How ignoring detection probability hurts biodiversity conservation

Conservation priorities and legal protections are often based on confirmed species occurrences. However, imperfect detection is likely the norm in biological surveys, resulting in negative consequences for conservation. Focusing on threatened species in the US and Canada, we show that detectability information appears to be lacking for most species that are conservation priorities. Although more research on species detection is needed, detectability estimates are important for many immediate decisions. Thus, we recommend: (1) estimating and accounting for detectability and designing rigorous surveys when confirming presence or absence is crucial. Otherwise, absence in surveys should be considered suggestive only and critical habitat should be managed even if species presences are unconfirmed. (2) When directly estimating detectability is prohibitively difficult, indirect estimates should be explored, for example through expert elicitation or trait-based predictors. (3) Detectability should be explicitly incorporated into decisions to ensure that surveys and management actions are directed where they have the greatest potential benefit.