The Himalayan Shrew belongs to the genus Soriculus, which is a monotypic genus. We investigated the phylogeographic patterns, speciation, divergence time, and demographic history of Soriculus nigrescens in southwestern China. A total of 128 samples from 29 regions were analyzed for both mitochondrial and nuclear genes. Phylogenetic analyses of the concatenated mtDNA and nuDNA data revealed three highly divergent lineages within the S. nigrescens. One group represented subspecies S. n. minors, another group represented subspecies S. n. nigrescens, which is made up of two Clades A and B. The species delimitation analyses, based on two methods, supported the species status of the two Clades of S. n. nigrescens. In addtion, it was found that individuals at different altitudes in Motuo were divided into two Clades. Bayesian skyline plotting analyses and ecological niche modeling also supported demographic and range expansions during the LGM for S. n. nigrescens. We propose that S. n. nigrescens appears to be composed of two putative species, and S. n. minor should be elevated to species status. Our study also suggested that climate change since the Miocene periods and the uplift of the QTP may have resulted in the diversification and speciation of S. nigrescens.

The extended female post-reproductive lifespan found in humans and some toothed whales remains an evolutionary puzzle. Theory predicts demographic patterns resulting in increased female relatedness with age (kinship dynamics) can select for a prolonged post-reproductive lifespan due to the combined costs of inter-generational reproductive conflict and benefits of late-life helping. Here we test this prediction using >40 years of longitudinal demographic data from the sympatric yet genetically distinct killer whale ecotypes: resident and Bigg’s killer whales. The female relatedness with age is predicted to increase in both ecotypes, but with a less steep increase in Bigg’s due to their different social structure. Here, we show that there is a significant post-reproductive lifespan in both ecotypes with >30% of adult female years being lived as post-reproductive, supporting the general prediction that an increase in local relatedness with age predisposes the evolution of a post-reproductive lifespan. Differences in the magnitude of kinship dynamics however, did not influence the timing or duration of the post-reproductive lifespan with females in both ecotypes terminating reproduction before their mid-40s followed by an expected post-reproductive period of ~20 years. Our results highlight the important role of kinship dynamics in the evolution of a long post-reproductive lifespan in long-lived mammals, while further implying that the timing of menopause may be a robust trait that is persistent despite substantial variation in demographic patterns among population.

The spatial-temporal patterns of fish assemblages in lotic systems can provide useful information in developing effective conservation measures. This study aimed to explore the spatiotemporal changes in fish assemblage and their association with environmental factors in mountain streams of Ren River, southwest China. Filed investigations were conducted at 18 sites during rainy and dry season in 2017. A total of 21 species, belonged to 3 orders, 8 families and 19 genera, were collected. Analysis of similarities (ANOSIM) showed fish assemblages structure varied significantly at the spatial scale, but not at the temporal scale. In low order sites, fish assemblages were mainly dominated by cold water and rheophilic species (e.g. Rhynchocypris oxycephalus, Scaphesthes macrolepis, Metahomaloptera omeiensis and Gnathopogon herzensteini), while those in high order sites were predominated by warm water and eurytopicity or stagnophilic species (e.g. Squalidus argentatus, Hemiculter leucisculus and Zacco platypus). Canonical correspondence analysis (CCA) showed fish assemblages were structured by a combination of large-scale landscape factors (e.g. altitude and C-link) and small-scale habitat features (e.g. channel width, water temperature and depth). Among these factors, landscape factors had the greatest influence on fish assemblage, while local habitat measures played less important roles or just acted in certain season.

Sexual size dimorphism (SSD) is caused by differences in selection pressures and life-history tradeoffs faced by males and females. Proximate causes of SSD may involve sex-specific mortality, energy acqui-sition, and energy expenditure for maintenance, reproductive tissues, and reproductive behavior. Using a quantitative, individual-based, eco-genetic model parameterized for North Sea plaice, we explore the importance of these mechanisms for female-biased SSD, under which males are smaller and reach sexual maturity earlier than females (common among fish, but also arising in arthropods and mammals). We consider two mechanisms potentially serving as ultimate causes: (1) male investments into male repro-ductive behavior might detract energy resources that would otherwise be available for somatic growth, and (2) diminishing returns on male reproductive investments might lead to reduced energy acquisition. In general, both of these can bring about smaller male body sizes. We report the following findings. First, higher investments into male reproductive behavior alone cannot explain the North Sea plaice SSD. This is because such higher reproductive investments require increased energy acquisition, which would cause a delay in maturation, leading to male-biased SSD contrary to observations. When account-ing for the observed differential (lower) male mortality, maturation is postponed even further, leading to even larger males. Second, diminishing returns on male reproductive investments alone can qualitative-ly account for the North Sea plaice SSD, even though the quantitative match is imperfect. Third, both mechanisms can be reconciled with, and thus provide a mechanistic basis for, the previously advanced Ghiselin-Reiss hypothesis, according to which smaller males will evolve if their reproductive success is dominated by scramble competition for fertilizing females, as males would consequently invest more into reproduction than growth, potentially implying lower survival rates relaxing male-male competition. Fourth, a good quantitative fit is achieved by combining both mechanisms while accounting for costs males incur during spawning.

The populations of the endemic gelada outside protected areas are less studied and population estimates are not available. As a result, a study was conducted to investigate population structure and distribution of geladas in Kotu forest and associated grasslands, in Northern Ethiopia. The study area was stratified into five habitats namely; grassland, wooded grassland, plantation forest, natural forest and bushland based on dominant vegetation type. Each habitat type was further divided into blocks and total counting technique was employed to count the individuals of geladas. The total mean number of gelada in the Kotu forest was 229 ± 6.11. The mean ratio of male to female was 1:1.178. Age composition of geladas comprised: 113 (49.34%) adults, 77 (33.62%) sub adults and 39 (17.03%) juveniles. The mean group size of gelada was 18± 2.0, out of which 2.5± 0.5 (13.89%) was all- male unit (AMU) and 15.5± 1.5 (86.11%) was one male unit (OMU) social system. The average band size was 45.0± 2.53. The highest number of geladas was recorded from grassland habitat 68 (29.87%) and the lowest from plantation forest habitat 34 (14.74%). Even though, the sex ratio was female biased, the proportion of juveniles to other age classes was very low, indicating negative consequences for the future viability of the gelada populations in the area. Geladas were widely distributed over open grassland habitat. For sustainable conservation of the geladas in the area there is a need for integrated management of the area with special attention on the conservation of the grassland habitat.

Northern range margin populations of the European fire-bellied toad (Bombina bombina) have rapidly declined during recent decades. Extensive agricultural land use has fragmented the landscape, leading to habitat disruption and loss, as well as eutrophication of ponds. In Northern Germany (Schleswig-Holstein) and Southern Sweden, this decline resulted in decreased gene flow from surrounding populations, low genetic diversity, and a putative reduction in adaptive potential, leaving populations vulnerable to future environmental and climatic changes. Previous studies using mitochondrial control region and nuclear transcriptome-wide SNP data detected introgressive hybridization in multiple northern B. bombina populations after presumed illegal release of toads from Austria. Here, we determine the impact of this introgression by comparing the body conditions (as a proxy for fitness) of introgressed and non-introgressed populations, and the genetic consequences in two candidate genes for putative local adaptation (the MHC II gene as part of the adaptive immune system and the stress response gene HSP70 kDa). We detected regional differences in body condition. We observed significantly elevated levels of within individual MHC allele counts in introgressed Swedish populations, associated with a tendency towards higher body weight, relative to regional non-introgressed populations. These differences were not observed among introgressed and non-introgressed German populations. Genetic diversity in both MHC and HSP was generally lower in northern than southern populations. Our study sheds light on the potential benefits of translocations of more distantly related conspecifics as a means to increase adaptive genetic variability and fitness of struggling range margin populations without distortion of local adaptation.

Chimpanzees Pan troglodytes are the closest extant relative of modern humans, and are often used as a model organism to help understand prehistoric human behavior and ecology. Originally presumed herbivorous, chimpanzees have been observed hunting 24 species of birds, ungulates, rodents, monkeys, and other primates, using an array of techniques from tools to group cooperation. Using the literature on chimpanzee hunting behavior and diet from 13 studies, we aimed to determine the prey preferences of chimpanzees. We extracted data on prey-specific variables such as targeted species, their body weight, and their abundance within the prey community, and hunter-specific variables such as hunting method, and chimpanzee group size and sex ratio. We used these in a generalized linear model to determine what factors drive chimpanzee prey preference. We calculated a Jacobs’ Index value for each prey species killed at two sites in Uganda and two sites in Tanzania. Chimpanzees prefer prey with a body weight of 7.6 ± 0.4 kg or less, which corresponds to animals such as juvenile bushbuck Tragelaphus scriptus and guereza colobus monkeys Colobus guereza. Sex ratio in chimpanzee groups appears to drive chimpanzee prey preference, where chimpanzees increasingly prefer prey when in male-dominated groups. Prey preference information from chimpanzee research can assist conservation management programs by identifying key prey species to manage, as well as contribute to a better understanding of the evolution of human hunting behavior.

Detectors for the passive acoustic monitoring (PAM) of bats have become invaluable research tools, especially for surveys, monitoring programs and environmental impact assessments. However, little is known about the small-scale (within-site) variability of PAM recordings and especially about the influence of detector identity and distance, and of microphone orientation on the statistical confidence of activity estimates and species detection probabilities. We recorded vocalizations in a homogeneous meadow with no trees, bushes or tall ground vegetation. Eight detector pairs were arranged in an octagon, the two detectors of a pair facing in opposite directions. The call sequences of eight species were analyzed. The deviations of individual detectors from the overall mean were generally small, but large outliers occurred both at the file (temporal resolution: five seconds) and the night (resolution: one night) scale. All devices detected the main temporal patterns of calling activity in the study period, but three devices deviated systematically from the others and the sensitivity of two devices deteriorated over time. Detector orientation and distance were significant, yet small, sources of variability. The probability of detecting the presence of species correlated with species’ activity and ranged on average from 100 % for bats in total to only 18.8 % for the least active Myotis myotis. The sample sizes necessary to achieve 90 % statistical confidence of activity estimates ranged from 7 to 16 detectors and from 5 to 12 nights, depending on taxon. Increasing the number of nights resulted in much higher confidence than increasing the number of detectors. We recommend PAM studies of bats to frequently calibrate detector sensitivity; deploying at least three detectors per study site; sampling longer periods instead of deploying more detectors; randomly assigning and swapping detectors among sites, treatments, strata, etc.; and statistically scrutinizing the sample data, especially for outliers.

1. Accurate biodiversity and population monitoring is a requirement for effective conservation decision-making. Survey method bias is therefore a concern, particularly when research programs face logistical and cost limitations. 2. We employed point counts (PCs) and autonomous recording units (ARUs) to survey avian biodiversity across elevational gradients in comparable temperate mountain habitats at opposite ends of the Americas (9 mountains in British Columbia (BC), Canada and 10 in southern Chile). We compared detected species richness against multi-year species inventories and examined differences in detection probability by family. By incorporating time costs, we assessed the performance and efficiency of single vs. combined methods. 3. ARUs were predicted to capture ~92% of species present in BC but only ~58% in Chile, despite Chilean mountain communities being less diverse. Community, rather than landscape composition, appears to be the driver of this dramatic difference. Chilean communities contain less-vocal species, which ARUs missed. Further, 6/14 families in BC were better detected by ARUs while 11/11 families in Chile were better detected by PCs. Where survey conditions differentially impacted methods, PC detection varied over the morning and with canopy cover in BC and ARU detection probability mostly varied seasonally in Chile. Within a single year of monitoring, neither method alone was predicted to capture the full avian community, with the exception of ARUs in the alpine and subalpine of BC. PCs contributed little to detected diversity in BC, but including this method resulted in negligible increases in total time costs. Combining PCs with ARUs in Chile significantly increased species detections, again, for little cost. 4. Combined methods were among the most efficient and accurate approaches to capturing diversity. We recommend conducting observer point counts, where possible, when ARUs are deployed and retrieved, in order to capture additional diversity and flag methodology biases with minimal additional effort.

1. Tropical deciduous forests show strong seasonal variations due to temporal dynamics of precipitation and temperature and therefore, resource availability for animals are also limited accordingly. Certain harsh environment even pushes animals to seasonal movements towards available resources. 2. We hypothesize that the density distribution of four sympatric ungulate species is structured by habitat covariates but more affected by seasonality. We then investigated density gradient of these species between contrasting season and correlated with environmental covariates. 3. We used distance-based density surface modelling with survey effort of 518 km in winter and 356 km in summer and with count data as a function of environmental variables in generalised additive modelling framework. We extrapolated seasonal abundance of each species and calculated coefficient of variation to ensure precision for the entire study area. 4. We observed a clear seasonal shift in the density distribution of all four species between summer (more abundant in valley) and winter (evenly distributed), significantly influenced by anthropogenic and topographic factors. Solitary species were congregated in larger groups during summer while group living species were in larger groups during winter. 5. Our study provides a clear understanding of species-habitat relationship as a function of seasonality in tropical forest and is useful in spatial prioritization of the habitats for relevant management inputs.

In spring of 2012, we studied the feeding habits of snow leopard using a comprehensive approach that combines fecal genetic sampling, macro and microscopic analysis of snow leopard diets and direct observation of Naur and livestock in Kangchenjunga Conservation Area of east Nepal. Out of collected 88 putative snow leopard scat samples from 140 transects (290 km) in 27 (4*4 km2) sampling grid cells, 83% were confirmed to be from snow leopard. The genetic analysis accounted for 19 individual snow leopards (10 male and 9 female) with a mean population size estimate of 24 (95% CI: 19- 29), and an average density of 3.9 snow leopards/100 km2 within 609 km2. Total available prey biomass of Naur and Yak was estimated at 355,236 kg (505 kg yak/km2 and 78 kg Naur/km2). From the available prey biomass, we estimated snow leopards consumed 7% annually which was comprised of wild prey (49%), domestic livestock (45%), and 6% unidentified items. The estimated 47,736 kg Naur biomass gives a snow leopard-Naur ratio of 1: 59 on a weight basis. The proportion of young Naur was estimated at 17%, with an almost double predation rate at 28%. Predators such as common leopard and wolf share the same habitat and might compete with snow leopard for prey which will likely influence future predator-prey associations in KCA. Along with livestock insurance scheme improvement, there needs to be a focus on improved livestock guarding as well as engaging and educating local people to be citizen scientists on the importance of snow leopard conservation, involving them in long-term monitoring programs and promotion of ecotourism.

1. Phyllostomid bats exhibit great diversity in skull size and morphology that reflects the degree of resource division and ecological overlap in the group. In particular, Stenodermatinae has high morphological diversification associated with cranial and mandibular traits that is associated with the ability to consume the full range of available fruits (soft and hard). In terms of morphology, performance (bite force) appears to play an important role in niche partitioning among bat species, however, very few studies have confirmed these relationships using functional cranial traits. 2. Here, we analyzed craniodental traits and their relationship to the bite force in 308 specimens distributed in seven species of stenodermatine bats with two foraging types: nomadic and sedentary frugivorous bats. We evaluated 19 functional traits of the skull and jaw related to feeding and bite force in live animals by correcting bite force with body size. We used a GLM model and post hoc tests to determine possible relationships and differences between cranial traits, species, and sex. 3. The results showed that there is significant interspecific variation between stenodermatines that are nomadic and sedentary. The greatest variation in bite force within species was explained by the mandibular toothrow length (MANDL) between sexes, which was greater in females. The larger species of Artibeus, together with Platyrrhinus helleri, Uroderma convexum and Sturnira giannae, which have a greater length of the skull, condylo-incisor, condylo-canine, mandibular toothrow and height of the coronoid, exhibit greater bite force. By contrast, the smaller species A. anderseni and A. phaeotis have short skulls and the lowest values of bite force, which suggests that the size of the skull confers a biomechanical advantage. 4. Our results highlight the usefulness of analyzing functional traits related to feeding to establish the performance of bats in terms of the bite force.

White-nose syndrome (WNS) has decimated hibernating bat populations across eastern and central North America for over a decade. Disease severity is driven by the interaction between bat characteristics, the cold-loving fungal agent, and the hibernation environment. While we further improve hibernation energetics models, we have yet to examine how spatial heterogeneity in host traits is linked to survival in this disease system. Here we develop predictive spatial models of body mass for the little brown myotis (Myotis lucifugus) and reassess previous definitions of the duration of hibernation of this species. Using data from published literature, public databases, local experts, and our own fieldwork, we fit a series of generalized linear models with hypothesized abiotic drivers to create distribution-wide predictions of pre-hibernation body fat and hibernation duration. Our results provide improved estimations of hibernation duration and identify a scaling relationship between body mass and body fat; this relationship allows for the first continuous estimates of pre-hibernation body mass and fat across the species’ distribution. We used these results to inform a hibernation energetic model to create spatially-varying fat use estimates for M. lucifugus. These results predict that WNS mortality of newly and soon-to-be infected M. lucifugus populations in western North America may be comparable to the substantial die-off observed in eastern and central populations.

Central Iran supports a diversity of carnivores, most of which are threatened by habitat loss and fragmentation. Carnivore conservation requires the identification and preservation of core habitats and ensuring connectivity between them. In the present study, we applied species distribution modeling to predict habitat suitability and used connectivity modeling to predict linkage (resistant kernel and factorial least-cost path analyses) for grey wolf and golden jackal in central Iran. For grey wolf, elevation, topographic roughness and distance from agriculture lands were the strongest predictors; however, for golden jackal, distance from agriculture lands, human settlements and topographic roughness were the most influential variables in predicting the occurrence of this species. Our results also indicated a high potential for large parts of the landscape to support the occurrence of these two canid species. The largest and the most crucial core habitats and corridor paths for the conservation of both species are located in the southern part of the study landscape. We found a small overlap between golden jackal corridor paths and core habitats with protected areas, which has important implications for conservation and future viability of the golden jackal populations. Some sections of core areas are bisected by roads, where most vehicle collisions with grey wolf and golden jackal occurred. We propose that effective conservation of both species would require integrated landscape-level management to reduce mortality risk, as well as protection of core areas and corridors and development of mitigation strategies to reduce vehicle collisions.

1. Stable isotopes represent a unique approach to provide insights into the ecology of organisms. δ13C and δ15N have specifically be used to obtain information on the trophic ecology and food web interactions. The trophic discrimination factor (TDF, Δ13C and Δ15N) describes the isotopic fractionation occurring from diet to consumer tissue and this value is critical to obtain precise estimates within any application of δ13C and δ15N. It is widely acknowledged that metabolism influences the TDF, being responsible for different TDFs between tissues of variable metabolic activity (e.g. liver vs. muscle tissue) or species body size (small vs. large). However, the connection between the variation of metabolism occurring within a single species during its ontogeny and TDFs has rarely been considered. 2. Here, we conducted a 9-month feeding experiment to report Δ13C and Δ15N of muscle and liver tissue for several weight classes of Eurasian perch (Perca fluviatilis), a widespread teleost often studied using stable isotopes, but without established TDFs for feeding on a natural diet. In addition, we assessed the relationship between the standard metabolic rate (SMR) and TDFs by measuring their oxygen consumption of the individuals. 3. Our results showed a significant negative relationship of SMR with Δ13C, but not with Δ15N of muscle or TDFs of liver tissue. SMR was significantly higher in perch juveniles, which translated to significantly lower Δ13C of muscle tissue. 4. In summary, our results emphasize the role of metabolism in shaping specific TDFs (i.e. Δ13C of muscle tissue), and especially highlight the substantial differences between individuals of different ontogenetic stages within a species. Our findings thus have direct implications for the use of stable isotope data and the applications of stable isotopes in food web studies.

In ecological communities, interactions between consumers and resources lead to the emergence of ecological networks and a fundamental problem to solve is to understand which factors shape network structure. Empirical and theoretical studies on ecological networks suggest predator body size is a key factor structuring patterns of interaction. Because larger predators consume a wider resource range, including the prey consumed by smaller predators, we hypothesized that variation in body size favors the rise of nestedness. In contrast, if resource consumption requires specific adaptations, predators are expected to consume distinct sets of resources, thus favouring modularity. We investigate these predictions by characterising the trophic network of a species-rich Amazonian snake community (62 species). Our results revealed an intricate network pattern resulting from larger species feeding on higher diversity of prey, promoting nestedness, and specific lifestyles feeding on distinct resources, promoting modularity. Species removal simulations indicated that the nested structure is favored mainly by the presence of five species of the family Boidae, which because of their body size and generalist lifestyles connect modules in the network. Our study highlights the particular ways traits affect the structure of interactions among consumers and resources at the community level.

In semi-arid environments, aperiodic rainfall pulses determine cycles of plant production and resource availability for higher trophic levels, creating strong bottom-up regulation. The influence of climatic factors on population vital rates often shapes the dynamics of small mammal populations in such resource-restricted environments. Using a 21-year biannual capture–recapture dataset (1993 to 2014), we examined the impacts of climatic factors on the population dynamics of the brush mouse (Peromyscus boylii) in semi-arid oak woodland of coastal-central California. We applied Pradel’s temporal symmetry model to estimate capture probability (p), apparent survival (φ), recruitment (f), and realized population growth rate (λ) of the brush mouse, and examined the effects of temperature, rainfall, and El Niño on these demographic parameters. The population was stable during the study period with a monthly realized population growth rate of 0.993 ± SE 0.032, but growth varied over time from 0.680 ± 0.054 to 1.450 ± 0.083. Monthly survival estimates averaged 0.817 ± 0.005 and monthly recruitment estimates averaged 0.175 ± 0.038. Survival probability and realized population growth were positively correlated with rainfall and negatively correlated with temperature. In contrast, recruitment was negatively correlated with rainfall and positively correlated with temperature. Brush mice maintained their population through multiple coping strategies, investing in high recruitment during warmer and drier periods and allocating more energy towards survival during cooler and wetter conditions. Although climatic change in coastal-central California will favor recruitment over survival, varying strategies may serve as a mechanism by which brush mice maintain resilience in the face of climate change. Our results indicate that rainfall and temperature are both important drivers of brush mouse population dynamics and will play a significant role in predicting the future viability of brush mice under a changing climate.

Dens are places for cavernicolous animals to hibernate, reproduce, and avoid predators and harsh weather conditions, and thus they have a vital impact on their survival. M. himalayana is the main large cavernicolous rodent on the Qinghai-Tibet Plateau. The analysis of den traits and their ecological functions can reveal mechanisms by which marmots have adapted to their environment, which is important for further understanding the ecological significance of this species. From July to August 2019 (warm season), we used unmanned aerial vehicles to fly at low altitudes and slow speeds to locate 131 marmot burrows (45 on shaded slopes, 51 on sunny slopes, and 35 on flat areas) in the northeastern Qinghai-Tibet Plateau. We then measured the physical characteristics (den density, entrance size, first tunnel length, volume, orientation and plant characteristics near the den entrance) of these dens on site. The physical parameters of the M. himalayana dens showed that they function to protect the marmots from natural enemies and bad weather, provide good drainage, and maintain a stable microclimate around the entrance. This is a result of the marmot’s adaptation to the harsh environment (cold and humidity) of the Qinghai-Tibet Plateau.

1. The description and analysis of animal behaviour over long periods of time is one of the most important challenges in ecology. However, most of these studies are limited due to the time and cost required by human observers. The collection of data via video recordings allows observation periods to be extended. However, their evaluation by human observers is very time-consuming. Progress in automated evaluation, using suitable deep learning methods, seems to be a forwardlooking approach to analyse even large amounts of video data in an adequate time frame. 2. In this study we present amulti-step convolutional neural network system for detecting animal behaviour states, which works with high accuracy. An important aspect of our approach is the introduction of model averaging and post-processing rules to make the system robust to outliers. 3. Our trained system achieves an in-domain classification accuracy of >0.92, which is improved to >0.96 by a postprocessing step. In addition, the whole system performs even well in an out-of-domain classification task with two unknown types, achieving an average accuracy of 0.93. We provide our system at https://github.com/Klimroth/Video-Action-Classifier-for-African-Ungulates-in-Zoos/tree/main/mrcnn_based so that interested users can train their own models to classify images and conduct behavioural studies of wildlife. 4. The use of a multi-step convolutional neural network for fast and accurate classification of wildlife behaviour facilitates the evaluation of large amounts of image data in ecological studies and reduces the effort of manual analysis of images to a high degree. Our system also shows that post-processing rules are a suitable way to make species-specific adjustments and substantially increase the accuracy of the description of single behavioural phases (number, duration). The results in the out-of-domain classification strongly suggest that our system is robust and achieves a high degree of accuracy even for new species, so that other settings (e.g. field studies) can be considered.

Artiodactyl prey species of Chile, especially guanacos (Lama guanicoe) are reported to be very susceptible to predation by pack hunting feral dogs. It has been previously suggested that guanacos and endemic South American deer may have evolved in the absence of pack-hunting cursorial predators. However, the paleoecology of canid presence in southern South America and Chile is unclear. Here, we review the literature on South American and Chilean canids, their distributions, ecologies and hunting behaviour. We consider both wild and domestic canids, including Canis familiaris breeds. We establish two known antipredator defense behaviours of guanacos: predator inspection of ambush predators, e.g. Puma concolor, and rushing at and kicking smaller cursorial predators, e.g. Lycalopex culpaeus. We propose that since the late Pleistocene extinction of hypercarnivorous group-hunting canids east of the Andes, there were no native species creating group-hunting predation pressures on guanacos. Endemic deer of Chile may have never experienced group hunting selection pressure from native predators. Even hunting dogs (or other canids) used by indigenous groups in the far north and extreme south of Chile (and presumably the center as well) appear to have been used primarily within ambush hunting strategies. This may account for the susceptibility of guanacos and other prey species to feral dog attacks. We detail seven separate hypotheses that require further investigation in order to assess how best to respond to the threat posed by feral dogs to the conservation of native deer and camelids in Chile and other parts of South America.

Diffusible iodine-based contrast-enhanced Computed-Tomography (diceCT) visualizes soft-tissue from microCT (µCT) scans of specimens to uncover internal features and natural history information without incurring physical damage via dissection. Unlike hard-tissue imaging, diceCT datasets are currently limited to a few individual specimens and taxonomically underrepresented. To initiate best practices for diceCT in a non-model group, we outline a guide for staining and high-throughput µCT scanning in snakes. We scanned the entire body and one region of interest (i.e., head) for 23 specimens representing 23 species from the clades Aniliidae, Dipsadinae, Colubrinae, Elapidae, Lamprophiidae and Viperidae. We generated 82 scans that include 1.25% Lugols iodine stained (soft tissue) and unstained (skeletal) data for each specimen. We found that duration of optimal staining time increased linearly with body size; head radius was the best indicator. Post-reconstruction of scans, optimal staining was evident by evenly distributed grayscale values and clear differentiation among soft-tissue anatomy. Under and over stained specimens produced poor contrast among soft-tissues, which was often exacerbated by user bias during “digital dissections” (i.e., segmentation). Regardless, all scans produced usable data from which we assessed a range of downstream analytical applications within ecology and evolution (e.g., predator-prey interactions, life history, and morphological evolution). Ethanol de-staining reversed the known effects of iodine on the exterior appearance of physical specimens, but required substantially more time than reported for other de-staining methods. We discuss the feasibility of implementing diceCT techniques for a new user, including approximate financial and temporal commitments, required facilities, and potential effects of staining on specimens. We present the first high-throughput workflow for full-body skeletal and diceCT scanning in snakes, which can be generalized to any elongate vertebrates, and increases publicly available diceCT scans for reptiles by an order of magnitude.

Identifying factors that influence sea otter (Enhydra lutris) population density can provide insight into why it varies spatially and temporally and when a recovering population has reached an equilibrium density because of food resources (i.e., carrying capacity K). Although food availability is widely recognized as an important extrinsic factor affecting sea otter density, how do we determine when a population has reached K? The goal of this study was to estimate K for Simpson Bay, Alaska by measuring the abundance of edible bivalves, the primary prey for sea otters for over 40 years. We then compared prey abundance and estimated replacement rate (i.e., the mean age of bivalves predated by sea otters) to estimated annual prey consumption based on the mean population density for the past 18 years. On average, 110 adult sea otters (5.2 km−2) have occupied Simpson Bay annually since 2001 consuming an estimated 176,660 kg of bivalves. The total mass (standing stock) of the major bivalves (predominately butter clams and stained macomas) was 785,730 kg, so adult sea otters consumed about 22% annually. Based on these observations and calculations, the estimated annual number of sea otters occupying Simpson Bay appears to be at or near K based on the replacement rate of food resources. However, other intrinsic (e.g., male territoriality and emigration) and extrinsic (e.g., predation, disease, human-related mortality) factors may influence equilibrium density, which varies spatially and temporally, resulting in a mosaic of subpopulations with different densities, rates of growth and discontinuous distributions. Understanding the balance among these factors may be one of the most challenging ecological questions for sea otter conservation and management as populations recover from their range-wide decimation during the Maritime Fur Trade in the late 18th and 19th centuries

The muskrat (Ondatra zibethicus) is an iconic species in Canada, valued for both its fur and its integral role in wetland ecosystems, and widely regarded for its perseverance. However, the resilience of this semi-aquatic mammal seems to be in question now as increasing evidence points to widespread population declines. Recent analyses of harvest data across North America suggest a reduction in their numbers, but this has not been widely corroborated by population surveys. In this study we replicated historic muskrat house count surveys at two large Great Lakes coastal wetlands and present confirmation that declines in muskrat harvest correspond to actual declines in muskrat abundance. At the Point Pelee National Park marsh and the Matchedash Bay-Gray Marsh wetland we found that mean muskrat house counts declined by 93% and 91% respectively between historic surveys 40-50 years ago and contemporary surveys over the past five years. The factors responsible for these dramatic declines remain unclear but there may be a relationship with changes in the habitat quality of these wetlands that have occurred over the same time frame. Not only is the loss of muskrats an issue for the resulting loss of the wetland ecosystem services they provide, but it may be an indication of broader marsh ecosystem degradation. As such, a scarcity of muskrats should be considered a red flag for the state of biodiversity in our wetlands. Continued surveys and ongoing research are needed to shed more light on the current status of muskrat populations and their marsh habitats across their native range. Keywords: Fur harvest; Muskrat; Ondatra; Population decline; Typha; Wetlands

Predation is the most common cause of nest failure in birds. While nest predation is relatively well studied in general, our knowledge is unevenly distributed across globe and taxa, with for example limited information on shorebirds breeding in sub-tropics. Importantly, we know fairly little about the timing of predation within a day and season. Here, we followed 499 nests of red-wattled lapwings (Vanellus indicus), a ground-nesting shorebird, to estimate a nest predation rate, and continuously monitored 231 of these nests for a sum of 2951 days to reveal how timing of predation changes over the day and season in a sub-tropical desert. We found that 324 nests hatched, 77 nests were predated, 38 failed for other reasons and 60 had unknown fate. Daily predation rate was 0.97% (95%CrI: 0.77% – 1.2%), which for a 30-day long incubation period translates into ~25% chance of nest being predated. Such predation rate is low compared to most other species. Predation events were distributed evenly across day and night, with a tendency for increased predation around sunrise. Predation rate and events were distributed evenly also across the season, although night predation was more common later in the season, perhaps because predators reduce their activity during daylight to avoid extreme heat. Indeed, nests were never predated upon when mid-day ground temperatures exceeded 45°C. Whether the activity pattern of predators indeed changes across the breeding season and whether the described predation patterns hold for other populations, species and geographical regions awaits future investigations.