Abstract Threats to biodiversity are well documented. However, to effectively conserve species and their habitats, we need to know which conservation interventions do (or do not) work. Evidence-based conservation evaluates interventions within a scientific framework. The Conservation Evidence project has summarized thousands of studies testing conservation interventions and compiled these as synopses for various habitats and taxa. In the present article, we analyzed the interventions assessed in the primate synopsis and compared these with other taxa. We found that despite intensive efforts to study primates and the extensive threats they face, less than 1% of primate studies evaluated conservation effectiveness. The studies often lacked quantitative data, failed to undertake postimplementation monitoring of populations or individuals, or implemented several interventions at once. Furthermore, the studies were biased toward specific taxa, geographic regions, and interventions. We describe barriers for testing primate conservation interventions and propose actions to improve the conservation evidence base to protect this endangered and globally important taxon.

A Severe Lack of Evidence Limits Effective Conservation of the World's Primates

German Centre for Integrative Biodiversity Research, Leipzig, Germany and with the Max Planck Institute for Evolutionary Anthropology, formerly the Department of Primatology, in Leipzig, Germany

Conservation Science Group, Department of Zoology, University of Cambridge, Cambridge, United Kingdom

Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia, Mexico

Mahidol University International College, Salaya, Thailand

Global Wildlife Conservation, Austin, Texas

Department of Anthropology, McGill University, Montreal, Quebec, Canada; with the School of Life Sciences, University of KwaZulu-Natal, Scottsville, Pietermaritzburg, South Africa; and with the Shaanxi Key Laboratory for Animal Conservation, at Northwest University, in Xi'an, China

Gibbon Conservation Centre, Assam, India

Borneo Nature Foundation, Palangka Raya, Central Kalimantan, Indonesia, and with the Department of Social Sciences, Oxford Brookes University, Oxford, United Kingdom

Stony Brook University, Stony Brook, New York

Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan

Institute of Zoology, Zoological Society of London, London, in the United Kingdom

Tai Chimpanzee Project, Centre Suisse des Recherche Scientifique, Abidjan, Cote d'Ivoire

Universidad San Francisco de Quito's Colegio de Ciencias Biológicas y Ambientales in Quito, Ecuador

Department of Engenharia Florestal, Federal University of Viçosa, Viçosa, Brazil

School of Life Sciences, Sun Yat-Sen University, Guangzhou, China

School of Human Sciences and with the School of Biological Sciences, University of Western Australia, Crawley, Western Australia, Australia

Asociación Primatológica Colombiana, Bogotá, Colombia

Deutsches Primatenzentrum, Leibniz-Institut für Primatenforschung, Göttingen, Germany

World Wide Fund for Wildlife Germany, Berlin, Germany

Southern Institute of Ecology, Hochiminh City, Vietnam

Community Baboon Sanctuary, Belize

Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Kent, United Kingdom

SW/Niger Delta Forest Project, part of the Foundation for Sustainability of Ecosystem, Wildlife, and Climate, Abuja, Nigeria

Wildlife Conservation Society Nigeria, Calabar, Nigeria

Centro Nacional de Pesquisa e Conservação de Primatas Brasileiros, in the Instituto Chico Mendes de Conservação da Biodiversidade. In João Pessoa, Brazil

Department of Anthropology and Archaeology, University of Calgary, Calgary, Alberta, Canada

Deutsches Primatenzentrum, Leibniz-Institut für Primatenforschung, Göttingen, Germany, and with the Department of Sociobiology/Anthropology, Faculty of Biology and Psychology, at Georg-August Universität, in Göttingen, Germany

Instituto Nacional da Mata Atlântica, in Espírito Santo, Brazil, and with the Instituto Pri-Matas, Minas Gerais, Brazil

Centre Suisse de Recherches Scientifiques, Abidjan, Côte d'Ivoire. Rebecca Kormos is affiliated with the Department of Integrative Biology, University of California, Berkeley

Freelance wildlife consultant, Hanoi, Vietnam

Shaanxi Key Laboratory for Animal Conservation, College of Life Sciences, Northwest University, Xi'an, China

Department of Anthropology and the Department of Ecology and Evolutionary Biology in the Program in the Environment and the School of Environment and Sustainability, Universit of Michigan in Ann Arbor, Michigan

Center of Excellence for Environmental Decisions, University of Queensland, Brisbane, Queensland, Australia, and with Borneo Futures, Bandar Seri Begawan, Brunei

Natural Science Laboratory, Faculty of Business Administration, Toyo University, Tokyo, Japan

Universität Leipzig, Dekanat der Fakultät für Lebenswissenschaften, Leipzig, Germany

Independent researcher, Leipzig, Germany

Conservación Internacional, Colombia, Bogotá

Royal Holloway University of London, Egham, United Kingdom

BirdLife International, both in Cambridge, United Kingdom

World Wide Fund for Wildlife Vietnam, Hanoi, Vietnam

Great Apes Survival Partnership, United Nations Environment Programme, Nairobi, Kenya

Groupe d’étude et de recherche sur les primates, Antananarivo, Madagascar

Department of Anthropology, Durham University, Durham, United Kingdom

Max Planck Institute for Evolutionary Anthropology, formerly the Department of Primatology, Leipzig, Germany

Bristol Zoological Society, Bristol Zoo Gardens, Bristol, United Kingdom

Operation Wallacea, Lincolnshire, United Kingdom

University of California San Diego, La Jolla, California, and with the Uaso Ngiro Baboon Project, Nairobi, Kenya

Departamento de Cíências Ambientais and the Programa Análise Ambiental Integrada, Universidade Federal de São Paulo, Sao Paulo, Brazil

Department of Environmental Studies, University of Oklahoma, Norman, Oklahoma

School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom

Faculty of Natural Sciences, University of Stirling, Stirling, Scotland, United Kingdom