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International policy is focused on increasing the proportion of the Earth's surface that is protected for nature1,2. Although studies show that protected areas prevent habitat loss3-6, there is a lack of evidence for their effect on species' populations: existing studies are at local scale or use simple designs that lack appropriate controls7-13. Here we explore how 1,506 protected areas have affected the trajectories of 27,055 waterbird populations across the globe using a robust before-after control-intervention study design, which compares protected and unprotected populations in the years before and after protection. We show that the simpler study designs typically used to assess protected area effectiveness (before-after or control-intervention) incorrectly estimate effects for 37-50% of populations-for instance misclassifying positively impacted populations as negatively impacted, and vice versa. Using our robust study design, we find that protected areas have a mixed impact on waterbirds, with a strong signal that areas managed for waterbirds or their habitat are more likely to benefit populations, and a weak signal that larger areas are more beneficial than smaller ones. Calls to conserve 30% of the Earth's surface by 2030 are gathering pace14, but we show that protection alone does not guarantee good biodiversity outcomes. As countries gather to agree the new Global Biodiversity Framework, targets must focus on creating and supporting well-managed protected and conserved areas that measurably benefit populations.

Humanity's impact on the environment is increasing, as are strategies to conserve biodiversity, but a lack of understanding about how interventions affect ecological and conservation outcomes hampers decision-making. Time series are often used to assess impacts, but ecologists tend to compare average values from before to after an impact; overlooking the potential for the intervention to elicit a change in trend. Without methods that allow for a range of responses, erroneous conclusions can be drawn, especially for large, multi-time-series datasets, which are increasingly available. Drawing on literature in other disciplines and pioneering work in ecology, we present a standardised framework to robustly assesses how interventions, like natural disasters or conservation policies, affect ecological time series.

1. Species’ population trends are fundamental to conservation. They are used to de-termine the state of nature, and to prioritize species for conservation action, for example through the IUCN red list. It is crucial to be able to quantify the degree to which population trend data can be trusted, yet there is not currently a straight-forward way to do so.2. We present a method that compares trends derived from various samples of ‘complete’ population time series, to see how often these samples correctly esti-mate the sign (i.e. direction) and magnitude of the complete trend. We apply our method to a dataset of 29,226 waterbird population time series from across North America.3. Our analysis shows that, for waterbirds, if a statistically significant (p < .05) trend is detected, even from only a few years, it is likely to reliably describe the sign (positive or negative) of the complete trend, but is unlikely to accurately match the percentage change in population per year. If no significant trend is detected, a many‐years long sample is required to be confident that the population is truly stable. Furthermore, an insignificant trend is more likely to be missing a decline rather than an increase in the population. Sampling infrequently, but regularly, was surprising reliable in determining trend sign, but poor at determining percentage change per year.4. By providing percentage estimates of reliability for combinations of sampling regimes and lengths, we have a means to determine the reliability of species population trends. This will increase the rigour of large‐scale population analy-ses by allowing users to remove time series that do not meet a reliability cut‐off, or weighting time series by reliability, and could also facilitate planning of future monitoring schemes. While the specific values estimated by our analysis might not be applicable to other taxa or systems, the methods are easily transferable, and we provide the tools to do so.

International policy is focused on increasing the proportion of the Earth's surface that is protected for nature

Conservation science is a crisis-oriented discipline focused on delivering robust answers to reducing human impacts on nature. To explore how the field might have changed during the past two decades, we analyzed 3,245 applications for oral presentations submitted to the Student Conference on Conservation Science (SCCS) in Cambridge, UK. SCCS has been running every year since 2000, aims for global representation by providing bursaries to early-career conservationists from lower-income countries, and has never had a thematic focus, beyond conservation in the broadest sense. We found that the majority of submissions to SCCS were based on primary biological data collection from local scale field studies in the tropics, contrary to established literature which highlights gaps in tropical research. Our results showed a small increase over time in submissions framed around how nature benefits people as well as a small increase in submissions integrating social science. Our findings also suggest that students and early-career conservationists could provide pathways to increased availability of data from the tropics and for addressing well-known biases in the published literature towards wealthier countries. We hope this research will motivate efforts to support student projects, ensuring data and results are published and made publicly available.

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.

There is increasing interest in the effectiveness of protected areas (PAs) for supporting populations of wildlife. While there are a number of association studies showing a relationship between protected areas and abundance or trends in wild species, studies with an appropriate counterfactual (what would have happened in the absence of protection) are rare. We use the world’s largest database on waterbird counts (covering 587 species at 21,989 sites globally) to answer three questions: 1) Do PAs have a positive impact on waterbird population trends relative to a counterfactual (this includes cases where a PA has lessened, but not halted, a population decline)?; 2) are PAs performing successfully by maintaining or increasing populations? and 3) what factors contribute to PA impact and performance? We selected 15,703 waterbird populations (here defined as a site species combination), consisting of 311 species at 870 protected sites, where PA designation occurred at least 5 years after the first survey date, and 5 years before the last. We will use this to compare trends before PA designation to those afterwards. We then matched these sites to unprotected sites with similar covariates in the years before PA designation, resulting in a matching dataset of 6,451 populations pairs consisting of 39 species at 769 pairs of protected and unprotected sites. We will use this to compare trends both before and after PA designation and inside and outside of PAs. Our results will shed light on the impact of PA on hundreds of waterbird species, providing much needed evidence regarding PA effectiveness. As PA performance is a sensitive subject and it is important to develop hypotheses before knowing the results (especially for the relatively complex data analysis used in matching protected and unprotected sites), we present a pre-analysis plan. This will ensure that the final paper’s analyses are hypotheses testing, rather than generating, and avoids the risk of, or perception of, data dredging.

Species are central to ecology and conservation. However, it is the interactions between species that generate the functions on which ecosystems and humans depend. Despite the importance of interactions, we lack an understanding of the risk that their loss poses to ecological communities. Here, we quantify risk as a function of the vulnerability (likelihood of loss) and importance (contribution to network stability in terms of species coexistence) of 4330 mutualistic interactions from 41 empirical pollination and seed dispersal networks across six continents. Remarkably, we find that more vulnerable interactions are also more important: the interactions that contribute most to network stability are those that are most likely to be lost. Furthermore, most interactions tend to have more similar vulnerability and importance across networks than expected by chance, suggesting that vulnerability and importance may be intrinsic properties of interactions, rather than only a function of ecological context. These results provide a starting point for prioritising interactions for conservation in species interaction networks and, in areas lacking network data, could allow interaction properties to be inferred from taxonomy alone.

Improving the use of scientific evidence in conservation policy has been a long-standing focus of the conservation community. A plethora of studies have examined conservation science-policy interfaces, including a recent global survey of scientists, policy-makers, and practitioners. This identified a list of top barriers and solutions to evidence use, which have considerable overlap with those identified by other studies conducted over the last few decades. The three top barriers – (i) that conservation is not a political priority, (ii) that there is poor engagement between scientists and decision-makers, and (iii) that conservation problems are complex and uncertain – have often been highlighted in the literature as significant constraints on the use of scientific evidence in conservation policy. There is also repeated identification of the solutions to these barriers. In this perspective, we consider three reasons for this: (1) the barriers are insurmountable, (2) the frequently-proposed solutions are poor, (3) there are implementation challenges to putting solutions into practice. We argue that implementation challenges are most likely to be preventing the solutions being put into practice and that the research agenda for conservation science-policy interfaces needs to move away from identifying barriers and solutions, and towards a detailed investigation of how to overcome these implementation challenges., DCR acknowledges the support of the University of East Anglia for supporting travel associated with this paper. WJS is funded by Arcadia. HSW is funded by a Cambridge Trust Cambridge-Australia Scholarship and a Cambridge Department of Zoology JS Gardiner Fellowship. BIS is supported by the Natural Environment Research Council as part of the Cambridge Earth System Science NERC DTP [NE/L002507/1]. RJR is supported by the Natural Environment Research Council as part of the Leeds-York SPHERES NERC DTP [NE/L002574/1]. TA acknowledges the Grantham Foundation for the Protection of the Environment, the Kenneth Miller Trust, and an Australian Research Council Future Fellowship (FT180100354).

Indirect interactions play an essential role in governing population, community and coevolutionary dynamics across a diverse range of ecological communities. Such communities are widely represented as bipartite networks: graphs depicting interactions between two groups of species, such as plants and pollinators or hosts and parasites. For over thirty years, studies have used indices, such as connectance and species degree, to characterise the structure of these networks and the roles of their constituent species. However, compressing a complex network into a single metric necessarily discards large amounts of information about indirect interactions. Given the large literature demonstrating the importance and ubiquity of indirect effects, many studies of network structure are likely missing a substantial piece of the ecological puzzle. Here we use the emerging concept of bipartite motifs to outline a new framework for bipartite networks that incorporates indirect interactions. While this framework is a significant departure from the current way of thinking about bipartite ecological networks, we show that this shift is supported by analyses of simulated and empirical data. We use simulations to show how consideration of indirect interactions can highlight differences missed by the current index paradigm that may be ecologically important. We extend this finding to empirical plant–pollinator communities, showing how two bee species, with similar direct interactions, differ in how specialised their competitors are. These examples underscore the need to not rely solely on network‐ and species‐level indices for characterising the structure of bipartite ecological networks.

Interactions between species generate the functions on which ecosystems and humans depend. However, we lack an understanding of the risk that interaction loss poses to ecological communities. Here, we quantify the risk of interaction loss for 4,330 species interactions from 41 empirical pollination and seed dispersal networks across 6 continents. We estimate risk as a function of interaction vulnerability to extinction (likelihood of loss) and contribution to network feasibility, a measure of how much an interaction helps a community tolerate environmental perturbations. Remarkably, we find that more vulnerable interactions have higher contributions to network feasibility. Furthermore, interactions tend to have more similar vulnerability and contribution to feasibility across networks than expected by chance, suggesting that vulnerability and feasibility contribution may be intrinsic properties of interactions, rather than only a function of ecological context. These results may provide a starting point for prioritising interactions for conservation in species interaction networks in the future., A study of 4,330 species interactions from 41 empirical pollination and seed dispersal networks across six continents reveals that species interactions which are most vulnerable to extinction are also the most important for ecological community stability; moreover, vulnerable interactions that are important for stability tend to be important and vulnerable wherever they occur.

Species’ population trends are fundamental to conservation, underpinning lUCN red-list classifications, many national lists of threatened species and are also used globally to convey to policy makers the state of nature. Clearly, it’s crucial to quantify how much we can trust population trend data. Yet many studies analyzing large numbers of population time series lack a straightforward way to estimate confidence in each trend. Here we artificially degrade 27,930 waterbird population time series to see how often subsets of the data correctly estimate the direction and magnitude of each population’s true trend. We find you need to sample many years to be confident that there is no significant trend in a population. Conversely, if a significant trend is detected, even from only a small subset of years, this is likely to be representative of the population’s true trend. This means that if a significant decline is detected in a population, it is likely to be correct and conservation action should be taken immediately, but if the trend is insignificant, confidence in this can only be high with many samples. Our full results provide a clear and quantitative way to assign confidence to species trends, and lays the foundation for similar studies of other taxa that can help to add rigor to large-scale population analyses.

Conservation policy decisions can suffer from a lack of evidence, hindering effective decision-making. In nature conservation, studies investigating why policy is often not evidence-informed have tended to focus on Western democracies, with relatively small samples. To understand global variation and challenges better, we established a global survey aimed at identifying top barriers and solutions to the use of conservation science in policy. This obtained the views of 758 people in policy, practice, and research positions from 68 countries across six languages. Here we show that, contrary to popular belief, there is agreement between groups about how to incorporate conservation science into policy, and there is thus room for optimism. Barriers related to the low priority of conservation were considered to be important, while mainstreaming conservation was proposed as a key solution. Therefore, priorities should focus on convincing the public of the importance of conservation as an issue, which will then influence policy-makers to adopt pro-environmental long-term policies. NERC (1653183) Grantham Foundation for the Protection of the Environment Kenneth Miller Trust (unknown) NERC (1653183) NERC (NE/L002507/1) European Commission (308454)

Article impact statement: Structured decision making can be used to identify an optimal source population for conservation introductions.

Millions of birds migrate to and from the Arctic each year, but rapid climate change in the High North could strongly affect where species are able to breed, disrupting migratory connections globally. We modelled the climatically suitable breeding conditions of 24 Arctic specialist shorebirds and projected them to 2070 and to the mid-Holocene climatic optimum, the world's last major warming event ~6000 years ago. We show that climatically suitable breeding conditions could shift, contract and decline over the next 70 years, with 66–83% of species losing the majority of currently suitable area. This exceeds, in rate and magnitude, the impact of the mid-Holocene climatic optimum. Suitable climatic conditions are predicted to decline acutely in the most species rich region, Beringia (western Alaska and eastern Russia), and become concentrated in the Eurasian and Canadian Arctic islands. These predicted spatial shifts of breeding grounds could affect the species composition of the world's major flyways. Encouragingly, protected area coverage of current and future climatically suitable breeding conditions generally meets target levels; however, there is a lack of protected areas within the Canadian Arctic where resource exploitation is a growing threat. Given that already there are rapid declines of many populations of Arctic migratory birds, our results emphasize the urgency of mitigating climate change and protecting Arctic biodiversity.