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At least 91 records · Page 5Linked to original sources
USGS2023

Sex-biased infections scale to population impacts for an emerging wildlife disease

Demographic factors are fundamental in shaping infectious disease dynamics. Aspects of populations that create structure, like age and sex, can affect patterns of transmission, infection intensity and population outcomes. However, studies rarely link these processes from individual to population-scale effects. Moreover, the mechanisms underlying demographic differences in disease are frequently unclear. Here, we explore sex-biased infections for a multi-host fungal disease of bats, white-nose syndrome, and link disease-associated mortality between sexes, the distortion of sex ratios and the potential mechanisms underlying sex differences in infection. We collected data on host traits, infection intensity and survival of five bat species at 42 sites across seven years. We found females were more infected than males for all five species. Females also had lower apparent survival over winter and accounted for a smaller proportion of populations over time. Notably, female-biased infections were evident by early hibernation and likely driven by sex-based differences in autumn mating behaviour. Male bats were more active during autumn which likely reduced replication of the cool-growing fungus. Higher disease impacts in female bats may have cascading effects on bat populations beyond the hibernation season by limiting recruitment and increasing the risk of Allee effects.

Proceedings of the Royal Society B: Biological Sci↗
USGS2023

Incorporating environmental heterogeneity and observation effort to predict host distribution and viral spillover from a bat reservoir

Predicting the spatial occurrence of wildlife is a major challenge for ecology and management. In Latin America, limited knowledge of the number and locations of vampire bat roosts precludes informed allocation of measures intended to prevent rabies spillover to humans and livestock. We inferred the spatial distribution of vampire bat roosts while accounting for observation effort and environmental effects by fitting a log Gaussian Cox process model to the locations of 563 roosts in three regions of Peru. Our model explained 45% of the variance in the observed roost distribution and identified environmental drivers of roost establishment. When correcting for uneven observation effort, our model estimated a total of 2340 roosts, indicating that undetected roosts (76%) exceed known roosts (24%) by threefold. Predicted hotspots of undetected roosts in rabies-free areas revealed high-risk areas for future viral incursions. Using the predicted roost distribution to inform a spatial model of rabies spillover to livestock identified areas with disproportionate underreporting and indicated a higher rabies burden than previously recognized. We provide a transferrable approach to infer the distribution of a mostly unobserved bat reservoir that can inform strategies to prevent the re-emergence of an important zoonosis.

Proceedings of the Royal Society B: Biological Sci↗
USGS2024

Season of death, pathogen persistence and wildlife behaviour alter number of anthrax secondary infections from environmental reservoirs

An important part of infectious disease management is predicting factors that influence disease outbreaks, such as R , the number of secondary infections arising from an infected individual. Estimating R is particularly challenging for environmentally transmitted pathogens given time lags between cases and subsequent infections. Here, we calculated R for Bacillus anthracis infections arising from anthrax carcass sites in Etosha National Park, Namibia. Combining host behavioural data, pathogen concentrations and simulation models, we show that R is spatially and temporally variable, driven by spore concentrations at death, host visitation rates and early preference for foraging at infectious sites. While spores were detected up to a decade after death, most secondary infections occurred within 2 years. Transmission simulations under scenarios combining site infectiousness and host exposure risk under different environmental conditions led to dramatically different outbreak dynamics, from pathogen extinction ( R < 1) to explosive outbreaks ( R > 10). These transmission heterogeneities may explain variation in anthrax outbreak dynamics observed globally, and more generally, the critical importance of environmental variation underlying host–pathogen interactions. Notably, our approach allowed us to estimate the lethal dose of a highly virulent pathogen non-invasively from observational studies and epidemiological data, useful when experiments on wildlife are undesirable or impractical.

Etosha National Park↗
USGS2024

Infection–nutrition feedbacks: Fat supports pathogen clearance but pathogens reduce fat in a wild mammal

Though far less obvious than direct effects (clinical disease or mortality), the indirect influences of pathogens are difficult to estimate but may hold fitness consequences. Here, we disentangle the directional relationships between infection and energetic reserves, evaluating the hypotheses that energetic reserves influence infection status of the host and that infection elicits costs to energetic reserves. Using repeated measures of fat reserves and infection status in individual bighorn sheep ( Ovis canadensis ) in the Greater Yellowstone Ecosystem, we documented that fat influenced ability to clear pathogens ( Mycoplasma ovipneumoniae ) and infection with respiratory pathogens was costly to fat reserves. Costs of infection approached, and in some instances exceeded, costs of rearing offspring to independence in terms of reductions to fat reserves. Fat influenced probability of clearing pathogens, pregnancy and over-winter survival; from an energetic perspective, an animal could survive for up to 23 days on the amount of fat that was lost to high levels of infection. Cost of pathogens may amplify trade-offs between reproduction and survival. In the absence of an active outbreak, the influence of resident pathogens often is overlooked. Nevertheless, the energetic burden of pathogens likely has consequences for fitness and population dynamics, especially when food resources are insufficient.

Wyoming↗
USGS2025

How will we prepare for an uncertain future? The value of open data and code for unborn generations facing climate change

As the impacts of climate change continue to intensify, humans face new challenges to long-term survival. Humans will likely be battling these problems long after 2100, when many climate projections currently end. A more forward-thinking view on our science and its direction may help better prepare for the future of our species. Researchers may consider datasets the basic units of knowledge, whose preservation is arguably more important than the articles that are written about them. Storing data and code in long-term repositories offers insurance against our uncertain future. To ensure open data are useful, data must be FAIR (Findable, Accessible, Interoperable, and Reusable) and be complete with all appropriate metadata. By embracing open science practices, contemporary scientists give the future of humanity the information to make better decisions, save time and other valuable resources, and increase global equity as access to information is made free. This, in turn, will enable and inspire a diversity of solutions, to the benefit of many. Imagine the collective science conducted, the models built, and the questions answered if all of the data researchers have collectively gathered were organized and immediately accessible and usable by everyone. Investing in open science today may ensure a brighter future for unborn generations.

Proceedings of the Royal Society, B↗
USGS2024

Greater plasticity in CTmax with increased climate variability among populations of tailed frogs

Temporally variable climates are expected to drive the evolution of thermal physiological traits that enable performance across a wider range of temperatures (i.e. climate variability hypothesis, CVH). Spatial thermal variability, however, may mediate this relationship by providing ectotherms with the opportunity to behaviourally select preferred temperatures (i.e. the Bogert effect). These antagonistic forces on thermal physiological traits may explain the mixed support for the CVH within species despite strong support among species at larger geographical scales. Here, we test the CVH as it relates to plasticity in physiological upper thermal limits (critical thermal maximum—CTmax) among populations of coastal tailed frogs ( Ascaphus truei ). We targeted populations that inhabit spatially homogeneous environments, reducing the potentially confounding effects of behavioural thermoregulation. We found that populations experiencing greater temporal thermal variability exhibited greater plasticity in CTmax, supporting the CVH. Interestingly, we identified only one site with spatial temperature variability and tadpoles from this site demonstrated greater plasticity than expected, suggesting the opportunity for behavioural thermoregulation can reduce support for the CVH. Overall, our results demonstrate one role of climate variability in shaping thermal plasticity among populations and provide a baseline understanding of the impact of the CVH in spatially homogeneous thermal landscapes.

Proceedings of the Royal Society B↗
USGS2025

Forecasting sea otter recolonization: Insights from isotopic analysis of modern and zooarchaeological populations

Retrospective datasets offer essential context for conservation by revealing species’ ecological roles before industrial-era human impacts. We analysed isotopic compositions of pre-industrial and modern sea otters ( Enhydra lutris ) to reconstruct pre-extirpation ecology and offer insights for management. Our study focuses on southeast Alaska (SEAK), where sea otters are recolonizing, and northern Oregon, where translocations are being considered. We measured bulk bone collagen δ 13 C and δ 15 N values and essential amino acid δ 13 C values of extirpated sea otters from archaeological contexts, and bulk isotopic values from vibrissae of modern SEAK sea otters. We compare these results with published isotopic data of potential prey and additional archaeological datasets. In SEAK, our data show pre-industrial sea otter populations consumed infaunal bivalves and used soft-sediment (33%) and kelp forest habitats (67%), with sub-regional variation. We anticipate current populations will expand into this historical niche, and conflict with regional traditional/subsistence bivalve fisheries will persist. In northern Oregon, isotopic data from extirpated sea otters indicate past consumption of low trophic level invertebrates and a stronger reliance on kelp forests (88%) rather than soft-sediment habitats, highlighting the importance of kelp forests for future translocations. Our work exemplifies the value of historical ecology in informing conservation strategies for recovering species.

Alaska, Oregon↗
USGS2024

The potential of remote sensing for improved infectious disease ecology research and practice

Outbreaks of Covid-19 in humans, Dutch elm disease in forests, and highly pathogenic avian influenza in wild birds and poultry highlight the disruptive impacts of emerging infectious diseases on public health, ecosystems, and economies. Infectious disease dynamics often depend on environmental conditions that drive occurrence, transmission, and outbreaks. Remote sensing can contribute to infectious disease research and management by providing standardized environmental data across broad spatial and temporal extents, often at no cost to the user. Here, we 1) conduct a systematic review of primary literature to quantify current uses of remote sensing in disease ecology and 2) synthesize qualitative information to identify opportunities for further integration of remote sensing into disease ecology. We identify that modern advances in airborne remote sensing are promoting early detection of forest pathogens and that satellite data is contributing to the study of geographically widespread human diseases. We discuss opportunities for increased use of data products that characterize vegetation, surface water, and soil; provide data at high spatio-temporal and spectral resolutions; and quantify uncertainty in measurements. Additionally, combining remote sensing with animal movement telemetry can provide novel insights into wildlife disease. Integrating these opportunities will advance research and management of infectious diseases.

Proceedings of the Royal Society B: Biological Sci↗
USGS2024

A systematic review of laboratory investigations into the pathogenesis of avian influenza viruses in wild avifauna of North America

The lack of consolidated information regarding the response of wild bird species to infection with avian influenza virus (AIV) is a challenge to both conservation managers and researchers alike, with related sectors also impacted, such as public health and commercial poultry. Using two independent searches, we reviewed published literature for studies describing wild bird species experimentally infected with avian influenza to assess host species’ relative susceptibility to AIVs. Additionally, we summarize broad-scale parameters for elements such as shedding duration and minimum infectious dose that can be used in transmission modelling efforts. Our synthesis shows that waterfowl (i.e. Anatidae) compose the vast majority of published AIV pathobiology studies, whereas gulls and passerines are less represented in research despite evidence that they also are susceptible and contribute to highly pathogenic avian influenza disease dynamics. This study represents the first comprehensive effort to compile available literature regarding the pathobiology of AIVs in all wild birds in over a decade. This database can now serve as a tool to all researchers, providing generalized estimates of pathobiology parameters for a variety of wild avian families and an opportunity to critically examine and assess what is known and identify where further insight is needed.

Proceeding of the Royal Society B↗
USGS2025

The importance of peripheral populations in the face of novel environmental change

Anthropogenically driven environmental change has imposed substantial threats on biodiversity, including the emergence of infectious diseases that have resulted in declines of wildlife globally. In response to pathogen invasion, maintaining diversity within host populations across heterogenous environments is essential to facilitating species persistence. White-nose syndrome is an emerging fungal pathogen that has caused mass mortalities of hibernating bats across North America. However, in the northeast, peripheral island populations of the endangered northern myotis ( Myotis septentrionalis ) appear to be persisting despite infection while mainland populations in the core of the species range have experienced sharp declines. Thus, this study investigated host and environmental factors that may contribute to divergent population responses. We compared patterns of pathogen exposure and infection intensity between populations and documented the environmental conditions and host activity patterns that may promote survival despite disease invasion. For island populations, we found lower prevalence and less severe infections, possibly due to a shorter hibernation duration compared to the mainland, which may reduce the time for disease progression. The coastal region of the northern myotis range may serve as habitat refugia that enables this species to persist despite pathogen exposure; however, conservation efforts could be critical to supporting species survival in the long term.

Proceedings of the Royal Society B, Biological Sci↗
USGS2025

Systematic shifts in the variation among host individuals must be considered in climate-disease theory

To make more informed predictions of host–pathogen interactions under climate change, studies have incorporated the thermal performance of host, vector and pathogen traits into disease models to quantify effects on average transmission rates. However, this body of work has omitted the fact that variation in susceptibility among individual hosts affects disease spread and long-term patterns of host population dynamics. Furthermore, and especially for ectothermic host species, variation in susceptibility is likely to be plastic, influenced by variables such as environmental temperature. For example, as host individuals respond idiosyncratically to temperature, this could affect the population-level variation in susceptibility, such that there may be predictable functional relationships between variation in susceptibility and temperature. Quantifying the relationship between temperature and among-host trait variation will therefore be critical for predicting how climate change and disease will interact to influence host–pathogen population dynamics. Here, we use a model to demonstrate how short-term effects of temperature on the distribution of host susceptibility can drive epidemic characteristics, fluctuations in host population sizes and probabilities of host extinction. Our results emphasize that more research is needed in disease ecology and climate biology to understand the mechanisms that shape individual trait variation, not just trait averages.

Proceedings of the Royal Society B: Biological Sci↗
USGS2025

The influence of human presence and footprint on animal space use in US national parks

Given the importance of protected areas for biodiversity, the growth of visitation to many areas has raised concerns about the effects of humans on wildlife. In 2020, the COVID-19 pandemic led to temporary closure of national parks in the United States, offering a pseudonatural experiment to tease apart the effects of permanent infrastructure and transient human presence on animals. We compiled GPS tracking data from 229 individuals of 10 mammal species in 14 parks and used third-order hierarchical resource selection functions to evaluate the influence of the human footprint on animal space use in 2019 and 2020. Averaged across all parks and species, animals avoided the human footprint, whether the park was open or closed. However, although animals in remote areas showed consistent avoidance, on average those in more developed areas switched from avoidance to selection when protected areas were closed. Findings varied across species: some responded consistently negatively to the footprint (wolves, mountain goats), some positively (mule deer, red fox) and others had a strong exposure-mediated response (elk, mountain lion). Furthermore, some species responded more strongly to the park closure (black bear, moose). This study advances our understanding of complex interactions between recreation and wildlife in protected areas.

western United States↗
USGS2025

Spring weather influences breeding propensity, the most important productivity component for Arctic-nesting lesser snow geese

Animal reproduction is composed of several stages, which collectively determine overall productivity. Yet, it is not fully understood how different productivity components contribute to population change. To bridge this gap, we leveraged integrated population modelling and transient life-table response experiments, together with population-level data on lesser snow geese ( Anser caerulescens caerulescens ) breeding on Wrangel Island, Russia, from 1970 to 2022. We assessed contributions of breeding propensity, clutch size, nest success, egg survival, hatching success and pre-fledging survival to population change, and tested hypotheses about the effects of environmental drivers and density dependence on different components. Breeding propensity contributed the most to variation in population growth, followed by nest success. These two components were negatively affected by the timing of snow melt. We found no overall deleterious effects of climate change on productivity. Density dependence had a positive effect on multiple productivity components, likely through predator swamping. Our results show the importance of breeding propensity to the population dynamics of this long-lived animal, which is notable because this productivity component is often overlooked. Our results also demonstrate that the effects of environmental conditions and density dependence can differ among animal populations of different sizes, locations and life histories.

Wrangel Island↗
USGS2025

Longer rorqual whale mothers produce more female offspring

Multiple hypotheses have arisen that predict how mammals with the ability to adapt fetal sex ratios should invest in male versus female offspring to maximize inclusive fitness, but large wild-population datasets necessary for testing these hypotheses are challenging to collect. We used whaling data ( n = 209 254 sexed fetuses from seven rorqual whale species) to test whether mothers with more resources to invest in offspring produce more male or female offspring. We first modelled fetal sex misidentification in the data and estimated that missexing occurred for fetuses under 30–120 cm across five of seven species. Using Bayesian generalized linear mixed models and a size-restricted dataset to account for misidentification, we estimated a 90% posterior probability that longer mothers have more female offspring overall, ranging from 77% for humpback whales to 99% for sei whales. Our results likely reflect both the difficulty of excluding small males from competition in aquatic environments and the exceptionally high costs of gestation and lactation in baleen whales.

Proceedings of the Royal Society B↗
USGS2026

Timing the tuxedo transformation: Moult phenology reflects breeding investment and intrinsic constraints in Adélie penguins

Vertebrate life histories are often divided into distinct periods, with the breeding season typically receiving the most research attention. For polar seabirds, non-breeding phases like moult remain understudied, despite their importance for survival and overall fitness. Adélie penguins ( Pygoscelis adeliae ) replace their highly specialized feathers during an approximately 19-day annual moult, typically carried out while fasting on sea ice. The required fast and elevated metabolic rate may create a significant energetic bottleneck. We analysed data from geolocating dive recorders deployed on known-age Adélie penguins and non-known-age pairs from two Ross Island colonies over three winters (2017–2019). Moult start date was influenced by breeding success, intrinsic factors (age, sex) and extrinsic factors (year), with males, older birds and successful breeders moulting later. Moult duration varied primarily with individual ID, though later initiation correlated with shorter duration, particularly when located further south. Moult duration was longer in the western Ross Sea, a region that was used exclusively by males. The association between moult start date and duration may lead to differential sex and breeding status effects, with older males more likely to face a trade-off between successful breeding and self-maintenance tasks like feather replacement.

Proceedings of the Royal Society B↗
USGS2025

From fences to roads: Changes in barrier behaviour of Mongolian gazelle across different types of linear infrastructure in Mongolia

Poorly designed linear infrastructure can reduce habitat connectivity and be major barriers for migratory wildlife. An important start at effective mitigation is understanding how individuals respond when barriers are encountered. This can be done via comparison of fine- and broad-scale behavioural responses to various anthropogenic barrier types. We classified fine-scale responses of 62 Mongolian gazelles ( Procapra gutturosa ) across different barrier types, seasons and times of day. We also investigated interactions at a broader scale by measuring the length of linear infrastructure traced, interaction duration and crossing success rate. We learned that gazelle behaviour varied according to barrier permeability, and that fences were major obstacles. Gazelles exhibited similar bouncing behaviour when confronted with paved roads as with fences, suggesting paved roads can act as semi-permeable barriers during high traffic volume. Broad-scale movement patterns revealed gazelles travelled considerable distances along fences—averaging 40.2 km, and up to 211.6 km—before moving away or crossing. Long-distance tracing movements can help identify areas with the strongest barrier effect and guide mitigation measures for current and future linear infrastructure. Designing infrastructure and implementing conservation strategies for ungulates in steppe ecosystems will benefit from taking into account behavioural responses at both fine and broad scales.

Proceedings of the Royal Society B: Biological Sci↗