Individual study: Culverts were used by mammals but not amphibians within wetlands in Canada
Fitzgibbon K. (2001) An evaluation of corrugated steel culverts as transit corridors for amphibians and small mammals at two Vancouver Island wetlands and comparative culvert trials. MA thesis. Royal Roads University, Vancouver, Canada.
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Install culverts or tunnels as road crossings
A replicated study in 2000 of eight dry and two wet culverts under highways through two wetlands on Vancouver Island, Canada (Fitzgibbon 2001) found no amphibian tracks within culverts. In trials with rough-skinned newts Taricha granulosa, a dark culvert was used significantly more than one with daylight (24 vs 6). However, there was no significant difference between use of 0.3 or 0.5 m diameter culverts (11 vs 19 newts), different substrates (bare: 22; cement: 11; soil: 17) or wet or dry culverts (8 vs 7–15 newts). Concentrations of aluminium, zinc, copper and lead within condensation deposits in culverts were 134–124,500 times greater than recommended for protecting freshwater aquatic life. Corrugated steel pipe culverts (29–36 x 0.6–1 m) were constructed in 1995. Aluminium track-plates covered with soot were installed 1–2 m inside each culvert and were monitored nine times in July–October 2000. There were three replicates of each trial (five for substrate) in which 10 newts had the choice of three adjacent culverts (3 x 0.3 m) over three days in September–November.