Individual study: A test of simple ledges for facilitating mammal passage through inundated culverts. Thesis
Kelley A. (2014) A test of simple ledges for facilitating mammal passage through inundated culverts. Thesis. Union College, New York.
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Install ledges in culverts under roads/railways
A before-and-after study in 2012–2013 at seven road sites in New York, USA (Kelley 2014) found that installing ledges within under-road culverts did not increase the number or diversity of small mammal species crossing through them, and only one of six species used ledges. Overall, a similar number of small mammal crossings of six species were recorded in the seven culverts before (total 55 crossings) and after (total 58 crossings) ledges were installed, although no statistical tests were carried out. Racoons Procyon lotor were the only species recorded using ledges and did so during 58% of crossings, but similar numbers were recorded before (total 47 crossings) and after (total 41 crossings) ledge installation. In May–June 2013, plywood ledges (14 cm wide) and access ramps were installed through seven under-road culverts (1–3 m wide, 1–2 m high, 6–25 m long) containing water. Cat food was placed on ledges and ramps once after installation. A motion-sensor camera monitored each of the seven culverts for 12 weeks in June–September before (2012) and after (2013) ledges were installed.
(Summarised by Anna Berthinussen)