Collected Evidence: Collected Evidence: Install barrier fencing along roads Seven of eight studies (including one replicated and two controlled studies) in Germany, Canada and the USA found that barrier fencing with culverts decreased amphibian road deaths, or decreased deaths provided that the fence length and material were effective. One found that low numbers of amphibians were diverted by barriers during breeding migrations. One replicated study in the USA found that barriers at least 0.6 m high were required to prevent green frogs and leopard frogs climbing over. Two studies in the Netherlands and USA found that treefrogs and 10% of common toads climbed over barrier fencing during breeding migrations. Collected, 14 Aug 2013 11:23:38 +0100Collected Evidence: Collected Evidence: Modify gully pots and kerbs One before-and-after study in the UK found that moving gully pots 10 cm away from the kerb decreased the number of great crested newts that fell in by 80%.  Collected, 22 Aug 2013 13:45:55 +0100Collected Evidence: Collected Evidence: Use humans to assist migrating amphibians across roads Two studies (including one replicated study) in Italy and the UK found that despite assisting toads across roads during breeding migrations, 64–70% of populations declined over 6–10 years. One study in the UK  found that despite assisting toads across roads during breeding migrations, at 7% of sites over 500 toads were still killed on roads. Five studies in Germany, the UK and Italy found that large numbers of amphibians were moved across roads by patrols. Numbers ranged from 7,532 toads moved before and after breeding to half a million moved during breeding migrations annually. In the UK, there were over 400 patrols and 71 patrols spent an average of 90 person-hours moving toads and had been active for up to 10 years.  Collected, 22 Aug 2013 13:52:12 +0100Collected Evidence: Collected Evidence: Use signage to warn motorists One study in the UK found that despite warning signs and human assistance, over 500 toads were killed on some roads.  Collected, 29 Aug 2013 15:56:32 +0100Collected Evidence: Collected Evidence: Close roads during seasonal amphibian migration Two studies (including one replicated study) in Germany found that large numbers of amphibians were protected from death during breeding migrations at road closure sites and at road closure sites with assisted crossings and barrier fences.  Collected, 29 Aug 2013 15:58:22 +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, 16 Sep 2013 12:20:30 +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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