The U.S. Fish and Wildlife Service has reviewed a petition seeking to protect the Sonoran population of desert tortoise as a distinct population segment (DPS) under the Endangered Species Act and announced today that the petition presents substantial information indicating that adding the Sonoran population of the desert tortoise to the federal list of threatened or endangered animals may be warranted. Today’s finding initiates a more thorough status review to determine whether the population warrants federal protection.
“The petition to protect the Sonoran desert tortoise under the Endangered Species Act provided substantial information to prompt a closer look at its status,” said Steve Spangle, the Service’s Arizona field supervisor. “We’ll now take a more in-depth look at the species and its threats to determine whether federal protection and recovery efforts are needed.”
On October 9, 2008, WildEarth Guardians and Western Watersheds Projects petitioned the Service to list the Sonoran population of the desert tortoise as a DPS within portions of Arizona, U.S. and Sonora, Mexico. The petitioners described the Sonoran desert tortoise population as all tortoises occuring east and south of the Colorado River in Arizona, extending south to the Yaqui River in southern Sonora, Mexico.
Today’s decision, commonly known as a 90-day finding, is based on scientific information about the species as provided in the petition requesting listing of the species under the Act. The petition finding does not mean that the Service has decided to list the tortoise. Rather, this finding is the first step in a process that triggers a more thorough review of all the biological information available.
The Service will undertake a more thorough status review of the species to determine whether to propose adding the species to the federal list of endangered and threatened wildlife and plants. To ensure this status review is comprehensive, the Service is soliciting information from state, tribal, and federal natural resource agencies and all interested parties regarding the Sonoran desert tortoise and its habitat.
Based on the status review, the Service will make one of three possible determinations:
01) Listing is not warranted, in which case no further action will be taken.
02) Listing as threatened or endangered is warranted. In this case, the Service will publish a proposal to list, solicit independent scientific peer review of the proposal, seek input from the public, and consider the input before a final decision about listing the species is made. The time between a species listing proposal and the final decision is typically one year.
03) Listing is warranted but precluded by other, higher priority activities. This means the species is added to the federal list of candidate species, and the proposal to list is deferred while the Service works on listing proposals for other species that are at greater risk. A warranted but precluded finding requires subsequent annual reviews of the finding until such time as either a listing proposal is published, or a not warranted finding is made based on new information.
The Sonoran population of the desert tortoise differs from the Mojave population of desert tortoises which occurs north and west of the Colorado River, and has been listed under the Act as threatened since 1989. The desert tortoise is currently listed as threatened in Mexico.
Desert tortoises are recognized by their gray to orange-brown, high, domed shell. The desert tortoise may reach eight to 15 inches in length and four to six inches in height, and may weigh eight to 15 pounds as adults. The Sonoran desert tortoise occurs predominantly in desert scrub habitat. Primarily herbivores, Sonoran desert tortoises eat a variety of fresh, residual, and dried annuals, perennials, and plant litter. Sonoran desert tortoises are largely inactive from mid-October to late February or early March when they overwinter in constructed burrows or rocky cavities or crevices.
Some of the threats to Sonoran desert tortoise that were identified in the petition include habitat loss resulting from urban development and improper livestock grazing, the release of captive tortoises that spread disease and affect population genetics, increased predation by coyotes and ravens that are benefiting from urban infiltration of wild areas, and increased invasive plant-driven fires.
The Sonoran desert tortoise is currently a popular household pet for many Arizona families. At this stage, it is premature to speculate whether the Sonoran desert tortoise will be listed or ramifications to captive tortoises. However, both federal and state wildlife agencies strongly encourage private citizens to never release captive tortoise back into the wild. Breeding captive desert tortoises is discouraged, as this may hurt on-going conservation efforts and contributes to the over-abundance of unwanted tortoises. Released captive tortoises pose a threat to wild populations through the spread of disease and genetic contamination.
Information regarding Sonoran desert tortoise status, threats or its habitat in Arizona and Mexico should be submitted via:
- http://www.regulations.gov. Follow the instructions for submitting comments to Docket FWS-R2-ES-2009-0032.
While the Service always welcomes species status information, in order to be considered in this status assessment, information should be submitted by Oct. 27, 2009.
Note to editors: Photographs of Sonoran desert tortoises are available at by contacting Jeff Humphrey at 602-242-0210 x222 or visiting http://www.fws.gov/southwest/es/arizona/Reptiles.htm . Today’s finding will be available upon publication at: http://www.fws.gov/southwest/es/arizona
