Cook, C.; Rao, M.; Clyne, P.; Rathbone, V.; Grantham, H.

Other effective area-based conservation measures (OECMs) have expanded area-based conservation to recognize sites that deliver effective biodiversity outcomes even if not managed for conservation. Yet our ability to identify sites likely to qualify as OECMs remains limited. To address this gap, we established and tested a set of indicators to judge whether sites meet the essential criteria to be considered OECMs, evaluating a large, global sample of 173 important conservation areas: 81 potential OECMs and 92 nearby protected areas. We found that most potential OECMs were largely in good condition with the potential to achieve conservation outcomes, but none currently met all the OECM criteria. Formally designated protected areas in our dataset performed better but the majority also failed the criteria. With so many important conservation areas unable to deliver effective conservation outcomes, our findings raise important questions about how to ensure area-based conservation promotes positive and sustained outcomes for biodiversity.