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Star Wars : heroes & villains
\"From Jedi to Sith to droids to stormtroopers, this collection of seven Star Wars Little Golden Books will introduce young readers to all the heroes and villains from the epic space saga!\" -- Back cover.
BOOK
Correlates of Research Effort in Carnivores: Body Size, Range Size and Diet Matter
Given the budgetary restrictions on scientific research and the increasing need to better inform conservation actions, it is important to identify the patterns and causes of biases in research effort. We combine bibliometric information from a literature review of almost 16,500 peer-reviewed publications on a well-known group of 286 species, the Order Carnivora, with global datasets on species' life history and ecological traits to explore patterns in research effort. Our study explores how species' characteristics influenced the degree to which they were studied (measured as the number of publications). We identified a wide variation in intensity of research effort at both Family and Species levels, with some of the least studied being those which may need protection in future. Our findings hint at the complex role of human perspectives in setting research agendas. We found that better-studied species tended to be large-bodied and have a large geographic range whilst omnivory had a negative relationship with research effort. IUCN threat status did not exhibit a strong relationship with research effort which suggests that the conservation needs of individual species are not major drivers of research interest. This work is the first to use a combination of bibliometric analysis and biological data to quantify and interpret gaps in research knowledge across an entire Order. Our results could be combined with other resources, such as Biodiversity Action Plans, to prioritise and co-ordinate future research effort, whilst our methods can be applied across many scientific disciplines to describe knowledge gaps.
Journal Article
Random versus Game Trail-Based Camera Trap Placement Strategy for Monitoring Terrestrial Mammal Communities
Camera trap surveys exclusively targeting features of the landscape that increase the probability of photographing one or several focal species are commonly used to draw inferences on the richness, composition and structure of entire mammal communities. However, these studies ignore expected biases in species detection arising from sampling only a limited set of potential habitat features. In this study, we test the influence of camera trap placement strategy on community-level inferences by carrying out two spatially and temporally concurrent surveys of medium to large terrestrial mammal species within Tanzania's Ruaha National Park, employing either strictly game trail-based or strictly random camera placements. We compared the richness, composition and structure of the two observed communities, and evaluated what makes a species significantly more likely to be caught at trail placements. Observed communities differed marginally in their richness and composition, although differences were more noticeable during the wet season and for low levels of sampling effort. Lognormal models provided the best fit to rank abundance distributions describing the structure of all observed communities, regardless of survey type or season. Despite this, carnivore species were more likely to be detected at trail placements relative to random ones during the dry season, as were larger bodied species during the wet season. Our findings suggest that, given adequate sampling effort (> 1400 camera trap nights), placement strategy is unlikely to affect inferences made at the community level. However, surveys should consider more carefully their choice of placement strategy when targeting specific taxonomic or trophic groups.
Journal Article
Prey availability and temporal partitioning modulate felid coexistence in Neotropical forests
Carnivores have long been used as model organisms to examine mechanisms that allow coexistence among ecologically similar species. Interactions between carnivores, including competition and predation, comprise important processes regulating local community structure and diversity. We use data from an intensive camera-trapping monitoring program across eight Neotropical forest sites to describe the patterns of spatiotemporal organization of a guild of five sympatric cat species: jaguar (Panthera onca), puma (Puma concolor), ocelot (Leopardus pardalis), jaguarundi (Herpailurus yagouaroundi) and margay (Leopardus wiedii). For the three largest cat species, we developed multi-stage occupancy models accounting for habitat characteristics (landscape complexity and prey availability) and models accounting for species interactions (occupancy estimates of potential competitor cat species). Patterns of habitat-use were best explained by prey availability, rather than habitat structure or species interactions, with no evidence of negative associations of jaguar on puma and ocelot occupancy or puma on ocelot occupancy. We further explore temporal activity patterns and overlap of all five felid species. We observed a moderate temporal overlap between jaguar, puma and ocelot, with differences in their activity peaks, whereas higher temporal partitioning was observed between jaguarundi and both ocelot and margay. Lastly, we conducted temporal overlap analysis and calculated species activity levels across study sites to explore if shifts in daily activity within species can be explained by varying levels of local competition pressure. Activity patterns of ocelots, jaguarundis and margays were similarly bimodal across sites, but pumas exhibited irregular activity patterns, most likely as a response to jaguar activity. Activity levels were similar among sites and observed differences were unrelated to competition or intraguild killing risk. Our study reveals apparent spatial and temporal partitioning for most of the species pairs analyzed, with prey abundance being more important than species interactions in governing the local occurrence and spatial distribution of Neotropical forest felids.
Journal Article
Global drivers of population density in terrestrial vertebrates
Aim: Although the effects of life history traits on population density have been investigated widely, how spatial environmental variation influences population density for a large range of organisms and at a broad spatial scale is poorly known. Filling this knowledge gap is crucial for global species management and conservation planning and to understand the potential impact of environmental changes on multiple species. Location: Global. Time period: Present. Major taxa studied: Terrestrial amphibians, reptiles, birds and mammals. Methods: We collected population density estimates for a range of terrestrial vertebrates, including 364 estimates for amphibians, 850 for reptiles, 5,667 for birds and 7,651 for mammals. We contrasted the importance of life history traits and environmental predictors using mixed models and tested different hypotheses to explain the variation in population density for the four groups. We assessed the predictive accuracy of models through cross-validation and mapped the partial response of vertebrate population density to environmental variables globally. Results: Amphibians were more abundant in wet areas with high productivity levels, whereas reptiles showed relatively higher densities in arid areas with low productivity and stable temperatures. The density of birds and mammals was typically high in temperate wet areas with intermediate levels of productivity. The models showed good predictive abilities, with pseudo-R2 ranging between 0.68 (birds) and 0.83 (reptiles). Main conclusions: Traits determine most of the variation in population density across species, whereas environmental conditions explain the intraspecific variation across populations. Species traits, resource availability and climatic stability have a different influence on the population density of the four groups. These models can be used to predict the average species population density over large areas and be used to explore macroecological patterns and inform conservation analyses.
Journal Article
Applying a random encounter model to estimate lion density from camera traps in Serengeti National Park, Tanzania
The random encounter model (REM) is a novel method for estimating animal density fromcamera trap data without the need for individual recognition. It has never been used to estimate the density oflarge carnivore species, despite these being the focus of most camera trap studies worldwide. In this context,we applied the REM to estimate the density of female lions (Panthera leo) from camera traps implemented inSerengeti National Park, Tanzania, comparing estimates to reference values derived from pride census data.More specifically, we attempted to account for bias resulting from non-random camera placement at lionresting sites under isolated trees by comparing estimates derived from night versus day photographs, betweendry and wet seasons, and between habitats that differ in their amount of tree cover. Overall, we recorded 169and 163 independent photographic events of female lions from 7,608 and 12,137 camera trap days carried outin the dry season of 2010 and the wet season of 2011, respectively. Although all REM models consideredover-estimated female lion density, models that considered only night-time events resulted in estimates thatwere much less biased relative to those based on all photographic events. We conclude that restricting REMestimation to periods and habitats in which animal movement is more likely to be random with respect tocameras can help reduce bias in estimates of density for female Serengeti lions. We highlight that accurateREM estimates will nonetheless be dependent on reliable measures of average speed of animal movement andcamera detection zone dimensions.
Journal Article
Fine Scale Phylogeography of Urban Western European Hedgehog Erinaceus europaeus in South‐East England
Preserving genetic diversity within species and populations is an important conservation goal, yet observed genetic structure can be influenced by both contemporary and historical processes. Here, we investigate the phylogeography of the western European hedgehog (Erinaceus europaeus) in Greater London, east and south‐east England, using DNA sequence analysis of a section of the mitochondrial cytochrome b gene and control region. We find seven haplotypes within the study region, of which six are novel, indicating higher diversity than previously identified in the UK. Comparison with published haplotypes from mainland Europe identified low sequence divergence from those found in France and Jersey. Most haplotypes were widespread within south‐east England, in contrast to strong spatial clustering of haplotypes seen at broader scales across Europe. However, local haplotype diversity varied within the study region, with some evidence supporting the view that genetic isolation has led to an absence of haplotypes in urban sites in central London. Broader UK‐wide sampling is recommended to ascertain whether additional haplotype lineages and geographic structuring exist at larger spatial scales in the UK. These findings may have important considerations for future hedgehog conservation efforts. Detailed investigation of the phylogeography of western European hedgehogs in Greater London, east and south‐east England using DNA sequence analysis of a section of mitochondrial cytb gene and control region identifies higher haplotype diversity than previously found in the UK. Little local‐scale spatial structuring is seen, in contrast to broader scales across mainland Europe, but there is some evidence of potentially low haplotype diversity in isolated urban sites in central London. These findings may have important considerations for future hedgehog conservation efforts.
Journal Article
The Costs of Carnivory
Mammalian carnivores fall into two broad dietary groups: smaller carnivores (<20 kg) that feed on very small prey (invertebrates and small vertebrates) and larger carnivores (>20 kg) that specialize in feeding on large vertebrates. We develop a model that predicts the mass-related energy budgets and limits of carnivore size within these groups. We show that the transition from small to large prey can be predicted by the maximization of net energy gain; larger carnivores achieve a higher net gain rate by concentrating on large prey. However, because it requires more energy to pursue and subdue large prey, this leads to a 2-fold step increase in energy expenditure, as well as increased intake. Across all species, energy expenditure and intake both follow a three-fourths scaling with body mass. However, when each dietary group is considered individually they both display a shallower scaling. This suggests that carnivores at the upper limits of each group are constrained by intake and adopt energy conserving strategies to counter this. Given predictions of expenditure and estimates of intake, we predict a maximum carnivore mass of approximately a ton, consistent with the largest extinct species. Our approach provides a framework for understanding carnivore energetics, size, and extinction dynamics.
Journal Article
Revealing kleptoparasitic and predatory tendencies in an African mammal community using camera traps
Camera trap data are increasingly being used to characterise relationships between the spatiotemporal activity patterns of sympatric mammal species, often with a view to inferring inter-specific interactions. In this context, we attempted to characterise the kleptoparasitic and predatory tendencies of spotted hyaenas Crocuta crocuta and lions Panthera leo from photographic data collected across 54 camera trap stations and two dry seasons in Tanzania’s Ruaha National Park. We applied four different methods of quantifying spatiotemporal associations, including one strictly temporal approach (activity pattern overlap), one strictly spatial approach (co-occupancy modelling), and two spatiotemporal approaches (co-detection modelling and temporal spacing at shared camera trap sites). We expected a kleptoparasitic relationship between spotted hyaenas and lions to result in a positive spatiotemporal association, and further hypothesised that the association between lions and their favourite prey in Ruaha, the giraffe Giraffa camelopardalis and the zebra Equus quagga, would be stronger than those observed with non-preferred prey species (the impala Aepyceros melampus and the dikdik Madoqua kirkii). Only approaches incorporating both the temporal and spatial components of camera trap data resulted in significant associative patterns. The latter were particularly sensitive to the temporal resolution chosen to define species detections (i.e. occasion length), and only revealed a significant positive association between lion and spotted hyaena detections, as well as a tendency for both species to follow each other at camera trap sites, during the dry season of 2013, but not that of 2014. In both seasons, observed spatiotemporal associations between lions and each of the four herbivore species considered provided no convincing or consistent indications of any predatory preferences. Our study suggests that, when making inferences on inter-specific interactions from camera trap data, due regards should be given to the potential behavioural and methodological processes underlying observed spatiotemporal patterns.
Journal Article