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Does the creation of artificial reefs benefit subtidal benthic invertebrates? Is the use of organic farming instead of conventi onal farming beneficial to bat conservation? Does installing wildlife warning reflectors along roads benefit mammal conservation? Does the installation of exclusion and/or escape devices on fishing nets benefit marine and freshwater mammal conservation? What Works in Conservation has been created to provide practitioners with answers to these and many other questions about practical conservation. This book provides an assessment of the effectiveness of 2526 conservation interventions based on summarized scientific evidence. The 2021 edition contains substantial new material on bat conservation, terrestrial mammal conservation and marine and freshwater mammals, thus completing the evidence for all mammal species categories. Other chapters cover practical global conservation of primates, amphibians, birds, forests, peatlands, subtidal benthic invertebrates, shrublands and heathlands, as well as the conservation of European farmland biodiversity and some aspects of enhancing natural pest control, enhancing soil fertility, management of captive animals and control of freshwater invasive species. It contains key results from the summarized evidence for each conservation intervention and an assessment of the effectiveness of each by international expert panels. The accompanying website www.conservationevidence.com describes each of the studies individually, and provides full references. This is the sixth edition of What Works in Conservati on, which is revised on an annual basis. As with all Open Book publications, this entire book is available to read and download for free on the publisher’s website at https://www.openbookpublishers.com/product/1490 where printed and ebook editions can also be bought.

Is reduced tillage in arable fields beneficial for farmland biodiversity? Is prescribed burning in grasslands beneficial for bird conservation? Does livestock exclusion from degraded peatlands benefit peatland conservation? Is the provision of artificial shelters effective for subtidal benthic invertebrate conservation? Do wind turbine modifications reduce bat fatalities? Does adding topsoil increase the abundance of heathland plants? Are interventions to reduce road impacts on amphibians effective? Do herbicides control invasive parrot's feather? What Works in Conservation has been created to provide practitioners with answers to these and many other questions about practical conservation.This book provides an assessment of the effectiveness of 1614 conservation interventions based on summarized scientific evidence. The 2020 edition contains new material on bat conservation and our first marine chapter, on Subtidal benthic invertebrate conservation. Other chapters cover practical global conservation of primates, peatlands, shrublands and heathlands, management of captive animals as well as an extended chapter on control of freshwater invasive species, the global conservation of amphibians, bats, birds and forests, conservation of European farmland biodiversity and some aspects of enhancing natural pest control, enhancing soil fertility and control of freshwater invasive species. It contains key results from the summarized evidence for each conservation intervention and an assessment of the effectiveness of each by international expert panels. The accompanying website www.conservationevidence.com describes each of the studies individually, and provides full references. This is the fourth edition of What Works in Conservation, which is revised on an annual basis.

Expert assessors Lynn V. Dicks, University of Cambridge, UK Ian Hodge, University of Cambridge, UK Clunie Keenleyside, Institute for European Environmental Policy, UK Will Peach, Royal Society for the Protection of Birds, UK Nicola Randall, Harper Adams University, UK Jörn Scharlemann, UNEP World Conservation Monitoring Centre, UK Gavin Siriwardena, British Trust for Ornithology, UK Henrik Smith, Lund University, Sweden Rebecca K. Smith, University of Cambridge, UK William J. Sutherland, Univ...

Expert assessors David Aldridge, University of Cambridge, UK Olaf Booy, Animal and Plant Health Agency, UK Manuel A. Duenas, Centre for Ecology & Hydrology, UK Alison Dunn, University of Leeds, UK Robert Francis, King’s College London, UK Belinda Gallardo, Pyrenean Institute of Ecology, Spain Nancy Ockendon, University of Cambridge, UK Trevor Renals, Environment Agency, UK Emmanuelle Sarat, International Union for Conservation of Nature, France Sonal Varia, The Centre for Agriculture and Bios...

Expert assessors Andrew Bennet, La Trobe University, Australia Brian van Wilgen, Stellenbosch University, South Africa Rob Marrs, University of Liverpool, UK Chris Diek, Royal Society for the Protection of Birds, UK G. Matt Davies, Ohio State University, USA David Le Maitre, CSIR, UK Giles Groome, Consultant Ecologist, UK Isabel Barrio, University of Iceland, Iceland James Adler, Surrey Wildlife Trust, UK ...

Expert assessors Graham L. Banes, University of Wisconsin-Madison, USA Sergio Marrocoli, Max Planck Institute for Evolutionary Anthropology, Germany Sarah Papworth, Royal Holloway University of London, UK Silviu O. Petrovan, University of Cambridge, UK Andrew J. Plumptre, Wildlife Conservation Society, Uganda Ricardo Rocha, University of Cambridge, UK Joanna M. Setchell, Durham University, UK Kathy Slater, Operation Wallace...

Expert assessors Silviu Petrovan, University of Cambridge, United Kingdom Anaelle Lemasson, JNCC, United Kingdom Ann Thornton, University of Cambridge, United Kingdom Lucy Shuff, Gardline Limited, United Kingdom Christopher Barrett, CEFAS, United Kingdom Scope of assessment: for native wild subtidal species across the world. Assessed: 2020. Effectiveness measure is the median % score for effectiveness. Certainty measure is ...

This book provides an assessment of the effectiveness of 1277 conservation interventions based on summarized scientific evidence. The 2018 edition contains new chapters covering practical global conservation of primates, peatlands, shrublands and heathlands, management of captive animals as well as an extended chapter on control of freshwater invasive species. Other chapters cover global conservation of amphibians, bats, birds and forests, conservation of European farmland biodiversity and some aspects of enhancing natural pest control, enhancing soil fertility and control of freshwater invasive species. It contains key results from the summarized evidence for each conservation intervention and an assessment of the effectiveness of each by international expert panels. The accompanying website www.conservationevidence.com describes each of the studies individually, and provides full references.

Husbandry interventions for captive breeding amphibians Expert assessors Kay Bradfield, Perth Zoo, Australia Jeff Dawson, Durrell Wildlife Conservation Trust, UK Devin Edmonds, Association Mitsinjo, Madagascar Jonathan Kolby, Honduras Amphibian Rescue and Conservation Center, Honduras Stephanie Jayson, Veterinary Department, Zoological Society of London, UK Daniel Nicholson, Queen Mary University of London, UK Silviu...

Expert assessors Rhett Harrison, Consultative Group on International Agricultural Research, Zambia Keith Kirby, University of Oxford, UK Gillian Petrokofsky, Biodiversity Institute Oxford, UK Rebecca K. Smith, University of Cambridge, UK William J. Sutherland, University of Cambridge, UK Tom Swinfield, Royal Society for the Protection of Birds, UK Scope of assessment: for the conservation of forest habitat (not specific spe...

No evidence found (no assessment) We have captured no evidence for the following intervention: • Provide specialist advice, assistance preparing conservation plans Evidence not assessed Provide training for land managers, farmers and farm advisers A study from the UK found farmers who were trained in how to implement agri-environment schemes created better quality wildlife habitat over five years. Assessment: this intervention has not been assessed. http://www.conservationevidence.com/actions...

No evidence found (no assessment) We have captured no evidence for the following interventions: Add water to peatlands to compensate for drought Plant shelter belts to protect peatlands from wind Build barriers to protect peatlands from the sea Restore/create peatlands in areas that will be climatically suitable in the future.

Unknown effectiveness (limited evidence) Provide owl nest boxes (tawny owl, barn owl) Two studies (one before-and-after study) from the Netherlands and the UK found providing nest boxes increased barn owl populations. A replicated study from the UK found a decrease in the proportion of breeding barn owls was not associated with the number of nest boxes. Assessment: unknown effectiveness — limited evidence (effectiveness 100 %; certainty 33 %). http://www.conservationevidence.com/actions/154 N...

No evidence found (no assessment) We have captured no evidence for the following interventions: Create a Marine Protected Area or set levels of legal protection where natural climate refugia occur to further promote the persistence and recovery of species facing climate change Limit, cease or prohibit the degradation and/or removal of carbon sequestering species and/or habitats Manage climate-driven range extensions of problematic species Promote natural carbon sequestration species and/or ha...

Beneficial Combine trap and repellent crops in a push-pull system • Parasitism: Two randomized, replicated, controlled studies from Kenya found that push-pull cropping systems increased parasitism of stem borer larvae. One of the studies found no effect on egg parasitism. • Natural enemies: Two randomized, replicated, controlled studies from Kenya and South Africa found push-pull systems had more natural predators, both in overall totals and the abundance of different predator groups. • Pests...

Strict protocols should be followed when carrying out these interventions to minimise potential spread of disease-causing agents such as chytrid fungi and Ranavirus. 1.13.1 Translocate amphibians Likely to be beneficial Translocate amphibians (amphibians in general) Overall, three global reviews and one study in the USA found that 65 % of amphibian translocations that could be assessed resulted in established breeding populations or substantial recruitment to the adult population. A further ...

Beneficial Restore or create species-rich, semi-natural grassland Twenty studies (including three randomized, replicated, controlled trials) from six countries found restored species-rich, semi-natural grasslands had similar invertebrate, plant or bird diversity or abundance to other grasslands. Seven studies (two randomized, replicated, controlled trials) from five countries found no clear effect on plant or invertebrate numbers, three replicated studies (of which two site comparisons) from ...

6.2.1 Multiple farming systems Unknown effectiveness (limited evidence) Retain/create habitat corridors in farmed areas • Vegetation structure: One study in Indonesia found that a peat swamp forest corridor contained 5,819 trees/ha: 331 large trees, 1,360 saplings and 4,128 seedlings. • Overall plant richness/diversity: The same study recorded 18–29 tree species (depending on size class) in the peat swamp forest corridor. • Assessment: unknown effectiveness – limited evidence (effectiveness ...

5.2.1 Livestock farming Likely to be beneficial Use wire fences within grazing areas to exclude livestock from specific forest sections Three of four studies, including one replicated, randomized, controlled study in Kenya, Israel, Mexico and Panama found that excluding livestock using wire fences increased the size, density or number of regenerating trees. One study found no effect on tree size and decreased tree density. Four of eight studies, including two replicated, randomized, controll...

3.12.1 Industrial pollution Likely to be beneficial Use visual and acoustic ‘scarers’ to deter birds from landing on pools polluted by mining or sewage Two studies from Australia and the USA found that deterrent systems reduced bird mortality on toxic pools. Four of five studies from the USA and Canada found that fewer birds landed on pools when deterrents were used, one found no effect. Two studies found that radar-activated systems were more effective than randomly-activated systems. One s...

Likely to be beneficial Grow non-crop plants that produce chemicals that attract natural enemies • Natural enemies: Four studies from China, Germany, India and Kenya tested the effects of growing plants that produce chemicals that attract natural enemies. Three (including one replicated, randomized, controlled trail) found higher numbers of natural enemies in plots with plants that produce attractive chemicals, and one also found that the plant used attracted natural enemies in lab studies. O...

No evidence found (no assessment) We have captured no evidence for the following interventions: Adapt bat roost structures to buffer against temperature extremes Enhance natural habitat features to improve landscape connectivity to allow for range shifts of bats Manage natural water bodies in arid areas to prevent desiccation Provide suitable bat foraging and roosting habitat at expanding range fronts.

Likely to be beneficial Legally protect peatlands • Peatland habitat: Two studies in Indonesia reported that peat swamp forest was lost from within the boundaries of national parks. However, one of these studies reported that forest loss was greater outside the national park. One before-and-after study in China reported that peatland area initially decreased following legal protection, but increased in the longer term. • Plant community composition: One before-and-after study in a bog in Denm...

6.9.1 Multiple sources of pollution Likely to be beneficial Divert/replace polluted water source (s) • Characteristic plants: One study in a fen in the Netherlands found that after a nutrient-enriched water source was replaced, along with other interventions to reduce pollution, cover of mosses characteristic of low nutrient levels increased. • Vegetation cover: Two studies in bogs in the UK and Japan reported that after polluting water sources were diverted, sometimes along with other inter...

Likely to be beneficial Install rope or pole (canopy) bridges One before-and-after study in Belize study found that howler monkey numbers increased after pole bridges were constructed over man-made gaps. Two studies in Brazil and Madagascar found that primates used pole bridges to cross roads and pipelines. Assessment: likely to be beneficial (effectiveness 50 %; certainty 50 %; harms 0 %). https://www.conservationevidence.com/actions/1457 No evidence found (no assessment) We have captured no...

10.5.1 Red-eared terrapin Trachemys scripta Likely to be beneficial Direct removal of adults Two studies, a replicated study from Spain using Aranzadi turtle traps, and an un-replicated study in the British Virgin Islands using sein netting, successfully captured but did not eradicate red-eared terrapin populations. Assessment: likely to be beneficial (effectiveness 40 %; certainty 50 %). https://www.conservationevidence.com/actions/1055 Unlikely to be beneficial Application of a biocide A r...

Likely to be beneficial Grow plants that compete with damaging weeds • Weed weight and cover: Nine studies from Australia, Slovakia, the UK and the USA tested the effects of planting species to compete with weeds. All (including four replicated, randomized, controlled trials) found reduced weed plant weight or ground cover, although two found this only in some years or conditions. • Weed reproduction and survival: Five studies (including three replicated, randomized, controlled trials) also f...

8.7.1 Modified fire regime No evidence found (no assessment) We have captured no evidence for the following interventions: Use prescribed burning to mimic natural fire cycle Use prescribed burning to reduce the potential for large wild fires Cut strips of vegetation to reduce the spread of fire. 8.7.2 Modified vegetation management Unknown effectiveness (limited evidence) Reinstate the use of traditional burning practices One before and after study in the UK ...

Remember, the effectiveness category for each intervention assumes that the aims of the intervention match your management goals. You should consider whether each intervention is necessary and appropriate in your focal peatland. 6.11.1 General habitat creation and restoration Likely to be beneficial Restore/create peatland vegetation (multiple interventions) • Plant community composition: One replicated, controlled, before-and-after study in the UK reported that the overall plant comm...

Unknown effectiveness (limited evidence) Reduce intensity of harvest • Moss cover: One replicated, controlled study in a bog in New Zealand reported that Sphagnum moss cover was higher, three years after harvesting, when some Sphagnum was left in plots than when it was completely harvested. • Assessment: unknown effectiveness – limited evidence (effectiveness 70 %; certainty 25 %; harms 0 %). Based on evidence from: bogs (one study). https://www.conservationevidence.com/actions/1744 No eviden...

Beneficial Prepare the ground before tree planting Six of seven studies, including five replicated, randomized, controlled studies, in Canada and Sweden found that ground preparation increased the survival or growth rate of planted trees. One study found no effect of creating mounds on frost damage to seedlings. Assessment: beneficial (effectiveness 78 %; certainty 73 %; harms 0 %). http://www.conservationevidence.com/actions/1263 Use mechanical thinning before or after planting Five of six s...

No evidence found (no assessment) We have captured no evidence for the following interventions: Remove residential or commercial development Maintain/create habitat corridors in developed areas.

1.2.1 Engage farmers and other volunteers Likely to be beneficial Engage landowners and other volunteers to manage land for amphibians Three studies, including one replicated and one controlled study, in Estonia, Mexico and Taiwan found that engaging landowners and other volunteers in habitat management increased amphibian populations and axolotl weight. Six studies in Estonia, the USA and UK found that up to 41,000 volunteers were engaged in habitat restoration programmes for amphibians and...

Likely to be beneficial Restore former mining sites Twelve studies evaluated the effects of restoring former mining sites on mammals. Eleven studies were in Australia and one was in the USA. COMMUNITY RESPONSE (8 STUDIES) Species richness (8 studies): A review in Australia found that seven of 11 studies indicated that rehabilitated areas had lower mammal species richness compared to unmined areas. Four of five replicated, site comparison studies, in Australia, found that mammal species richne...

9.3.1 Food Presentation Beneficial Scatter food throughout enclosure Four studies, including one replicated study, in the USA, found that scattering food throughout enclosures increased overall activity, feeding and exploration and decreased abnormal behaviours and aggression. Assessment: beneficial (effectiveness 80 %; certainty 80 %; harms 0 %). https://www.conservationevidence.com/actions/1315 Likely to be beneficial Hide food in containers (including boxes and bags) Three studies includi...

15.8.1 Invasive non-native/alien species/diseases Beneficial Remove/control non-native mammals Twenty-five studies evaluated the effects on non-controlled mammals of removing or controlling non-native mammals. Twenty-one studies were in Australia, and one was in each of France, the UK, Equador and the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (24 STUDIES) Abundance (21 studies): Ten of 18 controlled, before-and-after or site comparison studies, in Australia, found that after co...

7.8.1 Problematic animal/plant species and genes No evidence found (no assessment) We have captured no evidence for the following interventions: Reduce primate predation by non-primate species through exclusion (e.g. fences) or translocation Reduce primate predation by other primate species through exclusion (e.g. fences) or translocation Control habitat-altering mammals (e.g. elephants) through exclusion (e.g. fences) or translocation Control inter-specific ...

Unknown effectiveness (limited evidence) Maintain traditional orchards A replicated, controlled site comparison from Germany found more plant species in mown orchards than grazed or abandoned ones, but found no effects on wasps or bees. Two replicated site comparisons from Germany and Switzerland found traditional orchards managed under agri-environment schemes either did not have more plant species than controls or offered no clear benefits to birds. Assessment: unknown effectiveness — limit...

Beneficial Legally protect habitat for mammals Seven studies evaluated the effects of legally protecting habitat for mammals. One study each was in Zambia, the USA, Tanzania, Brazil, Nepal and India and one was a systematic review of sites with a wide geographic spread. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (7 STUDIES) Abundance (7 studies): A systematic review of protected areas across the globe found that 24 of 31 studies reported an increase in mammal populations in protected ...

9.1.1 Refining techniques using less threatened species Unknown effectiveness (limited evidence) Identify and breed a similar species to refine husbandry techniques prior to working with target species Two small, replicated interlinked studies in Brazil found that working with a less threatened surrogate species of frog first to establish husbandry interventions promoted successful breeding of a critically endangered species of frog. Assessment: unknown effectiveness (effectiveness 68 %; cer...

7.9.1 Garbage/solid waste No evidence found (no assessment) We have captured no evidence for the following interventions: Reduce garbage/solid waste to avoid primate injuries Remove human food waste that may potentially serve as food sources for primates to avoid disease transmission and conflict with humans. 7.9.2 Excess energy No evidence found (no assessment) We have captured no evidence for the following interventions: • Reduce noise pollution by restricting deve...

Likely to be beneficial Conserve roosting sites for bats in old structures or buildings Three studies evaluated the effects of conserving roosting sites for bats in old structures or buildings on bat populations. Two studies were in the UK and one was in Germany. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Abundance (1 study): One before-and-after study in the UK found that a greater number of bats hibernated in a railway tunnel after walls with access grilles were installed ...

Beneficial Reduce number of livestock Two before-and-after trials in the UK and South Africa and one replicated, controlled study in the UK found that reducing or stopping grazing increased the abundance or cover of shrubs. Two site comparison studies in the UK found that cover of common heather declined in sites with high livestock density, but increased in sites with low livestock density. One site comparison study in the Netherlands found that dwarf shrub cover was higher in ungrazed sites...

7.13.1 Provide benefits to local communities for sustainably managing their forest and its wildlife Unknown effectiveness (limited evidence) Provide monetary benefits to local communities for sustainably managing their forest and its wildlife (e.g. REDD, employment) One before-and-after study in Belize found that howler monkey numbers increased after the provision of monetary benefits to local communities alongside other interventions. However, one before-and-after study in Rwanda, Uganda an...

Likely to be beneficial Retain existing bat roosts and access points within developments Three studies evaluated the effects of retaining existing bat roosts and access points within developments on bat populations. Two studies were in the UK and one was in Ireland. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (3 STUDIES) Use (3 studies): One before-and-after study in Ireland found similar numbers of brown long-eared bats roosting within an attic after existing acc...

Beneficial Use collar-mounted devices to reduce predation by domestic animals Five studies evaluated the effects on mammals of using collar-mounted devices to reduce predation by domestic animals. Three studies were in the UK, one was in Australia and one was in the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (5 STUDIES) Survival (5 studies): Five replicated studies (including four randomized, controlled studies), in the UK, Australia and the USA, found that bells, a sonic device,...

Likely to be beneficial Control predatory mammals and birds (foxes, crows, stoats and weasels) Eight studies (including a systematic review) from France and the UK found predator control (sometimes alongside other interventions) increased the abundance, population size or productivity of some birds. A randomized, replicated, controlled study from the UK did not. Assessment: likely to be beneficial (effectiveness 90 %; certainty 60 %). http://www.conservationevidence.com/actions/699 Unknown ef...

Beneficial Regulate water levels Three studies, including one replicated, site comparison study, in the UK and USA found that maintaining pond water levels, in two cases with other habitat management, increased or maintained amphibian populations or increased breeding success. One replicated, controlled study in Brazil found that keeping rice fields flooded after harvest did not change amphibian abundance or numbers of species, but changed species composition. One replicated, controlled study...

2.6.1 Caving and tourism Likely to be beneficial Impose restrictions on cave visits Four studies evaluated the effects of imposing restrictions on cave visits on bat populations. One study was in each of the USA, Canada, Madagascar, and Turkey. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Abundance (2 studies): Two before-and-after studies in Canada and Turkey found that bat populations within caves increased after restrictions on cave visitors were imposed. BEHAVIOUR (2 ST...

Beneficial Exclude or limit number of visitors to reserves or protected areas Five studies evaluated the effects on mammals of excluding or limiting the number of visitors to reserves or protected areas. Three studies were in the USA, one was in Ecuador and one was in Thailand. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Abundance (1 study): A site comparison study in Ecuador found that a road with restricted access had a higher population of medium-sized and large mammals ...