Southern Sydney's urban koalas: community research and education at Campbelltown

We compiled an extensive database of koala sightings from the community. The records of koala sightings which met conditions for reliability were used in conjunction with vegetation mapping by the NSW National Parks and Wildlife in the Georges River catchment to produce relative exploitation (RE), or preference, indices. Shale/Sandstone Transition Forest with a high sandstone influence had the highest RE value (RE>1 indicates preference), indicating that it was highly preferred, followed by Upper Georges River Sandstone Woodland, and Western Gully Forest, with Riparian Scrub being marginally preferred. Shale/Sandstone Transition Forest with a low sandstone influence had an RE value of 0.92 (RE<1 indicates avoidance), but this low value is most likely because heavily impacted vegetation with <10% crown cover was included. Shale/Sandstone Transition Forest thus appears to be the vegetation type that koalas within the Georges River catchment most prefer.

Ward (2002) investigated differences between female koalas that could access vegetation, of various types, growing on shale substrates, and females with access only to vegetation growing on sandstone substrates, and found that the females with access to the shale substrate vegetation were heavier, in better condition, and had a higher fertility rate than females on sandstone substrates only. Vegetation growing on shale substrates has been extensively cleared, and the important Shale/Sandstone Transition Forest, represents only 3.7% of the extant vegetation in the Georges River catchment. Most of this vegetation is sandstone-derived, with the high and low categories of sandstone influence having, respectively, 58.1% and 77.6% of remaining vegetation classified as less than 10% crown cover. The clearing associated with urban areas, therefore, impact upon the koala population. As this population has been estimated to consist of only 90 to 200 individuals (Ward 2002), conserving vegetation on shale substrates and habitat links to other populations are high priorities. The listing of Shale/Sandstone Transition Forest and O'Hares Creek Shale Forest as Endangered Ecological Communities under the Threatened Species Conservation Act 1995 will support koala conservation in the Campbelltown area, but impacts such as altered fire regimes, mortalities from vehicles and dogs, weeds, and other impacts from urban areas must also be managed.