Defaunation in the Anthropocene

We live amidst a global wave of anthropogenically driven biodiversity loss: species and population extirpations and also, critically, declines in local abundance of species. Human impacts on animal biodiversity, particularly, are an under-recognized form of global environmental change. Among terrestrial vertebrates an estimated 322 species have recently become extinct, while populations of the remaining species show a 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show a 45% mean decline in abundance. Such defaunation will have broad cascading effects on ecosystem functioning and human well-being. Much remains unknown about this “Anthropocene defaunation”, and these knowledge gaps hinder our capacity to predict and limit its impacts. Clearly, however, defaunation will become not only a characteristic of the planet’s sixth mass extinction, but also a driver of global ecological change.