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Providing evidence to improve practice

Individual study: Barrier walls reduce wildlife mortality on a highway in Paynes Prairie State Reserve, Florida, USA

Published source details

Dodd C.K., Barichivich W.J. & Smith L.L. (2004) Effectiveness of a barrier wall and culverts in reducing wildlife mortality on a heavily traveled highway in Florida. Biological Conservation, 118, 619-631

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 Amphibian Conservation

A controlled, before-and-after study in 2001–2002 of a barrier wall linking culverts along a highway in Florida, USA (Dodd, Barichivich & Smith 2004) found that the wall significantly decreased amphibian road deaths, apart from treefrogs (Hylidae), which could climb over. A total of 19 amphibian road-kills were found on the 3 km section with barrier, compared to 326 kills on the 500 m section with no barrier. Treefrogs were excluded from these figures. Treefrog mortality increased after construction of the barrier and culverts (from 149 to 194 over three survey sections). In 2001, a 1 m high concrete wall with a 15 cm overhang was erected along the highway, parallel to a wetland prairie. The wall extended 3 km on each side of the road. Concrete culverts under the highway were increased from four to eight. The highway and grass verge were monitored from 200 m before the start of the barrier until 200 m past the end. Monitoring was undertaken on three consecutive days from dawn each week from March 2001 to March 2002.


Install barrier fencing along roads Terrestrial Mammal Conservation

A controlled, before-and-after study in 1998–2002 along a highway in Florida, USA (Dodd et al. 2004) found that a barrier wall-culvert system reduced mammal road-kills. After construction, 33 mammals of ≥12 species were recorded dead on the 2.8-km section of road with the barrier (2.8 km) compared to 50 mammals on a 400-m section without barriers. Of those killed along the barrier, 17 were rice rats Orozomys palustris, which climbed adjacent vegetation to get over the barrier. In 2000–2001, a 1-m-high concrete wall with 15-cm overhanging lip was constructed along a 2.8-km section of a highway. Eight concrete culverts were spaced 200–500 m apart below the wall. Roadkills were monitored on three days/week before (August 1998–1999) and after (March 2001-March 2002) barrier wall construction.

(Summarised by Rebecca K. Smith)

Install barrier fencing and underpasses along roads Terrestrial Mammal Conservation

A study in 2001–2002 along a highway in Florida, USA (Dodd et al. 2004) found that culverts, in areas with roadside barrier walls, were used by mammals but road casualties still occurred. Ten mammal species (and one species pair) were recorded using culverts. These included rice rat/hispid cotton rat Oryzomys palustris/Sigmodon hispidus (in five culverts), cotton mouse Peromyscus gossypinus (three culverts), round-tailed muskrat Neofiber alleni (three culverts) and southeastern short-tailed shrew Blarina carolinensis (two culverts). Other species used one culvert each. During the same period, ≥13 mammal species were recorded dead on the road. The most frequent casualties were rice rat (25), Virginia opossum Didelphis virginianus (15) and nine-banded armadillo Dasypus novemcinctus (10). Culverts reduced overall vertebrate road mortality, but separate mammal figures were not reported for before culverts were installed. Eight culverts (from 0.9 m diameter to 2.4 × 2.4 m cross-section, all 44 m long) were connected using prefabricated concrete barrier walls. Culverts were monitored from 14 March 2001 to 5 March 2002 using funnel traps, camera traps and sand track stations. Roadkills were monitored by walking the 3.2-km road over three consecutive days each week.

(Summarised by Rebecca K. Smith)