2019-03-12 P&E Agenda - Item 5 - Attachment 2 - Koala Infrastructure & Feasibility Report

intermediate habitats for smaller animals (Glista et al. 2009). These constructions are the most expensive
fauna crossing option and are unlikely to be adopted if other options are available.

Efficacy
The application of wildlife land-bridges is less common than wildlife underpasses. In 2008, van der Ree et al.
(2008) estimated the total number of wildlife crossing structures within Australia that had been formally
evaluated and reported on was approximately 100. Of those, only three were land-bridge overpasses. Some
examples include:

•    Bond and Jones (2008) studied the effect of crossing structures associated with the Compton Road
     upgrade south of Brisbane in 2004, confirming continuous use of the overpass by three species of
     macropod (red-necked wallaby, Macropus rufogriseus; swamp wallaby, Wallabia bicolor; and eastern
     grey kangaroo, Macropus giganteus) with brown hare (Lepus capensis) becoming increasingly common
     in summer 2006. The study concluded that rapid followed by continued use of the structure may have
     been attributed to fresh vegetative growth providing a valuable foraging resource for local herbivorous
     species.
•    Hayes (2006) monitored fauna use of two overpasses (cut and cover tunnel) and two dedicated fauna
     underpasses (3 x 3 m concrete box culvert) associated with the Pacific Highway, Yelgun to Cudgera Creek
     and Woodburn to Ferry Park Rest Area, north-eastern New South Wales. More large animals (macropods,
     canids, large lizards) were found using the overpasses than the underpasses.
•    A koala-specific overpass was built as part of the DTMR Koala Retrofit Works Program over Mount Cotton
     Road, south-east of Brisbane. At the conclusion of the monitoring period (December 2010 to February
     2013), there had been no evidence of koalas using the overpass (Jones et al. 2013). However, it is widely
     acknowledged that most structures require a period of acclimatisation before animals will use them
     (Jones et al. 2013) and while koalas may have begun to use the overpass, monitoring has not continued
     to prove use of the structure (Davis 2017).

Design considerations
Bond and Jones (2008) advocate intentional planting of appropriate vegetation as a means of facilitating
habituation by herbivorous species to wildlife overpasses.

3.1.4.          Canopy Bridges
Canopy bridges are inexpensive connections constructed at canopy height to encourage arboreal fauna to
cross roads and other canopy gaps. These connections may be applied where koalas cross roads in areas
impractical for underpasses or overpasses construction (Preece 2007; Goldingay & Dobner 2014). Rope-
bridges are an example of canopy bridge that has been tested for use by koalas.

Efficacy
Koalas are highly mobile on the ground but can traverse between trees using connecting branches or may
make short jumps between closely spaced trees where habitat allows (Goldingay & Taylor 2016). It follows
that koalas may use canopy bridges to move between trees or cross large canopy-gaps associated with roads.
However, no koalas were detected on rope-bridges installed and monitored on the Pacific Highway in New
South Wales in areas where koalas occurred (Goldingay et al. 2013), potentially reflecting unsuitable rope-
bridge design, absence of koalas during monitoring or preferred use of available underpasses (Goldingay &
Taylor 2016). Field testing of four different rope bridge designs suggested that rope-bridges are unsuited to
the behaviour and ecology of the koala (Goldingay & Taylor 2016). The study concluded that wildlife
underpasses and overpasses that facilitate walking along the ground appear to be more suited to enable safe
road-crossing by koalas (Goldingay & Taylor 2016).

Koala Infrastructure Audit & Feasibility Report                                                        Page 13

Noosa Council
17SUN-0087/1700860