Publications by authors named "Stephens P A"

Populations of many migratory taxa have been declining over recent decades. Although protected areas are a cornerstone for conservation, their role in protecting migratory species can be incomplete due to the dynamic distributions of these species. Here, we use a pan-European citizen science bird occurrence dataset (EurobirdPortal) with Spatiotemporal Exploratory Modelling to assess how the weekly distributions of 30 passerine and near passerine species overlap with protected areas in Europe and compare this to range adjusted policy protection targets.

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Background: Favourable Conservation status (FCS) is the overarching goal of the Habitats and Birds Directives, in which it is described as the situation in which a habitat or species is thriving throughout its natural range and is expected to continue to thrive. However, despite being introduced over thirty years ago, FCS has not been widely adopted as a conservation assessment framework. This systematic map aims to collate and characterise evidence to understand 1) how the term FCS is used in the literature, and 2) the context of its applications in policy and practice.

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Globally, human-wildlife conflicts continue to increase, owing to human population growth and expansion. Many of these conflicts concern the impacts of invasive non-native species. In the UK, the invasive, non-native grey squirrel Sciurus carolinensis negatively affects tree health and has caused the decline of the native red squirrel Sciurus vulgaris.

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Protected areas are traditionally the foundation of conservation strategy, but land not formally protected is of particular importance for the conservation of large carnivores because of their typically wide-ranging nature. In South Africa, leopard (Panthera pardus) population decreases are thought to be occurring in areas of human development and intense negative interactions, but research is biased towards protected areas, with quantitative information on population sizes and trends in non-protected areas severely lacking. Using Spatially Explicit Capture-Recapture and occupancy techniques including 10 environmental and anthropogenic covariates, we analysed camera trap data from commercial farmland in South Africa where negative human-wildlife interactions are reported to be high.

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Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amount and timing of animal activity varied widely.

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Article Synopsis
  • - Climate change is altering parasite transmission, influenced by factors like host density, temperature, and moisture, which can stress wild and domestic animals and challenge control methods.
  • - A model was applied to study how gut parasites interact with a montane wildlife-livestock system, focusing on host movements and their response to climate changes at different elevations.
  • - Findings reveal that host movement significantly impacts parasite infection pressure more than climate directly, indicating that understanding species migration is key to managing parasite risks for both wildlife and livestock.
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Background: Prior research has demonstrated that low- and low-middle-income countries (LLMICs) bear a higher burden of critical illness and have a higher rate of mortality from critical illness than high-income countries (HICs). There is a pressing need for improved critical care delivery in LLMICs to reduce this inequity. This systematic review aimed to characterise the range of critical care interventions and services delivered within LLMIC health care systems as reported in the literature.

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Article Synopsis
  • Detecting changes in biodiversity is complex due to its multifaceted nature and biases in temporal data.
  • A study analyzed population trends of native breeding birds in the UK and EU, revealing significant declines in bird abundance, particularly among smaller and more common species, while rarer and larger birds showed better stability.
  • Findings indicate that population trends are linked to body mass, climate suitability, migration strategies, and dietary niches, emphasizing the need for careful interpretation of biodiversity metrics as they can yield different insights.
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  • Occupancy models are essential for ecologists to analyze species occurrence, but choosing the right model can be complicated due to varying occupancy and detection variables.
  • The information-theoretic approach, especially Akaike's information criterion (AIC), is commonly used for model selection, but it can lead to inaccurate estimates due to collider bias, a form of confounding caused by adding variables.
  • Simulation results showed that while AIC and BIC can select useful models for predicting site-level occupancy, they should be used cautiously for understanding how environmental factors influence occupancy, whereas detection variable selection is generally more reliable.
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Ecosystem engineers affect other organisms by creating, maintaining or modifying habitats, potentially supporting species of conservation concern. However, it is important to consider these interactions alongside non-engineering trophic pathways. We investigated the relative importance of trophic and non-trophic effects of an ecosystem engineer, red deer, on a locally rare moth, the transparent burnet (Zygaena purpuralis).

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Introduction: Critical care in low-income and low-middle income countries (LLMICs) is an underdeveloped component of the healthcare system. Given the increasing growth in demand for critical care services in LLMICs, understanding the current capacity to provide critical care is imperative to inform policy on service expansion. Thus, our aim is to describe the provision of critical care in LLMICs with respect to patients, providers, location of care and services and interventions delivered.

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Article Synopsis
  • The study explores the use of animal-attached devices to track the behavior of hard-to-observe species by employing captive animals and domesticated surrogates for data calibration.
  • Using tri-axial accelerometers and magnetometers, researchers created models to classify behaviors, achieving over 98% accuracy with captive Alpine ibex and pygmy goats, but encountering challenges when classifying individual behaviors not used in training.
  • Findings indicate that while models can classify behaviors with high accuracy using the same species, domestic surrogates (like pygmy goats) struggle to predict the behaviors of wild relatives effectively, pointing to issues stemming from domestication effects.
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The spread of invasive species is a threat to ecosystems worldwide. However, we know relatively little about how invasive species affect the behaviour of native animals, even though behaviour plays a vital role in the biotic interactions which are key to understanding the causes and impacts of biological invasions. Here, we explore how invasive plants - one of the most pervasive invasive taxa - impact the behaviour of native animals.

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High numbers of threatened species might be expected to occur where overall species richness is also high; however, this explains only a proportion of the global variation in threatened species richness. Understanding why many areas have more or fewer threatened species than would be expected given their species richness, and whether that is consistent across taxa, is essential for identifying global conservation priorities. Here, we show that, after controlling for species richness, environmental factors, such as temperature and insularity, are typically more important than human impacts for explaining spatial variation in global threatened species richness.

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  • Prescribed fire is used to enhance biodiversity in savanna ecosystems, but there are gaps in understanding how wildlife responds to the varying compositions of these fire-managed landscapes.
  • In a study in North West Province, South Africa, researchers explored how the timing and types of fire influence bird species richness and functional diversity across different habitats.
  • Results showed that specific patterns of fire age and habitat configuration significantly affected bird diversity, highlighting the need for a deeper evaluation of functional diversity in conservation strategies to enhance ecosystem resilience.
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Camera trapping has become an increasingly reliable and mainstream tool for surveying a diversity of wildlife species. Concurrent with this has been an increasing effort to involve the wider public in the research process, in an approach known as 'citizen science'. To date, millions of people have contributed to research across a wide variety of disciplines as a result.

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Weather variations have the potential to influence species interactions, although effects on competitive interactions between species are poorly known. Both weather and competition can influence foraging behavior and survival of herbivores during nursing/weaning, a critical period in the herbivore life cycle. We evaluated the joint effects of weather and competition with red deer on the foraging behavior of adult female Apennine chamois in summer, and on winter survival of chamois kids.

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We address two fundamental ecological questions: what are the limits to animal population density and what determines those limits? We develop simple alternative models to predict population limits in relation to body mass. A model assuming that within-species area use increases with the square of daily travel distance broadly predicts the scaling of empirical extremes of minimum density across birds and mammals. Consistent with model predictions, the estimated density range for a given mass, 'population scope', is greater for birds than for mammals.

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An animal's choice of diet plays a large part in determining whether it will find food during a period of searching. This has profound implications for the likelihood of reproductive success or starvation and many other important questions in ecology.

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Climate change is predicted to increase migration distances for many migratory species, but the physiological and temporal implications of longer migratory journeys have not been explored. Here, we combine information about species' flight range potential and migratory refuelling requirements to simulate the number of stopovers required and the duration of current migratory journeys for 77 bird species breeding in Europe. Using tracking data, we show that our estimates accord with recorded journey times and stopovers for most species.

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Global climate change is a major threat to biodiversity. Large-scale analyses have generally focused on the impacts of climate change on the geographic ranges of species and on phenology, the timing of ecological phenomena. We used long-term monitoring of the abundance of breeding birds across Europe and the United States to produce, for both regions, composite population indices for two groups of species: those for which climate suitability has been either improving or declining since 1980.

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In recent decades, many ungulate populations have changed dramatically in abundance, resulting in cascading effects across ecosystems. However, studies of such effects are often limited in their spatial and temporal scope. Here, we contrast multi-species composite population trends of deer-sensitive and deer-tolerant woodland birds at a national scale, across Britain.

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Understanding the relationship between disease transmission and host density is essential for predicting disease spread and control. Using long-term data on sarcoptic mange in a red fox Vulpes vulpes population, we tested long-held assumptions of density- and frequency-dependent direct disease transmission. We also assessed the role of indirect transmission.

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The altitudinal shifts of many montane populations are lagging behind climate change. Understanding habitual, daily behavioural rhythms, and their climatic and environmental influences, could shed light on the constraints on long-term upslope range-shifts. In addition, behavioural rhythms can be affected by interspecific interactions, which can ameliorate or exacerbate climate-driven effects on ecology.

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