Collected Evidence: Collected Evidence: Remove midstorey from savannasA controlled study in Argentina found that in summer, but not overall, a control area had higher bird abundance and species richness than an area where shrubs were removed. There were also differences in community composition between treatments.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F336https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F336Sat, 28 Jul 2012 14:54:45 +0100Collected Evidence: Collected Evidence: Remove or control non-native crayfish We found no evidence for the effects of removing or controlling non-native crayfish on amphibian 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%2F797https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F797Thu, 22 Aug 2013 14:42:03 +0100Collected Evidence: Collected Evidence: Remove or control invasive cane toads We found no evidence for the effects of removing or controlling invasive cane toads on amphibian 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%2F798https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F798Thu, 22 Aug 2013 14:43:02 +0100Collected Evidence: Collected Evidence: Remove or control invasive Cuban tree frogs One before-and-after study in the USA found that the abundance of squirrel tree frogs and green tree frogs increased after removal of invasive Cuban tree frogs.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F822https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F822Fri, 23 Aug 2013 10:55:01 +0100Collected Evidence: Collected Evidence: Remove or control invasive bullfrogs One replicated, before-and-after study in the USA found that removing American bullfrogs significantly increased a population of California red-legged frogs. One before-and-after study in the USA and Mexico found that eradicating bullfrogs from the area increased the range of leopard frogs. One replicated, before-and-after study in the USA found that once bullfrogs had been removed, California red-legged frogs were found out in the open twice as frequently.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F825https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F825Fri, 23 Aug 2013 11:19:46 +0100Collected Evidence: Collected Evidence: Remove or control fish by drying out ponds One before-and-after study in the USA found that draining ponds to eliminate fish increased numbers of amphibian species. One replicated, before-and-after study in Estonia found that pond restoration, which sometimes included drying to eliminate fish, and pond creation increased numbers of species and breeding populations of common spadefoot toads and great crested newts compared to no management. Three studies (including one review) in the UK and USA found that pond drying to eliminate fish, along with other management activities in some cases, increased breeding success of frog or newt species.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F826https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F826Wed, 28 Aug 2013 11:56:43 +0100Collected Evidence: Collected Evidence: Remove or control fish by catching Four studies (including two replicated, controlled studies) in the USA found that removing fish by catching them significantly increased abundance of salamanders or frogs or increased recruitment, survival and population growth rate of cascades frog. One before-and-after study in the UK found that fish control had no significant effect on great crested newt populations and fish remained or returned within a few years. One replicated, before-and-after study in Sweden found that fish control did not increase green toad breeding success and fish were soon reintroduced.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F827https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F827Wed, 28 Aug 2013 13:51:49 +0100Collected Evidence: Collected Evidence: Remove or control fish using rotenone Three studies (including one replicated study) in Sweden, the UK and USA found that eliminating fish using rotenone increased numbers of amphibian species, abundance and recruitment or newt populations. One review in Australia, the UK and USA found that fish control, which included using rotenone, increased breeding success for four amphibian species. Two replicated studies in Pakistan and the UK found when rotenone was applied, many frogs died and a small number of newts showed symptoms of negative effects.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F828https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F828Wed, 28 Aug 2013 14:25:31 +0100Collected Evidence: Collected Evidence: Remove or control mammals One controlled study in New Zealand found that controlling rats had no significant effect on numbers of Hochstetter’s frog. One controlled study in New Zealand found that survival of Maud Island frogs was significantly higher in a predator-proof enclosure than in the wild. One study in New Zealand found that at 58% of translocated Hamilton's frogs survived the first year within a predator-proof enclosure.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F839https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F839Thu, 29 Aug 2013 15:39:17 +0100Collected Evidence: Collected Evidence: Remove nitrogen and phosphorus using harvested products We found no evidence of the effects of removing nitrogen and phosphorus using harvested products on forests. '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%2F1166https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1166Thu, 19 May 2016 08:54:56 +0100Collected Evidence: Collected Evidence: Remove oil from contaminated peatlands We found no studies that evaluated the effects, on peatland vegetation, of removing oil from contaminated peatlands. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F1788https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1788Tue, 28 Nov 2017 08:17:28 +0000Collected Evidence: Collected Evidence: Remove or capture non-native, invasive or other problematic species One study examined the effects of removing or capturing non-native, invasive or other problematic species on subtidal benthic invertebrates. The study was in the South Atlantic Ocean (Brazil).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Cnidarian abundance (1 study): One replicated, controlled, before-and-after study in the southwest Atlantic found that, regardless of the method used, removing invasive corals reduced the cover of native zoanthids. Sponge abundance (1 study): One replicated, controlled, before-and-after study in the southwest Atlantic found that the effect of removing invasive corals on the cover of native sponges varied with the removal method used. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2173https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2173Tue, 22 Oct 2019 12:23:21 +0100Collected Evidence: Collected Evidence: Remove or clean-up oil pollution following a spill One study examined the effects of removing and cleaning-up oil pollution following a spill on subtidal benthic invertebrates. The study was in the Baltic Proper (Sweden).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Mollusc condition (1 study): One replicated, controlled, before-and-after study in the Baltic Proper found that after cleaning-up spilled oil using high pressure hot water, crude oil content increased in mussels and did not naturally decrease over time, and was higher than in mussels from an uncleaned contaminated and a non-contaminated site. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2183https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2183Tue, 22 Oct 2019 12:43:22 +0100Collected Evidence: Collected Evidence: Remove litter from the marine environment We found no studies that evaluated the effects of removing litter from the marine environment on subtidal benthic invertebrate populations.   ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2204https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2204Tue, 22 Oct 2019 13:15:13 +0100Collected Evidence: Collected Evidence: Remove mid-storey vegetation in forest One study evaluated the effects on mammals of removing mid-storey vegetation in forest. This study was in the USA. COMMUNITY RESPONSE (1 STUDY) Richness/diversity (1 study): A randomized, replicated, controlled study in the USA found that after removing mid-storey vegetation, mammal species richness increased. POPULATION RESPONSE (1 STUDY) Abundance (1 study): A randomized, replicated, controlled study in the USA found that after removing mid-storey vegetation, mammal abundance increased. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2480https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2480Thu, 04 Jun 2020 11:15:08 +0100Collected Evidence: Collected Evidence: Remove or control competitors Two studies evaluated the effects on non-controlled mammals of removing or controlling competitors. One study was across Norway and Sweden and one was in Norway. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Reproductive success (1 study): A replicated, controlled study in Norway and Sweden found that red fox control, along with supplementary feeding, was associated with an increase in arctic fox litters. BEHAVIOUR (1 STUDY) Use (1 study): A controlled study in Norway found that where red foxes had been controlled arctic foxes were more likely to colonize. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2575https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2575Wed, 10 Jun 2020 11:11:57 +0100Collected Evidence: Collected Evidence: Remove or clean-up oil pollution following a spill We found no studies that evaluated the effects of removing or cleaning up oil pollution following a spill on marine and freshwater mammal populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F2870https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2870Mon, 08 Feb 2021 11:29:48 +0000Collected Evidence: Collected Evidence: Remove litter from marine and freshwater environments We found no studies that evaluated the effects of removing litter from marine and freshwater environments on marine and freshwater mammal populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F2895https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2895Mon, 08 Feb 2021 11:59:16 +0000Collected Evidence: Collected Evidence: Remove leaf litter before seeding/planting Three studies examined the effects of removing leaf litter before seeding/planting on grassland vegetation. One study was in each of Germany, Belgium and Hungary. VEGETATION COMMUNITY (0 STUDIES) VEGETATION ABUNDANCE (2 STUDIES) Sown/planted species abundance (1 study): One replicated, randomized, paired, controlled study in Hungary found that removing leaf litter before sowing seeds did not increase the cover of either of two sown grass species. Individual plant species abundance (1 study): One replicated, controlled study in Germany found that removing leaf litter before planting did not alter the biomass of ragged robin and marsh birdsfoot trefoil transplants in most cases. VEGETATION STRUCTURE (0 STUDIES) OTHER (3 STUDIES) Germination/Emergence (3 studies): Two of three replicated, controlled studies (one of which was also randomized and paired) in Germany, Belgium and Hungary found that removing leaf litter, and in one study also removing vegetation, before sowing seeds had mixed effects on the number of seedlings of sown plant species. The other study found no change in the number of seedlings of either of two grass species. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3414https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3414Fri, 25 Jun 2021 16:00:36 +0100Collected Evidence: Collected Evidence: Remove or control non-native reptile competitors We found no studies that evaluated the effects of removing or controlling non-native reptile competitors on reptile populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3696https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3696Fri, 10 Dec 2021 18:25:21 +0000Collected Evidence: Collected Evidence: Remove or control non-native/invasive plants Four studies evaluated the effects of removing or controlling non-native/invasive plants on reptile populations. Two studies were in Australia and one was in each of South Africa and the USA. COMMUNITY RESPONSE (1 STUDY) Richness/diversity (1 study): One replicated, randomized, controlled, before-and-after study in Australia found that areas where invasive Bitou bush were sprayed with herbicide had similar reptile species richness compared to unsprayed areas. POPULATION RESPONSE (4 STUDIES) Abundance (3 studies): Two of three replicated, controlled studies (including two randomized and two before-and-after studies) in the USA and Australia found that areas where invasive Bitou bush or para grass were controlled had a similar abundance of reptiles and combined reptiles and amphibians compared to areas with no control. One study also found that the abundance of delicate skinks was lower in areas with invasive control compared to unmanaged areas. The other study found that removing invasive non-native Sahara mustard had mixed effects on the abundance of Coachella Valley fringe-toed lizards and flat-tailed horned lizards. Reproductive success (1 study): One replicated, controlled, before-and-after study in South Africa found that in areas where an invasive plant was removed, nesting activity by Nile crocodiles increased more than in places with no removal. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3697https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3697Fri, 10 Dec 2021 18:27:22 +0000Collected Evidence: Collected Evidence: Remove or control invasive or problematic herbivores and seed eaters Seven studies evaluated the effects of removing or controlling invasive or problematic herbivores and seed eaters on reptile populations. Three studies were in Australia and one study was in each of Mauritius, New Zealand, the USA and the Galápagos. COMMUNITY RESPONSE (2 STUDIES) Richness/diversity (2 studies): One of two studies (one site comparison study and one controlled study) in the USA and Australia found that areas where feral horses had been removed had higher lizard and snake species richness than sites with horses. The other study found mixed effects of fencing in combination with removal of invasive mammals on reptile species richness. POPULATION RESPONSE (7 STUDIES) Abundance (7 studies): Four of seven studies (including four controlled studies) in Mauritius, New Zealand, the USA, Australia and the Galápagos found that controlling European rabbits, grey kangaroos or herbivores and predators, in some cases using fencing, had mixed effects on the number of sightings or abundance of different reptile species. Two studies found that when both rabbits and Pacific rats or feral goats were removed the abundance of lizards or the percentage of giant tortoises that were juveniles. The other study found that areas where feral horses had been removed had similar lizard and snake abundance compared to sites with horses. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3698https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3698Fri, 10 Dec 2021 18:35:27 +0000Collected Evidence: Collected Evidence: Remove or change turbine lighting to reduce insect attraction We found no studies that evaluated the effects on butterflies and moths of removing or changing turbine lighting to reduce insect attraction. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3843https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3843Tue, 05 Jul 2022 11:06:37 +0100Collected Evidence: Collected Evidence: Remove or control non-native predators We found no studies that evaluated the effects on butterflies and moths of removing or controlling non-native predators. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2F3884https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3884Tue, 26 Jul 2022 18:22:27 +0100Collected Evidence: Collected Evidence: Remove or control non-native or problematic plants Nine studies evaluated the effects on butterflies and moths of removing or controlling non-native or problematic plants. Five studies were in the USA and one was in each of Poland, South Africa, Australia and Mauritius. COMMUNITY RESPONSE (2 STUDIES) Richness/diversity (2 studies): Two studies (including one replicated, paired, site comparison study and one controlled study) in Mauritius and the USA found that sites where invasive plants were removed by weeding or cutting and applying herbicide (in one case along with fencing to exclude non-native pigs and deer) had a greater species richness of butterflies than untreated sites. One of these studies also found that sites where Chinese privet was removed had a similar species richness of butterflies to sites which had not been invaded. POPULATION RESPONSE (8 STUDIES) Abundance (7 studies): Four of six studies (including three controlled studies, one before-and-after study and two site comparison studies) in Poland, South Africa, the USA and Mauritius found that sites where trees and shrubs were removed or invasive plants were cut to a similar height to native plants, or removed by weeding or cutting and applying herbicide (in one case along with fencing to exclude non-native pigs and deer), had a greater abundance of Apollo butterflies, a higher density of Fender’s blue eggs, or higher total abundance of butterflies, compared to before removal or untreated sites. One of these studies also found that sites where Chinese privet was removed had a similar abundance of butterflies to sites which had not been invaded. The fifth study found that in plots where herbicide was applied to control invasive grasses, the abundance of Columbia silvery blue eggs and caterpillars was similar to unsprayed plots. The sixth study found that, after prescribed burning, an area where bracken fern was also removed had fewer Brenton blue butterfly eggs than an area without removal. One study in Australia reported that a population of purple copper butterfly caterpillars translocated to an area where invasive plants had been removed, along with host plant translocation and other habitat management, increased in number compared to at the time of translocation. Survival (2 studies): One replicated, randomized, paired, controlled study in the USA found that in plots where herbicide was applied to control invasive grasses, the survival of Columbia silvery blue eggs and caterpillars was similar to unsprayed plots. One replicated, randomized, controlled study in the USA found that one herbicide commonly used to control invasive grasses reduced the survival of snowberry checkerspot caterpillars, but two other herbicides did not affect the survival of snowberry checkerspot, Edith’s checkerspot or Baltimore checkerspot caterpillars. BEHAVIOUR (4 STUDIES) Use (3 studies): Two of three randomized, controlled studies (including two replicated, paired studies and one before-and-after study) in the USA found that sites where invasive oat-grass was cut to a similar height to native plants, or where Eastern white pine was removed, were used more by Fender’s blue and frosted elfin butterflies than untreated sites. The third study found that habitat use by Columbia silvery blue butterflies was similar in plots where herbicide was applied to control invasive grasses and in unsprayed plots. Behaviour change (1 study): One before-and-after study in Poland found that removal of trees and shrubs, in addition to the release of captive bred adults and pupae, allowed adults from two previously separated populations of Apollo butterflies to mix. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3890https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3890Thu, 28 Jul 2022 15:02:05 +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.

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