NatureServe Conservation Status
Determining which species and ecosystems are thriving and which are rare or declining is crucial for targeting conservation towards elements of biodiversity in greatest need. NatureServe and its member programs and collaborators use a suite of factors to assess the conservation status of plant, animal, and fungal species, as well as ecosystems (ecological communities and systems). The outcome of researching and recording information on the conservation status factors is the assignment of a conservation status rank with supporting documentation. For species these ranks provide an estimate of extinction risk, while ecosystems they provide an estimate of the risk of elimination. For more detailed information about conservation status ranks visit NatureServe Publications.
Conservation status ranks are based on a one to five scale, ranging from critically imperiled (G1) to demonstrably secure (G5). Status is assessed and documented at three distinct geographic scales-global (G), national (N), and state/province (S).
Relationship to Other Status Designations
NatureServe conservation status ranks are a valuable complement to legal status designations
assigned by government agencies such as the U.S. Fish and Wildlife Service and the National
Marine Fisheries Service in administering the U.S. Endangered Species Act (ESA), and the
Canadian Wildlife Service in administering the Species at Risk Act (SARA). NatureServe status
ranks, and the documentation that support them, are often used by such agencies in making
official determinations, particularly in the identification of candidates for legal protection.
Because NatureServe assessment procedures-and subsequent lists of imperiled and vulnerable
species-have different criteria, evidence requirements, purposes, and taxonomic coverage than
official lists of endangered and threatened species, they do not necessarily coincide.
For more information see Appropriate Use of NatureServe Conservation Status Assessments in Species Listing Processes.
The International Union for Conservation of Nature (IUCN) Red List of threatened species is similar in concept to NatureServe's global conservation status assessments. Due to the independent development of these two systems, however, minor differences exist in their respective criteria and implementation. Recent studies indicate that when applied by experienced assessors using comparable information, the outputs from the two systems are generally concordant. NatureServe is an active participant in the IUCN Red List Programme, and in the region covered by NatureServe Explorer, NatureServe status ranks and their underlying documentation often form a basis for Red List threat assessments. In recent years, NatureServe has worked with IUCN to standardize the ratings for shared information fields, such as Range Extent, Area of Occupancy, Population Size, and Threats. This standardization permits the sharing of information between organizations and countries, and allows the information to be used in both IUCN as well as NatureServe assessments.