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

Here we provide a review of available literature to understand measures used to mitigate wildlife vehicle-
strike and the barrier effect of roads, their efficacy and application to koala conservation. Knowledge of
koala’s willingness to use various kinds of road crossing-structures is relatively scant (AMBS 2012) and where
no koala-specific information has been published, examples of applications to other wildlife are discussed.
Design considerations are also included where information is available.

3.1.            Hard Infrastructure – Modifying Animal Behaviour
Modifying animal behaviour may help to address vulnerability to road-kill and barrier effects by preventing
fauna from accessing the road surface and allowing safe passage across roads. Commonly used methods
include wildlife exclusion fencing and wildlife crossing structures (culvert, underpass, overpass, rope bridges).
Some other methods include wildlife warning reflectors and repellents (chemical, visual, acoustic and electric
shock (Mason 1998)), the latter of which will not be discussed further as they are considered impractical for
application to this project and may negatively affect other fauna.

Wildlife exclusion fencing and wildlife crossing structures are most effective when implemented together.
Exclusion fences prevent wildlife from crossing the road surface, minimising road-kill but also preventing
wildlife from accessing resources on the opposite side of the road. Wildlife crossing structures allow safe
fauna passage across the road but fauna is unlikely to find and use the passage unless fencing funnels fauna
to the crossing infrastructure. Providing ample and appropriate crossing structures while preventing access
to the road surface will allow wildlife movement and minimise roadkill (Clevenger et al. 2003; Glista et al.
2009).

3.1.1.          Wildlife Exclusion Fencing
Fencing roads has been shown to reduce mortality, increase population persistence and facilitate movement
and gene flow when combined with wildlife crossings (Polak et al. 2014). The Koala-sensitive Design Guideline
(Department of Environment and Heritage Protection 2012) suggests three design options for koala exclusion
fencing to be used only in four identified situations where the fencing will prevent koalas from entering an
area that poses a direct threat to their safety. One of the identified situations is fencing to safeguard koalas
from high speed/high volume roads or train lines by funnelling koalas to safe crossing structures (fauna
underpasses or overpasses).

Efficacy
Wildlife exclusion fencing is an effective way to prevent wildlife from crossing the road surface, thereby
improving road safety for humans and protecting wildlife by minimising the risk of vehicle-wildlife collisions
in areas where exclusion fencing is installed and maintained. There is a large body of literature concluding
that fences are essential for reducing road-kill and that combining fencing with easily accessed safe passages
under and over the road improves the facilitation of safe road crossing by fauna. Some examples include:

•    Bond and Jones (2008) studied the effect of fencing associated with the Compton Road upgrade south of
     Brisbane in 2004. Monitoring of road-kill was undertaken for four months before construction and
     following the completion of construction. The surveys detected 13 large animals killed on the road during
     the four months pre-construction and two large animals killed on the road during the four months post-
     construction. These post-construction animals were a wood duck that flew onto the road and a red-
     necked wallaby that passed through a large hole deliberately cut in the fence. Three additional large
     animals were killed on the road during the 29 month post-construction monitoring period, at least one
     of which used a deliberately cut hole in the fence. The exclusion fencing was effective in preventing road-
     kill, except following human-related breaches in the fence (Bond & Jones 2008).
•    Cunnington et al. (2014) studied the effect of pre-existing drainage culverts on the mitigation of anuran
     road mortality in Canada. The study suggests that fencing is much more effective at reducing road
Koala Infrastructure Audit & Feasibility Report                                                            Page 8

Noosa Council
17SUN-0087/1700860