Collected Evidence: Collected Evidence: Create uncultivated margins around intensive arable or pasture fields Thirty-nine studies (including 13 replicated controlled trials of which three also randomized and four reviews) from eight European countries compared wildlife on uncultivated margins with other margin options. Twenty-four found benefits to some wildlife groups (including 11 replicated controlled trials of which one also randomised, and four reviews). Nineteen studies (including one randomized, replicated, controlled trial) from Germany, Ireland, Lithuania, Norway, the Netherlands and the UK found uncultivated margins support more invertebrates (including bees) and/or higher plant diversity or species richness than conventionally managed field margins or other field margin options. One replicated, controlled study showed that uncultivated margins supported more small mammal species than meadows and farmed grasslands. Four studies (two replicated UK studies, two reviews) reported positive associations between birds and field margins including food provision. A review from the UK found grass margins (including naturally regenerated margins) benefited plants and some invertebrates. Fifteen studies (including one randomized, replicated, controlled trial) from Germany, the Netherlands, Norway and the UK found that invertebrate and/or plant species richness or abundance were lower in naturally regenerated than conventionally managed fields or sown margins. Six studies (including one randomized, replicated, controlled trial) from Belgium, Germany and the UK found uncultivated margins did not have more plant or invertebrate species or individuals than cropped or sown margins. A review found grass margins (including naturally regenerated margins) did not benefit ground beetles. Five studies (including three replicated controlled trials) from Ireland and the UK reported declines in plant species richness and invertebrate numbers in naturally regenerated margins over time. One replicated trial found that older naturally regenerated margins (6-years old) had more invertebrate predators (mainly spiders) than newly established (1-year old) naturally regenerated margins. Five studies (including one replicated, randomized trial) from the Netherlands and the UK found that cutting margins had a negative impact on invertebrates or no impact on plant species. One replicated controlled study found cut margins were used more frequently by yellowhammers when surrounding vegetation was >60 cm tall. Seven studies (including four replicated controlled trials and a review) from Ireland, the Netherlands, Norway and the UK reported increased abundance or biomass of weed species in naturally regenerated margins. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F63https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F63Tue, 04 Oct 2011 14:51:45 +0100Collected Evidence: Collected Evidence: Provide nest boxes for bees (solitary bees or bumblebees) Ten studies (nine replicated trials and a review of studies) from Germany, Poland and the UK of solitary bee nest boxes all showed the nest boxes were readily used by bees. Two replicated studies found the local population size or number of emerging red mason bees increased when nest boxes were provided. One replicated trial in Germany showed that the number of occupied solitary bee nests almost doubled over three years with repeated nest box provision at a given site. Two replicated trials tested bumblebee nest boxes and both found very low uptake, 2% or less. Occupancy rates of solitary bee nest boxes, where reported (two replicated studies), were between 1 and 26% of available cavities. Five studies (four replicated trials and a review of studies) report the number of bee species found in the nest boxes – between 4.6 and 33 species. One replicated study from Germany found nest boxes should be placed 150-600 m from forage resources (Gathmann & Tscharntke 2002). A replicated study from Poland found the highest production of red mason bees per nest was from nesting materials of reed stems or wood. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F80https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F80Mon, 24 Oct 2011 21:15:42 +0100Collected Evidence: Collected Evidence: Manage hedgerows to benefit wildlife (includes no spray, gap-filling and laying) Ten studies from Switzerland and the UK (three replicated and controlled studies of which one was randomized) found that managing hedges for wildlife resulted in increased berry yields, species diversity or richness of plants and invertebrates and diversity or abundance of farmland birds. Five studies from the UK (including one replicated, controlled and randomized study) found that hedge management did not affect plant species richness, numbers of bumblebee queens or farmland birds. Two replicated studies have shown mixed or adverse effects, with hedge management having mixed effects on invertebrates or leading to reduced hawthorn berry yield. A replicated site comparison in the UK found hedges cut every two years had more suitable nesting habitat for grey partridge than other management regimes. A replicated study from the UK found that hawthorn berry yield was reduced when management involved removing fruit-bearing wood.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F116https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F116Tue, 01 Nov 2011 20:32:06 +0000Collected Evidence: Collected Evidence: Provide or retain set-aside areas in farmland We found 34 studies comparing use of set-aside areas with control farmed fields. Two were reviews, none were randomized, replicated, controlled trials. Of these, 20 (from Austria, Finland, Germany and the UK) showed benefits to or higher use by all wildlife groups considered. Twelve (from Finland, Germany, Ireland, Sweden and the UK) found some species or groups used set-aside more than crops, others did not. Two studies (all from the UK) found no effect, one found an adverse effect of set-aside. Three of the studies, all looking at skylarks, went beyond counting animal or plant numbers and measured reproductive success. Two from the UK found higher nest survival or productivity on set-aside than control fields. One from the UK found lower nest survival on set-aside. Fifteen studies (from Belgium, Germany, Sweden and the UK) monitored wildlife on set-aside fields, or in landscapes with set-aside, without directly comparing with control fields or landscapes. Three looked at set-aside age and found more plants or insects on set-aside more than a year old. Two compared use of different non-crop habitats and found neither insects nor small mammals preferred set-aside. Two showed increased bird numbers on a landscape scale after set-aside was introduced, amongst other interventions. Eight looked at effects of set-aside management such as use of fertilizer and sowing or cutting regimes. A systematic review from the UK found significantly higher densities of farmland birds on fields removed from production and under set-aside designation than on conventionally farmed fields in both winter and summer. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F156https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F156Thu, 29 Mar 2012 19:03:54 +0100Collected Evidence: Collected Evidence: Plant grass buffer strips/margins around arable or pasture fields Nineteen studies from Finland, the Netherlands, Sweden and the UK (including seven replicated controlled studies of which two were randomized, and three reviews), found that planting grass buffer strips (some margins floristically-enhanced) increased arthropod abundance, species richness and diversity. A review found grass margins benefited bumblebees and some other invertebrates but did not distinguish between the effects of several different margin types. Nine studies from the UK (including seven replicated studies of which two were controlled, and two reviews) found that planting grass buffer strips (some margins floristically-enhanced) benefits birds, resulting in increased numbers, densities, species richness and foraging time. Seven studies from the Netherlands and the UK (all replicated of which four were controlled and two randomized), found that planting grass buffer strips (some margins floristically-enhanced) increased the cover and species richness of plants. A review found grass margins benefited plants but did not distinguish between the effects of several different margin types. Five studies from Finland and the UK (including two replicated, controlled trials and a review), found that planting grass buffer strips benefits small mammals: including increased activity and numbers. Six studies from the Netherlands and the UK (including three replicated, controlled trials) found that planting grass buffer strips had no clear effect on insect numbers, bird numbers or invertebrate pest populations. A replicated site comparison found sown grassy margins were not the best option for conservation of rare arable plants. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F246https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F246Wed, 18 Jul 2012 11:47:21 +0100Collected Evidence: Collected Evidence: Plant nectar flower mixture/wildflower strips A total of 80 individual studies have in some way investigated the effects of flowering strips on biodiversity. Sixty-four individual studies show some benefits to one or more wildlife groups. Sixty-five individual studies reported the effects of flower strips on invertebrates. Of these, fifty reported positive effects. Forty-one studies from eight European countries (including five reviews and twenty-three replicated controlled studies, of which one randomized and two site comparisons) found evidence that flower strips had a positive influence on invertebrate numbers with increased abundance, species richness/diversity, or both. Ten studies (nine replicated of which two controlled) found invertebrates visited or foraged on flower strips but did not specify increases/decreases in numbers. Two studies found effects on ground beetles other than changes in numbers. One replicated controlled study showed that ground beetles were more active or had enhanced feeding/reproductive conditions in flower strips. A review found flower strips supported ground beetle species that were rarely found in crops. Fifteen studies reported mixed or negative effects of flower strips on invertebrates. Six studies found no significant effects. Twenty-one studies looked at the effects of flower strips on plants. Sixteen studies from seven European countries (including ten replicated controlled studies of which one randomized) found evidence that flower strips had higher plant cover, number of flowers, diversity, and species richness. One review found flower strips benefited plants but did not specify how. Four studies found negative or no effects of flower strips on the number or diversity of plant species. Five studies described the effects of different margin establishment or management techniques on plants. Seven studies investigated birds and wildflower strips. Four replicated, controlled studies from Switzerland and the UK (two of which were randomized) and one review of European studies found evidence that plots sown with a wildflower or legume seed mix had a positive influence on birds. Flower strips attracted more birds or bird species and the number of birds using flower strips increased over time. Eurasian skylarks preferentially foraged in, and nested in or near, sown weed patches and were less likely to abandon their territories when they included sown weed patches. However one replicated trial in Switzerland found barn owls avoided sown wildflower areas. Two winter recording periods of the same replicated, controlled study in the UK found there were not more bird species or individuals on wildflower plots compared to control margins. All five studies investigating the effects of wildflower strips on small mammals (four replicated studies from Switzerland and one review of studies from north-western Europe) found evidence that small mammals benefit from strips sown with wildflowers or flowers rich in pollen and nectar, with increases in abundance, density and species richness. One replicated study from Switzerland reported that most common vole home ranges and core regions of their territories were found within a wildflower strip. Nineteen studies (of which eight replicated, controlled) reported positive effects on biodiversity of sowing specific plant species including phacelia, and/or other plant species such as borage and red clover. Three replicated studies (two also controlled) found negative impacts or no effects on biodiversity of sowing phacelia. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F442https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F442Thu, 23 Aug 2012 15:37:16 +0100Collected Evidence: Collected Evidence: Plant wild bird seed or cover mixture Thirty individual studies investigated the effects on birds of sowing wild bird seed or cover mixture, 21 studies found positive effects. Fourteen studies from the UK (including one systematic review and nine replicated controlled trials of which four randomized, and three reviews) found that fields sown with wild bird cover mix had higher abundance, density, species diversity and species richness of birds than other farmland habitats. Six studies from the UK (including one review and two replicated studies) found that birds showed a preference for wild bird cover and used it significantly more than other habitats. One review found the grey partridge population increased substantially on farms where conservation measures including cover crops were in place. Nine replicated studies from France and the UK reported mixed or negative effects of wild bird cover on birds compared to other farmland habitats. Six studies found that mixtures including kale or a mixture of kale and/or other species attracted the largest number of bird species or highest bird abundance. Twelve studies from the UK looked at the effects of wild bird cover strips on invertebrates. Seven studies from the UK (including one review and four replicated controlled studies of which two were also randomized) found positive effects. Farmland habitats sown with wild bird cover mix were used more by butterflies, and had a higher abundance or species richness of butterflies and/or bees than other farmland habitats. One review found wild bird cover benefited invertebrates. Four studies (including one review and two replicated trials) reported mixed or negative effects of wild bird cover on invertebrate numbers compared with other farmland habitats. One study found that bees and butterflies showed preferences for particular plant species. Eight studies from the UK looked at plants and wild bird cover. Six studies (including two reviews and two replicated controlled trials) found that planting wild bird cover mix was one of the three best options for conservation of annual herbaceous plant communities, benefited plants and resulted in increased plant diversity and species richness. However two replicated studies (of which one a site comparison) found mixed/negative effects for plant species richness. One replicated trial from the UK found that small mammal activity was higher in wild bird cover than in the crop in winter but not in summer.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F594https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F594Fri, 12 Oct 2012 14:56:56 +0100Collected Evidence: Collected Evidence: Provide supplementary food for birds or mammals A total of 18 individual studies investigated the effects of providing supplementary food. Nine studies from France, Sweden and the UK (six replicated studies, of which five controlled and one also randomized and paired) found that the provision of supplementary food increased farmland bird abundance, breeding population size, density, body mass, hatching, nestling growth and fledging rates, increased overwinter survival of a declining house sparrow population and that fed male hen harriers bred with more females than control birds. Two studies did not separate the effects of several other interventions carried out on the same study site. Four studies from the UK and Finland (three replicated studies, of which one controlled and one randomized) found that farmland songbirds and field voles (field voles on unmown plots only) used supplementary food when provided, including the majority of targeted species such as tree sparrow, yellowhammer and corn bunting. Five replicated studies from the UK (of which two also controlled) found that the provision of supplementary food had no clear effect on farmland bird breeding abundance, European turtle dove reproductive success, territory size or territory density, overwinter survival of three stable house sparrow populations, tree sparrow nest box use, or the abundance of weed seeds on the soil surface. One replicated, controlled study from Sweden found no effect of supplementary food provision on common starling clutch size or nestling weight, and lower fledging rates in nests which received supplementary food compared to nests without supplementary food in one year. Four studies from the UK (two replicated of which one was also randomized and controlled) found that the use of supplementary food by farmland birds varied between species and region, depended upon the time of year and proximity to other feeding stations and natural feeding areas. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F648https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F648Thu, 18 Oct 2012 14:20:34 +0100Collected Evidence: Collected Evidence: Pay farmers to cover the cost of conservation measures (as in agri-environment schemes) Twenty-six studies from four European countries (including one UK systematic review and three European reviews) looked at the effects of agri-environment schemes on birds. Twenty-four studies (including one systematic review, six site comparisons and nine reviews) found increases in population size, density or more favourable population trends of some or all birds studied on sites with agri-environment schemes compared to non-scheme sites (some of these differences were seasonal). Eleven studies (including one systematic review and four reviews) found negative or no effects. One UK study found higher numbers of some birds where higher tier management was in place, another UK study found no difference between Entry Level or Higher Level Stewardship Scheme fields. One study from the Netherlands found that not all agri-environment scheme agreements were sited in ideal locations for black-tailed godwit. Eleven studies from five European countries (including three replicated paired site comparisons and two reviews) looked at the effects of agri-environment schemes on plants. Seven studies (including three replicated paired site comparisons and one European review) found agri-environment schemes maintained or had little or no effect on plants, plant diversity or species richness. Three studies found increases in plant species richness in areas with agri-environment schemes, two found decreases. A replicated site comparison study from Estonia found higher flower abundance on farms with agri-environment schemes in two out of four areas. A review found Environmentally Sensitive Areas in England had contributed to halting the loss of semi-natural grassland habitats but were less effective at enhancing or restoring grassland biodiversity. Ten studies from three European countries (including two replicated paired site comparisons and a review) looked at the effects of agri-environment schemes on invertebrates. Six studies (including two replicated site comparisons) showed agri-environment schemes maintained or had little or no effect on some invertebrates in terms of diversity, abundance, species richness or bee colony growth. Five studies found increases in abundance or species richness of some invertebrates. A UK study found agri-environment scheme prescriptions had a local but not a landscape-scale effect on bee numbers. Four studies (including two replicated site comparisons and a review) from the UK looked at the effects of agri-environment schemes on mammals. One study found positive effects, three studies found mixed effects in different regions or for different species. Three of the studies above found higher numbers of wildlife on land before agri-environment schemes were introduced. However two studies collecting baseline data found no difference in the overall number of birds or earthworms and soil microorganisms between areas with and without agri-environment schemes. A review found two out of three agri-environment schemes in Europe benefited wildlife. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F700https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F700Fri, 21 Dec 2012 14:38:13 +0000
What Works 2021 cover

What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.


Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust