(a) Part 424 provides rules for revising the Lists of Endangered and Threatened Wildlife and Plants and, where appropriate, designating or revising their critical habitats. Criteria are provided for determining species to be endangered or threatened and for designating critical habitats. Procedures for receiving and considering petitions to revise the lists and for conducting periodic reviews of listed species also are established.
(b) The purpose of these rules is to interpret and implement those portions of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.), that pertain to the listing of species and the determination of critical habitats.