The main direct cause of biodiversity loss is land use change (primarily for large-scale food production) which drives an estimated 30% of biodiversity decline globally. Second is overexploitation (overfishing, overhunting and overharvesting) for things like food, medicines and timber which drives around 20%.
Destruction, degradation and fragmentation of habitats. reduction of individual survival and reproductive rates through exploitation, pollution and introduction of alien species.
