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RENO FWO: Recovery Office working to Monitor Mojave Population of Threatened Desert Tortoise
California-Nevada Offices , July 28, 2010
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U.S. Fish and Wildlife biologists from the Desert Tortois Recovery Office look for evidence of animal presence during survey for desert tortoise.
U.S. Fish and Wildlife biologists from the Desert Tortois Recovery Office look for evidence of animal presence during survey for desert tortoise. - Photo Credit: n/a
Linda Allison (far right) demonstrates distance sampling using a polystyrene tortoise.
Linda Allison (far right) demonstrates distance sampling using a polystyrene tortoise. - Photo Credit: n/a

By Jeannie Stafford, Reno FWO

The U.S. Fish and Wildlife Service (USFWS) Desert Tortoise Recovery Office (DTRO), based in Reno, is developing recovery strategies for the Mojave population of the  threatened desert tortoise.  The DTRO focuses exclusively on research, monitoring, recovery plan implementation, and associated recovery permitting, and provides a centralized point of contact to coordinate these activities.

Established in 2005, the DTRO develops accurate, scientifically credible estimates of desert tortoise populations throughout its range in Nevada, Arizona north of the Colorado River, California, and Utah.   Linda Allison, the Service's lead biologist for this effort, trains approximately 60 biologists each year from various organizations to conduct a survey and monitoring method called "distance sampling" and to apply proper protocols and procedures for safely handling desert tortoise.  Prior to surveying for the species in the field, the biologists must demonstrate that they can accurately implement the survey protocol.  According to Allison, they must also demonstrate ability to properly handle desert tortoises, since tortoises are susceptible to infectious diseases and are vulnerable to overheating and death if improperly handled under the high temperature conditions characteristic of the desert environment. 

Allison noted that Biologists soon discover that even though a desert tortoise is a relatively sedentary animal, estimating their presence and population size has many challenges.  The animals are active during the daytime and inhabit the relatively open landscape of the desert.  They are sparsely distributed over vast areas of the Mojave Desert.  In addition, many tortoises are not visible because they are underground, and their use of burrows varies considerably even during the spring activity period and especially between years.   When they are out of their shelter, their camouflage -- the tortoises are cryptically colored and shaped -- makes them difficult to locate.

Despite the difficulties of monitoring the elusive Mojave population of desert tortoise, the Service is compiling annual population density estimates, an essential goal in tracking recovery of the species.  The Service is using this information in assessing the status of the desert tortoise and its progress toward recovery.


Contact Info: Jeannie Stafford, 775-861-6300, jeannie_stafford@fws.gov



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