The illusion of nature: perception and the reality of natural landscapes, as illustrated by vertebrate fauna in the Northern Territory, Australia

Biomass figures are compared for common native vertebrate species and common non-native vertebrate species (including fish, amphibian, reptile, bird and mammal species) across the Northern Territory, an area of ostensibly, largely unmodified natural system. The total biomass of the considered non-native species very substantially surpasses that of the common native vertebrate species considered; hence, the perception that this is a largely intact natural system is, to some extent, an illusion. This preponderance of biomass of non-native species may help explain the increasing evidence of ecosystem stress and decline of native species. An integrity index based on the relative biomass of native and non-native species may provide insight into the status and trends of ecological systems across different regions.