Individual study: Amphibian and reptile tunnels in the Netherlands
Zuiderwijk A. (1989) Amphibian and reptile tunnels in the Netherlands. Amphibians and Roads: Proceedings of the Toad Tunnel Conference, Rendsburg, Federal Republic of Germany, 67-74.
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Install barrier fencing along roads
A study of barrier fencing between five amphibian tunnels in Overveen in the Netherlands (Zuiderwijk 1989) found that 10% of the population of 2,000–3,000 common toads Bufo bufo climbed over the fencing during breeding migrations. The remaining toads walked along the fence, but only 4% used the tunnels. The others were captured in pitfall traps and carried across the road. The cast-iron tunnels had been installed nine years before the study. The road had permanent barrier fencing.
Use humans to assist migrating amphibians across roads
A replicated study in 1981–1987 of toad patrols in the Netherlands (Zuiderwijk 1989) found that assisting common toads Bufo bufo across roads did not prevent the decline of nine out of 14 (64%) populations over six years. About 80% of toad crossings had fences and pitfall traps, from which toads are collected and released on the other side of the road.
Install culverts or tunnels as road crossings
A replicated study of five amphibian tunnels with barrier fencing in Overveen in the Netherlands (Zuiderwijk 1989) found that only 4% of the population of 2,000–3,000 common toads Bufo bufo used the tunnels. Ten percent of the population broke over the barrier fencing. The remaining toads walked along the fence, were captured in pitfall traps and were carried across the road. In an experiment, toads were placed at tunnel entrances and 43% passed through within 24 hours. The cast-iron tunnels had been installed nine years before the study. They were 12 m long, 0.3 m in diameter and were buried 0.7 m under a road between a wooded dune and stream. The road had permanent barrier fencing.