A synthesis of recorded fine-scale threats to imperiled species in the United States.

Biodiversity in the United States faces mounting anthropogenic pressures, with an increasing number of species at risk of extinction. We present the most extensive synthesis of recorded threats confronting U.S. imperiled species to date, considering species assessments from NatureServe and the IUCN Red List for over 16,000 species. Our results demonstrate the value of identifying fine-scale threats species face. Species occupying multiple ecosystems tend to see more recorded threats on average, and threat prevalence differs by ecosystem. Certain taxa (particularly corals, reptiles, amphibians, bivalves, and mammals) face disproportionately high recorded threat numbers. Climate change is both the fastest-growing recorded threat and the most ubiquitous IUCN threat category among species with up-to-date assessments. This analysis also highlights significant data gaps, revealing that most imperiled species have outdated or incomplete threat assessments, and over half lack even an initial evaluation. Gaps are disproportionately found among invertebrates, plants, and fungi.