Bruce E. Young

Tulane University, New Orleans, Louisiana, United States

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Publications (30)291.89 Total impact

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    ABSTRACT: Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed in order to highlight urgent conservation cases and inform environmental policy with appropriate biodiversity information in a timely manner. We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles. Nearly one in five reptilian species are threatened with extinction, with another one in five species classed as Data Deficient. The proportion of threatened reptile species is highest in freshwater environments, tropical regions and on oceanic islands, while data deficiency was highest in tropical areas, such as Central Africa and Southeast Asia, and among fossorial reptiles. Our results emphasise the need for research attention to be focussed on tropical areas which are experiencing the most dramatic rates of habitat loss, on fossorial reptiles for which there is a chronic lack of data, and on certain taxa such as snakes for which extinction risk may currently be underestimated due to lack of population information. Conservation actions specifically need to mitigate the effects of humaninduced habitat loss and harvesting, which are the predominant threats to reptiles.
    Full-text · Dataset · Feb 2015
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    Bruce E. Young · Natalie S. Dubois · Erika L. Rowland
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    ABSTRACT: New tools and approaches are becoming available for wildlife conservation managers to help support climate adaptation activities, but few studies have documented how practitioners have applied these tools and perceive their utility. We surveyed the literature and users of the NatureServe Climate Change Vulnerability Index (CCVI), a tool that is widely used in North America to assess species' vulnerability to climate change, to characterize 1) how the tool has been used; 2) the objectives addressed by projects using the tool; 3) novel approaches that might be useful to other users; 4) how the results contributed to climate change adaptation planning; and 5) needed improvements recognized by users of the tool. Responses from 25 CCVI users, representing state agencies and natural heritage programs, conservation organizations, and universities, combined with published reports from 20 CCVI assessments, indicated that the CCVI has been applied to large numbers of species from diverse taxonomic groups. Results from these assessments have been used to communicate about climate change vulnerability, select species to be prioritized for management, inform management decisions, identify monitoring needs, and inform land-acquisition decisions. Users of the CCVI have developed novel ways to address uncertainty in climate and species natural-history data, involve stakeholders, evaluate migratory species, address specific management questions, and combine outputs with the results of parallel spatial analyses. To address user needs, future iterations of the tool should address climate exposure in the full life cycle of migratory species; better examine species dependent on specific vegetation microhabitats; and improve treatment of the effects of climate on diseases, parasites, and natural enemies. © 2014 The Wildlife Society.
    Full-text · Article · Feb 2015 · Wildlife Society Bulletin
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    ABSTRACT: Recognizing the imperiled status of biodiversity and its benefit to human well-being, the world's governments committed in 2010 to take effective and urgent action to halt biodiversity loss through the Convention on Biological Diversity's “Aichi Targets”. These targets, and many conservation programs, require monitoring to assess progress toward specific goals. However, comprehensive and easily understood information on biodiversity trends at appropriate spatial scales is often not available to the policy makers, managers, and scientists who require it. We surveyed conservation stakeholders in three geographically diverse regions of critical biodiversity concern (the Tropical Andes, the African Great Lakes, and the Greater Mekong) and found high demand for biodiversity indicator information but uneven availability. To begin to address this need, we present a biodiversity “dashboard” – a visualization of biodiversity indicators designed to enable tracking of biodiversity and conservation pe
    Full-text · Article · Nov 2014 · PLoS ONE
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    ABSTRACT: 1.Despite efforts in data collection, missing values are commonplace in life-history trait databases. Because these values typically are not missing randomly, the common practice of removing missing data not only reduces sample size, but also introduces bias that can lead to incorrect conclusions. Imputing missing values is a potential solution to this problem. Here, we evaluate the performance of four approaches for estimating missing values in trait databases (K-nearest neighbour (kNN), multivariate imputation by chained equations (mice), missForest and Phylopars), and test whether imputed datasets retain underlying allometric relationships among traits.2.Starting with a nearly complete trait dataset on the mammalian order Carnivora (using four traits), we artificially removed values so that the percent of missing values ranged from 10 to 80%. Using the original values as a reference, we assessed imputation performance using normalized root mean squared error. We also evaluated whether including phylogenetic information improved imputation performance in kNN, mice, and missForest (it is a required input in Phylopars). Finally, we evaluated the extent to which the allometric relationship between two traits (body mass and longevity) was conserved for imputed datasets by looking at the difference (bias) between the slope of the original and the imputed datasets or datasets with missing values removed.3.Three of the tested approaches (mice, missForest and Phylopars), resulted in qualitatively equivalent imputation performance, and all had significantly lower errors than kNN. Adding phylogenetic information into the imputation algorithms improved estimation of missing values for all tested traits. The allometric relationship between body mass and longevity was conserved when up to 60% of data were missing, either with or without phylogenetic information, depending on the approach. This relationship was less biased in imputed datasets compared to datasets with missing values removed, especially when more than 30% of values were missing.4.Imputations provide valuable alternatives to removing missing observations in trait databases as they produce low errors and retain relationships among traits. Although we must continue to prioritize data collection on species traits, imputations can provide a valuable solution for conducting macroecological and evolutionary studies using life-history trait databases.This article is protected by copyright. All rights reserved.
    Full-text · Article · Jul 2014 · Methods in Ecology and Evolution
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    Full-text · Dataset · Sep 2013
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    ABSTRACT: Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed in order to highlight urgent conservation cases and inform environmental policy with appropriate biodiversity information in a timely manner. We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles. Nearly one in five reptilian species are threatened with extinction, with another one in five species classed as Data Deficient. The proportion of threatened reptile species is highest in freshwater environments, tropical regions and on oceanic islands, while data deficiency was highest in tropical areas, such as Central Africa and Southeast Asia, and among fossorial reptiles. Our results emphasise the need for research attention to be focussed on tropical areas which are experiencing the most dramatic rates of habitat loss, on fossorial reptiles for which there is a chronic lack of data, and on certain taxa such as snakes for which extinction risk may currently be underestimated due to lack of population information. Conservation actions specifically need to mitigate the effects of human induced habitat loss and harvesting, which are the predominant threats to reptiles.
    Full-text · Article · Jan 2013 · Biological Conservation
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    ABSTRACT: Effective and targeted conservation action requires detailed information about species, their distribution, systematics and ecology as well as the distribution of threat processes which affect them. Knowledge of reptilian diversity remains surprisingly disparate, and innovative means of gaining rapid insight into the status of reptiles are needed in order to highlight urgent conservation cases and inform environmental policy with appropriate biodiversity information in a timely manner. We present the first ever global analysis of extinction risk in reptiles, based on a random representative sample of 1500 species (16% of all currently known species). To our knowledge, our results provide the first analysis of the global conservation status and distribution patterns of reptiles and the threats affecting them, highlighting conservation priorities and knowledge gaps which need to be addressed urgently to ensure the continued survival of the world’s reptiles. Nearly one in five reptilian species are threatened with extinction, with another one in five species classed as Data Deficient. The proportion of threatened reptile species is highest in freshwater environments, tropical regions and on oceanic islands, while data deficiency was highest in tropical areas, such as Central Africa and Southeast Asia, and among fossorial reptiles. Our results emphasise the need for research attention to be focussed on tropical areas which are experiencing the most dramatic rates of habitat loss, on fossorial reptiles for which there is a chronic lack of data, and on certain taxa such as snakes for which extinction risk may currently be underestimated due to lack of population information. Conservation actions specifically need to mitigate the effects of human-induced habitat loss and harvesting, which are the predominant threats to reptiles.
    Full-text · Article · Jan 2013 · Biological Conservation
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    ABSTRACT: Background: The Andes-Amazon basin of Peru and Bolivia is one of the most data-poor, biologically rich, and rapidly changing areas of the world. Conservation scientists agree that this area hosts extremely high endemism, perhaps the highest in the world, yet we know little about the geographic distributions of these species and ecosystems within country boundaries. To address this need, we have developed conservation data on endemic biodiversity (~800 species of birds, mammals, amphibians, and plants) and terrestrial ecological systems (~90; groups of vegetation communities resulting from the action of ecological processes, substrates, and/or environmental gradients) with which we conduct a fine scale conservation prioritization across the Amazon watershed of Peru and Bolivia. We modelled the geographic distributions of 435 endemic plants and all 347 endemic vertebrate species, from existing museum and herbaria specimens at a regional conservation practitioner's scale (1:250,000-1:1,000,000), based on the best available tools and geographic data. We mapped ecological systems, endemic species concentrations, and irreplaceable areas with respect to national level protected areas. Results: We found that sizes of endemic species distributions ranged widely (< 20 km 2 to > 200,000 km
    Full-text · Article · Dec 2012
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    ABSTRACT: The Andes-Amazon basin of Peru and Bolivia is one of the most data-poor, biologically rich, and rapidly changing areas of the world. Conservation scientists agree that this area hosts extremely high endemism, perhaps the highest in the world, yet we know little about the geographic distributions of these species and ecosystems within country boundaries. To address this need, we have developed conservation data on endemic biodiversity (~800 species of birds, mammals, amphibians, and plants) and terrestrial ecological systems (~90; groups of vegetation communities resulting from the action of ecological processes, substrates, and/or environmental gradients) with which we conduct a fine scale conservation prioritization across the Amazon watershed of Peru and Bolivia. We modelled the geographic distributions of 435 endemic plants and all 347 endemic vertebrate species, from existing museum and herbaria specimens at a regional conservation practitioner's scale (1:250,000-1:1,000,000), based on the best available tools and geographic data. We mapped ecological systems, endemic species concentrations, and irreplaceable areas with respect to national level protected areas. We found that sizes of endemic species distributions ranged widely (< 20 km2 to > 200,000 km2) across the study area. Bird and mammal endemic species richness was greatest within a narrow 2500-3000 m elevation band along the length of the Andes Mountains. Endemic amphibian richness was highest at 1000-1500 m elevation and concentrated in the southern half of the study area. Geographical distribution of plant endemism was highly taxon-dependent. Irreplaceable areas, defined as locations with the highest number of species with narrow ranges, overlapped slightly with areas of high endemism, yet generally exhibited unique patterns across the study area by species group. We found that many endemic species and ecological systems are lacking national-level protection; a third of endemic species have distributions completely outside of national protected areas. Protected areas cover only 20% of areas of high endemism and 20% of irreplaceable areas. Almost 40% of the 91 ecological systems are in serious need of protection (= < 2% of their ranges protected). We identify for the first time, areas of high endemic species concentrations and high irreplaceability that have only been roughly indicated in the past at the continental scale. We conclude that new complementary protected areas are needed to safeguard these endemics and ecosystems. An expansion in protected areas will be challenged by geographically isolated micro-endemics, varied endemic patterns among taxa, increasing deforestation, resource extraction, and changes in climate. Relying on pre-existing collections, publically accessible datasets and tools, this working framework is exportable to other regions plagued by incomplete conservation data.
    Full-text · Article · Jan 2012 · BMC Ecology

  • No preview · Chapter · Jan 2012
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    ABSTRACT: Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species.
    Full-text · Article · Oct 2010 · Science
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    ABSTRACT: Background/Question/Methods Resource managers increasingly seek to identify which species are most vulnerable to climate change-induced declines. To meet this need, we developed a practical, multifaceted rapid assessment tool, the "climate change vulnerability index." The index considers climate change exposure and species sensitivity. Exposure is the magnitude of projected climate change across the species' range within the assessment area. Species sensitivity includes intrinsic factors such as natural and life history traits that may reduce resilience (such as habitat specialization or a strong potential for disruption of key species interactions) and traits that suggest potential inability to adapt (such as low dispersal ability or reduced genetic diversity). The index also includes extrinsic factors related to a species' distribution, such as dispersal barriers and proximity to predicted sea level rise. Exposure and sensitivity are combined to generate a categorical vulnerability score (Extremely Vulnerable, Highly Vulnerable, Moderately Vulnerable, Not Vulnerable/Presumed Stable, or Not Vulnerable/Increase Likely). Results/Conclusions Preliminary results from a study of 216 vertebrates and mollusks in Nevada show that the index effectively sorted species, with the majority being Moderately Vulnerable or Not Vulnerable/Presumed Stable. 100% of mollusks, 80% of fish, 38% of amphibians, 30% of reptiles, 35% of mammals, and 4% of birds assessed were at least Moderately Vulnerable. Key vulnerability factors included limited hydrological niche, impacts from climate change mitigation-related land use changes, migration to or through a few vulnerable locations or lack of facultative distribution shifts, and dependence on vulnerable aquatic/wetland habitats. Good dispersal ability, broad physical habitat, migration to broad geographical areas or tendency to facultatively shift distribution, and broad temperature tolerance were factors that decreased vulnerability. The importance of limited hydrological niche and dependence on vulnerable aquatic/wetland habitats highlights the need for further exploration of the interaction among increasing temperatures, moisture, and wildlife habitats in Nevada. Further testing of the index at the state/province level is warranted, as well as testing at larger spatial scales.
    No preview · Conference Paper · Aug 2010
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    ABSTRACT: Seeking more precise knowledge of avian endemism on the east slope of the Andes in Peru and Bolivia, one of the most diverse faunal regions on Earth, we used distribution models based on locality records and 10–12 uncorrelated environmental variables to map the distributions of 115 species. Both maximum-entropy and deductive models reveal three areas of endemism, broadly supporting previous assessments of endemism in the region but showing much more detail. Regions such as the southwestern Cordillera de Vilcabamba and the Río Mapacho-Yavero valley in Cusco, Peru, and the Cordillera de Apolobamba in western Bolivia support a greater richness of endemic species than has been recognized, a result likely attributable to the ability of predictive models to partially control for biases in survey effort. National-level protected areas cover ≥1,000 km2 of the ranges, or four-fifths of the ranges of species with distributions <1,000 km2, of 77% of the endemic species. However, an analysis of summed irreplaceability, which emphasizes the locations of the most narrowly distributed endemics, showed that only 18% of these critical areas are currently protected. The fine-scale maps of endemic areas are suitable for regional and local-scale conservation planning, activities that can fill current gaps in protection of many species.
    Full-text · Article · Jul 2009 · The Auk
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    Full-text · Dataset · Dec 2008
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    ABSTRACT: Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action.
    Full-text · Article · Nov 2008 · Science
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    Full-text · Dataset · Oct 2008
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    ABSTRACT: Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action.
    Full-text · Article · Oct 2008 · Science
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    ABSTRACT: Although open-cup nesting birds generally face increased risk of nest depredation from forest edge predators and brood parasites in fragmented temperate landscapes, little information exists to assess such risks in tropical birds. We compared nesting success of real birds' nests in large and small forest fragments to a control site in Caribbean lowland wet forest of Costa Rica. Pooling across species, nesting success was significantly greater in unfragmented forest than in either small, isolated fragments or the La Selva Biological Reserve, which is at the tip of a forest 'peninsula' embedded in a largely deforested landscape. Nesting success in isolated fragments did not vary according to distance from edge, suggesting that predators in fragments act throughout these forest patches. The case for increased nest predation as a plausible mechanism to explain the documented decline of forest interior bird populations in this fragmented tropical landscape is enhanced by a simple demographic model that suggests nesting success is likely too low to maintain populations at La Selva and in the fragments. The fact that the large (> 1000 ha) La Selva forest reserve is experiencing nest predation rates similar to those in much smaller fragments is cause for concern. Our results make a strong case for additional studies to document the identities of nest predators in both fragmented and unfragmented forests in such tropical forest landscapes.
    Full-text · Article · Aug 2008 · Biotropica
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    ABSTRACT: Alford et al. question the working model underlying our test for a link between global warming and amphibian disappearances, and Di Rosa et al. criticize our emphasis on a single proximate agent, the chytrid fungus Batrachochytrium dendrobatidis. Both teams report key pieces of the amphibian-decline puzzle and new evidence from different parts of the world that climate change is a factor in these losses. Here we show why our working model was appropriate and highlight the complexity of the imminent threat to species survival that results as global warming conspires with various other agents.
    Full-text · Article · May 2007 · Nature
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    Bryan J Sigel · Thomas W Sherry · Bruce E Young
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    ABSTRACT: Since 1960, most of the forest surrounding the La Selva Biological Station, an intensively studied tropical research facility in Costa Rica, has been converted to agricultural uses. We used quantitative censuses and analysis of previously published categorical abundances to assess changes in the bird community, and we evaluated potential causes of species-specific changes by assessing their association with habitat, diet, participation in mixed-species flocks, and nest type. Approximately the same percentage of species increased as decreased in abundance from 1960 to 1999 (10–20% of all species, depending on method of assessment). Diet was the single most important trait associated with declining species. At least 50% of the species that declined have insectivorous diets. Use of forest habitat and participation in mixed-species flocks were also significant factors associated with declines, but nest type was unrelated to change in abundance. The species that increased in abundance tended to occur in open habitats and have omnivorous diets. These results reinforce the importance of several population risk factors associated with tropical understory insectivory and mixed-species flocking: patchy spatial distribution, low population density, large home range, and dietary specialization. La Selva's protected area (1611 ha), despite a forested connection on one boundary with a higher elevation national park, is apparently too small to maintain at least one major guild (understory insectivores). This first quantitative assessment of bird community change at La Selva highlights the need to intensify study of the mechanisms and consequences of biological diversity change in tropical forest fragments. Resumen: Desde 1960, la mayor parte del bosque que rodea a la Estación Biológica La Selva, un centro de investigación en Costa Rica, ha sido convertido a usos agrícolas. Usamos censos cuantitativos y el análisis de categorías de abundancia previamente publicadas para calcular cambios en la comunidad de aves, y evaluamos las potenciales causas de cambios especie-específicos mediante la estimación de su asociación con el hábitat, dieta, participación en parvadas mixtas y tipo de nido. Entre 1960 y 1990, el mismo porcentaje aproximado de especies aumentó y disminuyó en abundancia (10-20% de todas las especies, dependiendo del método de evaluación). La dieta fue el atributo individual más importante asociado con la declinación de especies. Por lo menos 50% de las especies que declinaron tiene dietas insectívoras. El uso del hábitat de bosque y la participación en parvadas mixtas también fueron factores significativos asociados con las declinaciones, pero el tipo de nido no estuvo relacionado con cambios en la abundancia. Las especies que incrementaron su abundancia tendieron a ocurrir en hábitats abiertos y a tener dietas omnívoras. Estos resultados refuerzan la importancia de varios factores de riesgo poblacional asociados con la insectivoría del sotobosque en los trópicos y con las parvadas mixtas: distribución espacial discontinua, baja densidad poblacional, rango de hogar amplio y especialización alimentaria. El área protegida de La Selva (1611 ha), a pesar de una conexión boscosa con un parque nacional de mayor altitud, aparentemente es muy pequeña para mantener a un gremio importante (insectívoros de sotobosque) Esta primera evaluación cuantitativa del cambio en la comunidad de aves en La Selva destaca la necesidad de intensificar el estudio de los mecanismos y consecuencias del cambio en la diversidad biológica en fragmentos de bosque tropical.
    Full-text · Article · Mar 2006 · Conservation Biology

Publication Stats

5k Citations
291.89 Total Impact Points

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Institutions

  • 2008
    • Tulane University
      • Department of Ecology and Evolutionary Biology
      New Orleans, Louisiana, United States
  • 1213
    • Southern Illinois University Carbondale
      • Department of Zoology
      Carbondale, IL, United States