Effectiveness of ledges in culverts for small mammal passage

Published source details Meaney C.A., Bakeman M., Reed-Eckert M. & Wostl E. (2007) Effectiveness of ledges in culverts for small mammal passage. Colorado Department of Transportation Research Branch USA report, no. CDOT-2007-9.
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This study is summarised as evidence for the following.

	Action	Category
	Install ledges in culverts under roads/railways Action Link

Install ledges in culverts under roads/railways

A study in 2005–2006 at six road sites in Colorado, USA (Meaney et al. 2007) found that ledges in under-road culverts were used by nine of 12 small mammal species and ledges with access ramps were used more often than ledges without access ramps. Nine of 12 small mammal species that passed through the culverts used ledges (see original paper for details). Overall, a greater number of small mammal crossings were recorded along ledges with access ramps installed (total 443 crossings) than along those without (total 262 crossings). Temporary wooden ledges (15 cm wide) were installed in six concrete culverts (1–5 m wide, 1–1.3 m high, 9–48 m long) containing water. At each of the six culverts, access ramps were alternately attached or removed for 8–10 two-week periods in May–September 2005 and 2006. Motion-sensor cameras recorded small mammal movements through the culverts during a total of 16–20 weeks in May–September 2005 and 2006.

(Summarised by: Anna Berthinussen)