High Encounter Rates Research Articles

Differential relative catchability of wild‐ and hatchery‐origin steelhead in the Deschutes River, Oregon

AbstractObjectiveWe assessed the relative proportions of wild‐ and hatchery‐origin summer steelhead Oncorhynchus mykiss caught by sport anglers in the Deschutes River, Oregon. Our objective was to evaluate if steelhead of wild or hatchery origin were equally or disproportionately captured by sport anglers relative to the overall run composition.MethodsWe conducted access‐based angler creel surveys of the Deschutes River steelhead fishery during 2000–2019 and 2021 to observe reported catch of wild and hatchery steelhead. We collated fishery‐independent hatchery‐wild composition data from three locations (two dams and one fish trap) bounding the fishery area we creel sampled. We then used a series of mixed‐effect logistic regression models fit to compare angler catch of wild‐ and hatchery‐origin steelhead relative to their composition at the fishery‐independent sampling locations.ResultThe best‐fit model suggests that anglers were more than twice as likely to observe a wild steelhead in their catch as compared with the chance of the fishery‐dependent sampling sites to observe a wild steelhead. Across all years, wild steelhead were 27–31% of the stock composition at the fishery‐independent sampling sites yet averaged 65% of angler catch.ConclusionDisproportionately high encounter rates of wild‐origin summer steelhead suggest that any adverse impacts associated with catch‐and‐release fishing may be magnified by this effect. We explore some potential mechanisms that could account for this difference and hypothesize that a difference in catchability between wild and hatchery steelhead is the most likely mechanism driving the observed patterns. Regardless of the mechanism, annual catch of wild steelhead is proportionally greater than expectations, given wild steelhead run size compared with that of hatchery steelhead.

Habitat Utilization of Endemic Green Pit Viper (<i>Peltopelor trigonocephalus</i>) in the Wet Zone, Sri Lanka

The endemic arboreal pit viper Peltopelor trigonocephalus is restricted to three climatic zones of Sri Lanka. In this study, the habitat utilization of P. trigonocephalus was investigated by active search and the quadrate method between April 2021 and March 2022. Data on 49 individuals of P. trigonocephalus were collected from riparian, forest, and open habitats. A high encounter rate was recorded in riparian habitats which included areas with thick vegetation. Based on Principal Component Analysis, some habitat variables were key determining factors of microhabitat preference of this species. Ambient temperature, distance to stream, canopy cover and light intensity were significantly affecting the occupied microhabitat structure. Ambushing behavior was more prominent and time-consuming than other behaviors, with 42.59% of recorded sit-and-wait hunting activity. The results of this research indicate that P. trigonocephalus actively selects and utilizes the most suitable macro and microhabitats in wet zones, providing crucial insights for the conservation and management of the species as well as its natural habitat.

Discovery of a Millisecond Pulsar Associated with Terzan 6

Observations show that globular clusters (GCs) might be among the best places to find millisecond pulsars (MSPs). However, the GC Terzan 6 seems to be an exception without any pulsar discovered, although its high stellar encounter rate suggests that it harbors dozens of them. We report the discovery of the first radio pulsar, PSR J1750–3116A, likely associated with Terzan 6 in a search of C-band (4–8 GHz) data from the Robert C. Byrd Green Bank Telescope with a spin period of 5.33 ms and dispersion measure (DM) ≃ 383 pc cm−3. The mean flux density of this pulsar is approximately 3 μJy. The DM agrees well with predictions from the Galactic free electron density model, assuming a distance of 6.7 kpc for Terzan 6. PSR J1750–3116A is likely an isolated MSP, potentially formed through dynamical interactions, considering the core-collapsed classification and the exceptionally high stellar encounter rate of Terzan 6. This is the highest radio frequency observation that has led to the discovery of a pulsar in a GC to date. While L-band (1–2 GHz) observations of this cluster are unlikely to yield significant returns due to propagation effects, we predict that further pulsar discoveries in Terzan 6 will be made by existing radio telescopes at higher frequencies.

Surveillance of ticks (Acari: Ixodidae) and tick-borne pathogens in Eastern Central Alabama.

Similar to other states in the southeastern United States, human cases of tick-borne diseases in Alabama have risen steadily over the last 2 decades. Nevertheless, limited data have been published on ticks or tick-borne pathogen (TBP) distributions since the 1990s. To better understand the risk of tick and TBP exposure in eastern central Alabama, ticks were sampled repeatedly across 8 sites associated with recreational use during May and June of 2015 to characterize tick density and diversity. Although habitats were similar across sites, tick density varied among locations. Seven species were collected, but 97.7% of 1,310 samples were the lone star tick, Amblyomma americanum (L.), the primary vector of ehrlichial agents and the tick species most commonly linked to alpha-gal syndrome and southern tick-associated rash illness. To investigate pathogen prevalence among sites, we tested A. americanum by a multiplex qPCR assay for 5 bacterial species, including 3 Ehrlichia spp. and 2 Rickettsia spp. None of the specimens tested positive for Panola Mountain Ehrlichia or Rickettsia parkeri. However, causative agents of human ehrlichiosis, Ehrlichia chaffeensis and Ehrlichia ewingii, occurred at half of the locations with, respectively, 0.27% and 0.45% of A. americanum infected on average. In contrast, Rickettsia amblyommatis, a tick endosymbiont suspected to be nonpathogenic, was found in 54.5% of the 1119 A. americanum tested. Despite low infection rates of Ehrlichia spp. in A. americanum, high encounter rates with this species in recreational deciduous woodlands suggest a moderate risk of tick bite and a low-to-moderate risk of TBP exposure in late spring.

Ghostbusting—Reducing bias due to identification errors in spatial capture‐recapture histories

Abstract Identifying individuals is key to estimating population sizes by spatial capture–recapture, but identification errors are sometimes made. The most common identification error is the failure to recognise a previously detected individual, thus creating a ‘ghost’ Johansson. This results in positively biased abundance estimates. Ghosts typically manifest as single detection individuals (‘singletons’) in the capture history. To deal with ghosts, we develop a spatial capture–recapture method conditioned on at least detections. The standard spatial capture–recapture (SCR) model is the special case of . Ghosts can mostly be excluded by fitting a model with (SCR‐2). We investigated the effect of ‘singleton’ ghosts on the estimation of the model parameters by simulation. The SCR method increasingly overestimated abundance with increasing percentage of ghosts, with positive bias even when only 10% of the detected individuals were ghosts, and bias between 43% and 71% when 30% were ghosts. Estimates from the SCR‐2 method showed lower bias in the presence of ghosts, at the cost of a loss of precision. The mean squared error of the estimated abundance from the SCR‐2 method was lower in all scenarios with ghosts under high encounter rates and for scenarios with 30% or more ghosts with low encounter rates. We also applied our method to capture histories from camera trap surveys of snow leopards (Panthera uncia) at two sites from Mongolia and find that the SCR method produced higher abundance estimates at both sites. Capture histories are susceptible to errors when generated from passive detectors such as camera traps and genetic samples. The SCR‐2 method can remove bias from ghost capture histories, at the cost of some loss in precision. We recommend using the SCR‐2 method in cases when there may be more than 10% ghosts or surveys with a large number of single detection capture histories, except perhaps when the sample size is very low.

Relatedness-based mate choice and female philopatry: inbreeding trends of wolf packs in a human-dominated landscape

Inbreeding can reduce offspring fitness and has substantial implications for the genetic diversity and long-term viability of populations. In social cooperative canids, inbreeding is conditioned by the geographic proximity between opposite-sex kin outside natal groups and the presence of related individuals in neighbouring groups. Consequently, challenges in moving into other regions where the species is present can also affect inbreeding rates. These can be particularly problematic in areas of high human density, where movement can be restricted, even for highly vagile species. In this study, we investigate the socio-ecological dynamics of Iberian wolf packs in the human-dominated landscape of Alto Minho, in northwest Portugal, where wolves exhibit a high prevalence of short-distance dispersal and limited gene flow with neighbouring regions. We hypothesise that mating occurs regardless of relatedness, resulting in recurrent inbreeding due to high kin encounter rates. Using data from a 10-year non-invasive genetic monitoring programme and a combination of relatedness estimates and genealogical reconstructions, we describe genetic diversity, mate choice, and dispersal strategies among Alto Minho packs. In contrast with expectations, our findings reveal relatedness-based mate choice, low kin encounter rates, and a reduced number of inbreeding events. We observed a high prevalence of philopatry, particularly among female breeders, with the most common breeding strategy involving the pairing of a philopatric female with an unrelated immigrant male. Overall, wolves were not inbred, and temporal changes in genetic diversity were not significant. Our findings are discussed, considering the demographic trend of wolves in Alto Minho and its human-dominated landscape.

Correlates and impacts of human-mammal conflict in the central part of Chitwan Annapurna Landscape, Nepal

Crop damage, predation on domestic animals and human attacks are often associated with human-wildlife conflict. The abundance and encounter rate of wild mammals are often associated with human wildlife conflict. Crop damage, livestock depredation and human injury and their relation with environmental factors and encounter rate of the mammals was evaluated in the central region of Chitwan Annapurna Landscape. The abundance and the encounter rate of large mammals were determined by dividing the study area into four different study blocks (A, B, C and D) based on river course and topography. A total of 150 transects (average length = 3.18 ± 0.11 km), were administrated for data collection. Similarly, information on human-wildlife conflict was collected using 600 semi-structured questionnaires (150 from each block). The chital was the most abundant mammal (encounter rate (ER) = 1.49 and relative abundance (RA) = 55.45%) in block A whereas muntjac had the highest encounter rate in blocks B, C and D (ER = 0.34, 0.31, 0.79 respectively) but the relative abundance of rhesus was comparatively higher in blocks B, C and D. The signs of tiger were reported from block A only whereas signs of leopard were reported from all blocks. But signs of Himalayan black bear were reported from B, C and D. The encounter rate of the mammals correlated with the monetary loss caused by them. Greater one-horned rhino, wild pig and chital in lowland and monkeys, northern red muntjac, and Himalayan black bear in mid-hills (blocks B, C and D) were the principal crop raiders with a total average annual loss of US$ 11.45 per household. Similarly, the total annual monetary loss by livestock depredation was US$ 76.60 per household. This study evaluated the encounter rate of mammals and their effects on the conflict with people. However, the negative effects arrived from human-wildlife conflicts always threaten large mammals. Hence, this study suggests future intensive studies related to mitigation and prevention methods to mitigate the issues of human-wildlife conflicts.

Quantifying the threat of wire snares using camera trapping data in India

Wire snaring is a prevalent method of hunting in tropical Asia driven by various factors, including occupational, subsistence, to meet demand for bushmeat and wildlife by-products at regional and international markets. While snaring is a common hunting practice in India, research on its local impacts is scant. This study aims to examine the impacts of snaring on wildlife using camera traps, deployed from 2013 to 2023 across different conservation management regimes in Karnataka, southern India. Seventeen independent snaring events of five different species were documented during the study. The mean encounter rate was 0.0386 (SD = ±0.001) and the highest encounter rate was recorded in non-protected areas. In addition, we recorded 34 snaring events during our forays on foot while collecting data on camera trapping where the highest snaring events were also recorded in non-protected areas (76.5 %). The study highlights the indiscriminate nature of snaring practices and outlines recommendations to curb its impacts on wildlife populations in India, especially in non-protected areas. The study results could help advocate for collective action against snaring practices, in protected and non-protected areas. This study also highlights that camera trapping has a limited ability to document snaring as a threat as forays on foot resulted in detecting much higher snaring events during the same study period.

Decadal increase in vessel interactions by a scavenging pelagic seabird across the North Atlantic

Fisheries waste is used by many seabirds as a supplementary source of food,1 but interacting with fishing vessels to obtain this resource puts birds at risk of entanglement in fishing gear and mortality.2 As a result, bycatch is one of the leading contributors to seabird decline worldwide,3 and this risk may increase over time as birds increasingly associate fishing vessels with food. Light-level geolocators mounted on seabirds can detect light emitted from vessels at night year-round.4 We used a 16-year time series of geolocator data from 296 northern fulmars (Fulmarus glacialis) breeding at temperate and arctic colonies to investigate trends of nocturnal vessel interactions in this scavenging pelagic seabird. Vessel attendance has progressively increased over the study period despite no corresponding increase in the number of vessels or availability of discards over the same time frame. Fulmars are highly mobile generalist surface feeders,5 so this may signal a reduction in available prey biomass in the upper water column, leading to increased reliance on anthropogenic food subsidies6 and increased risk of bycatch mortality in already threatened seabird populations. Individuals were consistent in the extent to which they interacted with vessels, as shown in other species,7 suggesting that population-level increases may be due to a higher proportion of fulmars following vessels rather than changes at an individual level. Higher encounter rates were correlated with lower time spent foraging and a geographically restricted overwintering distribution, suggesting an energetic advantage for these scavenging strategists compared with foraging for natural prey.

Sperm and northern bottlenose whale interactions with deep-water trawlers in the western North Atlantic.

Commercial fisheries have increased in all the world's oceans with diverse unintended impacts on marine ecosystems. As a result of resource overlap, interactions between cetaceans and fisheries are a common occurrence and, in many cases, can give rise to significant conservation issues. Research on the distribution and types of such interactions is important for efficient management. In this study, we describe the behaviors of two whale species: sperm whales (Physeter macrocephalus) and northern bottlenose whales (Hyperoodon ampullatus), interacting with benthic trawlers fishing off the eastern Grand Banks of the western North Atlantic in 2007. Whale interactions were only observed when vessels were targeting Greenland halibut (Reinhardtius hippoglossoides) in deep-water fishing areas and were most common during net hauling. Sperm whales and northern bottlenose whales appeared to engage in feeding behavior close to the surface during hauling, especially during the latter stages, suggesting they targeted fish escapees rather than discards. Using photo-identification methods, seven individual sperm whales were identified with multiple resights of six individuals being recorded over an almost two month period. The maximum distance between two resights was 234 km, suggesting individual sperm whales were repeatedly targeting and even following fishing vessels over multiple days and between fishing areas. By contrast, there were no photographic resights of individual northern bottlenose whales within this study, or with substantial photo-identification catalogues from other adjacent high density areas, suggesting that individuals of this species may be less likely to follow vessels or move between areas. This study documents the earliest confirmed records of northern bottlenose whales in this remote region. These interactions and high encounter rates may indicate that adjacent populations are recovering from the previous century of commercial whaling. Our study provides new insights and details on whale-fisheries interactions, which can inform future research and help managers understand the real and perceived impacts of depredation behaviour on fisheries and whales.

Optimal density of bacterial cells.

A substantial fraction of the bacterial cytosol is occupied by catalysts and their substrates. While a higher volume density of catalysts and substrates might boost biochemical fluxes, the resulting molecular crowding can slow down diffusion, perturb the reactions' Gibbs free energies, and reduce the catalytic efficiency of proteins. Due to these tradeoffs, dry mass density likely possesses an optimum that facilitates maximal cellular growth and that is interdependent on the cytosolic molecule size distribution. Here, we analyze the balanced growth of a model cell, accounting systematically for crowding effects on reaction kinetics. Its optimal cytosolic volume occupancy depends on the nutrient-dependent resource allocation into large ribosomal vs. small metabolic macromolecules, reflecting a tradeoff between the saturation of metabolic enzymes, favoring larger occupancies with higher encounter rates, and the inhibition of the ribosomes, favoring lower occupancies with unhindered diffusion of tRNAs. Our predictions across growth rates are quantitatively consistent with the experimentally observed reduction in volume occupancy on rich media compared to minimal media in E. coli. Strong deviations from optimal cytosolic occupancy only lead to minute reductions in growth rate, which are nevertheless evolutionarily relevant due to large bacterial population sizes. In sum, cytosolic density variation in bacterial cells appears to be consistent with an optimality principle of cellular efficiency.

Fin whales (Balaenoptera physalus) summering in the Ligurian Sea: distribution, encounter rate, mean group size and relation to physiographic variables

This paper investigates the distribution of Mediterranean fin whales (Balaenoptera physalus) between 1990-99 in the recently-established Pelagos Sanctuary for the Conservation of Mediterranean Marine Mammals. During the study period, 870 days were spent at sea, surveying a total of 73,046km, totalling 540 sightings of fin whales. Mean yearly whale encounter rates showed no significant differences in the first five years, but then steadily decreased between 1995-99. The highest encounter rates and largest mean aggregation size (mean=2.12; SD=1.32; SE=1.15) were in summer 1995 and the mean aggregation size throughout the study period was 1.75 (mode=1; SD=1.11; SE=0.05). Differences in mean aggregation size were significant between years, but not months. This is likely to be related to prey availability and to patchiness of plankton distribution. Generalised Linear Models were used to relate fin whale distribution to physiographic variables (mean, range and standard deviation of depth and slope, and distance from the nearest coast). Water depth was the most significant variable in describing fin whale distribution, with more than 90% of sightings occurring in waters deeper than 2,000m. This study demonstrates the deep water preference of fin whales in this area, emphasises the crucial role that this part of the western Ligurian Sea plays in the ecology of Mediterranean fin whales and provides recommendations for conservation and management measures in the area.

Distribution and encounter rates of the river dolphin (Inia geoffrensis boliviensis) in the central Bolivian Amazon

The ecology and conservation status of river dolphins (Inia sp.) distributed in the lowland rivers of Bolivia are poorly understood and only recently have basic studies been conducted to investigate their population size, taxonomic status, distribution, behaviour, environmental threats and ecology in this region. This paper examines the distribution and encounter rates of the bufeo (Inia sp.) in the middle reach of the Bolivian Amazon and was conducted in the Mamoré River and four of its tributaries during the low water season. Methods were employed which can be replicated during future surveys of Bolivian river dolphins and the results can be compared with those from surveys of Inia throughout its range. Sixty-two hours were spent surveying for dolphins, with 68% of the effort in Mamoré River and 32% in its tributaries. The Inia encounter rates reported here (1.6-5.8 dolphins km21) are the highest recorded anywhere in its broad geographic range; and indicate the importance of continuing and expanding surveys in this area. The mean group size was greatest in the Tijamuchi River (3.3±2.96) and smallest in the Yacuma River (1.8±0.75) and the maximum group size was 14. The high bufeo encounter rates in the central Bolivian Amazon can be taken as a reflection of the general environmental status of the region; however, a growing human population, associated with an increase in boat traffic and fishing activity, poses a future threat to bufeos and their aquatic habitats.

Cascading effects of social dynamics on the reproduction, survival, and population growth of mountain gorillas

AbstractWhilst the conservation impacts of density‐dependent population effects have been well studied, the impact that socially‐driven changes (e.g. group fissions that increase group density) can have on population growth in social species have only recently come to light. An increase in group density and intergroup encounters in a subpopulation of mountain gorillas Gorilla beringei beringei was shown to have driven a more than fourfold increase in infanticide, slowing population growth. In this study, we delve deeper into the consequences of these socially‐driven changes in group density, examining how patterns of reproduction and survival have changed in this subpopulation across more than 50 years. We show that adult female survival increased with strengthening conservation efforts early in the study, then remained stable, while age at first birth remained stable across the entire study. Interbirth intervals and female reproductive success did not vary significantly across time overall. However, socially‐driven increases in group density since the mid‐2000s appear to have had a cascade of effects. In addition to the increase in infant and adult male mortality from violence during intergroup encounters, higher encounter rates, and mortality were likely responsible for an increase in female transfers, which delayed reproduction. Females faced a 7.5‐month delay when transferring once and a 1.5‐year delay when transferring twice or more between births. We show these changes correspond with a 26.63% reduction in female reproductive success in 2007 to 2018, compared to 1994 to 2006, with females taking more than 2 years longer to produce an offspring that survived infancy. These findings demonstrate that social dynamics can have consequences for population growth beyond the immediate mortality effects of violent encounters. This further highlights the critical importance of social dynamics in the conservation of social species, particularly when populations are restricted to small or fragmented regions of habitat.

Altitudinal partitioning of syrphid flies (Diptera) increases along elevation gradients in pollinator communities in the Eastern Himalayas, India

ABSTRACT The diversity and altitudinal distribution patterns of syrphid flies in the Neora Valley National Park, in the Eastern Himalaya was studied, including the ramifications of pollination by drone fly (Eristalis tenax) showing Batesian mimicry of honeybees. Considering the altitudinal variation and visitation rate, the study found a total of 30 Syrphidae species, among which Eristalis himalayensis, E. tenax, Chrysogaster sp., Episyrphus balteatus, Paragus haemorrhous and Syrphus dalhousiae had the highest encounter rate. The maximum number of species was observed at ≥ 2500 m asl. The diversity of Syrphidae in the Neora Valley reflects the supremacy of these flies over other pollinator insects in the study area. The mean visit per hour of drone fly (E. tenax) was 21 ± 2.73SE (SE – standard error) individual at the lower altitudes but the rate was higher (37.1 ± 4.09SE) in the absence of honeybees at the higher altitudes. More information about the primary determinants of the dynamic nature of pollination is required in this area in order to understand plant–pollinator responses to global warming.

Wolf risk fails to inspire fear in two mesocarnivores suggesting facilitation prevails

Large carnivores not only supress mesocarnivores via killing and instilling fear, but also facilitate them through carrion provisioning. Hence, mesocarnivores frequently face a trade-off between risk avoidance and food acquisition. Here we used the raccoon dog and red fox in Białowieża Forest, Poland as models for investigating how large carnivores shape mesocarnivore foraging behaviour in an area with widespread large carnivore carrion provisioning. Using a giving up density experiment we quantified mesocarnivore foraging responses to wolf body odour across a landscape-scale gradient in wolf encounter rates. At locations with higher wolf encounter rates, raccoon dogs depleted feeding trays more than at plots with lower wolf encounter rates. Simulating wolf presence by adding wolf body odour caused raccoon dogs to deplete feeding trays more at locations with low wolf encounter rates, but less at locations with high wolf encounter rates. Fox foraging costs did not vary with the application of wolf body odour or wolf encounter rates. The frequency that the mesocarnivores visited experimental foraging patches was unaffected by wolf body odour or landscape level encounter rates. These results provide further evidence that large carnivore suppression can play a subordinate role to facilitation in determining mesocarnivore behaviour. The varying raccoon dog response to wolf odour across the landscape-scale gradient in wolf encounter rates shows how mesocarnivore-large carnivore interactions can be context-dependent. We suggest that rather than testing the effects of single risk cues on prey behaviour, future studies should focus on understanding how context modifies the ecological impacts of large carnivores.

Species' movement influence responses to habitat fragmentation

AbstractAimHuman conversion of land leads to habitat loss and fragmentation. The effects of habitat loss are well‐established, but the effects of fragmentation beyond those of habitat loss, “fragmentation per se” (FPS), are intensely debated. One area of debate is how different species might respond to FPS. We will answer whether FPS have more negative effects on species that spend more time in the matrix and less on species with higher potential patch encounter rates.LocationVirtual landscapes.MethodsWe simulated the effects of FPS on multiple species with different movement characteristics. All species moved with a random walk (RW), a correlated RW (CRW), or a habitat‐dependent walk (HDW). Species also had increasing habitat bias which caused individuals to have a higher probability of moving into a more suitable habitat. The walk type modified the rate at which species encountered habitat patches. Increased bias caused individuals to spend more time in suitable habitats and less time in the matrix between patches. All species experienced higher mortality in less suitable habitats. We analysed FPS effects on species for whom the fragmented focal habitat was the most suitable.ResultsWith bias, the species diversity of RW species declined with FPS, while FPS had little effect on the species diversity of species moving by CRW. For HDW species, spending less time in the matrix (moderate movement bias) caused species diversity to increase with FPS, but to decline with high bias.Main conclusionsThese results suggest that even for species that are dependent on fragmented habitat, FPS does not have a unidirectional effect. FPS can have a positive effect on species with high patch encounter rates (HDW with moderate bias) as their functional connectivity increases. These results help to explain why different studies show contradictory effects of FPS on biodiversity.

Gamma-Ray Spectral Properties of the Galactic Globular Clusters: Constraint on the Number of Millisecond Pulsars

Abstract We study the γ-ray spectra of 30 globular clusters (GCs) thus far detected with the Fermi Gamma-ray Space Telescope. Presuming that γ-ray emission of a GC comes from millisecond pulsars (MSPs) contained within the GC, a model that generates spectra for the GCs is built based on the γ-ray properties of the detected MSP sample. We fit the GCs’ spectra with the model, and for 27 of them, their emission can be explained as arising from MSPs. The spectra of the other three, NGC 7078, 2MS-GC01, and Terzan 1, cannot be fit with our model, indicating that MSPs’ emission should not be the dominant one in the first two and the third one has a unique hard spectrum. We also investigate six nearby GCs that have relatively high encounter rates compared to the comparison cases. The candidate spectrum of NGC 6656 can be fit with that of one MSP, supporting its possible association with the γ-ray source at its position. The five others do not have detectable γ-ray emission. Their spectral upper limits set limits of ≤1 MSPs in them, consistent with the numbers of radio MSPs found in them. The estimated numbers of MSPs in the γ-ray GCs generally match well those reported for radio pulsars. Our studies of the γ-ray GCs and the comparison nearby GCs indicate that the encounter rate should not be the only factor determining the number of γ-ray MSPs a GC contains.

Predicting spatial and seasonal patterns of wildlife–vehicle collisions in high-risk areas

Context Vehicle collisions with wildlife can injure or kill animals, threaten human safety, and threaten the viability of rare species. This has led to a focus in road-ecology research on identifying the key predictors of ‘road-kill’ risk, with the goal of guiding management to mitigate its impact. However, because of the complex and context-dependent nature of the causes of risk exposure, modelling road-kill data in ways that yield consistent recommendations has proven challenging. Aim Here we used a multi-model machine-learning approach to identify the spatio-temporal predictors, such as traffic volume, road shape, surrounding vegetation and distance to human settlements, associated with road-kill risk. Methods We collected data on the location, identity and wildlife body size of each road mortality across four seasons along eight roads in southern Tasmania, a ‘road-kill hotspot’ of management concern. We focused on three large-bodied and frequently affected crepuscular Australian marsupial herbivore species, the rufous-bellied pademelon (Thylogale billardierii), Bennett’s wallaby (Macropus rufogriseus) and the bare-nosed wombat (Vombatus ursinus). We fit the point-location data using ‘lasso-regularisation’ of a logistic generalised linear model (LL-GLM) and out-of-bag optimisation of a decision-tree-based ‘random forests’ (RF) algorithm for optimised predictions. Results The RF model, with high-level feature interactions, yielded superior out-of-sample prediction results to the linear additive model, with a RF classification accuracy of 84.8% for the 871 road-kill observations and a true skill statistic of 0.708, compared with 61.2% and 0.205 for the LL-GLM. The lasso rejected road visibility and human density, ranking roadside vegetation type and presence of barrier fencing as the most influential predictors of road-kill locality. Conclusions Forested areas with no roadside barrier fence along curved sections of road posed the highest risk to animals. Seasonally, the frequency of wildlife–vehicle collisions increased notably for females during oestrus, when they were more dispersive and so had a higher encounter rate with roads. Implications These findings illustrate the value of using a combination of attributive and predictive modelling using machine learning to rank and interpret a complexity of possible predictors of road-kill risk, as well as offering a guide to practical management interventions that can mitigate road-related hazards.

Factors Associated with Telemedicine Use for Chronic Disease Specialty Care in the Alaska Tribal Health System, 2015-2019.

Background:There are disparities in access to specialty care for chronic diseases in rural and minority populations. Telemedicine has been proposed to improve access.Introduction:The objective of this study was to identify predictors of telemedicine use for chronic disease specialty care in the Alaska Tribal Health System (ATHS) in the setting of usual care.Materials and Methods:We utilized data from the electronic health record (EHR) of patients from four regions in the ATHS. We queried the EHR to identify cases (ever users of telemedicine) and controls (never users), both of whom had chronic diseases requiring specialty care. Data were collected from 2015 through mid-2019.Results:We included 3,075 patients (799 ever users and 2,276 never users). In univariate analysis, ever users were older, more likely to be male, had more chronic conditions and higher encounter rates. There were differences by region, community, and type of specialty clinic. In our simple multivariate model, factors associated with telemedicine use included age, male gender, region, and outpatient visit rate per year. Having at least one cardiology clinic visit was also associated with telemedicine use, with the highest estimated odds ratio (5.27, p < 0.01).Discussion:This study describes factors associated with telemedicine use in the ATHS before the COVID-19 pandemic. We anticipate monitoring changes in these predictors over time, as we expect them to evolve.Conclusions:We found among factors associated with telemedicine use were age, gender, region, outpatient visit rate, and visits to a specific specialty clinic.