Determining the distribution and abundance of a regional koala population in south-east Queensland for conservation management

Abstract

Koala surveys were used to determine the distribution and abundance of a threatened regional koala population in south-east Queensland to assist with the development of effective conservation management programs. Daytime systematic searches of strip transects were conducted twice yearly from 1996 to 1999 to determine koala density at a number of sites in urban, remnant bushland and bushland strata. Mean density estimates for 27 survey sites ranged from 0.02 to 1.26 koalas ha–1. Koala densities were generally higher in large tracts and remnant patches of eucalypt bushland towards the centre of the region with lower but significant densities in urban areas. Two estimates of population size were obtained: 7230 (±1668, 95% confidence limit) and 6246 (±1444, 95% confidence limit). The estimate of 6246 was considered to provide a better indication of actual population size as it reduced the variation within strata and took into account the distribution of koalas across the region. It is likely that determining habitat areas for conservation based on where koalas actually occur rather than identifying distributions of 'preferred' tree species or community reports, as has been promoted in other studies, is a better indicator of the conservation significance of remnant habitat areas. Future koala-management programs should ensure that the significance of eucalypt bushland areas towards the centre of the study area is not compromised by future urban development and associated threats to koalas.

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

“…The key to the survival of urban koalas may be their ability to exploit patchy resources and find a mate in a fragmented landscape, but this may also increase the chance that they will suffer trauma from vehicles and dogs (Backhouse and Crouch 1990;Cork et al 2000;Phillips 2000;Dique et al 2004). 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.…”

“…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).…”

“…The Koala Coast is experiencing rapid human population growth and development (Queensland Government 2005), which has created concern for the long-term viability of the koala population. 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.…”

“…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.…”

Drought-driven change in wildlife distribution and numbers: a case study of koalas in south west Queensland

“…Surveys that count koalas through direct observation take many person hours and, although they are used in the more densely populated east coast koala populations and in smaller study areas (Gordon et al 1990;Melzer and Lamb 1996;Dique et al 2004), they are not practical for large areas with low-density populations (Sullivan et al 2002). Faecal pellet surveys are a well-established method of determining koala presence, and thus distribution and habitat selection (Phillips and Callaghan 2000;McAlpine et al 2006b).…”