[Code of Federal Regulations] [Title 50, Volume 7] [Revised as of January 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 50CFR424.21] [Page 859] TITLE 50--WILDLIFE AND FISHERIES CHAPTER IV--JOINT REGULATIONS (UNITED STATES FISH AND WILDLIFE SERVICE, PART 424_LISTING ENDANGERED AND THREATENED SPECIES AND DESIGNATING Subpart B_Revision of the Lists Sec. 424.21 Periodic review. At least once every 5 years, the Secretary shall conduct a review of each listed species to determine whether it should be delisted or reclassified. Each such determination shall be made in accordance with Sec. Sec. 424.11, 424.16, and 424.17 of this part, as appropriate. A notice announcing those species under active review will be published in the Federal Register. Notwithstanding this section's provisions, the Secretary may review the status of any species at any time based upon a petition (see Sec. 424.14) or upon other data available to the Service.