Evidence-Based Practice (EBP) requires that decisions are based on the best available, current, valid and relevant evidence. These decisions should be informed by the tacit and explicit knowledge of those making the decision and within the context of available resources.
Perhaps the best example comes from medical practice. Medical training used to consist of trainee doctors following consultants and learning from their experience. It was then realised that there were enormous discrepancies in practice between hospitals which, when compared, showed striking differences in recovery rate of patients between approaches. This led to evidence-based medicine in which the assessment of effectiveness underpins almost all current practice.
The approach to medical practice 30 years ago was similar to the current approach to nature conservation, so a number of people (Pullin & Knight 2001, Sutherland 2001, Sutherland et al. 2004) suggested that a similar revolution would benefit conservation management. The vision is that the assessment and dissemination of the effectiveness of conservation actions will be a routine part of conservation practice.
Conservation Evidence is a free, authoritative information resource aiming to support decisions about how to maintain and restore global biodiversity. The idea is to give busy conservationists access to the very latest and most relevant ecological knowledge to support their management, policy or funding decisions.
Conservation Evidence is also contributing to increasing the use of evidence-based practice in conservation by providing the tools and guidance needed to incorporate this evidence into conservation projects.
Unfortunately, Conservation Evidence cannot make recommendations for individual decisions. This is because it is difficult to give evidence-based conservation advice that is appropriate for every context. Instead, we provide evidence and an assessment of that evidence, which should be interpreted by conservationists who understand their own site and national or regional situation.
Conservation Evidence is for anybody wishing to find the scientific evidence behind a specific management intervention. Crucially, this information is made available for free, so anyone can read it and see what has worked – and what hasn’t. Our aim is to help break down the barrier between science and practice, so that where relevant science exists, conservation practitioners, managers, and policy makers have access to it. The hope is that this will result in better-informed decisions and more effective management.
It is compiled particularly for those working to support or protect biodiversity, such as land managers, conservationists, farmers, policymakers, researchers, advisors or consultants.
However, we would also encourage its use for general fact-finding, such as by students, teachers or anyone wanting to find out more about biodiversity conservation.
The website is a database of scientific studies that describe the effects of conservation interventions.
There are both individual pieces of evidence - summaries of studies published in our own Conservation Evidence Journal or other scientific journals, or from other sources of evidence such as reports ('grey literature') - and ‘action’ pages, with summaries of all of the studies that tested that action (or intervention). We also provide expert assessment of the effectiveness of each action based on the summarized evidence, see What Works in Conservation for more details.
There are two fundamental criteria for inclusion of studies on the website:
- - There must have been an intervention that conservationists would do
- - Its effects must have been monitored quantitatively
More specifically our inclusion criteria are:
1. Does the study measure the effect of an action that is or was under the control of humans, on wild taxa (including captives), habitats, or invasive/problem taxa? If yes, go to 2. If no, go to 3.
2. Could the action be put in place by a conservationist/decision maker to protect, manage or restore wild taxa or habitats, to reduce impacts of threats to wild taxa or habitats, or to control or mitigate the impact of the invasive/problem taxon on wild taxa or habitats? If yes, include. If no, exclude.
3. Does the study measure the effect of an action that is or was under the control of humans, on human behaviour that is relevant to conserving biodiversity? If yes, go to a. If no, exclude.
a) Does this study measure the effect of an action that is or was under human control on human behaviour (actual or intentional) which is likely to protect, manage or restore wild taxa or habitats, or reduce threats to wild taxa or habitats? If yes, go to b. If no, exclude.
b) Could the action be put in place by a conservationist, manager or decision maker to change human behaviour? If yes, include. If no, exclude.
We DO NOT include:
- - Theoretical modelling studies, as no action has been taken on the ground.
- - Correlative studies, i.e. studies that examine associations between biodiversity and habitat features without a clear link to a management action. Where correlative studies have strong conservation implications, they may be mentioned in the background sections for actions.
- - Studies solely reporting monitoring methods, species ecology, biodiversity surveys, or threats to biodiversity.
- - Studies with no quantitative monitoring of effects of actions including some review studies, descriptions of experiments with no results presented, or results presented qualitatively (as “success” or photographs).
- - Papers/reports with no additional scientific evidence including opinion pieces or papers that review literature but do not introduce any new data we have not covered already.
A conservation action or intervention is anything you might do to manage, protect, enhance or restore biodiversity or ecosystem services.
Actions/Interventions include types of habitat or species management, methods of species or site protection, methods of controlling invasive species, species reintroduction, captive breeding, legislation, and education programmes.
The International Union for the Conservation of Nature (IUCN)’s Conservation Actions Classification Scheme provides an overview of possible types of intervention.
Yes there are. We and others have quantified several biases in the scientific literature and we are working hard to address these.
First, there is geographic and taxonomic bias in the evidence base because funding and logistical constraints mean that published studies tend to test interventions in North America, Europe and Australasia. We have also found that fewer published tests of interventions tend to take place in locations with more threatened species, and that there are some severe gaps in the evidence for certain taxonomic orders and groups [1,2]. We are trying to encourage better prioritisation and funding of research that that tests conservation interventions by working with funders and various conservation NGOs, but also to investigate how much we can generalise and apply the findings of studies to different locations and taxonomic groups.
Second, language bias is a major issue more generally for science, and we know that as much as 30% of studies in conservation science are published in non-English languages[3,4]. Dr Tatsuya Amano is helping us integrate the non-English literature that tests conservation interventions through the translatE project (Transcending Language Barriers to Environmental Sciences) and we already have included several non-English studies in our database.
Third, the grey literature (i.e., unpublished or non-peer reviewed reports and studies that are often hard to find) is known to contain relevant studies that test conservation interventions and we are making concerted efforts to integrate these studies in our database.
Finally, a fundamental issue with published scientific evidence is publication bias, specifically the ‘file-drawer effect’, whereby positive results are more likely to be published than negative or neutral results. This is a major challenge to overcome, but we are promoting the publication of tests of interventions, regardless of their success or failure, through the Conservation Evidence journal and encouraging other journals and funders to promote similar approaches to addressing this bias. It is also possible that by integrating more non-English and grey literature studies we can address some of the bias against negative and neutral results.
Evidence is never perfect or completely unbiased, and it is important to understand that these biases that are present in our database are also systematic challenges that affect the whole of conservation – if the scientific literature suffers from biases, so will our database and summaries of scientific evidence unless we take action. Therefore, we are committed to addressing these biases and are working hard with various partners and stakeholders to improve the evidence base for conservation.
 Christie, A.P., Amano, T., Martin, P.A., Petrovan, S.O., Shackelford, G.E., Simmons, B.I., Smith, R.K., Williams, D.R., Wordley, C.F.R. and Sutherland, W.J. (2020). The challenge of biased evidence in conservation. Conservation Biology, Early View Article. https://doi.org/10.1111/cobi.13577
 Junker, J., Petrovan, S.O., Arroyo-Rodriguez, V., Boonratana, R., Byler, D., Chapman, C.A., Chetry, D., Cheyne, S.M., Christie, A.P., et al. (2020). Severe Lack of Evidence Limits Effective Conservation of the World’s Primates. Bioscience, Accepted Author Manuscript. https://doi.org/10.1093/biosci/biaa082
 Amano, T., González-Varo, J.P. and Sutherland, W.J. (2016). Languages Are Still a Major Barrier to Global Science. PLoS Biology, 14 (12), e2000933. doi: 10.1371/journal.pbio.2000933
 Amano, T. and Sutherland, W.J. (2013). Four barriers to the global understanding of biodiversity conservation: wealth, language, geographical location and security. Proceedings of the Royal Society B - Biological Sciences, 280 (1756), 20122649-20122649. doi: 10.1098/rspb.2012.2649
For each action, we have summarised and assessed evidence from the scientific literature about its effectiveness.
Each action page contains brief (approx. 200 word) descriptions of each study that we found that tested the action.
There is also a set of key messages that provide a descriptive index to the studies summarised. You can look at the key messages and then at the summary paragraph describing each study to get more details, and assess the quality of evidence and how relevant it is to your situation.
The evidence summarised for each action has also been assessed by a panel of experts to determine how effective the action is. For more details see What Works in Conservation.
An individual study is a short summary of a specific scientific study. Each is a brief (150-200 word) description that provides the background context, the conservation action(s) taken and the consequences. Studies come from systematic searches of scientific journals and other sources of scientific evidence including reports ('grey literature').
Each individual study has a separate page that provides the summary written for each of the actions that it tested. There is a link to each of those action pages, where you can read other evidence for the effectiveness of that action.
See also: The Site - What are the criteria for inclusion of studies on the website?
Synopses bring together all the evidence for the effects of actions for particular species groups, habitats or issues and contain all the ‘Action pages' for that topic.
Our series of synopses will eventually provide a comprehensive overview of the effectiveness of conservation actions worldwide.
The Conservation Evidence Journal is a peer-reviewed journal that publishes standard papers and short communications detailing the effectiveness of conservation actions. We aim to provide the key information for successful conservation as easily as possible.
What Works in Conservation provides expert assessment of the effectiveness of actions based on the summarized evidence.
Panels of experts have assessed the collated evidence for each action to determine effectiveness, certainty of the evidence and, in most cases, whether there are negative side-effects on the group of species or habitat of concern (harms). Using these assessments, actions are categorized based on a combination of effectiveness (the size of benefit or harm) and certainty (the strength of the evidence). The following categories are used: Beneficial, Likely to be beneficial, Trade-off between benefit and harms, Unknown effectiveness, Unlikely to be beneficial, Likely to be ineffective or harmful.
It is important to remember that this website is a guide to the evidence available for different conservation actions and as a starting point in assessing their effectiveness. The assessments are based on the available evidence for the target group of species or habitat for each action. The assessment may therefore refer to different species or habitat to the one(s) you are considering. Before making any decisions about implementing actions it is vital that you read the more detailed accounts of the evidence in order to assess their relevance for your study species or system.
There may also be significant negative side-effects on the target groups or other species or communities that have not been identified in the assessments.
A lack of evidence means that we have been unable to assess whether or not an action is effective or has any harmful impacts.
How should I use the website?
The information held on this site can be used for example, to guide conservation actions and management plans. However, it does not tell you what to do.
To use the website efficiently, you can search for information relevant to your work, and then assess how applicable the interventions are to your situation. For example, ask yourself:
- Do they deal with the same species or habitats?
- Which studies are the most relevant?
- How contingent are they on local conditions?
- How strong is the evidence one way or another?
Have a think, then apply the information to your situation and decide on the course of action most likely to succeed.
Conservation Evidence journal papers should be quoted in the form: Badley J. & Allcorn R.I. (2006) The creation of a new saline lagoon as part of a flood defence scheme at RSPB Freiston Shore Nature Reserve, Lincolnshire, England. Conservation Evidence, 3, 99-101.
What Works in Conservation should be quoted in the form: Sutherland, W.J., Dicks, L.V. Ockendon, N. & Smith, R.K. (2019) What Works in Conservation. Cambridge, UK: Open Book Publishers.
Conservation Evidence synopses should be quoted in the form: Dicks L.V., Showler D.A. & Sutherland W.J. (2010) Bee Conservation: Evidence for the effects of interventions. Synopses of Conservation Evidence. Pegasus Publishing, Exeter.
Summaries of individual studies should be cited as the original reference (as given at the top of each individual summary).
The Conservation Evidence Journal
The criteria for our online Conservation Evidence Journal are the same as for inclusion on the website:
- There must have been an action that conservationists would do
- Its effects must have been monitored quantitatively
Suitable actions include habitat creation, habitat restoration, translocations, reintroductions, mitigation, and invasive species control. All that is required is an action and quantitative monitoring. We do not include studies solely reporting monitoring methods, species ecology, biodiversity surveys, or threats to biodiversity.
We also welcome reports of unsuccessful interventions – a key part of our philosophy is that it is just as important to report when something doesn’t work as when it does. If you don’t publish this information then people will continue to try the same, ineffective actions time after time.
For details on how to submit a paper, please go to the Conservation Evidence Journal.
What Works in Conservation
The average of several experts’ opinions is likely to be a more reliable and accurate assessment than the opinion of a single expert. We therefore ask a panel of experts (listed in What Works in Conservation for each synopsis) to use their judgement to assess whether evidence within a synopsis indicates that an intervention is effective or not. They are also asked to assess how certain they are of the effectiveness given the quality of evidence available for that intervention (certainty of the evidence). Negative side-effects described in the collated evidence are also assessed for the species group or habitat of concern (harms). Experts base their assessment solely on the evidence in the synopsis.
We use a modified Delphi method to quantify the effectiveness and certainty of evidence of each intervention, based on the summarized evidence. The Delphi method is a structured process that involves asking a panel of experts to state their individual opinion on a subject by scoring anonymously. They can then revise their own scores after seeing a summary of scores and comments from the rest of the panel. Final scores are then collated. Scores and comments are kept anonymous throughout the process so that participants are not overly influenced by any single member of the panel.
For each intervention, experts are asked to read the summarized evidence in the synopsis and then score to indicate their assessment of the following:
Effectiveness: 0% = not effective, 100% = highly effective.
Certainty of the evidence: 0% = no evidence, 100% = high quality evidence; complete certainty. This is certainty of effectiveness of intervention, not of harms.
Harms: 0% = none, 100% = major undesirable effects.
The median score from all the experts’ assessments is calculated for the effectiveness, certainty and harms for each intervention. The overall effectiveness categorization is based on these median values, i.e. on a combination of the size of the benefit and harm and the strength of the evidence.
After one or two rounds of initial scoring, interventions are categorized by their overall effectiveness, as assessed by the expert panel. The median score from all the experts’ assessments is calculated for the effectiveness, certainty and harms for each intervention. Categorization is based on these median values, i.e. on a combination of the size of the benefit and harm and the strength of the evidence. The categories and their associated scores are listed in the table below. There is an important distinction between lack of benefit and lack of evidence of benefit.
|Overall effectiveness categories||Effectiveness scores||Certainty scores||Harm scores|
|Trade-offs between benefits & harms||≥40%||≥40%||≥20%|
|Unknown effectiveness||Any score||<40%||Any score|
|Unlikely to be beneficial||<40%||>60%||Any score|
Once interventions are categorized, experts are given the chance to object if they believe an intervention has been categorized incorrectly. Interventions that receive a specified number (depending on the size of the panel) of strong objections from experts are re-scored by the expert panel and re-categorized accordingly.
Note that while experts use standardised instructions there will be some variation between synopses in how the evidence is interpreted given the differences in evidence quality and quantity for different species groups and habitats.
Using the assessments
It is important to remember that this website is a guide to the evidence available for different conservation interventions and as a starting point in assessing their effectiveness. The assessments are based on the available evidence for the target group of species or habitat for each intervention. The assessment may therefore refer to different species or habitat to the one(s) you are considering. Before making any decisions about implementing interventions it is vital that you read the more detailed accounts of the evidence in order to assess their relevance for your study species or system.
There may also be significant negative side-effects on the target groups or other species or communities that have not been identified in the assessments.
A lack of evidence means that we have been unable to assess whether or not an intervention is effective or has any harmful impacts.
Although most interventions and synopses have been assessed to produce What Works in Conservation, some sections (notably the Bee Conservation synopsis) have not yet been assessed by an expert panel. These sections will be assessed soon.
Some interventions in the Farmland Conservation and Bird Conservation synopses have assessments of effectiveness and certainty but not of harms. This is because these assessments were carried out as part of different projects. Details of the assessment for interventions to deal with Invasive alien and other problematic species in the Bird Conservation synopsis are given in Walsh J.C., Dicks L.V. & Sutherland W.J. (2015) The effect of scientific evidence on conservation practitioners’ management decisions. Conservation Biology, 29, 88-98. The assessment methodology used on interventions in the Farmland Conservation synopsis is provided in Dicks L.V., Hodge I., Randall N.P., Scharlemann J.P.W., Siriwardena G.M., Smith H.G., Smith R.K. & Sutherland W.J. (2014) A Transparent Process for "Evidence-Informed" Policy Making. Conservation Letters, 7, 119-125.
So far we have completed 18 synopses, on amphibian conservation, bat conservation, bee conservation, bird conservation, forest conservation, marine mammal conservation, peatland conservation, primate conservation, shrubland and heathland conservation, terrestrial mammal conservation (excluding bats and primates), subtidal benthic invertebrate conservation, conservation on northern European farmland, enhancing natural pest control, enhancing soil fertility, sustainable agriculture in California and Mediterranean climates, sustainable aquaculture, control of freshwater invasive species and management of captive animals. All but the farmland and sustainable agriculture synopes are global in scope. The farmland synopsis includes evidence from northern Europe (all European countries west of Russia, but not those south of France, Switzerland, Austria, Hungary and Romania).
Funding from the Natural Environment Research Council allowed us to develop the synopses of actions for sustainable production on farmland (such as natural pest regulation, and soil quality) and in aquaculture.
Six global conservation synopses are currently being produced on the conservation of reptiles, marine fish (selected actions), terrestrial invertebrates (selected groups), wetlands (marshes and swamps), grasslands (selected actions) and enhancing biodiversity on marine artificial structures. Additional topics are also being added to the synopsis on the control of invasive species. We are also currently updating the synopsis on the conservation of birds.
Over the next five years, Conservation Evidence aims to produce synopses covering every major habitat and taxonomic group.
Each will be produced through thorough literature reviews and with an international panel of experts advising on the scope and structure of the synopsis, ensuring that they communicate the information that conservation practitioners need in the easiest and most useful way possible.
These synopses will be available individually, online (both as a downloadable PDF and as a searchable database) and some in print, but will also be combined online as a searchable database to provide an authoritative guide to conservation practice for any habitat and taxon, anywhere in the world.
Who are we?
See here: Conservation Evidence Team
How can I contribute to the Conservation Evidence project?
If you think that we’ve missed some evidence on the action articles, then email email@example.com and send us the details. You can also attach the evidence if you have access to it, but it has to be work that scientifically quantifies the consequences of interventions. We will periodically review the interventions and update them using your suggestions and further literature reviews.
In our synopses, we hope to have included all interventions used by conservationists. If we have missed techniques and practices that you know are being used or have been used in the past, please email firstname.lastname@example.org.
Similarly, if you think that there is a synopsis topic that would be particularly useful, then please contact us. We are always looking to collaborate with other institutions and organisations. If you think you could help plan or compile a synopsis then please do get in touch.
We need to know if this website and Conservation Evidence publications are as useful as they can be. If you have any suggestions for how to improve any aspect of Conservation Evidence, please let us know by emailing Harriet Downey at email@example.com.
How can I collect evidence?
Pick a simple action. Compare the consequences with either the situation beforehand, or in another equivalent (control) area without the action or compare different actions. Having multiple areas with the action and control greatly improves the quality of the science.
Do the easy bits! The essential components of monitoring can often be carried out quite quickly.
For example: if treating a large number of invasive shrubs by cutting and herbicide application, then it might be appropriate to mark and count a proportion of these, and subsequently record how many have died or regrown.
If documenting a reintroduction, give the number of surviving individuals after a given period of time and any indication of reproductive success.
Can't find an answer to your question?
Contact us, and we'll try to help you.