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Scatter plots, with line of best fit, showing correlation between the amount of time elapsed since rainfall and (left) the number of common frogs that used the culvert (R 2 = 0.026) (r = −0.190, n = 468, p = <0.001) and (right) between the number of common toads that used the culvert (R 2 = 0.017) (r = 0.148, n = 468, p = 0.001). Circle thickness indicates frequency of data point.
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In this paper, an update on the Dodecanese (Greece) herpetofauna is provided. In this Archipelago , 8 Amphibians (
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... The probability of detecting amphibians at tunnels and AOR and DOR increased during rainfall events, indicating that migration events are more likely to coincide with rain. Migration across roads and under-road tunnel usage by B. bufo increases with rainfall (Hartel et al., 2009;Gleeson et al., 2018) while the probability of detecting roadkill events of other species increases as daily precipitation increases (Hallisey et al., 2022). We found that detection probability also decreased with survey year, although this could be because only four surveys were conducted in the final year of the study. ...
Road traffic often inflicts higher mortality rates on amphibians than other vertebrates, especially where roads bisect migration pathways. To facilitate safe movements by amphibians between non-breeding and breeding habitats, under-road tunnels are being increasingly installed together with barrier fencing or walls. However, few observational studies have correlated aspects of road mitigation placement and design with amphibian population sizes. Here, we assessed the effectiveness of 13 under-road tunnels (ten cylindrical and three square-shaped) along a two-lane sealed road in northern Hungary positioned between upland forest habitat and a floodplain containing breeding ponds. Amphibian count surveys at tunnels and along road transects above tunnels were conducted at night during the spring migration period from 2009 to 2012. We detected a total of seven amphibian species, with the common toad (Bufo bufo) representing > 90% of individuals counted. Using community N-mixture modelling, we found that tunnels with larger-sized entrances and tunnels positioned near other tunnels had higher amphibian abundance. We also found that road mortality was higher above tunnels closest to breeding ponds for some species. Moreover, tunnel usage rates and road mortality rates were far lower and higher, respectively, than other studies that assessed similar species along European roads. These results imply that barrier walls and fencing were largely ineffective at directing amphibians towards the tunnels and were not preventing amphibians from accessing the road surface. Our results demonstrate the importance of placement and design in the usage of under-road tunnels by amphibians but underscore the need to maintain barrier fences and walls to reduce road mortality rates and connect amphibian habitats.
