Collected Evidence: Collected Evidence: Support or maintain low-intensity agricultural systems We captured no evidence for the effects of supporting low-intensity agricultural systems on bird populations. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F168https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F168Sun, 20 May 2012 13:05:15 +0100Collected Evidence: Collected Evidence: Reduce field size (or maintain small fields) We found no intervention-based evidence on the effects of reducing field sizes on bird populations. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F174https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F174Sun, 27 May 2012 14:51:15 +0100Collected Evidence: Collected Evidence: Provide or retain set-aside areas in farmland Three replicated studies and a review of five studies from Europe and North America examining species richness or diversity found that more species were found on set-aside than on crops. One found fewer species on set-aside than other agricultural habitats. All 21 studies, including a systematic review, 12 replicated experiments and two reviews, from Europe and North America that investigated population trends or habitat associations found that some species were found at higher densities or used set-aside more than other habitats, or were found on set-aside. Four studies (three replicated) from the UK found that some species were found at lower densities on set-aside compared to other habitats. Three of four replicated studies from the UK found that waders and Eurasian skylarks had higher productivities on set-aside, compared to other habitats. One study found that skylarks nesting on set-aside had lower productivity compared to those on cereal crops, and similar productivities to those on other crops. One replicated paired study from the UK found that rotational set-aside was used more than non-rotational set-aside, a replicated paired study found no differences between rotational and non-rotational set-aside. A review from Europe and North America found that naturally regenerated set-aside held more birds and more species than sown set-aside. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F175https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F175Sun, 27 May 2012 15:10:59 +0100Collected Evidence: Collected Evidence: Tree pollarding and tree surgery We found no evidence for the effects of tree pollarding and tree surgery on bird populations. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F186https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F186Sun, 10 Jun 2012 13:01:16 +0100Collected Evidence: Collected Evidence: Relocate nests at harvest time to reduce nestling mortalityA replicated controlled study from Spain found that clutches that were temporarily removed from fields during harvest and then replaced had higher hatching and fledging rates than control clutches. Effects were greater on clutches that were older when moved.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F195https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F195Wed, 27 Jun 2012 17:41:59 +0100Collected Evidence: Collected Evidence: Take field corners out of managementA replicated study in the UK found that overwinter survival of grey partridge Perdix perdix was higher where field corners were taken out of management than on other sites for one of three winters. There was no relationship with the intervention and brood size, the ratio of young to old birds or density changes.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F198https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F198Wed, 27 Jun 2012 17:57:04 +0100Collected Evidence: Collected Evidence: Reduce conflict by deterring birds from taking crops using bird scarers A controlled paired study in the USA found reduced levels of damage to almond orchards when American crow Corvus brachyrhynchos distress calls were broadcast, compared to the previous year. There were no decreases in control orchards. A replicated study in Pakistan found that four pest species were less abundant when reflector ribbons were hung above crops, compared to when ribbons were not used.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F199https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F199Thu, 28 Jun 2012 11:34:06 +0100Collected Evidence: Collected Evidence: Reduce conflict by deterring birds from taking crops using repellentsA replicated, randomised and controlled ex situ study in the USA found that dickcissels Spiza americana consumed less rice if it was treated with two repellents, compared to controls. Two other repellents did not reduce consumption as effectively.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F200https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F200Thu, 28 Jun 2012 11:40:17 +0100Collected Evidence: Collected Evidence: Use ‘mosaic management’ A replicated, controlled before-and-after study from the Netherlands found that northern lapwing Vanellus vanellus population trends changed from decreases to increases following the introduction of mosaic management. Three other waders did not show such a response. A replicated, paired sites study in the Netherlands found that black-tailed godwits Limosa limosa had higher productivity under mosaic management than other management types, and nests were less likely to be trampled by livestock.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F202https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F202Thu, 28 Jun 2012 11:52:32 +0100Collected Evidence: Collected Evidence: Sow crops in spring rather than autumn A replicated, controlled, paired sites study from Sweden found more bird species on areas with spring sown cereals, compared with winter cereals. A before-and-after study from the UK found that several species bred in the study site for the first time after the start of spring sowing. Three studies from Sweden and the UK, two replicated and controlled, found population increases after the start of spring sowing, or higher populations on sites with spring-sown cereals, compared to sites with winter cereals. A before-and-after study from the UK found that ten species did not increase after spring sowing began. No species decreased. A replicated, controlled paired sites study from Sweden found that the benefits of spring-sowing decreased with the proportion of autumn-sown crops in the surrounding area. A replicated, controlled study from Sweden found that hatching success was lower on spring-sown crops than autumn sown.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F207https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F207Sun, 15 Jul 2012 17:16:58 +0100Collected Evidence: Collected Evidence: Undersow spring cereals, with clover for example Three studies from the UK, two replicated, found that there were higher densities of some study species on undersown fields or margins, compared with other fields, or that use of fields increased after they were undersown. One of these (reported in two places) found that not all species nested at higher densities. One replicated study from the UK found that various measures of grey partridge population health declined as the amount of undersown cereal on sites increased. A replicated study from the UK found no relationship between the amount of undersown cereals on a site and the productivity of grey partridge on that site.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F208https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F208Sun, 15 Jul 2012 17:28:25 +0100Collected Evidence: Collected Evidence: Revert arable land to permanent grassland All five studies looking at the effects of reverting arable land to grassland found no clear benefit to birds. The studies monitored birds or grey partridges in the UK and wading birds in Denmark (4). They included three replicated controlled trials. 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 Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F210https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F210Sun, 15 Jul 2012 18:00:36 +0100Collected Evidence: Collected Evidence: Reduce tillage Four replicated and controlled studies from North America and Canada and the UK and two literature reviews found that some or all bird groups had higher species richness or diversity on reduced-tillage fields, compared to conventional field in some areas. Two replicated and controlled studies from Canada and the UK and a review found that some measures of diversity were lower, or no different, on reduced-tillage fields, compared to conventional fields. Five replicated and controlled studies from the USA and Europe, a small study and two reviews all found that some bird species are found at higher densities on fields with reduced tillage than conventional fields. Five replicated and controlled studies from the USA, Canada and Europe, and a review found that some or all species were found at similar or lower densities on reduced-tillage fields compared to conventional fields, with one finding that preferences decreased over time (possibly due to extreme weather) and another finding that preferences were only found in spring. Two controlled studies (one replicated) and a review found evidence for higher productivity, nesting success or earlier laying on reduced tillage fields, compared to conventional fields. One controlled study found no evidence for greater success or larger chicks on reduced-tillage fields.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F211https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F211Mon, 16 Jul 2012 17:11:41 +0100Collected Evidence: Collected Evidence: Use 1% barley in wheat crops for corn buntingsWe have found no studies investigating the impact of adding barley to wheat on corn bunting Miliaria calandra populations.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F212https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F212Mon, 16 Jul 2012 17:48:08 +0100Collected Evidence: Collected Evidence: Reduce management intensity on permanent grasslands for birds Four replicated trials and a review, of seven studies in total, found that some or all birds monitored were more abundant or foraged more on grasslands with lower management intensity than on conventionally managed agricultural grasslands. Four analyses from three replicated trials, of seven studies in total, found that some or all birds monitored were less or similarly abundant on grasslands with lower management intensity than on conventionally managed agricultural grasslands.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F219https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F219Tue, 17 Jul 2012 12:37:47 +0100Collected Evidence: Collected Evidence: Reduce grazing intensity Nine studies from the USA and the UK, one replicated and controlled, found increases in populations of some species on fields with reduced grazing, or increased use of such fields by birds. Three of the studies used multiple interventions at once. Five studies from Europe, four replicated and controlled, found that some or all species were no more numerous on fields with reduced grazing, compared to intensively-grazed fields. One paired sites study from the UK found that black grouse Tetrao tetrix populations increased at reduced grazing sites (and declined elsewhere), but that large areas of reduced grazing had lower densities of female grouse. A before-and-after study from the USA found that the number of species on plots with reduced grazing increased over time. A replicated, controlled study from four countries in Europe found no differences in the number of species on sites with low-intensity or high-intensity grazing. One replicated trial in the UK found that some bird groups preferred grassland short in winter (grazing effect simulated by mowing), and others preferred it long (unmown to simulate removal of livestock). Frequency and timing of the simulated grazing did not alter this preference.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F220https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F220Tue, 17 Jul 2012 13:28:12 +0100Collected Evidence: Collected Evidence: Provide short grass for wadersA replicated UK study found that common starlings and northern lapwings spent more time foraging on short swards, compared to longer grass, and that starlings captured more prey in short grass.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F221https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F221Tue, 17 Jul 2012 14:03:36 +0100Collected Evidence: Collected Evidence: Raise mowing height on grasslands to benefit birds A review from the UK found that raising mowing height may have increased productivity of Eurasian skylarks, but not sufficiently to maintain the local population. A randomised, replicated and controlled study from the UK found that no more foraging birds were attracted to plots with raised mowing heights, compared to plots with shorter grass.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F222https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F222Tue, 17 Jul 2012 14:06:08 +0100Collected Evidence: Collected Evidence: Protect nests from livestock to reduce trampling A before-and-after study from the Chatham Islands, New Zealand found that the population of Chatham Island oystercatcher increased following several interventions including the erection of fencing around individual nests. A replicated, controlled study in Sweden found that no southern dunlin nests were trampled when protected by cages; some unprotected nests were destroyed.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F237https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F237Tue, 17 Jul 2012 16:44:30 +0100Collected Evidence: Collected Evidence: Scare birds from fish farms One before-and-after study from Israel found that the population of pygmy cormorants in the area increased after birds were scared away from fish farms, possibly due to lower persecution. One of two studies that examined fish stocks found that fewer fish were taken from a farm when heron distress calls were played. The other study, a literature review, found no evidence for the effects of scaring birds on fish stocks. Two replicated studies from Belgium and Australia found that using foot patrols to disturb birds from fish farms did not reduce the number of birds present or fish consumption. Ten of eleven studies from across the world, three controlled, found evidence that playing distress calls or using other acoustic deterrents (some with flashes of light) reduced the number of birds at fish farms, or changed bird behaviours. One of these involved underwater broadcasting. One study found effects were only temporary and five found that birds became habituated to noises. Four studies, one replicated and controlled, two before-and-after, found that acoustic deterrents were not effective in scaring birds. Five of seven studies, one controlled, found evidence that visual deterrents (including inflatable ‘Scarey Man’ scarecrows) reduced the number of birds at fish farms. Three found evidence for habituation to deterrents and three studies found no evidence that visual deterrents were effective. Two studies examined other deterrents, finding that trained raptors were effective but that the effects of helicopters and ultra-light aircraft were either inconclusive or very temporary.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F244https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F244Wed, 18 Jul 2012 11:00:04 +0100Collected Evidence: Collected Evidence: Use electric fencing to exclude fish-eating birdsTwo before-and-after studies from the USA found that electric fencing reduced the use of fish ponds by great blue herons Ardea herodias and great egrets Casmerodius albus.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F247https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F247Wed, 18 Jul 2012 11:52:28 +0100Collected Evidence: Collected Evidence: Use ‘mussel socks’ to prevent birds from attacking shellfishA randomised, replicated controlled experiment in Canada found that fewer medium-sized mussels were taken from mussel socks with a protective ‘sleeve’, compared to un-sleeved socks. There were no differences for small or large mussels.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F250https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F250Wed, 18 Jul 2012 12:11:31 +0100Collected Evidence: Collected Evidence: Translocate birds away from fish farmsA study from the USA cited in a review found that translocating birds away from a fish farm appeared to reduce the number of birds at the farm. A study from Belgium found that translocating herons did not seem to be an effective way to reduce bird numbers at fish farms.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F251https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F251Wed, 18 Jul 2012 12:15:27 +0100Collected Evidence: Collected Evidence: Provide refuges for fish within pondsA controlled cross-over trial in the UK found that great cormorant Phalacrocorax carbo foraging success was lower in a pond with artificial refuges, compared to a control pond.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F253https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F253Wed, 18 Jul 2012 12:49:06 +0100Collected Evidence: Collected Evidence: Spray water to deter birds from pondsA replicated study from Sweden found that a rotating water spray deterred birds from fish ponds, but that birds often became used to the spray.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F255https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F255Wed, 18 Jul 2012 12:57:49 +0100
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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.

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