IUCN extinction criteria

The International Union for the Conservation of Nature (IUCN, 2012) has established global standards for the assessment of extinction events.

“The IUCN defines a taxon as ‘presumed extinct’ (in our case, equivalent to extirpated—or locally extinct) “when exhaustive surveys in known and/or expected habitat, at appropriate times (diurnal, seasonal, annual), throughout its historic range have failed to record an individual (IUCN 2012)”

However, it remains a major challenge to determine the evidentiary thresholds implied by these criteria (‘exhaustive’, ‘expected’, ‘appropriate’), not only to clarify the formal requirements for claims regarding extirpation but also to inform effective search methods and to assess the feasibility of meeting these requirements.

Our goal is to transform the abstract problem of assessing extinction into a structured, measurable, and actionable process. To that end, this documentation clarifies the steps and assumptions underlying the IUCN extinction criteria and proposes a practical methodology for applying them to infer extinction events in real-world contexts.