Collected 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 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: Create ponds for amphibians Twenty-eight studies investigated the colonization of created ponds by amphibians in general (rather than by targeted species, which are discussed below). All of the studies found that amphibians used some or all created ponds. Nine site comparison studies (including seven replicated studies) in Australia, Canada, Spain, the UK and USA compared amphibian numbers in created and natural ponds. Five found that numbers of species or breeding species were similar or higher in created ponds, and numbers of ponds colonized were similar. Four found that species composition differed, and comparisons between abundance of individual species, juvenile productivity and size at metamorphosis differed depending on species. One found that numbers of species were similar or lower depending on the permanence of created water bodies. One found that populations in created ponds were less stable. One review and two replicated, before-and-after studies in Denmark and the USA found that amphibians established stable populations in 50–100% of created ponds. Six replicated studies (including one randomized study) in France, the Netherlands, UK and USA found that amphibians used 64–100% and reproduced in 64–68% of created ponds, or used 8–100% and reproduced in 2–62% depending on species. One review and 15 studies (including 12 replicated studies, one of which was randomized) in Europe and the USA found that created ponds were used or colonized by up to 15 naturally colonizing species, up to 10 species that reproduced, as well as by captive-bred amphibians. Five replicated studies (including three site comparison studies) in Denmark, Estonia, France, Italy and the USA found that pond creation, and restoration in three cases, maintained and increased amphibian populations or increased numbers of species. Seven studies (including one review) in Austria, Denmark, Poland, the Netherlands and USA found that use or colonization of or reproductive success in created ponds was affected by pond age, permanence, vegetation cover, surrounding landscape, distance to existing ponds and presence of fish.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F869https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F869Wed, 11 Sep 2013 09:16:41 +0100Collected Evidence: Collected Evidence: Create wetland Fifteen studies investigated the effectiveness of creating wetlands for amphibians. Five site comparison studies (including four replicated studies) in the USA compared created to natural wetlands and found that created wetlands had similar numbers of amphibian species, amphibian abundance or communities depending on depth as natural wetlands. Two of the studies found that created wetlands had fewer amphibian species or lower abundance and different communities compared to natural wetlands. One site comparison study in the USA found that created wetlands had similar numbers of species to adjacent forest. One global review and two site comparison studies (including one replicated study) in the USA combined created and restored wetlands and compared them to natural wetlands and found that numbers of amphibian species and abundance was higher or similar, or higher in 54% of studies and similar in 35% of studies reviewed compared to natural wetlands. Three site comparison studies (including one replicated study) in the USA found that certain amphibian species were only found in created or natural wetlands. One before-and-after study in Australia found that captive-bred green and golden bell frog tadpoles released into a created wetland did not establish a self-sustaining population. Five studies (including two replicated studies) in Kenya and the USA that investigated colonization of created wetlands found that four to 15 amphibian species used or colonized the wetlands. One global review and three studies (including two replicated studies) in the USA found that numbers of amphibian species and amphibian abundance in created wetlands were affected by wetland design, vegetation, water levels, surrounding habitat, fish presence and distance to source wetlands.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F880https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F880Fri, 13 Sep 2013 11:16:59 +0100Collected Evidence: Collected Evidence: Install culverts or tunnels as road crossings Thirty-two studies investigated the effectiveness of installing culverts or tunnels as road crossings for amphibians. Six of seven studies (including three replicated studies) in Canada, Germany, Italy, Hungary and the USA found that installing culverts or tunnels significantly decreased amphibian road deaths; in one study this was the case only when barrier fencing was also installed. One found no effect on road deaths. Fifteen of 24 studies (including one review and 17 replicated studies) in Australia, Canada, Europe and the USA found that culverts/tunnels were used by amphibians, by 15–85% of amphibians or 3–15 species, or that 23–100% of culverts or tunnels were used by amphibians or used in 12 of 14 studies reviewed. The majority of culverts/tunnels had barrier fencing to guide amphibians to entrances. Four found mixed effects depending on species, or for toads depending on the site or culvert type. Five found that culverts were used by less than 10% of amphibians or were not used. The use of culverts/tunnels was affected by diameter in three of six studies, with wider culverts used more, length in one of two studies, with long culverts avoided, lighting in all three studies, with mixed effects, substrate in three of six studies, with natural substrates used more, presence of water in two of three studies, with mixed effects, entrance location in one and tunnel climate in one study. Six studies (including one replicated, controlled study) in Canada, Spain, the Netherlands and USA investigated the use of culverts with flowing water and found that they were used by amphibians, or rarely used by salamanders or not used, and were used more or the same amount as dry culverts. Certain culvert designs were not suitable for amphibians; one-way tunnels with vertical entry chutes resulted in high mortality of common toads and condensation deposits from steel culverts had very high metal concentrations. One study found that thousands of amphibians were still killed on the road.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F884https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F884Mon, 16 Sep 2013 12:20:30 +0100Collected Evidence: Collected Evidence: American bullfrog control: Biological control using native predators One replicated, controlled study conducted in Belgium found the introduction of the northern pike led to a strong decline in bullfrog tadpole numbers.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1039https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1039Fri, 03 Jul 2015 15:18:58 +0100Collected Evidence: Collected Evidence: American bullfrog control: Biological control of co-occurring beneficial species No evidence was captured on the effects of removing co-occurring beneficial species on the control of American bullfrogs. '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%2F1040https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1040Fri, 03 Jul 2015 15:19:09 +0100Collected Evidence: Collected Evidence: American bullfrog control: Habitat modification No evidence was captured on the effects of habitat modification on the control of American bullfrogs. '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%2F1041https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1041Fri, 03 Jul 2015 15:19:26 +0100Collected Evidence: Collected Evidence: American bullfrog control: Draining ponds and altering the length of time for which the pond contains water No evidence was captured on the effects of draining ponds or altering the length of time for which ponds contain water on the control of American bullfrogs. '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%2F1042https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1042Fri, 03 Jul 2015 15:20:07 +0100Collected Evidence: Collected Evidence: American bullfrog control: Pond destruction No evidence was captured on the effects of pond destruction on the control of American bullfrogs. '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%2F1043https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1043Fri, 03 Jul 2015 15:20:20 +0100Collected Evidence: Collected Evidence: American bullfrog control: Fencing No evidence was captured on the effects of fencing on the control of American bullfrogs. '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%2F1044https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1044Fri, 03 Jul 2015 15:20:33 +0100Collected Evidence: Collected Evidence: American bullfrog control: Direct removal of adults One replicated study in Belgium found catchability of adult bullfrogs in small shallow ponds using one double fyke net for 24 h to be very low. One small study in the USA found that bullfrog adults can be captured overnight in a single trap floating on the water surface. One replicated, controlled study in the USA found that bullfrog populations rapidly rebounded following intensive removal of the adults. One before-and-after study in France found a significant reduction in the number of recorded adults and juveniles following the shooting of metamorphosed individuals before reproduction, when carried out as part of a combination treatment.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1045https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1045Fri, 03 Jul 2015 15:20:46 +0100Collected Evidence: Collected Evidence: American bullfrog control: Direct removal of juveniles One replicated study in Belgium found double fyke nets were effective in catching bullfrog tadpoles in small shallow ponds. One before-and-after study in France found a significant reduction in the number of recorded adults and juveniles following the removal of juveniles by trapping, when carried out as part of a combination treatment.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1046https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1046Fri, 03 Jul 2015 15:20:59 +0100Collected Evidence: Collected Evidence: American bullfrog control: Collection of egg clutches Despite reference to removal of egg clutches in some studies using bilge pumps or nets, no evidence was captured on the effects of egg collection on American bullfrogs. '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%2F1047https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1047Fri, 03 Jul 2015 15:21:15 +0100Collected Evidence: Collected Evidence: American bullfrog control: Application of a biocide One replicated, controlled study in the USA found a number of chemicals killed American bullfrogs, including caffeine (10% solution), chloroxylenol (5% solution), and a combined treatment of Permethrin (4.6% solution) and Rotenone (1% solution).  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1048https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1048Fri, 03 Jul 2015 15:21:26 +0100Collected Evidence: Collected Evidence: American bullfrog control: Public education No evidence was captured on the effects of public education on the control of American bullfrogs. '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%2F1049https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F1049Fri, 03 Jul 2015 15:21:38 +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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