Using canopy bridges to link habitat for arboreal mammals: successful trials in the Wet Tropics of Queensland

Abstract

We investigated the use of inexpensive aerial bridges (rope canopy bridges) above roads and a highway by arboreal mammals in the Wet Tropics of Queensland, Australia. Three rope bridge designs were trialed, including a single rope, ladder-like bridges and tunnel-shaped bridges. Nine mammal species were recorded using canopy bridges, including five species or subspecies endemic to the Wet Tropics and three species listed as rare under State nature conservation legislation. Most of these species suffer severely from either the fragmentation or mortality impacts caused by roads. Over 50 crossings above a 15-m-wide tourist road were observed on an elevated ladder-like bridge. Longer (~40 m) rope bridges were used on several occasions by four species. Our observations suggest that canopy bridges can assist rare arboreal mammals to cross roads in the Wet Tropics, thereby reducing both the risk of road-kill and the potential for subpopulation isolation. Further research is required to ascertain the level of benefit afforded by canopy bridges for arboreal mammal populations. It is likely that rope canopy bridges will have broad application for a range of arboreal mammal species.

Canopy bridges as road overpasses for wildlife in urban fragmented landscapes

“…There are differences between our canopy bridge model and the pole bridge installed for the black lion tamarin (Leontopithecus chrysopygus Mikan, 1823) in the São Paulo state, Brazil (Valladares-Padua 1995), and also between our overpass and the canopy bridges installed in Australia (Soanes & van der Ree 2009, Weston et al 2011. The bridge in São Paulo is constructed using round wooden poles and is installed at a height of 6 m over the road, while in Australia there are two models of canopy overpass -a rope ladder (with the steps also formed by rope) and a rope tunnel.…”

“…The results obtained with the monitoring by local people show the usefulness of involving the community in conservation actions, but should be applied carefully, since there are differences in observational effort and detectability among different local people. The collaboration of local community has educative and interpretive value and is vital for the successful implementation of conservation activities (Lokschin et al 2007, Weston et al 2011.…”

“…Some efforts have been expended in monitoring passages, but the available information usually derives from a few intensive studies carried out in relatively few places (Forman et al 2003). Although the monitoring of wildlife underpasses has become more common recently (Beckmann et al 2010), only in Australia, to our knowledge, monitoring studies have been developed on the use of rope overpasses by arboreal mammals (Goosem et al 2006, Soanes & van der Ree 2009, Weston et al 2011. The use of wildlife passages is a precondition and first approximation to the effectiveness of these measures, even though it is not a direct measure of effectiveness, which should be demonstrated by indicators such as survival rates or gene flow, variables relatively difficult to obtain.…”

Edge effects on small mammals: Differences between arboreal and ground‐dwelling species living near roads in Brazilian fragmented landscapes

“…The connectivity of suitable forest patches has also been recognized as an important landscape feature for arboreal mammals (Reunanen et al 2002;Pardini et al 2005;Umetsu & Pardini 2007). Efforts to improve habitat quality and maintain vegetation structure, or even the construction of overpasses across roads to connect forested areas, can assist arboreal species conservation (Weston et al 2011;Soanes & van der Ree 2015).…”

Intentional Snake Road-Kill: A Case Study using Fake Snakes on a Brazilian Road

“…Roads may constitute a barrier (partial or complete), disrupting the movement of different species [6][7][8][9][10]. Roads may also represent linear clearings, hindering the approach of species inhabiting deep forests.…”