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Appropriate Use of NatureServe Conservation Status Assessments in Species Listing Processes
Determining which plants and animals are thriving and which are rare or declining is crucial for targeting conservation of the species, habitats and ecosystems in greatest need. NatureServe and its member Natural Heritage Programs have developed a consistent method for evaluating the relative imperilment of both species and ecological communities based on the best available science. These assessments lead to the designation of a conservation status rank.
Purpose of NatureServe Conservation Status Ranks
The purpose of the conservation status ranks developed by NatureServe is to assess the relative risk facing a species and does not imply that any specific action or legal status is needed to assure its survival. NatureServe is a non-advocacy organization and is committed to providing objective and reliable scientific data. Assessment by NatureServe of any species as being:
- Critically imperiled (G1)
- Imperiled (G2)
- Vulnerable (G3)
does not constitute a recommendation by NatureServe for listing under the U.S. Endangered Species Act (ESA) or Canadian Species-At-Risk Act (SARA).
In addition, specific conservation actions should not be automatically linked to any particular NatureServe conservation status assessment, but should instead be applied on a case-by-case basis following a careful analysis of threats and the measures needed to counteract them.
Use of NatureServe Conservation Status Ranks in Legal Listing Processes
NatureServe conservation status ranks are a valuable resource for government agencies such as the U.S. Fish and Wildlife Service, the Canadian Wildlife Service, and others responsible for administration of state and provincial species conservation laws.
These agencies consider NatureServe status ranks, and the documentation that supports them, as a key input for making official determinations about a species' need for legal protection. However, NatureServe status assessment procedures have different criteria, evidence requirements, purposes and taxonomic coverage than government lists of endangered and threatened species, and therefore these two types of lists should not be expected to coincide. For example, an important factor in many legal listing processes is the extent to which a species is already receiving protection of some type???a consideration not included in the NatureServe conservation status ranks.
We therefore encourage the use of data and status assessments developed by NatureServe as an important input to federal, state or provincial listing processes, but not as the sole basis. NatureServe encourages all government agencies, conservation organizations and private landowners to carefully consider these data and status assessments when developing their conservation priorities and plans.
Conservation Status Assessments
Conservation status ranks range from critically imperiled (1) to demonstrably secure (5). Status is assessed and documented at three distinct geographic scales:
- Global (G)
- National (N)
- Subnational (S) (i.e., state/province/municipal)
These status assessments are based on the best available information and consider a variety of factors such as species abundance, distribution, population trends and threats. (Documentation of the methods for developing these assessments is available at www.natureserve.org/explorer/ranking.htm.)
Global conservation status assessments (G-Ranks) generally are carried out by NatureServe scientists (including biologists in state and provincial member programs), with input from other experts. These assessments are widely used throughout the conservation community and are regarded as highly credible by scientists, government agencies and private-sector organizations.