non-food related objects, suggesting that their motivation to explore might be driven by "anthrophilia", that is, their experience of rewarding foraging on similar anthropogenic food sources. We conclude that varying levels of exposure to humans, predation and pre-exposure to human food packaging explain variation in "object curiosity" in our sample of vervet monkeys.

Use of marine debris as nest material by ospreys

The use of anthropogenic debris as nest-building materials may affect nest function. We study ospreys (Pandion haliaetus) on an island with scarce vegetation and high availability of beached marine debris. We describe the anthropogenic debris in osprey nests, evaluate the factors affecting its prevalence and abundance, and test its potential effects on breeding parameters. We also quantify plastic entanglements among adults and nestlings. Of the 36 studied nests, 92 % included non-natural items, with plastic being the most frequent material (88.9 %). Nests that were bigger and closer to the coast had more anthropogenic items. The abundance of anthropogenic items in nests did not correlate with osprey breeding parameters. We recorded two live entangled adult females, which represent 3.9 % of the adult population. Monitoring the abundance of anthropogenic debris and its effects on wildlife is necessary to guarantee long-term viability of coastal wildlife.

Revealing the capability of the European hake to cope with micro-litter environmental exposure and its inferred potential health impact in the NW Mediterranean Sea

Prevalence, abundance, concentration, size and composition of anthropogenic items (AIs) (synthetic and non-synthetic) ingested by Merluccius merluccius juvenile specimens and from near-bottom water samples from different localities off the Catalan coast (NW Mediterranean), were characterized. The potential effect of AIs on fish condition was assessed through different health indicators. Virtually all AIs found in fish and near-bottom water samples were fibres. A mean of 0.85 fibres/m3 from the surrounding water was observed. Fish ingested a mean of 1.39 (SD = 1.39) items/individual. Cellulosic fibres were predominant (77.8% of samples), except for Barcelona. No differences in ingested AIs abundance and composition off Barcelona between 2007 and 2019 were found. Small AIs from the environment matched ingested AIs composition. Hakes did not ingest large fibres despite being present in the environment, probably due to their feeding behaviour. No adverse health effects or parasites aggregations were detected to be potentially related to AIs ingestion.

First Documented Uses of Caves along the Coast of Albania by Mediterranean Monk Seals (Monachus monachus, Hermann 1779): Ecological and Conservation Inferences.

Simple SummaryPresent and past information on endangered species distribution, biology and ecology is essential to implement conservation measures. The first documented use of habitat by the Mediterranean monk seal along the coasts of Albania is here presented. This was confirmed through the use of infrared camera traps and by the findings of a seals’ scat, proving the use of two caves in the study area. The results of the analysis of the scat revealed the last meal (three fish species) as well as microplastics and other non-food items. The relevance of this research goes beyond national borders, providing essential upgraded information for the species in Albania, and it also represents important data on an Adriatic–Ionian Basin context for the protection and recovery of the species.Information on the habitat use of the Mediterranean monk seal (Monachus monachus) along the coast of Albania (Adriatic and Ionian Sea) has so far been limited to vague and generalised data. A survey conducted in the National Marine Park Karaburun-Sazan in the summer of 2019 identified two marine caves with morphological characteristics best suited for use by such species. The two caves were subsequently equipped with infrared camera traps in 2020. The recovery of a scat in one of the caves during the 2019 survey and the photographic material obtained confirmed the use of the cave. This research provides the first documentation of marine cave habitat use by the Mediterranean monk seal in Albania. Quantitative and qualitative assessment of specimens frequenting the area could not be performed due to the limited data obtained on seal presence along the Albanian coasts. Nevertheless, the retrieved information is relevant for Albania and for the species conservation. The collected scat was analysed for trophic and anthropogenic contamination data. Three species (gilthead sea bream, European sea bass, and garfish), as well as four anthropogenic items (including a piece of nylon net), were identified. The inferences resulting from the analyses of the data presented in this study provided additional information on the ecology of the species and its conservation priorities, which need to be contextualized at the Adriatic–Ionian regional scale.

Multispecies Assessment of Anthropogenic Particle Ingestion in a Marine Protected Area.

Simple SummaryPlastic pollution presents a growing concern for marine biodiversity, and among these, anthropogenic particles (APs) are entering marine ecosystems at an alarming rate from land and sea sources. In this study, we quantify the ingestion of APs across fish, sea urchins, sea cucumbers (echinoderms), bivalves (molluscs), and jellyfish (cnidarians), identify biotic and abiotic factors that might influence the ingested items; and identify ingestion patterns based on taxonomic groups, trophic guilds, and habitats. Ingestion of APs was observed in the majority of the species analyses with occurrence ranging from 0% to 100%. The study results indicate that plastic pollution poses a threat to species found within the marine protected area of the Cabrera Marine-Terrestrial National Park despite their protection status. The multispecies approach provided a better understanding of the high level of AP exposure to species, highlighting the associated damage to marine biodiversity related to marine waste.We have applied a multispecies ecosystem approach to analyse the ingestion of anthropogenic particles (AP) in the gastrointestinal tract of 313 individuals (17 fish species and 8 invertebrate species) from pelagic, demersal and benthic habitats in a marine protected area off the Western Mediterranean (Cabrera National Park). We have quantified and characterized the ingestion at several taxonomic levels of fish, sea urchins, sea cucumbers, bivalves, and jellyfish in relation to biotic/abiotic factors based on taxonomic groups, trophic guilds (functional groups) and habitats. AP ingestion occurrence ranged from 26 to 100% with no significant differences among taxonomic groups. The fish within the MPA showed an overall ingestion occurrence ranging from 0 to 100%, the echinoderms from 29 to 100%, the bivalves from 72 to 96% and the jellyfish 36% ingestion. The ecosystem approach applied to evaluate overall AP ingestion within the species reported that for trophic guilds, the omnivorous species ingested the highest amounts of anthropogenic items, while herbivores ingested significantly fewer items than all other trophic guilds. Moreover, no significant differences were found amongst habitats, indicating a homogeneous spatial distribution of APs at all studied habitats. The multispecies approach provided insight into the high APs exposure to species within Cabrera MPA, highlighting the potential harm linked with marine litter that threatens marine biodiversity.

Improved microplastic processing from complex biological samples using a customized vacuum filtration apparatus

AbstractPlastics represent the largest component of marine debris globally. In this context, it is essential to quantify the current extent of plastic pollution, including microplastics (MP; plastics < 5 mm), within marine abiotic and biotic compartments. Despite significant effort, MP studies still face methodological impediments to establish accurate and standardized protocols to separate, process and analyze MPs in environmental samples. Furthermore, underestimation and overestimation of MP contamination, either through loss of MPs or introduction of extraneous MPs during handling and processing, is concerning, particularly when assessing risk profiles for marine ecosystems. Presented here is a custom‐made stainless steel vacuum filtration apparatus designed to perform size‐tiered separation and facilitate retrieval of MPs from a variety of environmental sample matrices. Incorporating this apparatus into a standard MP workflow achieved efficient graduated separation of commonly found MP fragments and fibers, validated by spike‐recovery tests. As a case study, the gastrointestinal tracts of three juvenile Australian sharpnose sharks, Rhizoprionodon taylori, were processed using the filtration apparatus, and 46 anthropogenic items ranging from 0.021 to 8.87 mm were retrieved. This study demonstrates the effective use of the size‐tiered stainless steel vacuum filtration apparatus and an improved efficiency in downstream microphotography and spectroscopic analyses of MPs from a complex sample matrix. Finally, it contributes to the MP research field by delivering more reliable estimates of MP contamination in marine ecosystems.

Relationship between ocean area and incidence of anthropogenic debris ingested by longnose lancetfish (Alepisaurus ferox)

Marine debris is present between the sea surface and the sea floor, but few studies have investigated plastic in water column. Therefore, we chose longnose lancetfish (Alepisaurus ferox) as a sample, this study samples mesopelagic species that ingest marine debris in the water column. We conducted a survey of the stomach contents of longnose lancetfish caught by longline fishing in three areas (Sagami Bay, Northwestern Pacific Ocean about 190 km southeast of Kyushu, Indian Ocean about 1200 km southwest of Sumatra Island, Indonesia). A total of 164 longnose lancetfish were caught. Our results highlighted four marine debris patterns. First, longnose lancetfish caught near the coast had a higher frequency of ingested anthropogenic items (Sagami Bay: 69%) than longnose lancetfish caught in the open ocean area (Northwestern Pacific Ocean: 13%, Indian Ocean: 18%). Second, the size of the plastic present in the ocean in the sea area close to the coast ingested by longnose lancetfish tended to be smaller than in the open ocean area. Third, 93% of the anthropogenic items obtained from the stomach were plastic, of which ¿90% was either polypropylene (PP) or polyethylene (PE). And last, the sources of marine debris in the middle and deep regions of the open ocean are fishing activities carried out in that sea area and items that drift from the land without losing buoyancy. Our research makes new discoveries about characteristics of the marine debris in the ocean.

Assessment of the health status of the European anchovy (Engraulis encrasicolus) in the NW Mediterranean Sea from an interdisciplinary approach and implications for food safety

The European anchovy (Engraulis encrasicolus) is a small pelagic fish with an outstanding commercial value supporting important fisheries and is a key component of pelagic ecosystems in the Mediterranean Sea. Progressive reductions in the population size of this species has been observed in the Mediterranean Sea during recent decades, accompanied by a decline in the body condition, as well as the size/age of maturation. Nonetheless, the health status has not been yet assessed using a holistic approach. Herein, we analyse the health status of the European anchovy, integrating distinct indicators from fish condition, enzymatic biomarkers, presence of tissue alterations, and parasite descriptors. In addition, we analyse the presence of anthropogenic items (AIs) in the digestive tract of fish and their potential impact on health status. Additionally, we assess the differences between current AIs values and those recorded over 12 years ago. None of the health indicators studied provided evidence of relevant pathologic conditions affecting this fish species in the studied area. However, changes in the pattern of liver parenchyma were found. Compared with anchovy populations from other distribution areas, no zoonotic parasites were recorded in this study, demonstrating a reduced risks associated with foodborne transmission to humans. AIs, such as fibres and plastic particles, were found in the digestive tract of half of the fish analysed. A significant increase was detected in AIs prevalence between 2007 (40 %) and 2019 (70 %), alongside differences in the abundance and typology of the AIs, though this does not seem to have impacted fish health yet. Therefore, our work underscores the importance of implementing a regular program to monitor the health status of this key species to better understand population dynamics and their drivers.

Diets of Black Vultures and Turkey Vultures in Coastal South Carolina, USA with a Review of Species' Dietary Information

Food availability resulting from anthropogenic land-use changes may have contributed to the recent increase of Cathartes aura (Turkey Vulture) and Coragyps atratus (Black Vulture) populations. We assessed anthropogenic contributions to diets of these species by analyzing 176 pellets collected from communal roosts in coastal South Carolina. To provide further insight into diets, we conducted a literature review of pellet-based studies for both species. Our pellet analyses demonstrated consumption of 12 mammal species with Odocoileus virginianus (White-tailed Deer) as the primary food item, present in 65% of samples and constituting 35% average percent volume in pellets. Mephitis mephitis (Striped Skunk) and Procyon lotor (Raccoon) were also commonly consumed. Presence of anthropogenic items in 47% of pellets indicated substantial garbage consumption. Our review consisted of 14 studies and revealed wide variability in diet across study sites, with large mammals (>15 kg) typically comprising the majority of species consumed. We suggest that increasing deer populations provide an important source of carrion for vultures in this area and likely throughout eastern North America. Ungulate populations, roadkill, and garbage appear to contribute considerably to Turkey Vulture and Black Vulture diets. As such, mitigation of human–vulture conflict will require effective garbage and roadkill management as Turkey Vulture and Black Vulture populations increasingly expand.

Feeding strategy of pelagic fishes caught in aggregated schools and vulnerability to ingesting anthropogenic items in the western equatorial Atlantic Ocean

The present study aims to assess the diet composition of five commercial pelagic fishes caught in aggregated schools in the western Atlantic, quantify plastic and anthropogenic items in stomach contents, and analyze the possible relationship between their diet composition and the occurrence of anthropogenic items. We collected 807 stomachs from tunas (Thunnus albacares, Thunnus obesus, and Katsuwonus pelamis) and tuna-like species (Coryphaena hippurus and Elagatis bipinnulata) targeted by fisheries around data buoys in the western tropical Atlantic between 2011 and 2017. We quantified items of an anthropogenic origin by calculating frequency of occurrence. Feeding strategy was determined using a 3D scatterplot. Correspondence analysis (CA) was performed to determine the relationship between food items and the occurrence of anthropogenic materials (synthetic or organic). Fishing ropes and chum were the main items of an anthropogenic origin. Rainbow runner (E. bipinnulata) stomachs had the highest percentage of such items, whereas none were found in the bigeye tuna. The most affected species by anthropogenic items feed on epipelagic prey items, such as flying fishes. Organisms that aggregate around floating objects on the ocean surface and have a generalist diet are more likely to ingest synthetic items either accidently or actively. The present findings underscore the importance of environmental education programs to mitigate the impact of marine debris on organisms and ensure the health of individuals as well as the balance of the food web to which these species belong.

The elephant at the dump: how does garbage consumption impact Asian elephants?

We studied garbage consumption by Asian elephants at the Uddakandara garbage dump in southern Sri Lanka. Garbage at the dump was classified under six categories and quantified using a grid overlay. Elephants visiting the dump were individually identified by morphological criteria and items and quantities consumed by them were determined by focal animal sampling. Dung of elephants that did not consume garbage and those from the dump were compared quantitatively and dung constituents assessed by washing through three layered sieves. A total of 17 individual elephants visited the garbage dump during the study period, all of who were males. The observed sexual bias could be related to behavioural differences between the sexes. Elephants mostly consumed ‘fruits and vegetables’ and ‘prepared food’, possibly due to their higher palatability and nutritional value. Ingestion of polythene was incidental and associated with consuming prepared food. Proportions of the six categories in elephant diet and garbage piles were significantly different, indicating that elephants were highly selective when feeding. Elephant arrivals increased in response to unloading of garbage, suggesting attraction to fresh garbage. Dung analysis found that garbage consumption did not change the quantity and constituents of dung, except for the presence of anthropogenic items. As consumed anthropogenic items were regularly excreted, retention and obstruction of the alimentary tract are unlikely in elephants. Elephants feeding on garbage had better body condition than non-garbage consuming elephants, indicating that garbage provided better nutrition than natural food and was not detrimental to their health.

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.

Urban food subsidies reduce natural food limitations and reproductive costs for a wetland bird

There is a strong conservation need to understand traits of species that adapt to urban environments, but results have been equivocal. Wetland birds exhibit a strong phylogenetic signal towards urban tolerance; however, they have largely been ignored in urban studies. In their historic ranges, wetland birds inhabit dynamic systems, traveling long distances to locate food. This ability to exploit dynamic resources may translate to success in urban environments, areas characterized by novel food opportunities. We used the Wood Stork (Mycteria americana), a species of conservation concern, to determine if the ability to exploit resources in natural environments translated to exploitation of urban resources. During optimal natural foraging conditions, storks nesting in both urban and natural wetlands had narrow diet breadths and high productivity. However, during suboptimal conditions, urban stork diet expanded to include anthropogenic items, leading to increased productivity. Our study provides a mechanistic understanding of how a wetland species persists, and even thrives, in urban environments. We demonstrated that species inhabiting dynamic systems can exploit urban areas resulting in increased reproductive performance during suboptimal conditions. Together, urban environments may support biodiversity in a variety of ways, but species-specific mechanistic understanding will help highlight how to best mitigate potential threats of urbanization.

The diet of coyotes and red foxes in Southern New York

Coyotes (Canis latrans) and red fox (Vulpes vulpes) are both generalist predators presently found in the Northeastern United States. This study aimed to identify major prey items of both species in suburban New York, investigate consumption of anthropogenic resources, and examine seasonal changes in diet. Scat samples were collected from 2017 to 2018 for coyotes, and from 2011 to 2012 for red fox. Hairs, feathers, bone fragments and other scat components were classified by comparison with reference collections. Logistic regression was used to determine whether season or location predicted the presence of various food items. The most common food items for coyotes were white-tailed deer (Odocoileus virginianus), found in 54.2% of samples, and cricetid rodents, found in 16.9% of samples. For red fox the most common food items were birds, found in 39% of samples, and cricetid rodents, found in 37.8% of samples. Anthropogenic waste appeared in 11.9% of coyote scat samples and made up 1.3% of the total weight of items recovered from samples. No anthropogenic items were found in red fox scat, nor were remains from threatened piping plovers (Charadrius melodus), known to breed in the study area. Seasonal changes in diet were not detected for either species. Overall our results show that coyotes and red fox in suburban areas of Southern New York are persisting primarily on natural prey items, and not being subsidized by anthropogenic food sources.

Anthropoquinas: First description of plastics and other man-made materials in recently formed coastal sedimentary rocks in the southern hemisphere

Plastic, as a “flagship species”, represents how deeply humans impact the environment. Although scarce, the presence of plastic and other anthropogenic materials in rocks has already been reported in the literature, however, so far, not in the Southern Hemisphere. Thus, the objective of the present study was to report and describe samples of sedimentary rocks containing anthropogenic items cemented with biogenic and siliciclastic material – anthropoquinas – and to discuss implications to the establishment of the Anthropocene and geodiversity conservation. Six samples of anthropoquinas were evaluated, presenting different technofossils (metal bottle caps, ship nail, plastic earring and plastic fragment) and composition (lithic and biogenic fragments). Energy Dispersive X-ray Spectroscopy was conducted on two samples, reflecting differences regarding their genesis. The description of these rocks is concerning and reflects how deeply human behavior influences various natural compartments. Therefore, studies on the effects of marine litter on geodiversity are strongly encouraged.

Effects of urbanization on resource use and individual specialization in coyotes (Canis latrans) in southern California

Urban environments are unique because fragments of natural or semi-natural habitat are embedded within a potentially permeable matrix of human-dominated areas, creating increased landscape and, potentially, habitat heterogeneity. In addition, urban areas can provide diet subsidies for wildlife species in the form of fruiting ornamental plants, trash, and domestic animals. Ecological opportunity in the forms of habitat and food heterogeneity are thought to be important mechanisms in maintaining individual specialization. Identifying which contexts, traits, and mechanisms determine the success or failure of individuals within an urban wildlife population could potentially provide predictions about which populations may succeed in human-dominated landscapes and which may experience local extinction. We used both scat and stable isotope analysis of whiskers to investigate the degree to which coyotes (Canis latrans) utilized anthropogenic subsidies and exhibited individual diet specialization across the urban-rural gradient in southern California. Land use surrounding scat and isotope sample locations was also evaluated to determine the effect of land cover on diet. Human food constituted a significant portion of urban coyote diet (22% of scats, 38% of diet estimated by stable isotope analysis). Domestic cats (Felis catus) and ornamental fruit and seeds were also important items in urban coyote diets. Consumption of anthropogenic items decreased with decreasing urbanization. In suburban areas, seasonality influenced the frequency of occurrence of anthropogenic subsidies with increased consumption in the dry season. The amount of altered open space (areas such as golf courses, cemeteries, and landscaped parks) nearby had a negative effect on the consumption of anthropogenic items in both urban and suburban areas. Contrary to our hypothesis, urban coyotes displayed reduced between-individual variation compared to suburban and rural coyotes. It is possible that the core urban areas of cities are so densely developed and subsidized that wildlife inhabiting these areas actually have reduced ecological opportunity. Suburban animals had the broadest isotopic niches and maintained similar individual specialization to rural coyotes. Wildlife in suburban areas still have access to relatively undisturbed natural areas while being able to take advantage of anthropogenic subsidies in neighboring residential areas. Therefore, areas with intermediate urban development may be associated with increased ecological opportunity and specialization.

Urban herring gulls use human behavioural cues to locate food.

While many animals are negatively affected by urbanization, some species appear to thrive in urban environments. Herring gulls (Larus argentatus) are commonly found in urban areas and often scavenge food discarded by humans. Despite increasing interactions between humans and gulls, little is known about the cognitive underpinnings of urban gull behaviour and to what extent they use human behavioural cues when making foraging decisions. We investigated whether gulls are more attracted to anthropogenic items when they have been handled by a human. We first presented free-living gulls with two identical food objects, one of which was handled, and found that gulls preferentially pecked at the handled food object. We then tested whether gulls' attraction to human-handled objects generalizes to non-food items by presenting a new sample of gulls with two non-food objects, where, again, only one was handled. While similar numbers of gulls approached food and non-food objects in both experiments, they did not peck at handled non-food objects above chance levels. These results suggest that urban gulls generally show low levels of neophobia, but that they use human handling as a cue specifically in the context of food. These behaviours may contribute to gulls’ successful exploitation of urban environments.