Unveiling human impacts on global Key Biodiversity Areas: Assessing disturbance and fragmentation to inform conservation strategies

• KBAs show an average disturbance rate of ∼62 % with higher levels of habitat fragmentation. • One-fifth of KBAs are fully protected, and a significant portion remains unprotected. • Higher human disturbance does not necessarily lead to severe habitat fragmentation. • 80 % of KBAs necessitate intensity regulation and spatial planning of human activities. • Relocating or planning human activities is expected to mitigate fragmentation. Effective preservation of Key Biodiversity Areas (KBAs) is crucial to address biodiversity loss. Human-induced disturbance in these vital sites can exacerbate species extinction and challenge the Kunming-Montreal Global Biodiversity Framework (GBF). This study delves into the human disturbance and protection in terrestrial KBAs worldwide, focusing particularly on habitat fragmentation to devise tailored conservation strategies. Our results reveal widespread human disturbance across global KBAs, with an average Human Footprint Index of 12.3 and a disturbance rate of 62 %. Only one-fifth of KBAs are fully safeguarded by protected areas, and a significant portion remains unprotected, with even many highly protected sites under severe disturbance. Globally, human activities have led to substantial implicit habitat fragmentation in KBAs, resulting in a 70 % average decline in habitat size, with less than half of KBAs maintaining well-connected active habitats. These findings inform the classification of KBAs for priority conservation, with 80 % requiring both intensity regulation and spatial planning of human activities. Higher levels of human disturbance do not necessarily lead to more severe fragmentation, underscoring the potential for relocating or planning human activities to mitigate fragmentation. This research serves as a foundational assessment of human impacts on KBAs, providing a basis for KBA management and global conservation efforts to meet GBF goals.