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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.

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.

With efforts to restore large mammal populations following extirpations, it is vital to quantify how they are impacted by human activities and gain insights into population dynamics in relation to conservation goals. Our objective was to characterize cause-specific mortality of black bears (Ursus americanus) throughout their range. We first quantified cause-specific mortality for 247 black bears in one harvested and two non-harvested populations. We then simulated a small recolonizing population with and without anthropogenic mortality. Lastly, we conducted a meta-analysis of all published black bear mortality studies throughout North America (31 studies of 2630 bears). We found anthropogenic mortality was greater than natural mortality, non-harvest anthropogenic mortality (e.g. poaching, defense of property, etc.) was greater in non-harvested populations, and harvesting was one of the major causes of mortality for bears throughout their range. Our simulation indicated that removing anthropogenic mortality increased population size by an average of 23% in 15 years. We demonstrated that bears are exposed to high levels of anthropogenic mortality, and the potential for human activities to slow population growth in expanding populations. Management and conservation of wide-ranging mammals will depend on holistic strategies that integrate ecological factors with socio-economic issues to achieve successful conservation and coexistence.

5 pages, 3 figures.-- Data availability: Data will be made available on request, Sea turtles generally lay several clutches of eggs in a single nesting season. While a negative correlation between water temperatures and the time required between constitutive nesting events (termed the internesting interval) has been previously reported in loggerhead Caretta caretta and green turtles Chelonia mydas, it is not understood whether this relationship remains constant across other sea turtle species. Here, we expanded upon these previous studies on loggerhead and green turtles by using larger sample sizes and including data from species with a wider range of body-sizes; specifically: hawksbill Eretmochelys imbricata, leatherback Dermochelys coriacea, and olive ridley turtles Lepidochelys olivacea. In total, we compiled temperature data from biologgers deployed over internesting intervals on 23 loggerhead, 22 green, 7 hawksbill, 26 leatherback and 11 olive ridley turtles from nesting sites in 8 different countries. The relationship between the duration of the internesting interval and water temperatures in green and loggerhead turtles were statistically similar yet it differed between all other turtle species. Specifically, hawksbill turtles had much longer internesting intervals than green or loggerhead turtles even after controlling for temperature. In addition, both olive ridley and leatherback turtles exhibited thermal independence of internesting intervals presumably due to the large body-size of leatherback turtles and the unique capacity of ridley turtles to delay oviposition. The observed interspecific differences in the relationship between the length of the internesting interval and water temperatures indicate the complex and variable responses that each sea turtle species may exhibit due to environmental fluctuations and climate change, NJR was funded by the Spanish government (AEI) through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S). PST was funded by the Vicenç Mut program of the Govern de les Illes Balears. JT was funded by project AICO/2021/022 granted by Conselleria d'Innovació, Universitats, Ciència i Societat Digital, Generalitat Valenciana

Recent increases in turkey vulture (Cathartes aura) and black vulture (Coragyps atratus) populations in North America have been attributed in part to their success adapting to human-modified landscapes. However, the capacity for such landscapes to generate favorable roosting conditions for these species has not been thoroughly investigated. We assessed the role of anthropogenic and natural landscape elements on roosting habitat selection of 11 black and 7 turkey vultures in coastal South Carolina, USA using a GPS satellite transmitter dataset derived from previous research. Our dataset spanned 2006–2012 and contained data from 7916 nights of roosting. Landscape fragmentation, as measured by land cover richness, influenced roosting probability for both species in all seasons, showing either a positive relationship or peaking at intermediate values. Roosting probability of turkey vultures was maximized at intermediate road densities in three of four seasons, and black vultures showed a positive relationship with roads in fall, but no relationship throughout the rest of the year. Roosting probability of both species declined with increasing high density urban cover throughout most of the year. We suggest that landscape transformations lead to favorable roosting conditions for turkey vultures and black vultures, which has likely contributed to their recent proliferations across much of the Western Hemisphere.

Understanding the types and magnitude of human-caused mortality is essential for maintaining viable large carnivore populations. We used a database of cause-specific mortality to examine how hunting regulations and landscape configurations influenced human-caused mortality of North American gray wolves (

Interspecific competition within a carnivore guild can result in segregation along dietary, spatial, and temporal scales. Species interactions and resulting avoidance behavior can change seasonally as landscape features and resource abundance may fluctuate. In this study, we examined a carnivore guild in the Pantanal wetland of Brazil to determine whether temporal niche partitioning was a mechanism for coexistence, and if this differed between the wet and dry season. We used camera trapping data to fit kernel density functions of time observations for five species of carnivores to determine activity patterns. We calculated the coefficient of overlap between all species-pair’s activity patterns. Our results found support for temporal segregation among this carnivore guild, with stronger segregation evident during the dry season. Jaguars and pumas showed large overlap in activity in both seasons, while all three mesocarnivores (ocelot, tayra, and crab-eating fox) showed temporal avoidance toward pumas. Mesocarnivores displayed segregating temporal patterns between pairs in both seasons. Temporal segregation is a mechanism for coexistence within this carnivore guild, suggesting increased competition between species especially during the dry season. To maintain carnivore populations, a broader knowledge of interspecific interactions and how this may affect species, utilization or avoidance of habitats is needed. Given the complexities of interspecific interactions among carnivores, conservation efforts should address the needs of the entire guild rather than focus on a single species.

Vultures provide an essential ecosystem service through removal of carrion, but globally, many populations are collapsing and several species are threatened with extinction. Widespread declines in vulture populations could increase the availability of carrion to other organisms, but the ways facultative scavengers might respond to this increase have not been thoroughly explored. We aimed to determine whether facultative scavengers increase carrion consumption in the absence of vulture competition and whether they are capable of functionally replacing vultures in the removal of carrion biomass from the landscape. We experimentally excluded 65 rabbit carcasses from vultures during daylight hours and placed an additional 65 carcasses that were accessible to vultures in forested habitat in South Carolina, USA during summer (June–August). We used motion‐activated cameras to compare carrion use by facultative scavenging species between the experimental and control carcasses. Scavenging by facultative scavengers did not increase in the absence of competition with vultures. We found no difference in scavenger presence between control carcasses and those from which vultures were excluded. Eighty percent of carcasses from which vultures were excluded were not scavenged by vertebrates, compared to 5% of carcasses that were accessible to vultures. At the end of the 7‐day trials, there was a 10.1‐fold increase in the number of experimental carcasses that were not fully scavenged compared to controls. Facultative scavengers did not functionally replace vultures during summer in our study. This finding may have been influenced by the time of the year in which the study took place, the duration of the trials, and the spacing of carcass sites. Our results suggest that under the warm and humid conditions of our study, facultative scavengers would not compensate for loss of vultures. Carcasses would persist longer in the environment and consumption of carrion would likely shift from vertebrates to decomposers. Such changes could have substantial implications for disease transmission, nutrient cycling, and ecosystem functioning.

Protected areas are established for diverse conservation strategies, but their effectiveness for conserving species varies widely. We compiled studies that used telemetry to determine cause-specific mortality of North American mammals and compared mortality sources of animals monitored in areas classified as protected by the International Union for Conservation of Nature and non-protected areas. Our dataset consisted of 358 studies which monitored the fates of 28,925 individuals and documented 9348 mortalities of known cause across 66 mammalian species. Although anthropogenic mortality was found to be higher in protected areas, we did not find evidence that protected area status was associated with that difference. However, poaching was 75% lower in protected areas. Within protected areas, we found no evidence that number of years since protection nor IUCN category of protection influenced any mortality source, but proportion of anthropogenic mortality on average decreased by 4% with each additional 50 km2 in protected area size. Species body mass was an important factor determining susceptibility to harvest mortality and anthropogenic mortality overall. Protected areas in North America were associated with reduced poaching mortality of mammals, but the ecological importance of this reduction is likely influenced by population- and species-specific factors. Keywords: Telemetry, Conservation, Cause-specific mortality

As wildlife populations continue to decline worldwide, human-caused mortality of terrestrial vertebrates is of increasing importance. However, there is a limited understanding of how direct anthropogenic mortality compares in magnitude to natural mortality. Here, we present CauseSpec, a database of global terrestrial vertebrate cause-specific mortality. We compiled studies that used telemetry to monitor terrestrial vertebrates and determine cause of death. We distinguished between anthropogenic and natural mortality and also documented the specific mortality source where possible (e.g., harvest, vehicle collision, predation, and starvation). This database consists of 1,134 studies that collectively monitored the fates of 123,747 individual animals. From this, there are 43,998 deaths of known cause among 307 species. It is an updated version of the data set used in Hill et al. (2019) and will continue to be updated in the future. These data can be combined with data on species morphology and behavior to examine how species attributes influence susceptibility to various mortality sources. Our database also includes the geographic coordinates of the study site so that site attributes can be included in analyses. We also distinguish between adults and juveniles where possible, allowing for age-specific mortality analyses. Study start and end dates are available as well so that analyses of temporal changes in mortality are possible. Last, users can select all cause-specific mortality studies from a single species to perform a species-level analysis. The data set will allow users to circumvent a literature search, facilitating more rapid publication of large-scale vertebrate mortality studies and elucidating mortality patterns of terrestrial vertebrates around the world. There are no copyright or proprietary restrictions. We would like researchers to cite this paper if the associated database is used to find studies of interest for analysis.

Mortality of mammals from vehicle collisions is common, but there remain questions regarding how species traits influence vehicle collision vulnerability. We analyzed a database of North American mammal cause-specific mortality to examine factors influencing vehicle mortality. Our dataset consisted of 421 studies that monitored 34,798 individuals across 66 species including 740 vehicle mortalities. Vehicle mortality increased 4-fold over the study period (1965–2017), from 3% to 12% of total mortality between the first and last decade. Omnivores were more likely to die from vehicle mortality than herbivores. Vehicle mortality was highest for species at intermediate body masses (6–12 kg). Sociality, foraging behavior, diel behavior, and scavenging behavior did not influence vehicle mortality. The habitat and dietary flexibility of omnivores may put them at increased risk of vehicle collisions. The increase in vehicle collisions over the past 50 years reiterates the need for mitigation measures to conserve North American mammal populations.

Wildlife-vehicle collisions introduce a considerable amount of carrion into the environment, but scavenger use of this resource has not been extensively investigated. Scavengers may use roads for reliable foraging opportunities, but might also use roads for other purposes and encounter carrion opportunistically. We examined scavenging of carrion along linear features by placing 52 rabbit carcasses in each of three treatments in forested habitat during winter (Dec 2016-Mar 2017) in South Carolina, USA: roads, power line clearings (linear feature with fewer carcasses than roads due to lack of road kill), and forest interior. We used motion-activated cameras to compare arrival times and presence of vertebrate scavengers among treatments. There was no difference in proportion of carcasses scavenged or scavenger arrival time across treatments. No species arrived at roads quicker than other treatments. Turkey vultures (Cathartes aura) and coyotes (Canis latrans) scavenged equally across treatments, whereas gray foxes (Urocyon cinereoargenteus) scavenged along roads and power lines, but not in forests. We suggest that scavenger use of carrion near roads at this location during winter relates to factors other than carrion availability. Because some scavengers readily consumed carrion on roads, this resource has the potential to influence the ecology of these species.

Human activities frequently result in reptile mortality, but how direct anthropogenic mortality compares to natural morality has not been thoroughly investigated. There has also been a limited examination of how anthropogenic reptile mortality changes as a function of the human footprint. We conducted a synthesis of cause-specific North American reptile mortality studies based on telemetry, documenting 550 mortalities of known cause among 2461 monitored individuals in 57 studies. Overall 78% of mortality was the result of direct natural causes, whereas 22% was directly caused by humans. The single largest source of mortality was predation, accounting for 62% of mortality overall. Anthropogenic mortality did not increase with the human footprint or with species body mass, though predation mortality increased with decreasing human footprint. The relatively low amount of anthropogenic mortality compared to other taxa suggests that reptiles may be more impacted by indirect than direct anthropogenic mortality. As a result, mitigating these indirect impacts, which include habitat loss and introduction of invasive species, is essential for conservation of North American reptiles.

Knowledge of an animal’s behavior during particular life history stages can provide insights into habitat selection, and this can have important conservation implications. Gravid hawksbill turtles spend the internesting interval resting on the seafloor, but their diving behavior has only been previously examined in shallow-water habitats. We examined depth use of gravid hawksbills in a location of variable bathymetry to determine if hawksbills engage in deeper diving if deeper waters are available. We attached archival time-depth recorders onto hawksbills nesting at Sandy Point National Wildlife Refuge, St. Croix, US Virgin Islands, where the neritic zone ends within 500 m of the shoreline. We recorded seven internesting intervals from five individuals. Internesting intervals were characterized by long dives (mean 24.2 ± SD 22.3 min) to a constant depth, consistent with seafloor resting in a spatially restricted residence area. There was little variation in the water temperatures at all depths occupied (mean 29.06 ± SD 0.43 °C). Two turtles attained the deepest recorded dives for gravid hawksbills (95.1 and 84.4 m) and sometimes remained at depths greater than 60 m for up to 30 min. Although we recorded instances of relatively deep diving for the species, the overall pattern of seafloor resting and infrequent diving was consistent with hawksbills in other ocean basins with different offshore habitats. We propose that benthic resting is common behavior for gravid hawksbills globally, and protection of benthic habitats near the nesting beach should be a management priority.

We collected tissue samples from 41 nesting hawksbill turtles (Eretmochelys imbricata) at Sandy Point National Wildlife Refuge, St. Croix, US Virgin Islands, to characterize the genetic structure of this rookery in terms of mitochondrial DNA; we compared haplotype frequencies from this rookery to those from Buck Island, another hawksbill nesting beach on St. Croix. Pairwise FST comparisons showed that Sandy Point was demographically distinct from Buck Island (FST = 0.501, p < 0.001), a finding reinforced by significantly different haplotype frequencies (χ2 = 51.76, p < 0.001) and a lack of interchange of nesting females between both sites based on mark–recapture data. Our results support the delineation of the nesting populations at Sandy Point and Buck Island into separate units for the purposes of management.

© 2015 Hill et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Increasing sand temperatures resulting from climate change may negatively impact sea turtle nests by altering sex ratios and decreasing reproductive output. We analyzed the effect of nest shading and watering on sand temperatures as climate mitigation strategies in a beach hatchery at Playa Grande, Costa Rica. We set up plots and placed thermocouples at depths of 45cm and 75cm. Half of the plots were shaded and half were exposed to the sun. Within these exposure treatments, we applied three watering treatments over one month, replicating local climatic conditions experienced in this area. We also examined gravimetric water content of sand by collecting sand samples the day before watering began, the day after watering was complete, and one month after completion. Shading had the largest impact on sand temperature, followed by watering and depth. All watering treatments lowered sand temperature, but the effect varied with depth. Temperatures in plots that received water returned to control levels within 10 days after watering stopped. Water content increased at both depths in the two highest water treatments, and 30 days after the end of water application remained higher than plots with low water. While the impacts of watering on sand temperature dissipate rapidly after the end of application, the impacts on water content are much more lasting. Although less effective at lowering sand temperatures than shading, watering may benefit sea turtle clutches by offsetting negative impacts of low levels of rain in particularly dry areas. Prior to implementing such strategies, the natural conditions at the location of interest (e.g. clutch depth, environmental conditions, and beach characteristics) and natural hatchling sex ratios should be taken into consideration. These results provide insight into the effectiveness of nest shading and watering as climate mitigation techniques and illustrate important points of consideration in the crafting of such strategies., This study was funded by a grant from Earthwatch to Frank Paladino at Indiana University Purdue University at Fort Wayne (IPFW), by the Schrey Chair in Biology at IPFW, and by the Betz Chair of Environmental Science at Drexel University