Decline in the distribution of the Koala Phascolarctos cinereus in Queensland

We assessed decline in the distribution of P. cinereus in Queensland over the last century using historical data from P. cinereus surveys and the Queensland State Archives to measure change in extent of occurrence and area of occupancy. Broad distribution (extent of occurrence, measured with a minimum convex polygon) has contracted by about 27% and area of occupancy (measured with a 30 minute grid) by about 31%. The degree of contraction in area of occupancy correlates with the estimated extent of habitat loss, supporting suggestions that habitat loss has been, and may still be, the major threat to koalas in Queensland. Contraction in the overall range has occurred on the northern and western margins of the distribution (the Wet Tropics, Gulf Plains, Mitchell Grass Downs, and Mulga Lands Bioregions). Distribution showed a latitudinal change during the harvest period in the early 20th century, with an increase in area of occupancy in central Queensland and a decrease in southern and northern Queensland. This correlates with corresponding changes in population size. Analysis of distribution does not provide support for listing P. cinereus as vulnerable in Queensland or the South East Queensland Bioregion. Problems in measurement of area of occupancy and extent of occurrence are discussed. It is difficult to measure the areas accurately due to difficulty in meeting the underlying assumptions of the techniques.