Skip to Content


Draft Revised Recovery Plan for Mojave Population of the Desert Tortoise (Gopherus agassizii)

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Fish and Wildlife Service, Interior.


Notice of document availability for review and comment.


We, U.S. Fish and Wildlife Service (Service), announce the availability of a draft revised recovery plan for the Mojave population of the desert tortoise for public review and comment.


We must receive any comments on the draft recovery plan on or before November 3, 2008.


The draft recovery plan and reference materials are available for inspection, by appointment, during normal business hours at the following location: U.S. Fish and Wildlife Service, Nevada Fish and Wildlife Office, 1340 Start Printed Page 45237Financial Boulevard, Suite 234, Reno, NV 89502 (telephone: 775-861-6300). Submitted comments regarding the draft revised recovery plan will also be available for public inspection, by appointment, during normal business hours following the public review and comment period. Requests for copies of the draft revised recovery plan and submission of written comments or materials regarding the plan should be addressed to the Field Supervisor at the above address. You may also submit electronic comments on the recovery plan to: An electronic copy of the draft recovery plan is available at:​recovery/​index.html#plans.

Start Further Info


Roy Averill-Murray, Desert Tortoise Recovery Coordinator, at the above address or telephone number.

End Further Info End Preamble Start Supplemental Information



Recovery of endangered or threatened animals and plants is a primary goal of the Endangered Species Act (Act) (16 U.S.C. 1531 et seq. ) and our endangered species program. Recovery means improvement of the status of listed species to the point at which listing is no longer required under the criteria set out in section 4(a)(1) of the Act. Recovery plans describe actions considered necessary for the conservation of the species, establish criteria for downlisting or delisting listed species, and estimate time and cost for implementing the measures needed for recovery. The Recovery Plan for the Mojave Population of the Desert Tortoise (Gopherus agassizii) was first published in 1994 wherein the status of the species, threats, recovery actions and recovery criteria were presented. Since that time a great deal of effort has been dedicated to recovery and conservation activities, and additional information has been obtained through research and observation that allows us to better focus our recovery strategy. The revised recovery plan for the Mojave Population of the desert tortoise is the focus of this notice.

Section 4(f) of the Act directs the Secretaries of Interior and Commerce to develop and implement recovery plans for species listed as endangered or threatened, unless such plans will not promote the conservation of the species. We and the National Marine Fisheries Service, as appropriate, have been delegated responsibility for administering the Act. Section 4(f) of the Act requires that public notice, and an opportunity for public review and comment, be provided during development of recovery plans. We will consider all information presented during the public comment period on each new or revised recovery plan. Substantive comments may or may not result in changes to a recovery plan. However, any substantive comments regarding recovery plan implementation will be forwarded to appropriate Federal agencies or other interested entities so that they can take these comments into account during the implementation of their respective management programs. Individual responses to submitted comments will not be provided.

The desert tortoise is a large, herbivorous reptile that can reach 20 to 38 centimeters (cm) (8 to 15 inches (in)) in carapace length and 10 to 15 cm (4 to 6 in) in shell height. Hatchlings emerge from eggs at about 5 cm (2 in) in length. Adults have a domed carapace and relatively flat, unhinged plastrons (lower shells). Their shells are high-domed and greenish-tan to dark brown in color with tan scute (horny plate on the shell) centers. Adult desert tortoises weigh 3.6 to 6.8 kilograms (8 to 15 pounds). The forelimbs have heavy, claw-like scales and are flattened for digging. Hind limbs are more elephantine.

Throughout most of the Mojave Desert, the desert tortoise occupies a variety of habitats: From flats and slopes dominated by creosote bush (Larrea tridentata) scrub at lower elevations, to rocky slopes in the blackbrush (Coleogyne ramosissima) scrub, and juniper (Juniperus spp.) woodland interface at higher elevations. Records of desert tortoises range from below sea level to an elevation of 2,225 meters (m) (7,300 feet (ft)), with the most favorable habitat at elevations between 305 and 914 m (1,000 and 3,000 ft). Desert tortoises most commonly occur on gently sloping terrain with sandy-gravel soils that are friable for burrowing and where there is sparse cover of low-growing shrubs and a high diversity of both perennial and annual plants.

The desert tortoise occurs in the Mojave and Sonoran deserts in southern California, southern Nevada, Arizona, and the southwestern tip of Utah in the United States, as well as in Sonora and northern Sinaloa in Mexico. The listed Mojave population of the desert tortoise includes those animals living north and west of the Colorado River in the Mojave Desert of California, Nevada, Arizona, and southwestern Utah, and in the Sonoran (Colorado) Desert in California. A recovery plan was published in 1994 and critical habitat was also designated in all four States supporting the species.

Three other tortoise species in the genus Gopherus occur in the United States, and another occurs in Mexico; however, all are geographically separated from the Mojave population. The Sonoran population of the desert tortoise is significantly different both genetically and ecologically, but could be confused visually with tortoises of the Mojave population; therefore, we determined the Sonoran population also warranted protection as a threatened species under section 4(e) of the Endangered Species Act (similarity of appearance) when located outside of its natural range.

The vast majority of threats to the desert tortoise or its habitat are associated with human land uses. The threats identified in the 1994 Recovery Plan, and that formed the basis for listing the tortoise as a threatened species, continue to affect the species. Habitat loss, degradation, and fragmentation from urbanization, off-highway vehicle use in the desert, linear features such as roads and utility corridors, livestock grazing and mining, and military activities were cited as some of the primary reasons for the decline in desert tortoise populations. Disease and increased incidence of fire in the Mojave Desert have also been implicated in desert tortoise declines.

The data amassed between 1979 and 2002 from permanent study plots throughout the range of the species were used to explore regional and recovery-unit-level analyses and trends, and to develop within-population spatial analyses at various scales on the landscape and in different management units. Despite the challenges in comparing data from year to year, the apparent downward trend in desert tortoise populations in the western portion of the range that was identified at the time of listing is considered ongoing. Results from other portions of the range were inconclusive, but recent surveys of some populations found too few tortoises to produce population estimates, suggesting that declines may have occurred more broadly.

Collectively, the various analyses that have been performed do not suggest that implementation of specific management actions over time has abated declines of, or resulted in detectable increases in, desert tortoise populations across most of the range. The life history of the species (i.e., delayed reproductive maturity, low reproductive rates, and relatively high mortality early in life) is such that observing relatively rapid increases in populations is highly unlikely, even over the 23-year monitoring period evaluated.Start Printed Page 45238

Despite the clear demonstration that the threats identified at the time of listing impact individual tortoises, there are few data available to evaluate or quantify the effects of threats on desert tortoise populations. While current research results can lead to predictions about how local tortoise abundance should be affected by the presence of threats, quantitative estimates of the magnitude of these threats, or of their relative importance, have not yet been developed.

While precise correlations between the multitude of threats and desert tortoise populations have not been clearly shown, a great deal of effort has been put forth by research scientists and land managers to actively conserve the species. Substantive datasets pertaining to disease, non-native invasive plant species, and fire have been assembled over the years that will be used to inform decisions relative to desert tortoise recovery. Conservation actions such as land acquisitions, installing protective fencing, retiring grazing allotments, limiting off-highway vehicle access, and implementing restoration projects have been important recovery and management efforts based on our current state of knowledge regarding the threats facing the species.

The revised strategy emphasizes partnerships to direct and maintain focus on implementing recovery actions and a system to track implementation and effectiveness of those actions. The strategic elements listed herein are part of a multi-faceted approach designed to improve the 1994 Recovery Plan. The goals of the revised recovery plan are recovery and delisting of the desert tortoise. The objectives and recovery criteria address demography (maintain self-sustaining populations of desert tortoises within each recovery unit into the future); distribution (maintain well-distributed populations of desert tortoises throughout each recovery unit); and habitat (ensure that habitat within each recovery unit is protected and managed to support long-term viability of desert tortoise populations. The strategic elements include the following: (1) Develop, support, and build partnerships to facilitate recovery; (2) protect existing populations and habitat, instituting habitat restoration where necessary; (3) augment depleted populations in a strategic, experimental manner; (4) monitor progress toward recovery, includes population trend and effectiveness monitoring; (5) conduct applied research and modeling in support of recovery efforts within a strategic framework; and (6) implement a formal adaptive management program that integrates new information and utilizes conceptual models that link management actions to predicted responses by desert tortoise populations or their habitat. The success of this revised recovery strategy will rely heavily upon the involvement of our partners and our commitment to implementing the strategic elements listed above coupled with a functioning adaptive management program.

Public Comments Solicited

We solicit written comments on the draft revised recovery plan described in this notice. All comments received by the date specified above will be considered in development of a final revised recovery plan for the Mojave population of the desert tortoise.

Start Authority

Authority: The authority for this action is section 4(f) of the Endangered Species Act, 16 U.S.C. 1533(f).

End Authority Start Signature

Jim A. Bartel,

Acting Regional Director, Region 8, U.S. Fish and Wildlife Service.

End Signature End Supplemental Information

[FR Doc. E8-17520 Filed 8-1-08; 8:45 am]