The Distribution and Abundance of an Island Population
of Koalas (
Phascolarctos cinereus
) in the Far North of
Their Geographic Range

Denise C. McGregor, Sarah E. Kerr, Andrew K. Krockenberger*

Centre for Tropical Environmental and Sustainability Science, and School of Marine and Tropical Biology, James Cook University, Cairns, Queensland, Australia


Koalas are an iconic species of charismatic megafauna, of substantial social and conservation significance. They are widely
distributed, often at low densities, and individuals can be difficult to detect, making population surveys challenging and
costly. Consequently, koala population estimates have been limited and the results inconsistent. The aims of this study were
to estimate the distribution, relative abundance and population size of the koalas on Magnetic Island, far north Queensland.
Population densities were estimated in 18 different vegetation types present on the island using a Fecal Standing Crop
Method. Koala density ranged from 0.404 ha
21, recorded in forest red gum and bloodwood woodland, to absence from
eight of the vegetation types surveyed. The second highest density of 0.297 koalas ha
2was recorded in mixed eucalypt
woodland, which covers 45% of the island. The total abundance of koalas on Magnetic Island, not including those present in
urban areas, was estimated at 825
6175 (SEM). The large variation in koala density across vegetation types reinforces the
need for sampling stratification when calculating abundance over large areas, as uniformity of habitat quality cannot be
assumed. In this context, koala populations also occur in low densities in areas generally regarded as poor quality koala
habitat. These results highlight the importance of protecting vegetation communities not traditionally considered to have
high conservation value to koalas, as these habitats may be essential for maintaining viable, widespread, low-density
populations. The results from this study provide a baseline to assess future trends in koala distribution, density and
abundance on Magnetic Island.