L. J. Allison A. M. McLuckie M. Vaughn R. W. Murphy Kristin H. Berry 2021 <p>A provisional Red List Assessment of the widespread Desert Tortoise, <i>Gopherus agassizii</i> (<i>sensu lato</i>), was performed at a Desert Tortoise Council workshop in 2010 and updated by the IUCN Tortoise and Freshwater Turtle Specialist Group (TFTSG) in 2011, at which time the Mojave Desert subpopulation, now considered <i>G. agassizii</i> (<i>sensu stricto</i>) following taxonomic analysis and splitting into three separate species (<i>G. agassizii</i>, <i>G. morafkai</i>, and <i>G. evgoodei</i>), was assessed as Critically Endangered A2bce+A4bce based on population reduction (decreasing density), habit loss of over 80% over three generations (90 years), including past reductions and predicted future declines, as well as the effects of disease (upper respiratory tract disease / mycoplasmosis). <i>Gopherus agassizii</i> (<i>sensu stricto</i>) comprises tortoises in the most well-studied 30% of the larger range; this portion of the original range has seen the most human impacts and is where the largest past population losses had been documented. A recent rigorous range-wide population reassessment of <i>G. agassizii</i> (<i>sensu stricto</i>) has demonstrated continued adult population and density declines of about 90% over three generations (two in the past and one ongoing) in four of the five <i>G. agassizii</i> recovery units and inadequate recruitment with decreasing percentages of juveniles in all five recovery units. As such, we reaffirm the prior assessment of the taxonomically restricted Mojave Desert Tortoise, <i>G. agassizii</i>, as Critically Endangered, and add criterion “a” for direct population observations: CR A2abce+A4abce. The previously defined widespread species <i>G. agassizii</i> (<i>sensu lato</i>) was last assessed as Vulnerable on the IUCN Red List in 1996; a separate assessment currently in progress by the TFTSG for the Sonoran Desert Tortoise, <i>G. morafkai</i> (previously considered part of <i>G. agassizii</i>) has provisionally assessed that species as Vulnerable.</p> application/pdf 10.2305/IUCN.UK.2021-2.RLTS.T97246272A3150871.en en IUCN Gopherus agassizii article