Summary1. Although conceptually robust, it has proven difficult to find practical measures of niche width that are simple to obtain, yet provide an adequate descriptor of the ecological position of the population examined. 2. Trophic niche has proven more tractable than other niche dimensions. However, indices used as a proxy for trophic niche width often suffer from the following difficulties. Such indices rarely lie along a single scale making comparisons between populations or species difficult; have difficulty in combining dietary prey diversity and evenness in an ecologically meaningful way; and fail to integrate diet over ecological time-scales thus usually only comprise single snapshots of niche width. 3. We propose an alternative novel method for the comparison of trophic niche width: the use of variance of tissue stable isotope ratios, especially those of nitrogen and carbon. 4. This approach is a potentially powerful method of measuring trophic niche width, particularly if combined with conventional approaches, because: it provides a single measure on a continuous axis that is common to all species; it integrates information on only assimilated prey over time; the integration period changes with choice of tissue sampled; and data production is theoretically fast and testing among populations simple. 5. Empirical studies are now required to test the benefits of using isotopic variance as a measure of niche width, and in doing so help refine this approach.

© 2 0 1 6 M a c m i l l a n P u b l i s h e r s L i m i t e d , p a r t o f S p r i n g e r N a t u r e . A l l r i g h t s r e s e r v e d .risk -have guided assessments, now for 82,845 species. Assessors assign species to categories, including 'near-threatened' , 'vulnerable' , 'endangered' or 'critically endangered' depending on their population size; past, current and projected population trends; geographic range and other symptoms of extinction risk. Species in the latter three groups are collectively referred to as 'threatened' .To assess the relative prevalence of current hazards to biodiversity, we quantified threat information for 8,688 near-threatened or threatened species belonging to species groups in which all known species have been assessed (for complete list of taxa included, see Supplementary Information; go.nature.com/2ajen88).The basic message emerging from these data is that whatever the threat category or species group, overexploitation and agriculture have the greatest current impact on biodiversity (see 'Big killers').Of the species listed as threatened or near-threatened, 72% (6,241) are being overexploited for commerce, recreation or subsistence. The Sumatran rhinoceros (Dicerorhinus sumatrensis), Western gorilla (Gorilla gorilla) and Chinese pangolin (Manis penta dactyla, a scaly mammal), for instance, are all illegally hunted as a result of high market demand for their body parts and meat. These are just three of the more than 2,700 species affected by hunting or fishing, or by people collecting live specimens for the pet trade. At the same time, unsustainable logging is contributing to the decline of more than 4,000 forest-dependent species, such as the Bornean wren-babbler (Ptilocichla leucogrammica), India's Nicobar shrew (Crocidura nicobarica), and the Myanmar snub-nosed monkey (Rhinopithecus strykeri).The expansion and intensification of agricultural activity is imperilling 5,407 species -62% of those listed as threatened or near-threatened. Africa's cheetah (Acinonyx jubatus), Asia's hairy-nosed otter (Lutra sumatrana) and South America's huemul deer (Hippocamelus bisulcus) are among more than 2,300 species affected by livestock farming and aquaculture. And the Fresno kangaroo rat (Dipodomys nitratoides) and the African wild dog (Lycaon pictus) are two of more than 4,600 species currently under threat from land modification associated with the production of food, fodder or fuel crops.Meanwhile, anthropogenic climate change -including increases in storms, flooding, extreme temperatures or drought that exceed background variability, as well as sea-level rise -is currently affecting 19% of species listed as threatened or near-threatened. Hooded seals (Cystophora cristata) are among the 1,688 species affected. These have dropped in abundance by 90% in the northeastern Atlantic Arctic over the past few decades More than 80% of species analysed are harmed by more than one sub-class threat. OVER-EXPLOITATION BIG KILLE SOverexploitation and agriculture are the most prevalent threats faci...

The world's human population is becoming concentrated into cities, giving rise to concerns that it is becoming increasingly isolated from nature. Urban public greenspaces form the arena of many people's daily contact with nature and such contact has measurable physical and psychological benefits. Here we show that these psychological benefits increase with the species richness of urban greenspaces. Moreover, we demonstrate that greenspace users can more or less accurately perceive species richness depending on the taxonomic group in question. These results indicate that successful management of urban greenspaces should emphasize biological complexity to enhance human well-being in addition to biodiversity conservation.

There is mounting empirical evidence that interacting with nature delivers measurable benefits to people. Reviews of this topic have generally focused on a specific type of benefit, been limited to a single discipline, or covered the benefits delivered from a particular type of interaction. Here we construct novel typologies of the settings, interactions and potential benefits of people-nature experiences, and use these to organise an assessment of the benefits of interacting with nature. We discover that evidence for the benefits of interacting with nature is geographically biased towards high latitudes and Western societies, potentially contributing to a focus on certain types of settings and benefits. Social scientists have been the most active researchers in this field. Contributions from ecologists are few in number, perhaps hindering the identification of key ecological features of the natural environment that deliver human benefits. Although many types of benefits have been studied, benefits to physical health, cognitive performance and psychological well-being have received much more attention than the social or spiritual benefits of interacting with nature, despite the potential for important consequences arising from the latter. The evidence for most benefits is correlational, and although there are several experimental studies, little as yet is known about the mechanisms that are important for delivering these benefits. For example, we do not know which characteristics of natural settings (e.g., biodiversity, level of disturbance, proximity, accessibility) are most important for triggering a beneficial interaction, and how these characteristics vary in importance among cultures, geographic regions and socio-economic groups. These are key directions for future research if we are to design landscapes that promote high quality interactions between people and nature in a rapidly urbanising world.

Boakes et al. compile and analyze a historical dataset of 170,000 bird sightings over two centuries and show how changing trends in data gathering may confound a true picture of biodiversity change.

Summary 1.Geographic range size and how it changes through time is one of the fundamental ecological and evolutionary characteristics of a species, and a strong predictor of extinction risk. However, the measurement of range size remains a substantial challenge. Indeed, there is significant confusion in the literature as to how this should be done, particularly in the context of the distinction between the fundamentally different concepts of extent of occurrence (EOO) and area of occupancy (AOO), and the use of these quantities, including in assessments of the threat status of species. 2. Here we review the different approaches to determining the geographic distributions of species, the measurement of their range sizes, the relationships between the two, and other difficulties posed by range size measurement (especially those of range discontinuities when measuring EOO, and spatial scale when measuring AOO). 3. We argue that it is important to (i) distinguish the estimation of the distribution of a species from the measurement of its geographic range size; (ii) treat measures of EOO and AOO as serving different purposes, rather than regarding them as more or less accurate ways of measuring range size; and (iii) measure EOO including discontinuities in habitat or occupancy. Synthesis and applications.With the availability and collation of extensive data sets on species occurrences, a rapidly increasing number of studies are investigating geographic range size, and particularly how various measures of range size predict macroecological patterns and inform assessments of the conservation status of species and areas. The distinction between EOO and AOO is becoming blurred in many contexts, but most particularly in that of threatened species assessments for Red Listing. Continued progress in these fields demands greater clarity in the meaning and derivation of measures of geographic range size. The two principal measures serve different purposes, and should not be regarded as alternatives that simply differ in accuracy.

Meeting international targets for expanding protected areas could simultaneously contribute to species conservation, but only if the distribution of threatened species informs the future establishment of protected areas.

There are many barriers to using science to inform conservation policy and practice. Conservation scientists wishing to produce management-relevant science must balance this goal with the imperative of demonstrating novelty and rigor in their science. Decision makers seeking to make evidence-based decisions must balance a desire for knowledge with the need to act despite uncertainty. Generating science that will effectively inform management decisions requires that the production of information (the components of knowledge) be salient (relevant and timely), credible (authoritative, believable, and trusted), and legitimate (developed via a process that considers the values and perspectives of all relevant actors) in the eyes of both researchers and decision makers. We perceive 3 key challenges for those hoping to generate conservation science that achieves all 3 of these information characteristics. First, scientific and management audiences can have contrasting perceptions about the salience of research. Second, the pursuit of scientific credibility can come at the cost of salience and legitimacy in the eyes of decision makers, and, third, different actors can have conflicting views about what constitutes legitimate information. We highlight 4 institutional frameworks that can facilitate science that will inform management: boundary organizations (environmental organizations that span the boundary between science and management), research scientists embedded in resource management agencies, formal links between decision makers and scientists at research-focused institutions, and training programs for conservation professionals. Although these are not the only approaches to generating boundary-spanning science, nor are they mutually exclusive, they provide mechanisms for promoting communication, translation, and mediation across the knowledge–action boundary. We believe that despite the challenges, conservation science should strive to be a boundary science, which both advances scientific understanding and contributes to decision making.Logrando que la Ciencia de la Conservación Trasponga la Frontera Conocimiento-AcciónResumenHay muchas barreras para utilizar ciencia para informar a la política y práctica de la conservación. Los científicos de la conservación que desean producir ciencia relevante para el manejo deben equilibrar esta meta con el imperativo de demostrar novedad y rigor en su ciencia. Los tomadores de decisiones que buscan que sus decisiones se basen en evidencias deben equilibrar el deseo de conocimientos con la necesidad de actuar a pesar de la incertidumbre. La generación de ciencia que informe efectivamente a las decisiones de manejo requiere que la producción de información (los componentes del conocimiento) sea sobresaliente (relevante y oportuna), creíble (autoritativa, verosímil y confiable) y legítima (desarrollada mediante un proceso que considera los valores y perspectivas de todos los actores relevantes) a la vista tanto de investigadores como de tomadores de decisiones. Percibimos tres r...