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

3.              Literature Review
Roads and traffic decrease the amount and quality of available habitat, enhance mortality due to vehicle
collisions, act as a barrier preventing access to resources and divide animal populations into smaller and more
vulnerable fractions (Jaeger et al. 2005). The effect of roads on fauna populations depend on

•    the species’ road avoidance behaviour (i.e., noise avoidance, road surface avoidance, and car avoidance);
•    population sensitivity effects of roads;
•    road size; and
•    traffic volume (Jaeger et al. 2005).

Koalas are largely solitary and occupy reasonably well defined home ranges, however, both male and female
home ranges can overlap (White 1999; Mitchell 1990; Ellis et al. 2002). Movements between trees are usually
made along the ground and, particularly in fragmented peri-urban areas, this includes movements across
roads (Rhodes et al. 2014). Friends of the Koala data showed that during 2011-12, only 10 of 52 koalas hit by
vehicles in the broader Northern Rivers area of New South Wales survived (Goldingay & Dobner 2014). Dique
et al. (2003) found that a disproportionate number of male koalas of approximately 2-4 years of age were hit
by vehicles during the koala speed zone trial on the Koala Coast. Males generally have larger home ranges
and move greater distances than females, particularly during the breeding season, with the result that males
tend to cross roads more frequently than females (Rhodes et al. 2014).

The effects of roads on wildlife are a widespread ecological problem (Bissonette 2002) and mitigating these
effects represent a significant investment by authorities. The ecological and conservation benefits must
therefore be considered when planning such infrastructure, rather than making decisions solely based on
engineering or planning expediency (Dexter et al. 2016) to avoid over-capitalising on ineffective measures.
Long-term monitoring and credible research on the value of such structures must also exist to provide
support for these decisions (Clevenger & Waltho 2005; Thorne et al. 2009; Taylor & Goldingay 2010; van der
Ree et al. 2011).

Mitigation measures used to reduce the effects of roads and road mortality on wildlife populations fall into
two broad categories (Glista et al. 2009):

•    modification of animal behaviour – address vulnerability to road-kill and barrier effects
•    modification of motorist behaviour – address vulnerability to road-kill

These can be categorised into soft or hard infrastructure, following the Noosa Shire Koala Conservation Plan
2016 (Noosa Council 2016):

•    hard infrastructure – structures that generally involve the modification of animal behaviour such as
     exclusion and guiding fences, bridges, underpasses, culverts and koala ladders
•    soft infrastructure – measures that generally involve the modification of motorist behaviour such as
     speed limit reductions, signs, road markings and improved street lighting

Numerous strategies with varying degrees of success are regularly used to mitigate the effects of roads on
wildlife, including speed reduction measures, fencing, road crossings, culverts under roads, overpasses,
lighting, signs, road threshold treatments and wildlife reflectors (Rhodes et al. 2014). Glista et al. (2009) found
that the frequency at which road mortality mitigation measures are implemented does not correlate with
their perceived effectiveness and that the most promising measures are often used the least. Dictation by
economic factors, evaluation of mitigation success based on opinion rather than research and inferior
mitigation design are a poor use of resources and may lead to further ecological problems (Glista et al. 2009).

Koala Infrastructure Audit & Feasibility Report                                                              Page 7

Noosa Council
17SUN-0087/1700860