Koala mortality on roads in south-east Queensland: the koala speed-zone trial

Abstract

In 1995, the Queensland Parks and Wildlife Service, the Queensland Department of Main Roads and Redland Shire Council initiated the Koala Speed Zone Trial in the Koala Coast, south-east Queensland. The aim of the trial was to assess the effect of differential speed signs on the number of koalas (Phascolarctos cinereus) hit by vehicles in the Koala Coast from 1995 to 1999. On the basis of information collected by the Queensland Parks and Wildlife Service 1407 koalas were hit by vehicles in the Koala Coast during the five-year study (mean 281 koalas per year, range 251–315). Monitoring of vehicle speeds by the Queensland Department of Main Roads suggested that there was no significant reduction in vehicle speed during the trial period from August to December. Consequently, there was no evidence to suggest that a reduction in the number of koalas hit by vehicles occurred during the trial. Approximately 70% of koalas were hit on arterial and sub-arterial roads and approximately 83% did not survive. The location of each koala hit was recorded and the signed speed limit of the road was noted. Most koalas that were hit by vehicles were young healthy males. Pooling of data on koala collisions and road speed limits suggested that the proportion of koalas that survived being hit by vehicles was slightly higher on roads with lower speed limits. However, vehicle speed was not the only factor that affected the number of koalas hit by vehicles. It is suggested that habitat destruction, koala density and traffic volume also contribute to road-associated koala mortality in the Koala Coast.

Ecology and movement of urban koalas adjacent to linear infrastructure in coastal south-east Queensland

“…Our findings are consistent with other studies that have shown a high probability of trauma for koalas moving in and through fragmented and heavily urbanised areas in south-east Queensland (e.g. Dique et al 2003aDique et al , 2003c. One of the koalas that was killed by a train (F2) had crossed the rail line by climbing over chainwire fencing while a safe underpass under the rail line for pedestrians was within metres of the animal's crossing point.…”

“…Koala populations in south-east Queensland are experiencing rapid reductions in range (Dique et al 2003a(Dique et al , 2004. This decline has mostly been attributed to habitat fragmentation (Martin and Handasyde 1999) and loss through clearing for agriculture and urban development (Cogger et al 2003;Sullivan et al 2004;Gordon et al 2006;Lane 2008;DERM 2009).…”

“…mahogany gliders, Petaurus gracilis: Asari et al 2010), but such movements often end in trauma and death (e.g. koalas : Canfield 1991;Dique et al 2003a). Vehicle collisions have been reported as a key threat to the viability of koala populations in parts of Victoria and New South Wales (Lee and Martin 1988;Canfield 1991;Lunney et al 1996).…”

“…In this region estimates of koala numbers were over 6000 in 1999 (Dique et al 2004) and~2000 in 2010, with the population declining by~6% per annum over that time (DERM 2010). Previous research in this region has focussed on the ecology (Thompson 2001;Dique et al 2004), mortality (Dique et al 2003a), and general movements (Dique et al 2003b) of bushland koalas. However, little is known about the ecology of koalas inhabiting urban and remnant vegetation patches in Redland City.…”

Roads and macropods: interactions and implications

“…Despite warning signs being commonly used, there is little evidence that they significantly change driver behaviour and reduce road-kill rates (Dique et al 2003;Al-Ghamdi and AlGadhi 2004). Standard kangaroo warning signs were ineffective at reducing macropod road-kill rates immediately following erection along the Northern Highway in central Victoria in 1978 (Coulson 1982).…”