The challenge of biased evidence in conservation.

Efforts to tackle the current biodiversity crisis need to be as efficient and effective as possible given chronic underfunding. To inform decision-makers of the most effective conservation actions, it is important to identify biases and gaps in the conservation literature to prioritize future evidence generation. We used the Conservation Evidence database to assess the state of the global literature that tests conservation actions for amphibians and birds. For the studies in the database, we investigated their spatial and taxonomic extent and distribution across biomes, effectiveness metrics, and study designs. Studies were heavily concentrated in Western Europe and North America for birds and particularly for amphibians, and temperate forest and grassland biomes were highly represented relative to their percentage of land coverage. Studies that used the most reliable study designs-before-after control-impact and randomized controlled trials-were the most geographically restricted and scarce in the evidence base. There were negative spatial relationships between the numbers of studies and the numbers of threatened and data-deficient species worldwide. Taxonomic biases and gaps were apparent for amphibians and birds-some entire orders were absent from the evidence base-whereas others were poorly represented relative to the proportion of threatened species they contained. Metrics used to evaluate effectiveness of conservation actions were often inconsistent between studies, potentially making them less directly comparable and evidence synthesis more difficult. Testing conservation actions on threatened species outside Western Europe, North America, and Australasia should be prioritized. Standardizing metrics and improving the rigor of study designs used to test conservation actions would also improve the quality of the evidence base for synthesis and decision-making.

El Desafío de la Evidencia Sesgada en la Conservación Resumen Los esfuerzos para lidiar con la actual crisis de la biodiversidad necesitan ser tan eficientes y efectivos como sea posible dado el crónico subfinanciamiento. Para informar a los órganos de decisión sobre las acciones de conservación más efectivas, es importante identificar los sesgos y las brechas en la literatura de la conservación para priorizar generación de evidencias en el futuro. Usamos la base de datos Conservation Evidence para evaluar el estado de la literatura mundial que analiza las acciones para la conservación de anfibios y aves. Para los estudios dentro de la base de datos, investigamos su extensión espacial y taxonómica y su distribución a lo largo de biomas, medidas de efectividad y diseños de estudio. Los estudios se concentraron principalmente en Europa Occidental y en América del Norte en el caso de las aves y particularmente para los anfibios. Los biomas con mayor representación en relación con su porcentaje de cobertura de suelo fueron el bosque templado y los pastizales. Los estudios que utilizaron el diseño más confiable - impacto del control antes- después y ensayos controlados al azar - fueron los que presentaron mayor restricción geográfica y menor presencia dentro de la base de evidencias. También encontramos relaciones espaciales negativas entre el número de estudios y el número de especies amenazadas o con pocos datos a nivel mundial. Los sesgos y las brechas taxonómicas fueron evidentes para los anfibios y las aves - hubo órdenes enteros ausentes en la base de evidencias - mientras que otros taxones estuvieron representados pobremente en relación con la proporción de especies amenazadas que albergan. Las medidas utilizadas para evaluar la efectividad de las acciones de conservación con frecuencia fueron incompatibles entre los estudios, lo que las hace potencialmente menos comparables directamente y también dificulta la síntesis de las evidencias. Se debe priorizar el análisis de las acciones para la conservación de las especies que se encuentran fuera de Europa Occidental, América del Norte y Australasia. La estandarización de las medidas y el mejoramiento del rigor de los diseños de estudio que se usan para evaluar las acciones de conservación también mejoraría la calidad de la base de evidencias para la síntesis y la toma de decisiones.

Ten-year assessment of the 100 priority questions for global biodiversity conservation.

In 2008, a group of conservation scientists compiled a list of 100 priority questions for the conservation of the world's biodiversity. However, now almost a decade later, no one has yet published a study gauging how much progress has been made in addressing these 100 high-priority questions in the peer-reviewed literature. We took a first step toward reexamining the 100 questions to identify key knowledge gaps that remain. Through a combination of a questionnaire and a literature review, we evaluated each question on the basis of 2 criteria: relevance and effort. We defined highly relevant questions as those that - if answered - would have the greatest impact on global biodiversity conservation and quantified effort based on the number of review publications addressing a particular question, which we used as a proxy for research effort. Using this approach, we identified a set of questions that, despite being perceived as highly relevant, have been the focus of relatively few review publications over the past 10 years. These questions covered a broad range of topics but predominantly tackled 3 major themes: conservation and management of freshwater ecosystems, role of societal structures in shaping interactions between people and the environment, and impacts of conservation interventions. We believe these questions represent important knowledge gaps that have received insufficient attention and may need to be prioritized in future research.

Worldwide insect declines: An important message, but interpret with caution.

A recent paper claiming evidence of global insect declines achieved huge media attention, including claims of "insectaggedon" and a "collapse of nature." Here, we argue that while many insects are declining in many places around the world, the study has important limitations that should be highlighted. We emphasise the robust evidence of large and rapid insect declines present in the literature, while also highlighting the limitations of the original study.

Heard but not seen: Comparing bat assemblages and study methods in a mosaic landscape in the Western Ghats of India.

We used capture (mist-netting) and acoustic methods to compare the species richness, abundance, and composition of a bat assemblage in different habitats in the Western Ghats of India. In the tropics, catching bats has been more commonly used as a survey method than acoustic recordings. In our study, acoustic methods based on recording echolocation calls detected greater bat activity and more species than mist-netting. However, some species were detected more frequently or exclusively by capture. Ideally, the two methods should be used together to compensate for the biases in each. Using combined capture and acoustic data, we found that protected forests, forest fragments, and shade coffee plantations hosted similar and diverse species assemblages, although some species were recorded more frequently in protected forests. Tea plantations contained very few species from the overall bat assemblage. In riparian habitats, a strip of forested habitat on the river bank improved the habitat for bats compared to rivers with tea planted up to each bank. Our results show that shade coffee plantations are better bat habitat than tea plantations in biodiversity hotspots. However, if tea is to be the dominant land use, forest fragments and riparian corridors can improve the landscape considerably for bats. We encourage coffee growers to retain traditional plantations with mature native trees, rather than reverting to sun grown coffee or coffee shaded by a few species of timber trees.