Collected 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: 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: 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: 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: Reduce electrocutions by using plastic, not aluminium, leg rings to mark birdsA replicated and controlled study in the USA found no evidence for lower electrocution rates for raptors marked with plastic leg rings, compared to metal ones.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F270https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F270Thu, 19 Jul 2012 16:27:10 +0100Collected Evidence: Collected Evidence: Reduce seabird bycatch by releasing offal overboard when setting longlinesTwo replicated and controlled studies in the South Atlantic and sub-Antarctic Indian Ocean found significant reductions in the number of albatross and petrels attacking baits and being caught when offal was released overboard during line setting.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F299https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F299Tue, 24 Jul 2012 17:39:55 +0100Collected Evidence: Collected Evidence: Reduce gillnet deployment time to reduce seabird bycatch We found no evidence for the effects on seabird bycatch rates of reducing gill net deployment time. '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%2F304https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F304Tue, 24 Jul 2012 18:11:14 +0100Collected Evidence: Collected Evidence: Reduce visitor group size We found no intervention-based studies examining the effects of reducing visitor numbers on bird populations. However, a single, replicated study in forests in Spain in 2004 (Remacha et al. 2011) found that fewer birds, but not fewer species, were observed as visitor number increased. This effect was largely due to decreases in collared dove Streptopelia decaocto presence and serin Serinus serinus abundance. Remacha, C., Perez-Tris, J. & Antonio Delgado, J. (2011) Reducing visitors’ group size increases the number of birds during educational activities: Implications for management of nature-based recreation,Journal of Environmental Management, 92, 1564–1568. '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%2F312https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F312Wed, 25 Jul 2012 17:36:40 +0100Collected Evidence: Collected Evidence: Reduce predation by translocating predatorsTwo studies from France and the USA found local population increases or reduced predationfollowing the translocation of predators away from an area.  A study in Saudi Arabia found that predation was no lower when predators were translocated from the bird release site.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F393https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F393Thu, 09 Aug 2012 13:39:34 +0100Collected Evidence: Collected Evidence: Reduce nest predation by excluding predators from nests or nesting areasA 2011 systematic review found that excluding predators from nests significantly increased hatching success, although individual barriers around nests sometimes had adverse impacts. See also: Physically protect nests from predators using non-electric fencing; Physically protect nests with individual exclosures/barriers or provide shelters for chicks; Protect bird nests using electric fencing; Use artificial nests that discourage predation; Guard nests to prevent predation; Plant nesting cover to reduce nest predation; Protect nests from ants; Use multiple barriers to protect nests; Use naphthalene to deter mammalian predators; Use snakeskin to deter mammalian nest predators; Play spoken-word radio programs to deter predators; Use 'cat curfews' to reduce predation; Use lion dung to deter domestic cats; Use mirrors to deter nest predators; Use ultrasonic devices to deter cats; Can nest protection increase nest abandonment?; and Can nest protection increase predation of adults and chicks?Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F396https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F396Thu, 09 Aug 2012 14:28:57 +0100Collected Evidence: Collected Evidence: Reduce predation by translocating nest boxesTwo studies from Europe found that predation rates were lower for relocated nest boxes, compared to controls.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F420https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F420Fri, 17 Aug 2012 16:18:38 +0100Collected Evidence: Collected Evidence: Reduce inter-specific competition for nest sites of ground nesting seabirds by removing competitor species Four studies from Canada and the UK found increased tern Sterna spp. populations following the control or exclusion of gulls Larus spp. In two studies many interventions were used, making it impossible to tell which was responsible. One study from the UK and one from Canada found that controlling large gulls had no impact on smaller species. Two studies from the USA and UK found that exclusion devices successfully reduced the numbers of gulls at sites, although one found that they were only effective at small colonies and the other found that methods varied in their effectiveness and practicality.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F422https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F422Fri, 17 Aug 2012 16:21:39 +0100Collected Evidence: Collected Evidence: Reduce inter-specific competition for nest sites of woodpeckers by removing competitor species All four studies we captured describe the management of red-cockaded woodpeckers Picoides borealis in open pine forests in the USA. One small study found an increase in woodpecker population following the removal of southern flying squirrels Glaucomys volans, whilst a second found a population increase following squirrel removal, along with other interventions and a third found that reintroductions were  successful when squirrels were controlled. A randomised, replicated and controlled before-and-after study found fewer holes were occupied by squirrels following control efforts, but that occupancy by red-cockaded woodpeckers was no higher.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F423https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F423Fri, 17 Aug 2012 17:09:55 +0100Collected Evidence: Collected Evidence: Reduce inter-specific competition for nest sites of songbirds by removing competitor species Two studies from Australia found increases in bird populations and species richness after the control of noisy miners Manorina melanocephala – a native but hyper-competitive species. A controlled study from Italy found that blue tits Parus caeruleus nested in more nest boxes when hazel dormice Muscardinus avellanarius were excluded from nest boxes over winter.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F424https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F424Fri, 17 Aug 2012 17:28:29 +0100Collected Evidence: Collected Evidence: Reduce inter-specific competition for nest sites by modifying habitats to exclude competitor speciesA replicated controlled study from the USA found no impact of midstorey clearance on the occupation of red-cockaded woodpecker Picoides borealis nesting cavities by southern flying squirrels Glaucomys volans.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F425https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F425Fri, 17 Aug 2012 17:32:51 +0100Collected Evidence: Collected Evidence: Reduce inter-specific competition for food by removing or controlling competitor species Two controlled before-and-after studies from the UK found that six species of wildfowl showed significant increases following the removal of fish from lakes. Three other species did not show increases. A study from France found that grey partridges Perdix perdix increased at a site with several interventions, including the control of competitor species. A before-and-after study from Spain found no change in the rate of kleptoparasitic attacks on herons after the culling of gulls at a colony.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F428https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F428Fri, 17 Aug 2012 17:54:16 +0100Collected Evidence: Collected Evidence: Reduce nest ectoparasites by providing beneficial nesting materialA randomised, replicated and controlled experiment in Canada found lower numbers of some, but not all, parasites in nests provided with beneficial nesting material, but that there was no effect on fledging rates or chick condition.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F439https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F439Thu, 23 Aug 2012 14:26:34 +0100Collected Evidence: Collected Evidence: Reduce pesticide or herbicide use generally A single small study from the UK investigated population level effects of reduced chemical inputs, and found that the populations of some species increased when pesticide use was restricted alongside other interventions. Three studies, two replicated, one controlled, from the UK found that some or all species were found at higher densities on sites with reduced pesticide inputs, in one case with other interventions as well. Five studies from the UK, four replicated, four controlled, found that some or all species were not found at higher densities on fields or sites with reduced chemical inputs, or were not associated with reduced inputs. A controlled before-and-after study from the UK found that grey partridge Perdix perdix chicks had higher survival on sites with reduced pesticide applications. A replicated study from the UK found that reduced chemical inputs had a negative relationship with partridge brood size and no relationship with survival or the ratio of young to old birds.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F454https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F454Wed, 29 Aug 2012 14:08:01 +0100Collected Evidence: Collected Evidence: Reduce incidental mortality from birds being attracted to artificial lights We found no evidence for reduced incidental mortality from birds being attracted to artificial lights. '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%2F466https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F466Wed, 29 Aug 2012 16:14:05 +0100Collected Evidence: Collected Evidence: Reduce the intensity of lighthouse beams We found no evidence for the effects of reducing the intensity of lighthouse beams on bird mortality. '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%2F468https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F468Wed, 29 Aug 2012 16:25:43 +0100Collected Evidence: Collected Evidence: Rehabilitation of injured and treated birds Two replicated studies from the USA and UK found that 40% and 25% of raptors were released following rehabilitation. The USA study also found that 32% of owls were released. Three replicated studies from the USA all found relatively high survival of released raptors, with only 2.4% of birds being recovered (i.e. found dead, 1) and 66–68% survival over two weeks and six weeks. One study found that mortality rates were higher for owls than raptors.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F476https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F476Thu, 30 Aug 2012 13:15:35 +0100Collected Evidence: Collected Evidence: Release birds in groupsA replicated study from New Zealand found that released black stilts Himantopus novaezelandiae were more likely to move long distances after release if they were released in larger groups.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F634https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F634Sun, 14 Oct 2012 23:34:47 +0100Collected Evidence: Collected Evidence: Release birds in ‘coveys’ A replicated study in Saudi Arabia found that houbara bustard Chlamydotis undulata macqueenii survival was low when chicks were released in coveys with flightless females. A review of cackling goose Branta hutchinsii conservation and a replicated study in England found that geese and grey partridge Perdix perdix releases were more  successful for birds released in coveys than for young birds released on their own or adults released in pairs.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F635https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F635Sun, 14 Oct 2012 23:35:50 +0100Collected Evidence: Collected Evidence: Release birds as adults or sub-adults, not juveniles Three replicated studies found that malleefowl Leipoa ocellata, houbara bustards Chlamydotis undulata macqueenii and cackling geese Branta hutchinsii released as sub-adults, not juveniles had higher survival rates. A replicated study from New Zealand found lower survival for black stilts Himantopus novaezelandiae released as sub-adults, compared with juveniles. Two replicated studies from Hawaii and Saudi Arabia found lower survival for Hawaiian geese Branta sandvicensis and bustards released as wing-clipped sub-adults, compared with birds released as juveniles. Three replicated studies found no differences in survival between ducks, vultures and ibises released at different ages, but a second study of the vulture release programme found that birds released when more than three years old had lower reproductive success than birds released at an earlier stage.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F636https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F636Sun, 14 Oct 2012 23:39:47 +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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