Conservation Evidence: Evidence Data

Collected Evidence: Collected Evidence: Captive breeding frogs Thirty-three studies investigated the success of breeding frogs in captivity. Twenty-three of 33 studies, three of which were reviews and 30 replicated studies, across the world found that amphibians produced egg in captivity, in four cases by captive-bred females. Seven found mixed results, with some species of frogs or 17–50% of captive populations reproducing successfully in captivity, but with other species difficult to maintain or raise to adults. One found that frogs did not breed successfully in captivity and another that all breeding frogs died. Seventeen of the studies found that captive-bred frogs were raised successfully to hatching, tadpoles, froglets or adults in captivity. One found that froglet survival was low and another that three species were not successfully raised to adulthood. Four replicated studies (including one small study) in,Canada, Fiji, Hong Kong and Italy found that 30–88% of eggs hatched or survival to metamorphosis was 75%, as froglets was 17–51% or to adults was 50–90% in captivity. One review and four replicated studies (including two small studies) in Germany, Italy and the USA found that reproductive success of frogs in captivity depended on temperature or a simulated wet and dry season, but not on whether frogs were housed in high or low maintenance facilities. Three replicated studies (including one small study) in Germany, Australia and Canada found that egg or tadpole development in captivity was affected by parental care, density or temperature. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F835https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F835Thu, 29 Aug 2013 09:25:18 +0100Collected Evidence: Collected Evidence: Translocate frogs Eight of ten studies (including five replicated studies) in New Zealand, Spain, Sweden, the UK and USA found that translocating frog eggs, juveniles or adults established breeding populations at 100% or 79% of sites. Two found that breeding populations of two species were initially established but went extinct within five years or did not establish. Five studies (including one replicated study) in Italy, New Zealand and the USA found that translocated juveniles or adults survived the winter, had high survival, survived up to two years, or up to eight years with predator exclusion. One study in the USA found that survival was lower for Oregon spotted frogs translocated as adults compared to eggs and lower than that of resident frogs. Five studies (including three replicated studies) in Canada, New Zealand and the USA found that translocations of eggs, juveniles or adults resulted in little or no breeding at one or three of four sites. Two studies (including one before-and-after study) in the USA found that 60–100% of translocated frogs left the release site and 35–73% returned to their original pond within 1–32 days. Two before-and-after studies New Zealand and the USA found that frogs lost weight during the 30 days after translocation or became heavier than animals at the donor site. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F861https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F861Fri, 06 Sep 2013 14:31:31 +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: Head-start amphibians for release Twenty-two studies head-started amphibians from eggs and monitored them after release. Six of 10 studies (including five replicated studies) in Denmark, Spain, the UK and USA and a global review found that released head-started tadpoles, metamorphs or juveniles established breeding frog populations or increased populations of frogs or toads. Two found mixed results with breeding populations established in 12 of 17 studies reviewed or at two of four sites. Two found that head-started metamorphs or adults did not prevent a frog population decline or establish a breeding toad population. For five of the studies, release of captive-bred individuals, translocation or habitat management were also carried out. Nine of 10 studies (including nine replicated studies) in Australia, Canada, Europe and the USA found that head-started amphibians released as tadpoles, metamorphs or adults metamorphosed successfully, tended to survive the first season, winter or year or bred successfully. One found adult survival was 1–17% over four years and one found limited breeding following the release of adults. Four replicated studies in Australia, the UK and USA found that frog survival to metamorphosis and size at metamorphosis was greater and time to metamorphosis shorter in head-started compared to wild animals. One replicated study in Canada found that young head-started leopard frogs were smaller than those in the wild. One replicated study in Australia found that corroboree frog tadpoles released earlier had higher survival, but metamorphosed two weeks later than those released a month later. Three studies (including one replicated study) in the USA only provided results for head-starting in captivity. Two found that Houston toad eggs could be captive-reared to tadpoles, but only one successfully reared adults. Three studies (including two replicated studies) in Canada and the USA found that during head-starting, amphibian growth rate, size, stress levels and survival was affected by the amount of protein provided, housing density or enclosure location. One found that mass, stress levels and survival were not affected by the amount of food or habitat complexity. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F881https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F881Fri, 13 Sep 2013 13:02:34 +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 +0100