Environmental contamination alters ecological interactions among organisms, including those associated with parasitism. Contaminants can mediate parasitic relationships at multiple scales by changing host vulnerability to infection and disrupting transmission-relevant contacts. The overall effect of contamination on parasitism remains poorly understood, yet the interplay between these stressors has significant implications for animal and human health. We conducted a community-scale field study to evaluate whether trace element contaminants derived from coal combustion residuals and nuclear fission products alter the dynamics of haemosporidian blood parasites, dipteran vectors, and avian hosts in riparian and wetland habitats in South Carolina, USA. We captured 329 individuals of 31 passerine bird species and 195 Culex mosquito vectors at two sites affected by coal combustion waste, two sites affected by nuclear fission waste, and two reference sites. We evaluated whether blood concentrations of zinc, copper, mercury, and selenium and whole-body radioactivity concentrations because of cesium-137 predicted the likelihood of single and coinfections by Plasmodium, Haemoproteus, and Leucocytozoon within passerine hosts. We also evaluated whether the likelihood of Plasmodium infection in Culex vectors differed with the presence of site-level contamination. Individual passerine hosts inhabiting coal combustion waste sites had significantly higher blood selenium concentrations than those at reference sites, and blood selenium was negatively associated with the likelihood of Leucocytozoon infection. The likelihood of infection with Plasmodium did not vary between vectors at contaminated versus reference sites. The transfer of low-dose, waste-derived selenium to wildlife may bolster individual response to some parasites and increase the reservoir capacity of host populations. Our findings highlight complex effects of trace elements on wildlife disease dynamics and reveal priorities for future research in contaminated habitat.

Per-and polyfluoroalkyl substances (PFAS) are widespread contaminants known for high resistance to degradation, toxicity, and significant rates of bioaccumulation. Evidence indicates that various factors, such as compound structure and environmental characteristics, strongly influence the uptake, distribution, and transport of PFAS. Previous studies have reported PFAS bioaccumulating in both aquatic and terrestrial environments; however, few have compared both within the same site. This study measured, characterized, and compared PFAS concentrations in an aquatic and terrestrial system impacted by aqueous film forming foam (AFFF) on the Savannah River Site (SRS). Results indicated distinct differences in PFAS concentrations and compositions among aquatic and terrestrial species, taxonomic groups, and trophic levels. Perfluoroalkyl carboxylic acids (PFCAs) were the dominant PFAS subgroup in surface water, sediment, and topsoil. Sum (Sigma) PFAS concentrations of 26 compounds were higher in aquatic than terrestrial species. We observed biodilution among aquatic organisms, with levels in invertebrates exceeding those of fish, and biomagnification in terrestrial species, with levels in vultures exceeding those of passerines, followed by invertebrates. Long chain compounds dominated PFAS compositions in both systems. Specifically, terrestrial system showed positive relationships between delta 15N and concentrations of PFCAs, perfluoroalkane sulfonic acids (PFSAs), fluorotelomer sulfonates (FTSs), and per-fluorinated sulfonamides (FOSAAs). Linear regressions between individual PFAS concentrations and delta 15N demonstrated positive relationships for perfluorododecanesulfonic acid (PFDoS) in terrestrial systems, suggesting potential biomagnification. Our findings fill gaps in understanding the movement of PFAS, evaluating their ecological risks, and developing environmental management strategies for these contaminants.

Bird-aircraft collisions (bird strikes) pose threats to aviation safety and avian life. One of the tenets of airport-based management strategies to prevent bird strikes is the reduction of bird density within established separation distances from air operations areas. The rationale is that higher local bird densities could increase the spatial and temporal overlap in the use of airspace by both birds and aircraft, leading to a higher frequency of bird strikes. However, the strength and direction of this relationship have not been evaluated across published studies. This is an important gap, given how entrenched this assumed relationship has become to allocate limited resources to airport wildlife management. In this study, we assessed the strength of the relationship between avian abundance and bird strikes across studies using a meta-analytic approach. Through a reproducible literature search and screening criteria, we identified 20 outcomes (i.e., effect sizes) from 13 studies. We conducted a multilevel meta-analysis and found a positive correlation (Pearson's r = 0.520, 95% confidence intervals: 0.308-0.683), supporting the positive relationship between bird abundance and bird strike frequency. We additionally found evidence that the existing literature has high levels of between-study heterogeneity and publication bias, low statistical power, and multiple methodological concerns. These issues suggest that our effect size estimation should be interpreted with care. Given the limitations of the published literature testing this relationship, we provide a set of methodological recommendations for improving future experiments. We call for prioritizing the empirical testing of the abundance-bird strike relationship on and near airports across the world, and the standardization of bird survey approaches. These future tests are key to aligning management efforts to local airport needs.

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

Worldwide, vehicle collisions with large ungulates such as deer (Odocoileus spp.) and wild pigs (Sus scrofa) cause billions of dollars in damages and injure thousands of drivers, with most collisions occurring during low-light conditions. Recent research evaluating increased frontal vehicle illumination with a rear-facing lightbar has shown promise, but its effectiveness when paired with different headlight types remains unexplored. Furthermore, light-emitting diode (LED) headlights have grown in popularity compared to tungsten-halogen (halogen), yet no study has investigated their effects on free-ranging wildlife behaviour. Compared to halogen headlights, LED headlights produce more blue light, which more closely matches the peak sensitivities of deer and wild pig photoreceptors, potentially affecting their responses. In this study, we investigated how headlight type, increased frontal vehicle illumination via a rear-facing lightbar, and vehicle speed influenced white-tailed deer (Odocoileus virginianus) and wild pig responses to an approaching vehicle using infrared videography and GPS data. We evaluated flight probability, flight initiation distance (FID) and each encounter's danger level. Over 2 years, we conducted 95 weekly nighttime drives along a 75-km paved route in South Carolina, USA. For deer, LED headlights had no effect on their avoidance behaviour, whereas for wild pigs, LED headlights increased FIDs by 88.5 m. Lightbar illumination mitigated the effects of increased freezing and dangerously close FIDs by deer at faster vehicle speeds, when crash severity is usually highest. For wild pigs, lightbar illumination increased FIDs at faster vehicle speeds, providing drivers with more time to respond. Synthesis and applications. Generally, LED headlights had neutral or beneficial effects on wildlife responses, suggesting they could reduce collisions given the increased illumination levels they provide drivers. Additionally, our results support previous research indicating increased frontal vehicle illumination can reduce dangerous encounters with wildlife. Our findings suggest that simple modifications to vehicles, such as increased frontal vehicle illumination and the use of LED headlights, can result in large economic and driver safety benefits when scaled to the millions of wildlife-vehicle collisions that occur yearly.Read the free Plain Language Summary for this article on the journal's .

Despite the ecological importance of avian scavengers such as vultures, demographic information that is essential to their conservation and management remains limited. The goal of this study was to evaluate survival and mortality risk in black vultures (Coragyps atratus), a protected native species of conflict management concern in the United States. Here, we combined monitoring data from a 28-year period to estimate annual survival rates among age classes and test for seasonal and age-related patterns in mortality risk. Using dead recovery information, we also summarized the causes and timing of annual mortalities. Additionally, we tested whether mortality risk was affected by aspects of landscape composition and configuration, as well as human development. Average annual survival was high overall (0.95, 95% CI: 0.92-0.98), with estimate precision markedly improved by combining datasets (72.1%-84.2% increase). Mortality risk differed by season and age class such that vultures experienced 68.7% more hazard during the breeding season, and adults experienced 66.2% less hazard than juveniles. Among the mortality causes, 67% were anthropogenic, 4% were natural, and the remaining 29% were unknown. Additionally, greater land cover diversity (Shannon diversity index) reduced mortality risk, whereas measures of landscape configuration and human development had no effect. High survival rates help explain this species' population growth and range expansion and further inform allowable take for sustainable management practices. Moreover, the identified seasonal and age-related vulnerabilities may help guide lethal control of human-vulture conflicts in an ecologically relevant manner. Maintaining diverse landscapes may also enhance survival overall, facilitating conservation of this species and other avian scavengers.

Animal-vehicle collisions (AVCs) are ubiquitous in developed regions of the world and pose risks to both wildlife and humans. In the United States, collisions with deer (Odocoileus spp.) cause billions of dollars in economic losses and thousands of human injuries annually. The current AVC literature has largely focused on factors unrelated to driver behavior including AVC hotspots, wildlife movement, and damages caused by AVCs. However, despite being a component in every AVC, few studies have investigated driver behavior during animal-vehicle interactions. Here, we systematically reviewed literature databases to identify factors influencing driver behavior during these interactions and to highlight apparent gaps in the literature. We found that vehicle speed, road attributes, environmental conditions, and vehicle types show inconsistent associations with AVCs and the mechanisms by which they influence driver behavior is not well understood. Many studies focused on mitigation methods to influence driver behavior, including various warning signs; however, the effectiveness of these systems varies considerably. Other topics including wildlife attributes, roadway illumination, and inherent driver attributes directly influence driver behavior, but are understudied. Most studies relied on seemingly logical explanations for results or associations between variables to identify these influences, but few studies directly tested how specific variables influenced driver behavior and detection ability of wildlife. Given that driver behavior influences every potential AVC, future research should directly investigate the behavioral and perceptual mechanisms behind driver detection of wildlife and other factors influencing overall driver behavior during wildlife-vehicle interactions.

Releases of coal combustion and nuclear fission wastes create contaminated landscapes that pose long-term management challenges. Efforts to facilitate the natural attenuation of legacy wastes in the environment can provide attractive habitat for passerine birds. Passerines have diverse foraging and nesting behaviors that lead to heterogenous contaminant exposure, yet few studies investigate contaminant uptake in passerines on a community scale. This study evaluated whether variation in habitat use strategies among passerines predicted the ongoing uptake of waste-derived elements by birds inhabiting coal combustion and nuclear fission legacy waste areas on the Savannah River Site in South Carolina. Blood concentrations of selenium, arsenic, mercury, zinc, copper, and lead were measured in 362 birds from 35 species. Whole-body radioactivity concentrations due to cesium-137 were measured in vivo in 143 birds from 31 species using a novel, field-based gamma spectrometry system. Generalized linear mixed effects models were used to evaluate whether trophic category and degree of terrestriality predicted contaminant burdens among passerine communities. Selenium, mercury, arsenic, and cesium-137 were elevated in passerines inhabiting legacy waste sites compared to those at reference sites. Blood concentrations of selenium and mercury varied by trophic category, whereas arsenic and cesium-137 increased with degree of terrestriality. The behavioral correlates of contaminant uptake among passerines provide insight into the mobility of waste-derived elements in ecosystems and inform species-level risk assessments. Future studies should use in vivo gamma spectrometry to conduct long-term field studies that evaluate the effects of internal radiation in small-bodied wildlife.

Wildlife collisions with aircraft have serious safety and economic implications. Strike risk models are used to assess the probability of an adverse event between wildlife and aircraft, providing information to guide wildlife management at airports. In the strike risk model actively used across the USA, species-specific strike risk is a product of severity and frequency. The severity component of risk, termed relative hazard score (RHS), is a composite variable that indexes the probability of aircraft damage, severe damage, and effect on flight when aircraft are struck by a species, whereas frequency is the number of strikes recorded per species. Our objectives were to update RHS values by incorporating recent strike data available for birds and mammals, update the active strike risk model, and investigate seasonal differences in bird strike risk across species. Using data from the Federal Aviation Administration (FAA)'s National Wildlife Strike Database (NWSD) for the years 2010-2023, we calculated RHS for 132 bird species and 16 mammal species. We found that large-bodied birds, such as the red-tailed hawk (Buteo jamaicensis; risk = 1,225,479), Canada goose (Branta canadensis; risk = 918,744), and turkey vulture (Cathartes aura; risk = 552,026) continue to pose the highest nationwide risk, with species-specific risk ranks fluctuating seasonally. Notably, our analysis highlights one facet of the dynamic nature of wildlife risk at airports, emphasizing the importance of adaptive management strategies that consider seasonal changes in strike risk. We also identify limitations in the current risk assessment model, suggesting future improvements through bias-corrected bird surveys and telemetry data to refine our understanding of species behavior and movement patterns in airport settings. Our findings provide insights for airport wildlife biologists to prioritize management actions, reduce wildlife-related risk, and improve aviation safety.

Vehicle collisions with deer (Odocoileus spp.) cause billions of dollars in damages and injure thousands of drivers every year in the United States, and few mitigation methods have proven effective. However, recent research suggests that vehicle lighting might influence white-tailed deer (Odocoileus virginianus; hereafter, deer) responses to oncoming vehicles. Most new vehicles are manufactured with light emitting diode (LED) headlights which differ in total radiance and wavelength of light emitted compared to the previous industry standard of tungsten-halogen (halogen) headlights. Also, frontal vehicle illumination through rear-facing lighting has shown promise in enhancing deer responses to vehicles, but its effectiveness has not been tested under various headlight conditions (headlight type or intensity). As such, it remains unclear how these aspects of vehicle lighting affect deer responses to an approaching vehicle. We used 23 captive, wild-type deer to investigate how variations in vehicle lighting affect deer responses to an approaching vehicle at night, when most collisions occur. We released deer into a 95 m long, 3 m wide chute and approached them from the opposite end with an electric golf cart outfitted with two versions of stock 2017-2020 Ford Fusion headlights (LED and halogen) and a 51 cm rear-facing lightbar to test how vehicle lighting affected deer avoidance behaviors in an imminent, head-on collision scenario. Each deer received eight lighting treatments consisting of unique combinations of headlight type (LED vs. halogen), light intensity (low vs. high beam), and rear-facing lighting (lightbar off vs. on). We measured deer alert and flight behavior using infrared videography. We found that the halogen, high beam, lightbar off treatment had the greatest probability of evoking an alert response. Furthermore, when the lightbar was off, high beams appeared to increase alert probability for halogen headlights. Also, we found evidence that high beam, halogen headlights tend to increase alert probability over high beam, LED headlights, when the lighbar was off. We found no effect of our lighting treatments on deer alert distance, flight probability, or flight initiation distance. Across all behavioral responses, the random effect deer ID explained 0.86-9.19 x more variation than our lighting treatments, reflecting large differences in responses among deer. Overall, we found that vehicle lighting can impact deer behavior during an imminent, head-on collision scenario, although lighting was ineffective at increasing favorable flight behaviors. Future research should investigate how vehicle lighting treatments affect free-ranging, wild deer in a variety of real-world scenarios and at longer approach distances.

Wastewater treatment wetlands are cost-effective strategies for remediating trace metals in industrial effluent. However, biogeochemical exchange between wastewater treatment wetlands and adjacent environments provides opportunities for trace metals to cycle in surrounding ecosystems. The transfer of trace metals to wildlife inhabiting treatment wetlands must be considered when evaluating wetland success. Using passerine birds as bioindicators, we conducted a multi-tissue analysis to investigate the mobilization of zinc, copper, and lead derived from wastewater to terrestrial wildlife in treatment wetlands and surrounding habitat. In addition, we evaluate the strength of relationships between metal concentrations in non-lethal (blood and feathers) and lethal (muscle and liver) sample types for estimation of toxicity risk. From July 2020 to August 2021, 177 passerines of seven species were captured at two wetlands constructed to treat industrial wastewater and two reference wetlands in the coastal plain of South Carolina. Feather, blood, liver, and muscle samples from each bird were analyzed for fourteen metals using inductively coupled plasma mass spectrometry and direct mercury analysis. Passerines inhabiting wastewater treatment wetlands accumulated higher concentrations of zinc in liver, copper in blood, and lead in feathers than passerines in reference wetlands, but neither blood nor feather concentrations were correlated with internal tissue concentrations. Of all the detected metals, only mercury in the blood showed a strong predictive relationship with mercury in internal tissues. This study indicates that trace metals derived from wastewater are bioavailable and exported to terrestrial wildlife and that passerine biomonitoring is a valuable tool for assessing metal transfer from treatment wetlands. Regular blood sampling can reveal proximate trace metal exposure but cannot predict internal body burdens for most metals.

Vehicle collisions with birds are financially costly and dangerous to humans and animals. To reduce collisions, it is necessary to understand how birds respond to approaching vehicles. We used simulated (i.e., animals exposed to video playback) and real vehicle approaches with mallards ( Anas platyrynchos) ) to quantify flight behavior and probability of collision under different vehicle speeds and times of day (day vs . night). Birds exposed to simulated nighttime approaches exhibited reduced probability of attempting escape, but when escape was attempted, fled with more time before collision compared to birds exposed to simulated daytime approaches. The lower probability of flight may indicate that the visual stimulus of vehicle approaches at night (i.e., looming headlights) is perceived as less threatening than when the full vehicle is more visible during the day; alternatively, the mallard visual system might be incompatible with vehicle lighting in dark settings. Mallards approached by a real vehicle exhibited a delayed margin of safety (both flight initiation distance and time before collision decreased with speed); they are the first bird species found to exhibit this response to vehicle approach. Our findings suggest mallards are poorly equipped to adequately respond to fast-moving vehicles and demonstrate the need for continued research into methods promoting effective avian avoidance behaviors.

Vehicle collisions with birds are financially costly and dangerous to humans and animals. To reduce collisions, it is necessary to understand how birds respond to approaching vehicles. We used simulated (i.e., animals exposed to video playback) and real vehicle approaches with mallards (Anas platyrynchos) to quantify flight behavior and probability of collision under different vehicle speeds and times of day (day vs. night). Birds exposed to simulated nighttime approaches exhibited reduced probability of attempting escape, but when escape was attempted, fled with more time before collision compared to birds exposed to simulated daytime approaches. The lower probability of flight may indicate that the visual stimulus of vehicle approaches at night (i.e., looming headlights) is perceived as less threatening than when the full vehicle is more visible during the day; alternatively, the mallard visual system might be incompatible with vehicle lighting in dark settings. Mallards approached by a real vehicle exhibited a delayed margin of safety (both flight initiation distance and time before collision decreased with speed); they are the first bird species found to exhibit this response to vehicle approach. Our findings suggest mallards are poorly equipped to adequately respond to fast-moving vehicles and demonstrate the need for continued research into methods promoting effective avian avoidance behaviors.

Deployment of mouse carcasses laced with acetaminophen has become a common management tool to control invasive brown tree snakes (Boiga irregularis; BTS) on Guam. Additionally, anticoagulant rodenticides may be used to control invasive rats (Rattus spp.) if their populations increase due to predator release in the wake of BTS eradication. However, there has been little research examining how scavengers on Guam could be incidentally exposed to toxicants by scavenging carcasses of animals that die from these population control strategies. Furthermore, there is a limited understanding of how the proliferation of invasive species on Guam has influenced the composition of the scavenger community. We investigated these topics by examining scavenger consumption of mouse, rat, and BTS carcasses on Guam in both a coastal and upland site during the wet (May–Aug 2016) and dry season (Jan–Apr 2017). We documented carcass consumption by 9 species, which scavenged 48% of carcasses. Interactions between season, habitat, and carcass type influenced probability of scavenging, and appeared to be driven by consumption by the two main scavenger species, BTS and cane toads (Rhinella marina), both of which are invasive on Guam. Baiting programs should consider the potential for toxin exposure to land crabs (Coenobita spp., Birgus latro), native species that scavenged at every combination of carcass type, habitat, and season. Overall, 60% of scavenging events were attributed to species considered pests that are recent introductions to Guam. Invasive species on Guam are the primary scavengers of small vertebrate carrion, suggesting a substantial role in trophic dynamics that extends beyond predation.

Roost locations can be an important contributor to vulture conflicts with humans, but factors influencing roost-site selection at a landscape level remain largely unexplored. Further, there has been little research comparing how these factors vary between nocturnal and diurnal roosting sites. We used remote cameras to document daily variation in vulture use of 21 roosts (20 communication/water towers and 1 natural roost) near Beaufort, South Carolina, USA from October 2019–August 2020. Numbers of vultures on roosts increased with decreasing urban cover and with greater distance to water, but were not influenced by habitat fragmentation or elevation. Roosts surrounded by greater proportions of urban cover were used more often during the day, whereas roosts adjacent to less urban cover were more commonly used at night. We suggest that this relationship results from a greater daytime association with human development, areas that likely provide food and favorable soaring conditions for vultures. Vultures tended to depart nocturnal roosts before sunrise and return within two hours of sunset, indicating that aircraft collision risk resulting from movement around nocturnal roosts would be elevated during these times. Several communication towers routinely had > 100 vultures roosting on them at once, likely contributing to conflict with humans. Our findings reiterate the generalism of these species and their capacity to exploit novel structures for roosting, which has likely contributed to range expansions and resultant increases in human-vulture conflicts over the past several decades.

Wildlife-vehicle collisions are dangerous for motorists; however, few studies have addressed driver detection of roadside animals, and none have evaluated detection of free-ranging wildlife. We used 24 volunteer drivers, infrared videography, a 75-km route, and free-ranging wildlife to quantify factors influencing (1) probability of wildlife detection, (2) detection distance, and (3) probability of dangerous encounters (i.e., detection distance < distance required for braking) for multiple species at night in South Carolina, USA. Detection probability of white-tailed deer (Odocoileus virginianus) was impacted by multiple driver, animal, and roadside factors. Deer detection distances increased by 20.99 m when drivers used high-beam headlights and 23.36 m when deer were moving but decreased by 0.71 m for every minute into a drive. Every encounter with wild pigs (Sus scrofa) and most encounters with small mammals were considered dangerous. Our findings suggest most drivers cannot safely detect deer, wild pigs, and small mammals at night.

The Human Influence Index (HII) quantifies anthropogenic landscape pressures by combining eight measures of human influence: human population density, built environments, crop lands, pasture lands, lights, roads, railways and navigable waterways. The comparative influence of the HII components on cause-specific mammal mortality remains unexplored. Using a database of North American mammal cause-specific mortality, we compared the influence of these components on proportion of mammal mortality resulting from harvest, vehicle collision, predation, and overall anthropogenic mortality. Our dataset consisted of 487 studies that monitored the fates of 48,551 individuals across 70 species with 17,837 mortalities of known cause. For both adults and juveniles, human population density best explained proportion of mortality from anthropogenic causes and showed a positive relationship. Human population density also provided best model fit for adult harvest mortality at low HII values. Lights, built environments, and human population density explained similar variation in adult vehicle mortality, whereas human population density provided best fit for vehicle mortality of juveniles. Predation was negatively associated with human population density and provided best model fit for both age classes. Our work indicates that the effectiveness of conservation programs for North American mammals could be enhanced by reducing the negative consequences of human population density.

Scavenging is a pervasive foraging strategy among vertebrates, yet researchers have only recently begun to reveal the complex implications of scavenging dynamics. Scavenging studies have predominantly used lower trophic level (i.e., herbivore) species as carrion bait, and the few studies that have used higher trophic level (i.e., carnivore) carrion have found these carcass types are generally avoided by vertebrates or scavenged by fewer species than similarly sized herbivore carcasses. No studies have assessed the fate of carcasses of obligate scavengers. To investigate potential differences in scavenging dynamics among avian carrion representing different guilds and trophic levels, we conducted scavenging trials using 20 replicates of two obligate scavenger species (i.e. black vulture, Coragyps atratus ; turkey vulture, Cathartes aura ) and two lower trophic level species, chicken ( Gallus gallus domesticus ), and mallard ( Anas platyrhynchos ). Carcass trials were conducted at the Savannah River Site, SC, USA, and monitored with remote cameras. We hypothesized carcasses of vultures would persist longer and have a distinct scavenging community compared to lower trophic level carcasses (mallard and chicken). As expected, turkey and black vulture carcasses persisted in the environment longer, were less likely to be entirely consumed by vertebrate scavengers, and had a different scavenging community than mallard and chicken carcasses. These results contribute to the growing body of evidence suggesting higher trophic level carrion is exploited differently by vertebrate scavengers. Our findings suggest nutrients derived from vulture carcasses are likely largely reincorporated into lower trophic levels.

Animals seem to rely on antipredator behavior to avoid vehicle collisions. There is an extensive body of antipredator behavior theory that have been used to predict the distance/time animals should escape from predators. These models have also been used to guide empirical research on escape behavior from vehicles. However, little is known as to whether antipredator behavior models are appropriate to apply to an approaching high-speed vehicle scenario. We addressed this gap by (a) providing an overview of the main hypotheses and predictions of different antipredator behavior models via a literature review, (b) exploring whether these models can generate quantitative predictions on escape distance when parameterized with empirical data from the literature, and (c) evaluating their sensitivity to vehicle approach speed using a simulation approach wherein we assessed model performance based on changes in effect size with variations in the slope of the flight initiation distance (FID) vs. approach speed relationship. The slope of the FID vs. approach speed relationship was then related back to three different behavioral rules animals may rely on to avoid approaching threats: the spatial, temporal, or delayed margin of safety. We used literature on birds for goals (b) and (c). Our review considered the following eight models: the economic escape model, Blumstein’s economic escape model, the optimal escape model, the perceptual limit hypothesis, the visual cue model, the flush early and avoid the rush (FEAR) hypothesis, the looming stimulus hypothesis, and the Bayesian model of escape behavior. We were able to generate quantitative predictions about escape distance with the last five models. However, we were only able to assess sensitivity to vehicle approach speed for the last three models. The FEAR hypothesis is most sensitive to high-speed vehicles when the species follows the spatial (FID remains constant as speed increases) and the temporal margin of safety (FID increases with an increase in speed) rules of escape. The looming stimulus effect hypothesis reached small to intermediate levels of sensitivity to high-speed vehicles when a species follows the delayed margin of safety (FID decreases with an increase in speed). The Bayesian optimal escape model reached intermediate levels of sensitivity to approach speed across all escape rules (spatial, temporal, delayed margins of safety) but only for larger (> 1 kg) species, but was not sensitive to speed for smaller species. Overall, no single antipredator behavior model could characterize all different types of escape responses relative to vehicle approach speed but some models showed some levels of sensitivity for certain rules of escape behavior. We derive some applied applications of our findings by suggesting the estimation of critical vehicle approach speeds for managing populations that are especially susceptible to road mortality. Overall, we recommend that new escape behavior models specifically tailored to high-speeds vehicles should be developed to better predict quantitatively the responses of animals to an increase in the frequency of cars, airplanes, drones, etc. they will face in the next decade.

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.