Plaintiffs, WildEarth Guardians and Western Watersheds Project, bring this action against Defendant, Ken Salazar, U.S. Secretary of the Interior (“the Secretary”), in his official capacity, to force him to carry out his duties under the Endangered Species Act (“ESA”). 16 U.S.C. §§ 1531 et seq. The Secretary has failed to comply with his mandatory duty under the ESA to make preliminary findings on Plaintiffs’ petition to list the Sonoran Desert Tortoise (Gopherus agassizii) (“desert tortoise”) as an endangered or threatened species under the ESA. This lawsuit seeks to force the Secretary to make the overdue finding on Plaintiffs’ petition.