Conservation Evidence: Evidence Data

Collected Evidence: Collected Evidence: Increase the proportion of natural/semi-natural vegetation in the farmed landscape Of four studies captured, one, a replicated and controlled paired sites study from Australia, found that farms with plantings of native vegetation held more species than those without. The effect was smaller than that explained by variation in the amount of natural habitat remaining on farms. A replicated study from Switzerland found more species in areas under the Ecological Compensation Area scheme than areas not under it. A before-and-after study from Switzerland found that the populations of three bird species increased after an increase in the amount of land under the Ecological Compensation Scheme. This study found that three species were more found more than expected on Ecological Compensation Scheme land. Another replicated study from Switzerland found that some habitats held more birds if they were close to ECA habitat but that the amount of Ecological Compensation Scheme in an area had no impact on population densities. A small study from the UK found no effect of habitat creation on grey partridge populations. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F171https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F171Sun, 20 May 2012 13:21:01 +0100Collected Evidence: Collected Evidence: Pay farmers to cover the costs of bird conservation measures Three reviews from the UK of three studies captured reported population increases of three species after the introduction of specially-designed agri-environment schemes. These species were cirl buntings, corncrakes and Eurasian thick-knees. One of these found that many other species continued to decline. Twenty-two of 25 studies all from Europe, including a systematic review, examining local population levels or densities found that at least some birds studied were at higher densities, had higher population levels or more positive population trends on sites with agri-environment schemes, compared to non-agri-environment scheme sites. Some studies found that differences were present in all seasons, others in either summer or winter. Fifteen studies from Europe, including a systematic review, found that some or all species were not found at higher densities, had similar or lower population levels, showed similar population trends on sites with agri-environment schemes, compared with non-agri-environment scheme sites, or showed negative population trends. A study from the Netherlands found that many agri-environment scheme farms were sited in areas where they were unlikely to be effective. One small study from the UK found no differences between winter densities of seed-eating birds on UK Higher Levels Stewardship sites, compared with those under Entry Level Stewardship. A replicated study from the UK found that grey partridge survival was higher on agri-environment scheme sites than non-scheme sites. This difference was not significant every year. Two of three studies investigating reproductive productivity, including one replicated study, found that productivity was higher on farms under agri-environment schemes. One replicated study from the UK found no effect of agri-environment schemes on productivity. A review (Vickery et al. 2010) found that the amount of land entering an agri-environment scheme was on target, but that some options were not being used at high enough rates to help many species. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F172https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F172Sun, 20 May 2012 14:06:41 +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%2Fconservationevidencejournal.com%2Factions%2F175https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F175Sun, 27 May 2012 15:10:59 +0100Collected Evidence: Collected Evidence: Manage hedges to benefit birds The one study of six that investigated species richness found no difference in species richness between a UK site with wildlife-friendly hedge management and three control sites. Seven studies from the UK and Switzerland, five replicated, found that some species studied increased in relation to managed hedges or were more likely to be found in managed hedges, compared to other habitats. Two investigated several interventions at once. One replicated study found that species that showed positive responses to hedge management in some regions showed weak or negative responses in other parts of the UK. Four studies from the UK found that some species declined or showed no response to wildlife-friendly management of hedges. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F177https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F177Wed, 30 May 2012 13:46:53 +0100Collected Evidence: Collected Evidence: Manage ditches to benefit wildlife Three out of four replicated studies from the UK found that some farmland birds responded positively to the presence of ditches managed for wildlife. All three also found that some species did not respond positively or responded negatively to management. A replicated, controlled and paired sites study from the UK found that bunded ditches were visited by more birds than non-bunded ditches. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F180https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F180Wed, 30 May 2012 14:17:50 +0100Collected Evidence: Collected Evidence: Plant wild bird seed or cover mixture All seven studies (based on five replicated experiments and a review) that investigated species richness or diversity were from the UK and found that fields or farms with wild bird cover had higher bird diversity than those without, or that more species were found in wild bird cover than in surrounding habitats. Thirty-two studies out of 33 from the UK and North America that examined abundance and population data, found that bird densities, abundances, nesting densities or use of wild bird cover was higher than in other habitats or management regimes, or that sites with wild bird cover had higher populations than those without. These studies included a systematic review and seven randomised, replicated and controlled studies. Some studies found that this was the case across all species or all species studied, while others found that only a subset showed a preference. Four studies investigated other interventions at the same time. Thirteen of the 33 studies (all replicated and from Europe and the USA), found that bird populations or densities were similar on wild bird cover and other habitats, that some species were not associated with wild bird cover or that birds rarely used wild bird cover. Three studies from the UK and Canada, two replicated, found higher productivities for some or all species monitored on wild bird cover, compared to other habitats. Two replicated and controlled studies from Canada and France found no differences in reproductive success between wild bird cover and other habitats for some or all species studied. Three studies from Europe and the USA investigated survival, with two finding higher survival of grey partridge Perdix perdix released on wild bird cover or of artificial nests in some cover crops. The third found that survival of grey partridge was lower on farms with wild bird cover, possibly due to high predation. Five studies from the UK, three replicated, found that some wild bird cover crops were preferred to others. A randomised, replicated and controlled study and a review from the UK found that the landscape surrounding wild bird cover and their configuration within it affected use by birds. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F187https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F187Sun, 10 Jun 2012 13:10:33 +0100Collected Evidence: Collected Evidence: Plant nectar flower mixture/wildflower strips for birds Two replicated and controlled studies from the UK (one randomised) and a European review out of seven studies captured found that more birds used nectar/wildflower strips than crops or land under other management. Two studies of a replicated and controlled experiment in the UK found that no more birds used nectar/wildflower strips in winter than used land under other management. A replicated, controlled study from Switzerland found that Eurasian skylarks Alauda arvensis were more likely to nest in patches of fields sown with annual weeds than in crops, and were less likely to abandon nests in these patches. A randomised, replicated and controlled study from the UK found that field margin management affected their use by birds more than the seed mix used on them. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F189https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F189Sat, 16 Jun 2012 19:33:52 +0100Collected Evidence: Collected Evidence: Create uncultivated margins around intensive arable or pasture fields for birds A replicated, controlled study from the USA found that three sparrow species found on uncultivated margins were not found on mown field edges. A replicated study from Canada found fewer species in uncultivated margins than in hedges or in trees planted as windbreaks. Three replicated studies from the USA and UK, one controlled, found that some birds were associated with uncultivated margins, or that birds were more abundant on margins than on other habitats. One study found that these effects were very weak. Four replicated studies (two of the same experiment) from the UK, two controlled, found that uncultivated margins contained similar numbers of birds in winter, or that several species studied did not show associations with margins. A replicated, controlled study from the UK found that yellowhammers Emberiza citrinella used uncultivated margins more than crops in early summer, but use fell in uncut margins in late summer. Cut margins however, were used more than other habitat types late in summer. A replicated study from the UK found high rates of survival for grey partridge Perdix perdix released in margins. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F190https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F190Sat, 16 Jun 2012 19:47:53 +0100Collected Evidence: Collected Evidence: Plant grass buffer strips/margins around arable or pasture fields for birds One replicated controlled study from the USA found that there were more species in fields bordered by margins than unbordered fields. Two replicated studies from the UK, one with paired sites, found no effect of field margins on species richness. A replicated, controlled study from the UK found that more birds and more species used sown strips in fields than the fields themselves, but even more used field margins. Nine studies from the UK and USA, seven replicated, two controlled, found more positive population trends, higher populations or strong habitat associations for some or all species for sites with grass margins to fields. One study investigated multiple interventions. Three replicated studies from the UK found that grass field margins did not have a positive effect on populations of some or all bird species investigated. Both studies that examined habitat use (one replicated, both from the UK) found that species used margins more than other habitats. A randomised, replicated and controlled study from the UK found that birds used cut margins more than uncut margins during winter but less than other management regimes during summer. The authors argue that management type is more important than the seed mix used to sow the margins. A replicated study from the UK found that grey partridge Perdix perdix had smaller broods in grass margins than other habitat types. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F191https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F191Wed, 27 Jun 2012 16:39:04 +0100Collected Evidence: Collected Evidence: Leave overwinter stubbles The three studies from the UK (one replicated) that report population-level changes found positive effects of over-winter stubble provision, but all investigated multiple interventions at once. Eight studies from the UK, including a systematic review, found that at least some species or groups of farmland birds were positively associated with over-winter stubbles, or were found on stubbles. Three studies investigated multiple interventions without separating the effects of each. Two studies reported that seed-eating birds in particular were more abundant on stubbles. One of the eight studies found that no more positive responses to stubbles were found than would be expected by chance. A replicated, randomised and controlled study from the UK found that 22 of 23 species did not preferentially use stubbles compared to cover crops. A replicated study from the UK found that the area of stubble in a site was negatively related to grey partridge Perdix perdix brood size. Five studies from the UK, four replicated, found that stubble management affected use by birds. Some species or groups were more common on cut stubbles, some on uncut and some showed preferences for barley over wheat. One study found that only Eurasian skylarks Alauda arvensis were more common on stubbles under agri-environment schemes, and only on highly prescriptive schemes. One study found that all seed-eating species were more abundant on stubbles under agri-environment schemes in one of two regions studied. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F203https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F203Mon, 09 Jul 2012 15:13:01 +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%2Fconservationevidencejournal.com%2Factions%2F208https%3A%2F%2Fconservationevidencejournal.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%2Fconservationevidencejournal.com%2Factions%2F210https%3A%2F%2Fconservationevidencejournal.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%2Fconservationevidencejournal.com%2Factions%2F211https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F211Mon, 16 Jul 2012 17:11:41 +0100Collected Evidence: Collected Evidence: Leave uncropped, cultivated margins or plots, including lapwing and stone curlew plots Two studies and two reviews examined population-level effects of uncropped margins or plots. A before-and-after study from the UK and two reviews found an increase in Eurasian thick-knee Burhinus oedicnemus numbers following a scheme that promoted plots (amongst other interventions); a replicated study from the UK found no effect of plots on grey partridge density changes. Four studies (three replicated) and a review from the UK found that at least one species was associated with lapwing plots or used them for foraging or nesting. One replicated study from the UK found that 11 species were not associated with plots; another found that fewer birds used the plots than cropland in two out of three UK regions. Two of the three studies that examined productivity (one replicated) found that nesting success of birds was higher in fallow fields or lapwing plots than in crops. A replicated study from the UK found that grey partridge Perdix perdix productivity was not related to the amount of lapwing plots on a site and that the proportion of young partridges in the population was lower on sites with lots of cultivated fallow plots. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F213https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F213Tue, 17 Jul 2012 11:09:12 +0100Collected Evidence: Collected Evidence: Create skylark plots for bird conservation A before-and-after study found an increase in Eurasian skylark Alauda arvensis population on a farm after the creation of skylark plots; a replicated, controlled study from the UK found higher densities of skylarks on fields with plots, compared to those without. No other studies investigated population-level effects. Two UK studies, one replicated and controlled, found that skylark productivity was higher in plots or in fields with plots than in controls. One replicated and controlled study from Switzerland found no differences in productivity between territories that included plots and those that did not. Two replicated studies (one controlled) from Denmark and Switzerland found that skylark plots were used by skylarks more than expected. A replicated and controlled study from the UK found that seed-eating songbirds did not use skylark plots more than surrounding crops. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F214https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F214Tue, 17 Jul 2012 11:43:29 +0100Collected Evidence: Collected Evidence: Create beetle banks A small UK study found that a site with beetle banks had increasing populations of rare or declining species, although several other interventions were used on this site. A literature review from the UK found that grey partridge Perdix perdix populations were far larger on sites with beetle banks and other interventions than on other farms. Two replicated studies from the UK also investigated population-level effects: one found that no bird species were strongly associated with beetle banks; the second found no relationship between beetle banks and grey partridge population density trends. A UK literature review found that two bird species nested in beetle banks and that some species were more likely to forage in them than others. A study in the UK found that one of two species used beetle banks more than expected. The other used them less than other agri-environment options. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F217https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F217Tue, 17 Jul 2012 12:04:26 +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%2Fconservationevidencejournal.com%2Factions%2F219https%3A%2F%2Fconservationevidencejournal.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%2Fconservationevidencejournal.com%2Factions%2F220https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F220Tue, 17 Jul 2012 13:28:12 +0100Collected Evidence: Collected Evidence: Delay haying/mowing Two reviews from the UK found that the population of corncrakes Crex crex increased following the implementation of two initiatives to encourage farmers to delay mowing (and provide cover and use corncrake-friendly techniques). A replicated and controlled paired sites study from the Netherlands found no evidence that waders and other birds were more abundant in fields with delayed mowing, compared to paired controls. A replicated and controlled before-and-after study from the Netherlands found that fields with delayed mowing held more birds than controls, but did so before the start of the scheme. Population trends did not differ between treatments. A replicated, controlled study from the USA found that destruction of nests by machinery was lower and late-season nesting higher in late-cut fields, compared with early-cut fields. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F223https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F223Tue, 17 Jul 2012 14:29:48 +0100Collected Evidence: Collected Evidence: Leave uncut rye grass in silage fields for birds Two reviews from the UK found that leaving rye grass uncut, or with only a single cut, benefited seed-eating birds and two replicated, controlled studies from the UK found that seed-eating birds were more abundant on uncut plots. Two replicated and controlled studies and a review, all from the UK, found that seed-eating birds were more abundant on uncut and ungrazed plots than on uncut and grazed plots. A replicated, controlled study from the UK found that the responses of non-seed-eating birds were less certain than seed-eaters, with some species avoiding uncut rye grass. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F224https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F224Tue, 17 Jul 2012 15:04:39 +0100Collected Evidence: Collected Evidence: Maintain traditional water meadows A replicated study from the UK found that northern lapwing and common redshank populations increased on nature reserves managed to maintain water meadows. Two replicated studies from the Netherlands found that there were more waders or birds overall on specially managed meadows or 12.5 ha plots including several management interventions than on conventional fields, but one study found that these differences were present before the management scheme was introduced and the other found no differences between individual fields under different management. A replicated study from the UK found that common snipe decreased on nature reserves managed to maintain water meadows and a replicated before-and-after study from the Netherlands found that wader population trends on specially managed meadows were no different to those on conventionally-managed meadows. A replicated study from the UK found that lapwing populations on three of four water meadow sites managed for conservation did not have high enough productivity to maintain population levels. All three sites were judged deficient in at least one management category. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F229https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F229Tue, 17 Jul 2012 15:37:55 +0100Collected Evidence: Collected Evidence: Exclude grazers from semi-natural habitats Two replicated (one controlled) studies from the USA found higher species richnesses on sites with grazers excluded; a replicated and controlled study from Argentina found lower species richness in ungrazed sites and a study from the USA found no difference. Seven studies from the USA (three controlled, two replicated) found that overall bird abundance, or the abundances of some species were higher in sites with grazers excluded; seven studies from the USA and Argentina found that overall abundance or the abundances of some species were lower on sites without grazers, or did not differ between treatments. Three studies from the USA investigated productivity and found it higher in sites with grazers excluded. In one study this difference was only found on improved, not unimproved pastures. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F236https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F236Tue, 17 Jul 2012 15:59:50 +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%2Fconservationevidencejournal.com%2Factions%2F244https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F244Wed, 18 Jul 2012 11:00:04 +0100Collected Evidence: Collected Evidence: Disturb birds at roosts One controlled study from the USA investigated the effects of harassment on fish predation, and found there were fewer double-crested cormorants Phalacrocorax auritus on, and fewer fish were taken from, fish ponds near roosts which were harassed, compared with undisturbed roosts. A review found that there was a reduction in the number of cormorants foraging near roosts after night-time disturbance. Four studies, two replicated, from the USA and Israel, found that cormorants moved away from roosts where they were disturbed at night. One study found that this effect was only temporary. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F245https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F245Wed, 18 Jul 2012 11:42:12 +0100Collected Evidence: Collected Evidence: Use netting to exclude fish-eating birds Two replicated studies from Germany and the USA found that netting or closely-spaced string barriers reduced losses of fish or deterred fish-eating birds from fish ponds. A review concluded that excluding birds was an effective way to reduce damage. A series of tests in the Netherlands found that netting or nylon lines over ponds did not prevent birds from landing, but did alter behaviour, whilst a before-and-after study from the USA found that fewer great blue herons Ardea Herodias landed at fish ponds with netting, but that they stayed longer. Two replicated studies from Germany and Israel found that some birds became entangled in netting or closely-spaced string barriers over fish ponds. The Israeli study found that dark, small meshed netting entangled fewer birds than other netting types. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F248https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F248Wed, 18 Jul 2012 12:00:45 +0100