Through our candidate assessment process, we identify species for which the best scientific and commercial data available indicates that a proposal for listing is appropriate, using the listing factors in section 4 of the ESA.

The listing factors are: the present or threatened destruction, modification, or curtailment of the species’ habitat or range; overutilization for commercial, recreational, scientific, or educational purposes; disease or predation; the inadequacy of existing regulatory mechanisms; and, other natural or manmade factors affecting the species’ continued existence.

Florida leafwing, photo by H.L. Salvato

Also, we re-assess species previously identified as candidates to update their status and determine if they can be removed from the candidate list or if their listing priority should change.

The species assessment document (including citations of the scientific literature and other sources of information), prepared by the Candidate Conservation staff, is provided to the Service Director, who makes the final decision as to whether a species should be elevated or removed from candidate status or have its listing priority number changed.

The annually updated assessments of individual species also are the basis for a summary document, the Candidate Notice of Review (CNOR)). The CNOR is published in the Federal Register to provide our partners with an updated list of candidate species [Link to candidate list].

We gather species information from many sources including State fish and wildlife agencies, other Federal agencies, universities, and tribes. One chief source of information is the network of State Natural Heritage Programs databases, which track species that are already imperiled, and those that are declining or at-risk (NatureServe’s Explorer website provides online access to some of this data). The recently completed State Wildlife Action Plans are another source of information of wildlife species of greatest conservation concern to States and Territories.

With its range reduced from 45 streams in 15 States to 20 streams in 10 States, the spectaclecase mussel has declined. Seven populations of the species are represented by a single specimen each. The good news is that three relatively strong populations remain in the Meramec and Gasconade Rivers in Missouri, the St. Croix River in Minnesota and Wisconsin, and the upper Clinch River in Tennessee, where Fish and Wildlife Service biologist Gary Wege, pictured here, found this beauty during an October 2004 survey. Information gathered from these studies will further determine the status of the species and guide conservation. Photo by Mike Davis, MNDNR

Identification of candidate species and the factors influencing their status, and the assignment of listing priority numbers, assists us and our partners in identifying and prioritizing conservation efforts that are most likely to be effective in removing the need for listing. We assign a listing priority number to a species based on evaluating the magnitude and immediacy of threats to it, as well as its taxonomic distinctiveness. This number is a key factor in the Service’s decisions about proceeding with a formal proposal to list a species (see 1983 published guidance on listing priority numbers). Listing priority numbers range from 1 to 12; a species with a listing priority of 1 would have the highest priority for listing.

Conducting assessments and making decisions to elevate or remove species from candidate status requires careful analysis and documentation of the best available scientific information regarding a species and factors influencing its status, as well as the known effects of ongoing conservation efforts.

We evaluate how conservation efforts have removed or reduced threats to the species. At the time we make our decision on whether to elevate a species to candidate status, or remove a species from candidate status, some of these conservation efforts may have been planned but not yet implemented, or have been implemented but not yet demonstrated whether they are effective in reducing or removing threats to a species. We evaluate some efforts using our Policy for the Evaluation of Conservation Efforts When Making Listing Decisions (PECE) 2003 (a joint policy with NOAA-Fisheries). Click here for the Policy and a link to the News release. PECE was developed to provide a set of consistent standards for evaluating individual conservation efforts to identify those for which there is a high level of certainty of implementation and effectiveness in removing threats to a species.

The CNOR provides an opportunity to submit information or comments on current candidate species or on species that the Service should assess to determine if they should become a candidate species. To submit information or comments on a species, contact the Regional office that has the lead for the species. This information is found by clicking on the species in the candidate list. For Regional offices, click here.

Click here, to view a map of the number candidate species in each state.

Brian Lang of the New Mexico Department of Game and Fish (left) and Dr. David Berg of the University of Miami-Ohio (right) collect three candidate species: Phantom springsnail, Phantom Cave snail, and diminutive amphipod, from Phantom Lake Spring in west Texas. Inset: Diminutive amphipod and Phantom Cave snails. Photos by Nathan Allan, FWS

By giving the public early notification of the status of candidate species through the CNOR, we encourage proactive conservation efforts that can result in removing the need for listing [Link to list of species not listed due to conservation efforts].

The Camp Shelby burrowing crayfish (Fallicambarus gordoni) is found in a localized wetland area in the DeSoto National Forest, Mississippi, on land leased by the Mississippi Army National Guard for Camp Shelby, and used as troop and tank training grounds. The habitat for this crayfish is vulnerable to activities that can directly destroy its burrows, compact the soil, or alter the hydrology of its pitcher plant dominated wetland habitat. Protective measures and management initiated by the US Forest Service and MS National Guard have removed all threats that were the basis of this crayfish’s candidate status. These long-term management commitments were formalized in a Candidate Conservation Agreement between the US Forest Service, MS National Guard, MS Department of Wildlife Fisheries and Parks, and the Service, with the result that listing the species under the ESA is unnecessary and it has been removed from candidate status.

Camp Shelby Burrowing Crayfish, Photo by Michael Duran, TNC

National Marine Fisheries Service Office of Protected Resources (part of NOAA), which has jurisdiction over most marine species, maintains a list of "species of concern" [ NOAA Office of protected resources ]. While similar to our candidate species in that NOAA is evaluating these species for possible listing under the ESA, these species are not as far along in the listing process since more information is needed before they can be proposed for listing. NMFS also maintains a list of “candidate” species which are similar to ours.