Collected Evidence: Collected Evidence: Manage heather by swiping to simulate burning A replicated controlled trial in Northern Ireland found that heather moorland subject to flailing to simulate burning had more plant species eight years after the management, than control unflailed plots, but fewer plant species than burned plots.  Collected, 14 Jan 2012 15:19:00 +0000Collected Evidence: Collected Evidence: Manage heather, gorse or grass by burning A long-term replicated controlled trial in Switzerland found that annual spring burning of calcareous grassland did not increase plant species richness relative to abandoned plots, after 15 years. A replicated controlled trial in Northern Ireland found that heather moorland subject to a single burn had more plant species eight years after the management, than control unburned plots.  Collected, 14 Jan 2012 15:22:28 +0000Collected Evidence: Collected Evidence: Create scrapes and pools Three studies from Sweden and the UK (including two site comparisons one of which was replicated) found that the creation of scrapes and pools provided habitat for a range of plant, invertebrate or bird species and resulted in increased aquatic macroinvertebrate diversity. One of these studies found constructed pools supported locally or nationally scarce species of plant and water beetle. A study in Sweden found that a combination of large surface area, high shoreline complexity and shallow depth resulted in increased bird, bottom-dwelling invertebrate and aquatic plant diversity. However there were fewer fish species than in natural wetlands. Two replicated studies from Ireland and the UK (one controlled paired study and a site comparison) found that bird visit rates were higher but invertebrate numbers varied in ditch-fed paired ponds compared with dry controls and total macroinvertebrate and beetle richness did not differ between artificial and natural ponds, although communities did differ.  Collected, 14 Jan 2012 15:30:46 +0000Collected Evidence: Collected Evidence: Provide owl nest boxes (Tawny owl, Barn owl) Two studies from the UK (a before-and-after study and a controlled study) found that the provision of owl nest boxes in farm buildings maintained barn owl nesting and roosting activity and resulted in an increase in population density. A study from the Netherlands found that the barn owl population increased with increased availability of nest boxes. A replicated, controlled study in Hungary found that juvenile barn owls fledged from nest boxes were significantly less likely to be recovered alive than those reared in church towers. A replicated study from the UK investigating barn owl nest site use, found that the number of occupied nest sites and the proportion breeding decreased from 2001 to 2009, but were unaffected by the number of boxes.  Collected, 14 Jan 2012 15:38:54 +0000Collected Evidence: Collected Evidence: Provide nest boxes for birds Two studies (including one before and after study) from the Netherlands and the UK found that following the provision of nest boxes there was an increase in the number of Eurasian kestrel clutches and breeding tree sparrows. One replicated study from Switzerland found the number of Eurasian wryneck broods in nest boxes declined over five years whilst the number of Eurasian hoopoe broods increased. Eight studies from Finland, the Netherlands, Sweden, Switzerland and the UK (six were replicated) found that nest boxes in agricultural habitats were occupied by Eurasian kestrel, long-eared owl, common starling, tits Parus spp., tree sparrow, stock dove and jackdaw, and Eurasian wryneck and Eurasian hoopoe. Whilst two studies from the UK (a replicated, paired site study and a controlled study) found that carrion crows did not nest in artificial trees and tree sparrows showed a preference for nest boxes in wetland habitat, compared to those in farmland sites. Two replicated studies from Sweden found that nest success within boxes was related to the amount of pasture available and nest boxes positioned higher above the ground had higher occupancy, numbers of eggs and numbers of hatched young.  Collected, 14 Jan 2012 15:49:39 +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, 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, 18 Jul 2012 11:47:21 +0100Collected Evidence: Collected Evidence: Manage the agricultural landscape to enhance floral resources One large replicated controlled trial showed that the average abundance of long-tongued bumblebees on field margins was positively correlated with the number of ‘pollen and nectar’ agri-environment agreements in a 10 km grid square. Collected, 03 Aug 2012 12:08:24 +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, 23 Aug 2012 15:37:16 +0100Collected Evidence: Collected Evidence: Plant new hedges Two studies from France and the UK compared newly planted hedges with control areas. Both (including one replicated trial) found newly planted hedges had higher abundance, species richness or diversity of beetles or spiders than crop fields or field margins. The replicated study also found vascular plant species diversity and grass species richness were higher in newly planted hedges than recently established grass field margins. A review found newly established hedges supported more ground beetles than older hedges. A small-scale study from the UK found that local hawthorn plants exhibited better growth and were more stock proof than those of eight other provenances. A literature review found lower pest outbreaks in areas with new hedges. A replicated study in the UK found that the diversity of arthropods supported by newly planted hedges varied between seven different plant species An unreplicated site comparison study in Germany found that two out of 85 ground beetle species used newly planted hedges as stepping stones for dispersal. Results from the same study found that invertebrates that moved passively (attached to mammals and birds), such as snails, benefited most from the hedge-islands compared to actively moving ground beetles and harvestmen. Collected, 11 Sep 2012 15:38:22 +0100Collected Evidence: Collected Evidence: Use traditional breeds of livestock Two UK studies (one replicated) and a review reported differences in quantities of plant species grazed, vegetation structure and invertebrate assemblages between areas grazed with different breeds of sheep or cattle. A small, replicated study found that Hebridean sheep grazed more purple moor grass than Swaledale sheep, but the resulting density of purple moor grass and heather did not differ. A UK study found that at reduced grazing pressure, traditional and commercial cattle breeds created different sward structures and associated invertebrate assemblages. One replicated trial from France, Germany and the UK found grazing by traditional rather than commercial livestock breeds had no clear effect on the number of plant species or the abundance of butterflies, grasshoppers, birds, hares, or ground-dwelling arthropods in general. Collected, 11 Sep 2012 15:57:52 +0100Collected Evidence: Collected Evidence: Create skylark plots All four studies from the UK and Switzerland (two replicated and controlled, and one review) investigating the effect of skylark plots on Eurasian skylarks, found a positive effect, reporting increases in skylark population size, breeding density, duration or success or a lower likelihood of skylarks abandoning their territory relative to fields without plots. A replicated study from Denmark found that skylarks used undrilled patches within cereal fields more than expected by an even distribution across the landscape. Four studies reported the effect of undrilled patches on wildlife other than skylarks. Three studies from the UK (including two replicated studies, of which one also controlled and a review) found benefits to plants and invertebrates. Whilst two studies (both replicated, one also controlled) from the UK found no significant differences in the number of some invertebrates or seed-eating songbirds between skylark plots and conventional crop fields. One replicated study from the UK investigated different skylark plot establishment techniques. Plots that were undrilled had greater vegetation cover and height than plots established by spraying out with herbicide. Collected, 11 Sep 2012 16:08:32 +0100Collected Evidence: Collected Evidence: Increase crop diversity All four studies (including one replicated, controlled study and one review) from Belgium, Germany, Hungary and unspecified European countries reported a positive effect of crop rotations on ground beetles or plants. Three studies found higher ground beetle species richness and/or abundance and one study found higher plant species richness in rotation fields or on farms with more crops in rotation compared to monoculture fields. A study from Hungary found that fields in monoculture had a more stable and abundant ground beetle community than fields within a rotation.  Collected, 25 Sep 2012 12:08:33 +0100Collected Evidence: Collected Evidence: Convert or revert arable land to permanent grassland All seven individual studies (including four replicated studies, of which two also controlled and a review) looking at the effects of reverting arable land to grassland found no clear benefit to wildlife. The studies monitored UK birds in winter and summer, wading birds in Denmark, grey partridges, brown hares in the UK, and plants in the Czech Republic. One of the studies, a controlled before-and-after study from the UK, showed that grey partridge numbers fell significantly following the reversion of arable fields to grassland.  Collected, 25 Sep 2012 12:33:31 +0100Collected Evidence: Collected Evidence: Leave cultivated, uncropped margins or plots (includes 'lapwing plots') Nineteen individual studies looked at the effect of uncropped, cultivated margins or plots on wildlife. Seventeen studies from the UK and northwest Europe (six reviews and seven replicated studies of which two were site comparisons, one a before-and-after trial and one was controlled and randomized) found that leaving uncropped, cultivated margins or plots on farmland provides benefits to some or all target farmland bird species, plants, invertebrates, and mammals. These wildlife benefits included increased species richness of plants, bumblebees, species richness and abundance of spiders, abundance of ground-dwelling invertebrates and ground beetles, increased stone curlew breeding population size, northern lapwing hatching success, Eurasian skylark nesting success and the establishment, abundance or species richness of rare arable plant species. A replicated study found northern lapwing, Eurasian skylark, grey partridge and yellow wagtail bred in lapwing plots. Two studies (a replicated study and a review) from the UK found that leaving uncropped, cultivated margins or plots on farmland had no effect on 11 out of 12 farmland bird species or ground beetles. A replicated site comparison study in the UK found fewer seed-eating birds on fallow plots for ground-nesting birds in two out of three regions. One review from the UK found evidence that pernicious weeds were more commonly found on uncropped cultivated margins than conservation or conventional headlands. A replicated site comparison from the UK found the proportion of young grey partridges in the population was lower in areas with a high proportion of uncropped cultivated margins and plots. Collected, 25 Sep 2012 14:57:25 +0100Collected Evidence: Collected Evidence: Create open patches or strips in permanent grassland Two studies (both randomized, replicated and controlled) investigated the effects of creating open strips in permanent grassland. One trial from the UK found that more Eurasian skylarks used fields containing open strips, but variations in skylark numbers were too great to draw conclusions from this finding. One trial from Scotland found insect numbers in grassy headlands initially dropped when strips were cleared.  Collected, 25 Sep 2012 17:19:06 +0100Collected Evidence: Collected Evidence: Plant cereals in wide-spaced rows One replicated, controlled randomized study and four reports from the same replicated, controlled study in the UK investigated the effects of planting cereals in wide-spaced rows on birds, invertebrates and plants. Both studies found no or inconsistent differences in plant and invertebrate abundance and/or species richness between wide-spaced row and control fields. The replicated controlled study found higher undesirable weed cover, and one study found no significant difference in weed cover in fields with wide-spaced rows compared to control fields. One study found significantly lower invertebrate abundances and fewer Eurasian skylark nests in wide-spaced row fields than control fields or fields with undrilled patches. However it also found an increase in the body condition of nestlings over the breeding season in wide-spaced row fields compared with control fields.  Collected, 26 Sep 2012 16:47:40 +0100Collected Evidence: Collected Evidence: Restrict certain pesticides A small scale study in the UK found that using the fungicides Propiconazole and Triadimefon reduced chick food insect abundance less than using Pyrazophos. A replicated, controlled trial in Switzerland found that applying metaldehyde slug pellets in a 50 cm band along the field edge adjacent to wildflower strips provided equivalent crop protection to broadcasting the pellets across the whole field.  Collected, 28 Sep 2012 15:37:14 +0100Collected Evidence: Collected Evidence: Connect areas of natural or semi-natural habitat All four studies (including one site comparison and two replicated trials) from the Czech Republic, Germany and the Netherlands investigating the effects of habitat corridors or restoring areas of natural or semi-natural habitat between existing patches found some degree of colonization of these areas by invertebrates or mammals. However for invertebrates one unreplicated site comparison reported that the colonization process was slow (Gruttke 1994), and three studies found that the extent of colonization varied between invertebrate taxa. One small, replicated study from the Czech Republic investigated colonization of two bio-corridors by small mammal species. It found more small mammal species in the bio-corridors than in an adjacent forest or arable fields. All three studies from Germany and the Netherlands looking at the effects on invertebrates found mixed results. One replicated study found more species of some wasps (cavity-nesting wasps and caterpillar-hunting wasps) in grass strips connected to forest edges than in isolated strips. An unreplicated study found that the abundance of three ground beetle species substantially increased in an arable field undergoing restoration to heathland but that typical heathland species failed to colonize over the 12 year period. One study found that two out of 85 ground beetle species used a meadow and hedge-island strip extending from semi-natural habitats into arable farmland. In the same study the habitat strip did not function well for ground beetles and harvestmen but was colonized by snails and spiders. Collected, 04 Oct 2012 11:08:34 +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, 12 Oct 2012 14:56:56 +0100Collected Evidence: Collected Evidence: Provide 'sacrificial' grasslands to reduce the impact of wild geese on crops All six studies from the UK (including four replicated, controlled trials) found that managing grasslands for geese increased the number grazing there. Two replicated, controlled studies found that fertilized and cut areas were grazed by more white-fronted geese or brent geese than control areas. A replicated, controlled trial found that re-seeded and fertilized wet pasture fields were used by more barnacle geese than control fields, and that fertilized areas were used less than re-seeded ones. A replicated, controlled study found that spring fertilizer application increased the use of grassland fields by pink-footed geese. A replicated study found that plots sown with white clover were preferred by dark-bellied brent geese compared to plots sown with grasses. However, four of the studies found that the birds were moving within a relatively small area (i.e. within the study site) and therefore the grasslands may not reduce conflict with farmers.  Collected, 15 Oct 2012 16:28:48 +0100Collected Evidence: Collected Evidence: Sow rare or declining arable weeds Two studies from the UK (both replicated, controlled and randomized) found that the establishment of rare or declining arable weeds depended upon cover crop, cultivation, timing of cut and year or a combination of cultivation in autumn and herbicide treatment.  Collected, 16 Oct 2012 13:52:39 +0100Collected Evidence: Collected Evidence: Create rotational grass or clover leys A controlled study in Finland found that creating clover leys resulted in higher spider abundance and fewer pest insects than a barley control plot. A study in the UK found that one-year ley plots had significantly lower earthworm species richness and abundance than three-and-a-half-year leys. A replicated study in the UK found that grass leys had fewer plant species than nine other conservation measures.  Collected, 16 Oct 2012 15:45:06 +0100Collected Evidence: Collected Evidence: Restore or create wood pasture One replicated controlled trial in Belgium found that protection from grazing enhanced the survival and growth of tree seedlings planted in pasture. One replicated study in Switzerland found that cattle browsing increased the mortality of tree saplings of four species, and reduced average shoot production and total above-ground biomass. Browsing frequency decreased with increasing height of the surrounding vegetation.  Collected, 17 Oct 2012 15:01:11 +0100Collected Evidence: Collected Evidence: Use scaring devices (eg. gas guns) and other deterrents to reduce persecution of native species One replicated, controlled trial in Germany found phosphorescent tape was more effective than normal yellow tape at deterring deer from an area, but had no effect on wild boar or European hare.  Collected, 17 Oct 2012 17:00:06 +0100
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