Endangered species lack research on the outcomes of conservation action

Abstract Given widespread biodiversity declines, there is an urgent need to ensure that conservation interventions are working. Yet, evidence regarding the effectiveness of conservation actions is often lacking. Using a case study of 209 terrestrial species listed as Endangered in Canada, we conducted a literature review to collate the evidence base on conservation actions to: (1) explore the outcomes of actions documented for each species and (2) identify knowledge gaps. Action‐oriented research constituted only 2% of all peer‐reviewed literature across target species, and for 61% of species, we found no literature investigating outcomes of conservation actions. Protected areas, habitat creation, artificial shelter, and alternative farming practices were broadly beneficial for most species for which these actions were assessed. Habitat restoration actions were most frequently studied, but 38% of these actions were harmful, ineffective, or demonstrated mixed results. The effectiveness of prescribed burns, alternative timber harvesting approaches, and vegetation control was examined for the greatest number of species, yet 17%–30% of these actions demonstrated negative effects. Our synthesis demonstrates a lack of published evidence for many actions implemented for the recovery of species at risk of extinction, highlighting an alarming gap in the conservation literature.