Effectiveness of rope bridge arboreal overpasses and faunal underpasses in providing connectivity for rainforest fauna

  • Published source details Goosem M., Weston N. & Bushnell S. (2005) Effectiveness of rope bridge arboreal overpasses and faunal underpasses in providing connectivity for rainforest fauna. Proceedings of the 2005 International Conference on Ecology and Transportation, Center for Transportation and the Environment, North Carolina State University, Raleigh NC, USA, 304-318.


This study is summarised as evidence for the following.

Action Category

Install rope bridges between canopies

Action Link
Terrestrial Mammal Conservation

Install tunnels/culverts/underpasses under roads/railways

Action Link
Reptile Conservation

Install tunnels/culverts/underpass under roads

Action Link
Terrestrial Mammal Conservation
  1. Install rope bridges between canopies

    A study in 2000–2002 along a road through highland rainforest in Queensland, Australia (Goosem et al. 2005) found that all three rope bridges across the road were used by arboreal marsupials. Across the three rope bridges, six species of possums, Lumholtz’s tree kangaroos Dendrolagus lumholtzi and fawn-footed melomys Melomys cervinipes were recorded, with 5–7 species/crossing recorded. The number of crossings was not documented. In 1995, a canopy bridge tunnel was erected 7 m above a 7-m-wide tree gap over a low-traffic road (4 vehicles/day). The bridge comprised a 50 × 50-cm rope tunnel, 14 m long, made of 10-mm silver rope attached to wooden poles, erected amongst trees on the roadside. In 2000, a 10-m-long, 50-cm-wide rope-bridge was erected 7 m high, spanning a 5-m gap over a forestry track. Additionally, a 25-cm-wide rope ladder was placed initially over the same track, then lengthened and moved in 2001 to span a 14-m-wide gap over a road carrying 150 vehicles/day. Mammal crossings were monitored in 2000–2002, through scat and hair analysis, remote photography and spotlighting surveys.

    (Summarised by: Ricardo Rocha)

  2. Install tunnels/culverts/underpasses under roads/railways

    A before-and-after, site comparison study in 2000–2003 in forest in Queensland, Australia (Goosem et al. 2005) found that installing road underpasses did not reduce numbers of reptiles killed on a highway (although reptile numbers recorded were very low). In the two years after three road underpasses were installed under a highway, two reptiles were counted dead on the road, compared to one reptile in the year before underpass construction. As a comparison, numbers of roadkill reptiles counted on a nearby section of road without an underpass were higher (1 year after installation: 22 reptiles killed; 2 years after: 26 killed). In 2001, a high-altitude highway through rainforest was widened and upgraded to include three concrete wildlife underpasses (3.4 m high, 3.7 m wide). Underpasses incorporated ground cover to simulate the forest floor and arboreal structures (see paper for details). For 12 months prior to underpass construction, two 0.5 km long road transects were surveyed weekly for roadkill by walking either side of the highway. After underpass construction, reptile roadkill was monitored by walking 0.5 km long road transects. Two similar transects were walked on a highway without underpasses 5 km north of the upgraded highway.

    (Summarised by: Katie Sainsbury)

  3. Install tunnels/culverts/underpass under roads

    A study in 2001–2003 on a road through rainforest in Queensland, Australia (Goosem et al. 2005) found that underpasses beneath the road were used by a range of mammals. There were 237 crossings recorded by brown bandicoots Isoodon obesulus, 233 by red-legged pademelons Thylogale stigmatica, 230 by coppery brushtail possums Trichosurus vulpecula johstoni, two by Lumholtz’s tree-kangaroos Dendrolagus lumholtzi, 53 by rodents and 13 by dogs Canis lupus familiaris or dingoes Canis dingo. Three underpasses (3.4 m high, 3.7 m wide), installed in 2001 below an upgraded two-lane road, were studied. Habitat enhancement features were added to each, such a soil, leaf and branch litter, rocks and logs and also vertical tree branches, to enable escape off the tunnel floor. Underpass use was monitored by weekly checks, over three years, for animal tracks in 1-m-wide strips of sand. Infrared-triggered cameras were used occasionally to confirm identifications.

    (Summarised by: Ricardo Rocha)

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