A new book, free to download, brings together evidence to help conservationists choose the most effective strategies to conserve species and habitats. What Works in Conservation 2018, the third edition of the What Works series from the Conservation Evidence project, is a digest of data from over 5,000 scientific tests of over 1,200 conservation interventions (actions of any sort that conservationists could take to protect biodiversity). Freely available from https://www.openbookpublishers.com/product/696, the book summarizes the evidence available from https://www.conservationevidence.com.

This new edition is over 50% larger than that of last year, reflecting the number of new conservation interventions that have been summarized and assessed since then. Comprehensive new chapters have been added on the conservation of primates, shrublands and heathlands, and peatlands, as well as a chapter on management actions for some animal groups in captivity. The chapter on control of freshwater invasive species has been extended since 2017 to cover additional invasive species, and the other chapters from previous editions cover global conservation of amphibians, bats, birds and forests, conservation of European farmland biodiversity, and some aspects of enhancing natural pest control and soil fertility.

The book uses expert assessment, elicited over two rounds of Delphi scoring, to score interventions using a traffic light system. This scoring system comprises three components, (effectiveness of the intervention, certainty of the evidence, and harms arising from the intervention), and the scores from these components are combined to give each intervention a category ranging from ‘Beneficial’ to ‘Likely to be ineffective or harmful’. It also identifies where the evidence is insufficient to make such judgements. For those who desire greater detail, links to the more in-depth evidence describing each individual study are provided.

The interventions covered include species and habitat management strategies, but go beyond this to include interventions on livelihood, economic and other incentives; education and awareness; law and policy; and land/water protection. This gives the reader an overview of a wide range of available conservation techniques they could try, and the evidence for how well each has worked. The book also highlights what we do not know: where the team found no studies for an intervention this is indicated, providing a useful indication to researchers of where to target future efforts. For example, for bats 48 of the 78 interventions reviewed returned no studies, and for primates a third of interventions had been tested but as a result of insufficient or unclear evidence they were classed as ‘Unknown effectiveness’. If researchers systematically tested the interventions with the least evidence, we'd soon learn a lot more about how to conserve the natural world more effectively.

The concept of evidence-based conservation is often promoted without sufficient consideration of how conservationists are expected to ensure their work is evidence-based. This book is one easy way in which practitioners and policy-makers can assess the degree to which their decisions align with current evidence, making it practical to turn a paradigm into a reality.