Fifteen years of comprehensive biodiversity monitoring in Booderee National Park has revealed a major ecological surprise: localised collapses of populations of many of the park’s mammal species over the period. At many long-term sites across the park, the number of native mammals almost halved between 2003 and 2016. The biodiversity monitoring encompassed a range of vertebrate groups including mammals, birds, reptiles and frogs, as well as native vegetation. This has clearly established that it is mammal species only that have experienced these losses in Booderee.