Fragmentation effects on an endangered species across a gradient from the interior to edge of its range.

Understanding how habitat fragmentation affects individual species is complicated by challenges associated with quantifying species-specific habitat and spatial variability in fragmentation effects within a species' range. We aggregated a 29-year breeding survey data set for the endangered marbled murrelet (Brachyramphus marmoratus) from >42,000 forest sites throughout the Pacific Northwest (Oregon, Washington, and northern California) of the United States. We built a species distribution model (SDM) in which occupied sites were linked with Landsat imagery to quantify murrelet-specific habitat and then used occupancy models to test the hypotheses that fragmentation negatively affects murrelet breeding distribution and that these effects are amplified with distance from the marine foraging habitat toward the edge of the species' nesting range. Murrelet habitat declined in the Pacific Northwest by 20% since 1988, whereas the proportion of habitat comprising edges increased by 17%, indicating increased fragmentation. Furthermore, fragmentation of murrelet habitat at landscape scales (within 2 km of survey stations) negatively affected occupancy of potential breeding sites, and these effects were amplified near the range edge. On the coast, the odds of occupancy decreased by 37% (95% confidence interval [CI] -54 to 12) for each 10% increase in edge habitat (i.e., fragmentation), but at the range edge (88 km inland) these odds decreased by 99% (95% CI 98 to 99). Conversely, odds of murrelet occupancy increased by 31% (95% CI 14 to 52) for each 10% increase in local edge habitat (within 100 m of survey stations). Avoidance of fragmentation at broad scales but use of locally fragmented habitat with reduced quality may help explain the lack of murrelet population recovery. Further, our results emphasize that fragmentation effects can be nuanced, scale dependent, and geographically variable. Awareness of these nuances is critical for developing landscape-level conservation strategies for species experiencing broad-scale habitat loss and fragmentation.

Efectos de la fragmentación sobre las especies en peligro a lo largo de un gradiente desde el interior hasta el borde de su distribución Resumen Es complicado entender el efecto de la fragmentación del hábitat sobre las especies individuales debido a los retos asociados con la cuantificación de hábitats específicos por especie y la variabilidad espacial de los efectos de la fragmentación dentro de la distribución de la especie. Combinamos los datos de un censo reproductivo realizado durante 29 años para el mérgulo jaspeado (Brachyramphus marmoratus) de >42,000 sitios boscosos a lo largo del noroeste del Pacífico (Oregón, Washington, y el norte de California, EE. UU.). Construimos un modelo de distribución de especie (MDE) en el cual los sitios ocupados estuvieron vinculados con imágenes de Landsat para cuantificar el hábitat específico del mérgulo y después usamos los modelos de ocupación para comprobar la hipótesis de que la fragmentación afecta negativamente la distribución reproductiva de la especie y que estos efectos se amplifican con la distancia entre el hábitat de forrajeo marino y el borde de la distribución de anidación de la especie. El hábitat del mérgulo declinó en la zona en un 20% a partir de 1988, mientras que la proporción de hábitat que comprende bordes incrementó en un 17%, lo que indica un aumento en la fragmentación. Además, la fragmentación del hábitat del mérgulo a escala de paisaje (a de 2 km de las estaciones de censo) afectó negativamente a la ocupación de sitios potenciales de reproducción y estos efectos se amplificaron cerca del borde de la distribución. La probabilidad de ocupación disminuyó en un 37% (95% IC -54 a 12) por cada 10% de incremento en el hábitat de borde (es decir, fragmentación) en la costa, pero en el borde de la distribución (88 km tierra adentro), esta probabilidad disminuyó en un 99% (95% IC 98 a 99). De forma contraria, la probabilidad de ocupación incrementó en un 31% (95% IC 14 a 52) por cada 10% de incremento en el hábitat de borde local (a 100 m de las estaciones de censo). La evasión de la fragmentación a gran escala y el uso de hábitats con calidad reducida y fragmentados a nivel local podría explicar la falta de recuperación poblacional del mérgulo. Más allá, nuestros resultados resaltan que los efectos de la fragmentación pueden estar matizados, depender de la escala y tener variación geográfica. Es importante tener conciencia de estos matices para desarrollar estrategias de conservación a nivel paisaje para las especies que experimentan fragmentación y pérdida del hábitat a gran escala.

Effects of climate and human activity on the current distribution of amphibians in China.

In China, as elsewhere, amphibians are highly endangered. Anthropogenic environmental change has affected the distribution and population dynamics of species, and species distributions at a broad scale are strongly driven by climate and species' ability to disperse. Yet, current knowledge remains limited on how widespread human activity affects the distribution patterns of amphibians in China and whether this effect extends beyond climate. We compiled a relatively comprehensive database on the distribution of 196 amphibian species in China from the literature, public databases, and field data. We obtained 25,826 records on almost 50% of known species in China. To test how environmental factors and human activities influence the current distribution of amphibians (1960-1990), we used range filling, which is species realized ranges relative to their potential climate distribution. We used all species occurrence records to represent realized range and niche models to predict potential distribution range. To reduce uncertainty, we used 3 regression methods (beta regression, generalized boosted regression models, and random forest) to test the associations of species range filling with human activity, climate, topography, and range size. The results of the 3 approaches were consistent. At the species level, mean annual precipitation (climate) had the most effect on spatial distribution pattern of amphibians in China, followed by range size. Human activity ranked last. At the spatial level, mean annual precipitation remained the most important factor. Regions in southeastern of China that are currently moist supported the highest amphibian diversity, but were predicted to experience a decline in precipitation under climate change scenarios. Consequently, the distributions of amphibians will likely shift to the northwest in the future, which could affect future conservation efforts.

En China, como en todos lados, los anfibios están gravemente en peligro. El cambio ambiental antropogénico ha afectado la distribución y dinámica poblacional de especies, y la distribución de especies a gran escala están muy influidas por el clima y la habilidad de dispersión de las especies. Sin embargo, el conocimiento actual sigue siendo limitado sobre cómo la actividad humana generalizada afecta a los patrones de distribución de anfibios en China y si este efecto se extiende más allá del clima. A partir de literatura, bases de datos públicas y datos de campo, integramos una base datos relativamente completa sobre la distribución de 196 especies de anfibios en China. Obtuvimos 25,826 registros de casi 50% de las especies conocidas en China. Para probar cómo los factores ambientales y las actividades humanas influyen en la distribución actual de anfibios (1960-1990), utilizamos la ocupación de rango, que contrasta los rangos de distribución observada de las especies en relación con su distribución climática potencial. Utilizamos los registros de ocurrencia de todas las especies para representar el rango observado y modelos de nicho para predecir el rango de distribución potencial. Para reducir la incertidumbre, utilizamos 3 métodos de regresión (regresión beta, modelos de regresión acelerada generalizada y bosque aleatorio) para probar las asociaciones de la ocupación de rango de especies con la actividad humana, clima, topografía y extensión de rango. Los resultados de los tres métodos fueron consistentes. A nivel de especie, la precipitación media anual (clima) tuvo el mayor efecto sobre el patrón de distribución de anfibios en China, seguida por la extensión del rango. La actividad humana ocupó el último lugar. A nivel espacial, la precipitación media anual siguió como el factor más importante. Las regiones en el sureste de China que aun son húmedas sostuvieron la mayor diversidad de anfibios, pero se pronosticó que la precipitación declinará bajo escenarios de cambio climático. Consecuentemente, la distribución de anfibios muy probablemente cambiará hacia el noreste, lo cual podría afectar esfuerzos futuros de conservación.

Climate suitability as a predictor of conservation translocation failure.

The continuing decline and loss of biodiversity has caused an increase in the use of interventionist conservation tools, such as translocation. However, many translocation attempts fail to establish viable populations, with poor release site selection often flagged as an inhibitor of success. We used species distribution models (SDMs) to predict the climate suitability of 102 release sites for amphibians, reptiles, and terrestrial insects and compared suitability predictions between successful and failed attempts. We then quantified the importance of climate suitability relative to 5 other variables frequently considered in the literature as important determinants of translocation success: number of release years, number of individuals released, life stage released, origin of the source population, and position of the release site relative to the species' range. Probability of translocation success increased as predicted climate suitability increased and this effect was the strongest among the variables we considered, accounting for 48.3% of the variation in translocation outcome. These findings should encourage greater consideration of climate suitability when selecting release sites for conservation translocations and we advocate the use of SDMs as an effective way to do this.

Idoneidad Climática como Pronosticador del Fracaso de la Reubicación por Conservación Resumen La continua declinación y pérdida de la biodiversidad ha ocasionado un incremento en el uso de herramientas intervencionistas de conservación como la reubicación. Sin embargo, muchos intentos de reubicación fracasan en el establecimiento de poblaciones viables, y generalmente se identifica a la mala selección de sitios de liberación como el inhibidor del éxito. Usamos modelos de distribución de especies (MDE) para predecir la idoneidad climática de 102 sitios de liberación para anfibios, reptiles e insectos terrestres y comparamos las predicciones de idoneidad entre los intentos fallidos y los exitosos. Después cuantificamos la importancia de la idoneidad climática en relación a otras cinco variables consideradas frecuentemente en la literatura como determinantes importantes del éxito de la reubicación: el número de años de liberaciones, el número de individuos liberados, la etapa de vida durante la liberación, la fuente de la población de origen y la posición del sitio de liberación en relación a la extensión de la especie. La probabilidad del éxito de la reubicación incrementó conforme aumentó la idoneidad climática pronosticada y este efecto fue el más fuerte entre las variables que consideramos, representando el 48.3% de la variación del resultado de la reubicación. Estos hallazgos deberían promover una mayor consideración de la idoneidad climática cuando se seleccionan sitios de liberación para reubicaciones por conservación y abogamos que el uso de los MDE es un método efectivo para hacer esto.

Redescription of the snake Lachesis melanocephala (Squamata: Viperidae): Designation of a neotype, natural history, and conservation status

Introduction: The Black-headed Bushmaster (Lachesis melanocephala) is a large venomous snake that inhabits tropical moist forest, wet forest, montane and premontane wet forest in Southwestern Costa Rica and extreme Western Panama. Objective: We assign a neotype for the species due to the loss of the original holotype and update the information on its geographical distribution, natural history, and conservation status. Methods: To determine the conservation status of L. melanocephala, we modeled its potential distribution using the species` locality records and distribution modeling analysis implemented in MaxEnt. Based on the species' potential distribution, we evaluate the loss of its original habitat and estimate the percentage of its distribution area that is currently protected by the country's protected area system. Results: The potential distribution of the species was estimated at 10 139 km2, including areas where the species currently occurs and historical areas where the species has been registered but is nowadays considered locally extinct. About 29 % of that potential distribution overlaps with protected wild areas, so less than a third of the potential distribution of the species is under protection. Conclusions: During the last decade, accelerated habitat loss and growing evidence of declining natural populations indicate the need for urgent protective measures to prevent the extinction of this species in the foreseeable future.

Introducción: La serpiente Plato Negro (Lachesis melanocephala) es una especie venenosa de gran tamaño, endémica de los bosques lluviosos del Pacífico sur y suroeste de Costa Rica y el extremo oeste de Panamá. Objetivo: Se asigna un neotipo para la especie debido a la pérdida del holotipo original y se presentan datos actualizados de su distribución geográfica, historia natural y estado de conservación. Métodos: Para determinar el estado de conservación de L. melanocephala, reconstruimos su distribución potencial utilizando los registros de localidad de la especie y el análisis de modelado de distribución implementado en MaxEnt. En función de la distribución potencial de la especie, evaluamos la pérdida de su hábitat original y calculamos el porcentaje de su área de distribución que actualmente está protegida por el sistema de áreas protegidas del país. Resultados: La distribución potencial de la especie se estimó en 10 139 km2, incluyendo áreas donde la especie se encuentra actualmente y áreas históricas donde la especie se ha registrado, pero se considera localmente extinta. Cerca del 29 % de esa distribución potencial se traslapa con áreas silvestres protegidas, por lo que menos de una tercera parte de la distribución potencial de la especie está bajo protección. Conclusiones: La degradación acelerada de su hábitat y la disminución evidente de sus poblaciones durante la última década señalan la necesidad de tomar medidas urgentes de protección para evitar el riesgo de extinción a corto plazo o mediano plazo.

Incorporating fragmentation and non-native species into distribution models to inform fluvial fish conservation.

Fluvial fishes face increased imperilment from anthropogenic activities, but the specific factors contributing most to range declines are often poorly understood. For example, the range of the fluvial-specialist shoal bass (Micropterus cataractae) continues to decrease, yet how perceived threats have contributed to range loss is largely unknown. We used species distribution models to determine which factors contributed most to shoal bass range loss. We estimated a potential distribution based on natural abiotic factors and a series of currently occupied distributions that incorporated variables characterizing land cover, non-native species, and river fragmentation intensity (no fragmentation, dams only, and dams and large impoundments). We allowed interspecific relationships between non-native congeners and shoal bass to vary across fragmentation intensities. Results from the potential distribution model estimated shoal bass presence throughout much of their native basin, whereas models of currently occupied distribution showed that range loss increased as fragmentation intensified. Response curves from models of currently occupied distribution indicated a potential interaction between fragmentation intensity and the relationship between shoal bass and non-native congeners, wherein non-natives may be favored at the highest fragmentation intensity. Response curves also suggested that >100 km of interconnected, free-flowing stream fragments were necessary to support shoal bass presence. Model evaluation, including an independent validation, suggested that models had favorable predictive and discriminative abilities. Similar approaches that use readily available, diverse, geospatial data sets may deliver insights into the biology and conservation needs of other fluvial species facing similar threats.

Riqueza potencial de las especies de ranas y mariposas diurnas en tres unidades biogeográficas del nororiente de Colombia: implicaciones para la conservación / Potential species richness of frogs and diurnal butterflies in three biogeographical units from northeastern colombia: conservation implications

ABSTRACT We present an estimation of the potential species richness of frogs, and diurnal butterflies distributed in the departments of Norte de Santander and Santander, Colombia, and analyze the implications for conservation of such high Andean species. From June 2012 to May 2016, we sampled across the Almorzadero, Santurbán and Tamá biogeographical units to gather presence data of 7 anuran species and 29 butterflies species from the superfamily Papilionoidea. We modeled the potential distribution of each species, converted every model to binary, and the sum up of unique species per cell allowed to estimate the model of potential richness, generating the total number of species for every 1 km2 cell. Every model was validated against field data, vegetation cover, and altitude. Our results suggest the existence of species' concentration zones, specifically in the places of convergence between biogeographical units; it was evident the high levels of data deficiency in some places. Finally, it was clear the importance of these zones as a continuum of biogeographic conditions to maintain the biological diversity.

RESUMEN Presentamos una estimación de la riqueza potencial y las implicaciones para la conservación de especies altoandinas de anuros y de mariposas diurnas, distribuidas en los departamentos de Norte de Santander y Santander. Durante junio de 2012 y mayo de 2016 se realizaron muestreos de campo en las unidades biogeográficas de Almorzadero, Santurbán y Tamá, para registrar los datos de presencia de siete especies de anfibios del orden Anura y 29 de mariposas de la superfamilia Papilionoidea. Realizamos modelamientos de la distribución potencial de cada especie, convertimos cada modelo en binario, y la suma de especies únicas por celda permitió estimar el modelo de riqueza potencial, obteniendo el número total de especies por cada celda de 1 km2; a su vez, los modelos fueron superpuestos sobre información de campo, cobertura vegetal y altitudinal. Nuestros resultados sugieren que existen zonas concretas de concentración de especies en las zonas de convergencia entre las unidades biogeográficas, así como zonas con vacíos de información. Resaltamos la importancia de estas zonas como un continuo de condiciones biogeográficas para mantener la diversidad.

Integrated models to support multiobjective ecological restoration decisions.

Many objectives motivate ecological restoration, including improving vegetation condition, increasing the range and abundance of threatened species, and improving species richness and diversity. Although models have been used to examine the outcomes of ecological restoration, few researchers have attempted to develop models to account for multiple, potentially competing objectives. We developed a combined state-and-transition, species-distribution model to predict the effects of restoration actions on vegetation condition and extent, bird diversity, and the distribution of several bird species in southeastern Australian woodlands. The actions reflected several management objectives. We then validated the models against an independent data set and investigated how the best management decision might change when objectives were valued differently. We also used model results to identify effective restoration options for vegetation and bird species under a constrained budget. In the examples we evaluated, no one action (improving vegetation condition and extent, increasing bird diversity, or increasing the probability of occurrence for threatened species) provided the best outcome across all objectives. In agricultural lands, the optimal management actions for promoting the occurrence of the Brown Treecreeper (Climacteris picumnus), an iconic threatened species, resulted in little improvement in the extent of the vegetation and a high probability of decreased vegetation condition. This result highlights that the best management action in any situation depends on how much the different objectives are valued. In our example scenario, no management or weed control were most likely to be the best management options to satisfy multiple restoration objectives. Our approach to exploring trade-offs in management outcomes through integrated modeling and structured decision-support approaches has wide application for situations in which trade-offs exist between competing conservation objectives.

The importance of incorporating functional habitats into conservation planning for highly mobile species in dynamic systems.

The distribution of mobile species in dynamic systems can vary greatly over time and space. Estimating their population size and geographic range can be problematic and affect the accuracy of conservation assessments. Scarce data on mobile species and the resources they need can also limit the type of analytical approaches available to derive such estimates. We quantified change in availability and use of key ecological resources required for breeding for a critically endangered nomadic habitat specialist, the Swift Parrot (Lathamus discolor). We compared estimates of occupied habitat derived from dynamic presence-background (i.e., presence-only data) climatic models with estimates derived from dynamic occupancy models that included a direct measure of food availability. We then compared estimates that incorporate fine-resolution spatial data on the availability of key ecological resources (i.e., functional habitats) with more common approaches that focus on broader climatic suitability or vegetation cover (due to the absence of fine-resolution data). The occupancy models produced significantly (P < 0.001) smaller (up to an order of magnitude) and more spatially discrete estimates of the total occupied area than climate-based models. The spatial location and extent of the total area occupied with the occupancy models was highly variable between years (131 and 1498 km2 ). Estimates accounting for the area of functional habitats were significantly smaller (2-58% [SD 16]) than estimates based only on the total area occupied. An increase or decrease in the area of one functional habitat (foraging or nesting) did not necessarily correspond to an increase or decrease in the other. Thus, an increase in the extent of occupied area may not equate to improved habitat quality or function. We argue these patterns are typical for mobile resource specialists but often go unnoticed because of limited data over relevant spatial and temporal scales and lack of spatial data on the availability of key resources. Understanding changes in the relative availability of functional habitats is crucial to informing conservation planning and accurately assessing extinction risk for mobile resource specialists.

The value of using feasibility models in systematic conservation planning to predict landholder management uptake.

Understanding the social dimensions of conservation opportunity is crucial for conservation planning in multiple-use landscapes. However, factors that influence the feasibility of implementing conservation actions, such as the history of landscape management, and landholders' willingness to engage are often difficult or time consuming to quantify and rarely incorporated into planning. We examined how conservation agencies could reduce costs of acquiring such data by developing predictive models of management feasibility parameterized with social and biophysical factors likely to influence landholders' decisions to engage in management. To test the utility of our best-supported model, we developed 4 alternative investment scenarios based on different input data for conservation planning: social data only; biological data only; potential conservation opportunity derived from modeled feasibility that incurs no social data collection costs; and existing conservation opportunity derived from feasibility data that incurred collection costs. Using spatially explicit information on biodiversity values, feasibility, and management costs, we prioritized locations in southwest Australia to control an invasive predator that is detrimental to both agriculture and natural ecosystems: the red fox (Vulpes vulpes). When social data collection costs were moderate to high, the most cost-effective investment scenario resulted from a predictive model of feasibility. Combining empirical feasibility data with biological data was more cost-effective for prioritizing management when social data collection costs were low (<4% of the total budget). Calls for more data to inform conservation planning should take into account the costs and benefits of collecting and using social data to ensure that limited funding for conservation is spent in the most cost-efficient and effective manner.

Predicting the spatial distribution of a seabird community to identify priority conservation areas in the Timor Sea.

Understanding spatial and temporal variability in the distribution of species is fundamental to the conservation of marine and terrestrial ecosystems. To support strategic decision making aimed at sustainable management of the oceans, such as the establishment of protected areas for marine wildlife, we identified areas predicted to support multispecies seabird aggregations in the Timor Sea. We developed species distribution models for 21 seabird species based on at-sea survey observations from 2000-2013 and oceanographic variables (e.g., bathymetry). We applied 4 statistical modeling techniques and combined the results into an ensemble model with robust performance. The ensemble model predicted the probability of seabird occurrence in areas where few or no surveys had been conducted and demonstrated 3 areas of high seabird richness that varied little between seasons. These were located within 150 km of Adele Island, Ashmore Reef, and the Lacepede Islands, 3 of the largest aggregations of breeding seabirds in Australia. Although these breeding islands were foci for high species richness, model performance was greatest for 3 nonbreeding migratory species that would have been overlooked had regional monitoring been restricted to islands. Our results indicate many seabird hotspots in the Timor Sea occur outside existing reserves (e.g., Ashmore Reef Marine Reserve), where shipping, fisheries, and offshore development likely pose a threat to resident and migratory populations. Our results highlight the need to expand marine spatial planning efforts to ensure biodiversity assets are appropriately represented in marine reserves. Correspondingly, our results support the designation of at least 4 new important bird areas, for example, surrounding Adele Island and Ashmore Reef.

Detecting extinction risk from climate change by IUCN Red List criteria.

Anthropogenic climate change is a key threat to global biodiversity. To inform strategic actions aimed at conserving biodiversity as climate changes, conservation planners need early warning of the risks faced by different species. The IUCN Red List criteria for threatened species are widely acknowledged as useful risk assessment tools for informing conservation under constraints imposed by limited data. However, doubts have been expressed about the ability of the criteria to detect risks imposed by potentially slow-acting threats such as climate change, particularly because criteria addressing rates of population decline are assessed over time scales as short as 10 years. We used spatially explicit stochastic population models and dynamic species distribution models projected to future climates to determine how long before extinction a species would become eligible for listing as threatened based on the IUCN Red List criteria. We focused on a short-lived frog species (Assa darlingtoni) chosen specifically to represent potential weaknesses in the criteria to allow detailed consideration of the analytical issues and to develop an approach for wider application. The criteria were more sensitive to climate change than previously anticipated; lead times between initial listing in a threatened category and predicted extinction varied from 40 to 80 years, depending on data availability. We attributed this sensitivity primarily to the ensemble properties of the criteria that assess contrasting symptoms of extinction risk. Nevertheless, we recommend the robustness of the criteria warrants further investigation across species with contrasting life histories and patterns of decline. The adequacy of these lead times for early warning depends on practicalities of environmental policy and management, bureaucratic or political inertia, and the anticipated species response times to management actions.