Expert knowledge is used widely in the science and practice of conservation because of the complexity of problems, relative lack of data, and the imminent nature of many conservation decisions. Expert knowledge is substantive information on a particular topic that is not widely known by others. An expert is someone who holds this knowledge and who is often deferred to in its interpretation. We refer to predictions by experts of what may happen in a particular context as expert judgments. In general, an expert-elicitation approach consists of five steps: deciding how information will be used, determining what to elicit, designing the elicitation process, performing the elicitation, and translating the elicited information into quantitative statements that can be used in a model or directly to make decisions. This last step is known as encoding. Some of the considerations in eliciting expert knowledge include determining how to work with multiple experts and how to combine multiple judgments, minimizing bias in the elicited information, and verifying the accuracy of expert information. We highlight structured elicitation techniques that, if adopted, will improve the accuracy and information content of expert judgment and ensure uncertainty is captured accurately. We suggest four aspects of an expert elicitation exercise be examined to determine its comprehensiveness and effectiveness: study design and context, elicitation design, elicitation method, and elicitation output. Just as the reliability of empirical data depends on the rigor with which it was acquired so too does that of expert knowledge.

One of the most pressing issues facing the global conservation community is how to distribute limited resources between regions identified as priorities for biodiversity conservation. Approaches such as biodiversity hotspots, endemic bird areas and ecoregions are used by international organizations to prioritize conservation efforts globally. Although identifying priority regions is an important first step in solving this problem, it does not indicate how limited resources should be allocated between regions. Here we formulate how to allocate optimally conservation resources between regions identified as priorities for conservation--the 'conservation resource allocation problem'. Stochastic dynamic programming is used to find the optimal schedule of resource allocation for small problems but is intractable for large problems owing to the "curse of dimensionality". We identify two easy-to-use and easy-to-interpret heuristics that closely approximate the optimal solution. We also show the importance of both correctly formulating the problem and using information on how investment returns change through time. Our conservation resource allocation approach can be applied at any spatial scale. We demonstrate the approach with an example of optimal resource allocation among five priority regions in Wallacea and Sundaland, the transition zone between Asia and Australasia.

Expert judgement informs a variety of important applications in conservation andnatural resource management, including threatened species management, environmental impact assessment and structured decision-making. However, expert judgements can be prone to contextual biases. Structured elicitation protocols mitigate these biases, and improve the accuracy and transparency of the resulting judgements. Despite this, the elicitation of expert judgement within conservation and natural resource management remains largely informal. We suggest this may be attributed to financial and practical constraints, which are not addressed by many existing structured elicitation protocols.2. In this paper, we advocate that structured elicitation protocols must be adopted when expert judgements are used to inform science. In order to motivate a wider adoption of structured elicitation protocols, we outline the IDEA protocol. The protocol improves the accuracy of expert judgements and includes several key steps which may be familiar to many conservation researchers, such as the four-step elicitation, and a modified Delphi procedure ("Investigate," "Discuss," "Estimate" and "Aggregate"). It can also incorporate remote elicitation, making structured expert judgement accessible on a modest budget.3. The IDEA protocol has recently been outlined in the scientific literature; however, a detailed description has been missing. This paper fills that important gap by clearly outlining each of the steps required to prepare for and undertake an elicitation. 4. While this paper focuses on the need for the IDEA protocol within conservation and natural resource management, the protocol (and the advice contained in this paper) is applicable to a broad range of scientific domains, as evidenced by its application to biosecurity, engineering and political forecasting. By clearly outlining the IDEA protocol, we hope that structured protocols will be more widely understood and adopted, resulting in improved judgements and increased transparency when expert judgement is required. K E Y W O R D SDelphi, expert elicitation, forecasting, four-step elicitation, IDEA protocol, quantitative estimates, structured expert judgement

Conservation priority-setting schemes have not yet combined geographic priorities with a framework that can guide the allocation of funds among alternate conservation actions that address specific threats. We develop such a framework, and apply it to 17 of the world's 39 Mediterranean ecoregions. This framework offers an improvement over approaches that only focus on land purchase or species richness and do not account for threats. We discover that one could protect many more plant and vertebrate species by investing in a sequence of conservation actions targeted towards specific threats, such as invasive species control, land acquisition, and off-reserve management, than by relying solely on acquiring land for protected areas. Applying this new framework will ensure investment in actions that provide the most cost-effective outcomes for biodiversity conservation. This will help to minimise the misallocation of scarce conservation resources.

Elicitation of expert opinion is important for risk analysis when only limited data are available. Expert opinion is often elicited in the form of subjective confidence intervals; however, these are prone to substantial overconfidence. We investigated the influence of elicitation question format, in particular the number of steps in the elicitation procedure. In a 3-point elicitation procedure, an expert is asked for a lower limit, upper limit, and best guess, the two limits creating an interval of some assigned confidence level (e.g., 80%). In our 4-step interval elicitation procedure, experts were also asked for a realistic lower limit, upper limit, and best guess, but no confidence level was assigned; the fourth step was to rate their anticipated confidence in the interval produced. In our three studies, experts made interval predictions of rates of infectious diseases (Study 1, n = 21 and Study 2, n = 24: epidemiologists and public health experts), or marine invertebrate populations (Study 3, n = 34: ecologists and biologists). We combined the results from our studies using meta-analysis, which found average overconfidence of 11.9%, 95% CI [3.5, 20.3] (a hit rate of 68.1% for 80% intervals)-a substantial decrease in overconfidence compared with previous studies. Studies 2 and 3 suggest that the 4-step procedure is more likely to reduce overconfidence than the 3-point procedure (Cohen's d = 0.61, [0.04, 1.18]).

Expert judgements are essential when time and resources are stretched or we face novel dilemmas requiring fast solutions. Good advice can save lives and large sums of money. Typically, experts are defined by their qualifications, track record and experience [1], [2]. The social expectation hypothesis argues that more highly regarded and more experienced experts will give better advice. We asked experts to predict how they will perform, and how their peers will perform, on sets of questions. The results indicate that the way experts regard each other is consistent, but unfortunately, ranks are a poor guide to actual performance. Expert advice will be more accurate if technical decisions routinely use broadly-defined expert groups, structured question protocols and feedback.

Aim Decision-making for conservation management often involves evaluating risks in the face of environmental uncertainty. Models support decision-making by (1) synthesizing available knowledge in a systematic, rational and transparent way and (2) providing a platform for exploring and resolving uncertainty about the consequences of management decisions. Despite their benefits, models are still not used in many conservation decision-making contexts. In this article, we provide evidence of common objections to the use of models in environmental decision-making. In response, we present a series of practical solutions for modellers to help improve the effectiveness and relevance of their work in conservation decision-making.Location Global review.Methods We reviewed scientific and grey literature for evidence of common objections to the use of models in conservation decision-making. We present a set of practical solutions based on theory, empirical evidence and best-practice examples to help modellers substantively address these objections.Results We recommend using a structured decision-making framework to guide good modelling practice in decision-making and highlight a variety of modelling techniques that can be used to support the process. We emphasize the importance of participatory decision-making to improve the knowledgebase and social acceptance of decisions and to facilitate better conservation outcomes. Improving communication and building trust are key to successfully engaging participants, and we suggest some practical solutions to help modellers develop these skills.Main conclusions If implemented, we believe these practical solutions could help broaden the use of models, forging deeper and more appropriate linkages between science and management for the improvement of conservation decision-making.

Priorities for conservation investment at a global scale that are based on a single taxon have been criticized because geographic richness patterns vary taxonomically. However, these concerns focused only on biodiversity patterns and did not consider the importance of socioeconomic factors, which must also be included if conservation funding is to be allocated efficiently. In this article, we create efficient global funding schedules that use information about conservation costs, predicted habitat loss rates, and the endemicity of seven different taxonomic groups. We discover that these funding allocation schedules are less sensitive to variation in taxon assessed than to variation in cost and threat. Two-thirds of funding is allocated to the same regions regardless of the taxon, compared with only one-fifth if threat and cost are not included in allocation decisions. Hence, if socioeconomic factors are considered, we can be more confident about global-scale decisions guided by single taxonomic groups.biodiversity hotspots ͉ costs ͉ dynamic planning ͉ priority regions ͉ congruence R ecent global-scale analyses have found that the geographic species richness patterns of different taxonomic groups have low congruence (1-3). These results cast doubt on the generality of global conservation priority regions, which are often delineated based on a single taxon (1-5). These sets of high-priority regions offer conflicting conservation investment priorities because the most effective funding allocation depends on the taxon used to measure biodiversity. However, the biodiversity value of a region is only one of a number of factors that influence where conservation funds should be spent to best safeguard biodiversity (2). Both the cost of conservation action and predicted rates of habitat loss vary greatly across space (6-8), and these factors interact with biodiversity value to determine the relative priority of different regions (6, 9-11).To test whether conservation spending priorities are sensitive to the taxon used to measure biodiversity, we efficiently allocated funding between the world's 34 terrestrial ''biodiversity hotspots'' ( Fig. 1a; ref. 12) by using seven different taxonomic measures of biodiversity [the number of endemic mammals, amphibians, birds, reptiles, freshwater fishes, tiger beetles, and vascular plants (12)]. An allocation schedule was also calculated by using all terrestrial vertebrates combined. We used the biodiversity hotspots as a test case because they are regions of exceptional biodiversity value (each contains Ͼ0.5% of all vascular plant species as endemics) that are under threat (Ͼ70% of their original habitat has already been destroyed), but do not account for the relative cost of conservation in each region. We determined efficient funding allocation schedules for the hotspots by integrating biodiversity, conservation costs, and habitat loss rates into a dynamic decision-theory framework (13), with the objective of minimizing total species loss.For each of the seven taxonomic groups, we...