BEE CONSERVATION: evidence for the effects of interventions Lynn V. Dicks, David A. Showler & William J. Sutherland Based on evidence captured at www.conservationevidence.com Advisory Board We thank the following people for advising on the scope and content of this synopsis. Professor Andrew Bourke, University of East Anglia, UK Dr Claire Carvell, Centre for Ecology and Hydrology, UK Mike Edwards, Bees, Wasps and Ants Recording Society, UK Professor Dave Goulson, University of Stirling & Bumblebee Conservation Trust, UK Dr Claire Kremen, University of California, Berkeley, USA Dr Peter Kwapong, International Stingless Bee Centre, University of Cape Coast, Ghana Professor Ben Oldroyd, University of Sydney, Australia Dr Juliet Osborne, Rothamsted Research, UK Dr Simon Potts, University of Reading, UK Matt Shardlow, Director, Buglife, UK Dr David Sheppard, Natural England, UK Dr Nick Sotherton, Game and Wildlife Conservation Trust, UK Professor Teja Tscharntke, Georg‐August University, Göttingen, Germany Mace Vaughan, Pollinator Program Director, The Xerces Society, USA Sven Vrdoljak, University of Stellenbosch, South Africa Dr Paul Williams, Natural History Museum, London, UK About the authors Lynn Dicks is a Research Associate in the Department of Zoology, University of Cambridge. David Showler is a Research Associate in the School of Biological Sciences, University of East Anglia and the Department of Zoology, University of Cambridge. William Sutherland is the Miriam Rothschild Professor of Conservation Biology at the University of Cambridge. 1 About this book The purpose of Conservation Evidence synopses This book, Bee Conservation, is the first in a series of synopses that will cover different species groups and habitats, gradually building into a comprehensive summary of evidence on the effects of conservation interventions for all biodiversity throughout the world. By making evidence accessible in this way, we hope to enable a change in the practice of conservation, so it can become more evidence‐based. We also aim to highlight where there are gaps in knowledge. Conservation Evidence synopses do Conservation Evidence synopses do not Bring together scientific evidence Include evidence on the basic ecology captured by the Conservation Evidence of species or habitats, or threats to project (over 2,000 studies so far) on them the effects of interventions to conserve wildlife List all realistic interventions for the Make any attempt to weight or species group or habitat in question, prioritise interventions according to regardless of how much evidence for their importance or the size of their their effects is available effects Describe each piece of evidence, Weight or numerically evaluate the including methods, as clearly as evidence according to its quality possible, allowing readers to assess the quality of evidence Work in partnership with conservation Provide answers to conservation practitioners, policymakers and problems. We provide scientific scientists to develop the list of information to help with decision‐ interventions and ensure we have making covered the most important literature 2 Who this synopsis is for If you are reading this, we hope you are someone who has to make decisions about how best to support or conserve biodiversity. You might be a land manager, a conservationist in the public or private sector, a farmer, a campaigner, an advisor or consultant, a policymaker, a researcher or someone taking action to protect your own local wildlife. Our synopses summarise scientific evidence relevant to your conservation objectives and the actions you could take to achieve them. We do not aim to make your decisions for you, but to support your decision‐making by telling you what evidence there is (or isn’t) about the effects that your planned actions could have. When decisions have to be made with particularly important consequences, we recommend carrying out a systematic review, as the latter is likely to be more comprehensive than the summary of evidence presented here. Guidance on how to carry out systematic reviews can be found from the Centre for Evidence‐Based Conservation at the University of Bangor (www.cebc.bangor.ac.uk). The Conservation Evidence project The Conservation Evidence project has three parts: 1. An online, open access journal Conservation Evidence publishes new pieces of research on the effects of conservation management interventions. All our papers are written by, or in conjunction with, those who carried out the conservation work and include some monitoring of its effects. 2. An ever‐expanding database of summaries of previously published scientific papers, reports, reviews or systematic reviews that document the effects of interventions. 3. Synopses of the evidence captured in parts one and two on particular species groups or habitats. Synopses bring together the evidence for each possible intervention. They are freely available online and available to purchase in printed book form. These resources currently comprise over 2,000 pieces of evidence, all available in a searchable database on the website www.conservationevidence.com. Alongside this project, the Centre for Evidence‐Based Conservation (www.cebc.bangor.ac.uk) and the Collaboration for Environmental Evidence (www.environmentalevidence.org)y carr out and compile systematic reviews of 3 evidence on the effectiveness of particular conservation interventions. These systematic reviews are included on the Conservation Evidence database. Of the 59 bee conservation interventions identified in this synopsis, one is the subject of a current systematic review (Systematic Review number 72: Does delaying the first mowing date increase biodiversity in European farmland meadows? http://www.environmentalevidence.org/SR72.html). We identify an immediate need for a systematic review in relation to one other set of interventions (agri‐environment schemes), and a potential need for systematic reviews for two further interventions, should they become more widely practised (nest boxes for solitary bees and captive rearing of bumblebees). Scope of the Bee Conservation synopsis This synopsis covers evidence for the effects of conservation interventions for native, wild bees. It is restricted to evidence captured on the website www.conservationevidence.com. It includes papers published in the journal Conservation Evidence, evidence summarised on our database and systematic reviews collated by the Collaboration for Environmental Evidence. It does not include evidence from the substantial literature on husbandry methods for the largely domesticated honey bee Apis mellifera. It does include husbandry methods where they are relevant to native, wild bee species that are declining or threatened, such as bumblebees (Bombus spp.) and stingless bees (Meliponinae). Although the number of managed honey bee colonies is known to have declined in Europe and America, it is seldom the native subspecies that is kept and so we consider this to be outside the remit of Conservation Evidence. We do include some interventions and evidence relating to the conservation of subspecies of Apis mellifera in areas where they are native. Evidence from all around the world is included. If there appears to be a bias towards evidence from northern European or North American temperate environments, this reflects a current bias in the published research that is available to us. How we decided which bee conservation interventions to include Our list of interventions has been agreed in partnership with an Advisory Board made up of international conservationists and academics with expertise in bee conservation. Although the list of interventions may not be exhaustive, we have tried to include all actions that have been carried out or advised to support populations or communities of wild bees. 4 How we reviewed the literature In addition to evidence already captured by the Conservation Evidence project, we have searched the following sources for evidence relating to bee conservation: four specialist bee or insect conservation journals, from their first publication date to the end of 2009 (Apidologie, Journal of Apicultural Research, Insect Conservation and Diversity, Journal of Insect Conservation); ISI Web of Knowledge searched for papers with ‘bee’ as a search term, from 1997 to 2009 inclusive; all reports concerning bees published by Natural England or the UK Bumblebee Working Group up to 2009; other relevant papers or books frequently cited within the bee conservation literature, going back to 1912. In total, 168 individual studies are covered in this synopsis, all included in full or in summary on the Conservation Evidence website. The criteria for inclusion of studies in the Conservation Evidence database are as follows: There must have been an intervention that conservationists would do Its effects must have been monitored quantitatively In some cases, where a body of literature has strong implications for conservation of a particular species group or habitat, although it does not directly test interventions for their effects, we refer the reader to this literature. For example, the proportion of natural habitat in farmland has often been shown to affect bee diversity, but no studies have yet intervened by restoring natural or semi‐natural habitat and monitoring the effect on bees in surrounding farmland. In cases such as these, we briefly refer to the relevant literature, but present no evidence. How the evidence is summarised Conservation interventions are grouped primarily