The distribution of threatened species around Australia provides an indication of current human impacts on native biota. The 2014 data on threatened species listed in the EPBC Act that occur within the coastal zone (50 kilometres from shore) show the highest density of threatened species on the east coast of Australia, particularly around the urban centres of Sydney, Brisbane and Cairns (Figure COA13). Other areas of high density are the east coast of Tasmania, the Northern Territory around Darwin, and isolated pockets of south-west Western Australia. Not surprisingly, these patterns are correlated with areas of dense human population, except for patches in the north of Australia (e.g. the Kimberley region), which are relatively unmodified. SoE 2011 suggested that the high number of threatened species in the north may reflect the high overall diversity of tropical systems, rather than areas of elevated impact. However, differences in the intensity of sampling, pressures such as cane toads affecting northern reptiles and mammals, and overseas pressures on migratory shorebirds, may contribute to this pattern.