2022 update shows Western Australia’s mammals continue to decline

Abstract

We update the list of indigenous mammals known from each of Western Australia’s mainland bioregions since European settlement, assess their regional status in terms of extent of occurrence, then compare these regional status lists and derived faunal attrition values with those published in 2006. Seven bioregions show substantially more faunal attrition since 2006, including the Avon Wheatbelt, Victoria Bonaparte and Northern Kimberley. The status of 27 species has worsened in at least one bioregion, an average of 1.7 species per bioregion across the 26 bioregions. We also examine potential explanatory factors associated with faunal attrition across the bioregions using beta regression and AIC-based model selection. Faunal attrition was strongly associated with low average annual rainfall, a low proportion of species that shelter in rockpile habitat, high environmental change, a high proportion of species in the ‘Critical Weight Range’ and, to a lesser degree, a high proportion of omnivorous species. Only conservation management outside of havens can reverse this downward trend.