'Homebuilders of the desert'

“Tortoises are the homebuilders of the desert,” said Scott Cambrin, a senior biologist for the Clark County (Nevada) Desert Conservation Program. “A loss for the desert tortoise is a loss for the entire ecosystem.” Shown here, a recently released Mojave desert tortoise. Credit: USFWS

Desert tortoises are an essential part of their desert habitat — their burrows provide homes for lizards, snakes, owls and other creatures

March 22, 2018

Multiple agencies are currently collaborating with the U.S. Fish and Wildlife Service to raise the number of Mojave desert tortoises in areas where the populations are too low to be sustainable. The tortoises are brought in from areas where they have been displaced by human interference to protected areas with lower populations.

Increasing desert tortoise populations

There are many conservation efforts in place to protect the Mojave desert and its inhabitants. However, even with these programs, sometimes more assistance is needed. Tortoise populations are naturally slow to increase when their population has dwindled. One of the ways that conservation experts are helping is to make use of translocation, a method of moving an animal from one place to another.

The Boulder City Conservation Easement, which covers 80,000 acres south of Boulder City, Nevada, is one of the locations available for the translocation of desert tortoise. It is protected from future construction for the next 30 years. Credit: USFWS

The desert tortoise is an essential part of desert habitat. Their burrows provide homes for lizards, snakes, burrowing owls and other creatures. “Tortoises are the homebuilders of the desert,” said Scott Cambrin, a senior biologist for the Clark County (Nevada) Desert Conservation Program. “A loss for the desert tortoise is a loss for the entire ecosystem.”

Unfortunately, humans can interfere with desert tortoise populations, such as through the construction of cities, subdivisions, military activities, and even solar installation projects. People driving off marked paths can damage tortoise burrows or even run over the reptiles.

“We hope over the long-term that translocated tortoises will reproduce with the resident tortoises for a viable population,” said Roy Averill-Murray, desert tortoise recovery coordinator for the U.S. Fish and Wildlife Service, shown here performing a  final health assessment on a desert tortoise. Credit: USFWS

“You have a whole range of things across the desert that have really impacted tortoises and caused tortoise populations to decline,” said Roy Averill-Murray, desert tortoise recovery coordinator for the U.S. Fish and Wildlife Service for the Pacific Southwest Region.

Research suggests that at least 3.9 tortoises per square kilometer are needed for a sustainable population, but the numbers in many areas are much lower. Some recent surveys in southern Nevada locations estimated only 1.9 tortoises per square kilometer.

“It’s thought that the population (in these areas) will go extinct without any help,” said Cambrin.

As a result, multiple land management and conservation agencies are working together to remove threats and improve the tortoise habitat in protected conservation areas. They include the U.S. Fish and Wildlife Service, with its extensive knowledge of recovery needs, as well as the Great Basin Institute.

The Institute offers personnel and research expertise for conservation efforts. Many of the tortoises donated to these efforts come from the U.S. Geological Survey. The Bureau of Land Management has experience in land management and conservation.

BLM can also provide land for the tortoises to be placed, along with the Clark County Desert Conservation Program.

Good Homes: The Boulder City Conservation Easement

Finding an appropriate place to move tortoises is one of the most important aspects of translocation projects. Potential sites should have an unsustainably low population of desert tortoises, but still be a suitable habitat. The sites should have conservation efforts in place to keep construction from developing the area.

“The process of moving a tortoise to an augmentation site starts months ahead of time,” said Kimberleigh Field, a desert tortoise recovery biologist with the U.S. Fish and Wildlife Service, shown here documenting tortoises on the day of the release with Terry Christopher, associate director of the Great Basin Institute. Credit: USFWS

One such location is available at the Boulder City Conservation Easement, which covers 80,000 acres south of Boulder City, Nevada, and is protected from future construction for the next 30 years. Precautions have been taken to protect tortoises from harmful situations, such as roads and highways. Some of the tortoises that are being moved will be transported to the easement.

Moving desert tortoises

Tortoises for translocation come from a variety of sources, but the main three are those found in construction sites, collected for previous research, and private owners who are unable to continue care of their pets. In the fall of 2016, when a group of 38 tortoises were moved, they came from a recently completed research project by the U.S. Geological Survey.

Scott Cambrin, senior biologist for the Clark County (Nevada) Desert Conservation Program, and Kimberleigh Field, discuss their health assessment of a desert tortoise. Credit: USFWS

“The process of moving a tortoise to an augmentation site starts months ahead of time,” said Kimberleigh Field, a desert tortoise recovery biologist with the U.S. Fish and Wildlife Service. “The animals need to go through a quarantine period, and they have their health assessed multiple times, just to make sure that that individual is fit for survival in the wild.”

Surveys of the native animals are an integral part of site preparation. A health assessment is done on the native tortoise population to ensure they will not infect a newcomer with pathogens. For the Boulder City translocation, surveys were also done on the local predators, to help determine if extra measures are needed to keep the new tortoises safe.

If the tortoises are deemed healthy enough for the move and their quarantine is successful, the last preparations are made for the move. Biologists hydrate the tortoises over the course of a few days prior to release, since they will be unfamiliar with their surroundings when they are first moved to the new area. It may be a year before they get a drink in the wild.

Scientists also take the weather into consideration before transport: they do not move tortoises when the weather will be too hot or cold. They will look at the weather forecast, not just for the day of release, but the entire week. Having good weather will give the tortoise enough time to find food, water and shelter.

Home free: A recently released desert tortoise takes in its new surroundings as the translocation team looks on. Credit: USFWS

Once the tortoises are released, they are checked on every few months. To help with identification, the animals are tagged twice: once with a sticker that is glued to their shell, and with notches made to the shell in case the sticker falls off.

Clockwise from top: Kimberleigh Field (USFWS), Glen Knowles (USFWS), Terry Christopher (GBI), Cody Anderson (GBI), Brent Sparks (GBI), Scott Cambrin (DCP), Roy Averill-Murray (USFWS) after the translocation of desert tortoises at Boulder City Conservation Easement. Credit: USFWS

In 2016, 38 tortoises were selected for translocation and were moved to a section of the easement. Another group of tortoises were initially released in the same area in 2014. The latest release helped raise the population to about 3.6 per square kilometer.

Looking to the future

The U.S. Fish and Wildlife Service continues to evaluate the effects of projects that disturb desert tortoise habitat. The short-term goal however is a population augmentation program to successfully translocate tortoises from approved projects into suitable areas.

“Preliminary success can be judged anywhere from two to five years from now,” said Averill-Murray. “We hope over the long-term that translocated tortoises will reproduce with the resident tortoises for a viable population,” said Averill-Murray.

Given the length of time for desert tortoises to reach maturity, ultimate success will be determined in 20 to 30 years by evaluating overall population growth.

The agencies working together for the tortoise translocation efforts hope that a strategic approach can build on investments made through multiple recovery actions being applied in the many conservation areas, which will help the species recover faster.


Desert tortoises go through multiple health assessments while in quarantine to help ensure their survival when released back into the wild. Credit: USFWS

Guidance for public ownership of desert tortoises

Despite the need to increase tortoise populations in the wild, if you own a desert tortoise and can no longer take care of it, do not release it into the desert. It may have diseases that could infect other populations in the area.

The Tortoise Group (http://tortoisegroup.org/) can help find a new home for your tortoise if you can no longer care for your pet. They can also provide information on how to ensure your tortoise’s safety.

If you would like to have a desert tortoise as a pet, do not take them from the wild. Many people are looking for homes for their tortoises, and the Tortoise Group can also help you adopt a desert tortoise. If you see a wild desert tortoise, leave it alone unless it is in immediate danger (such as on a highway).

Finally, to protect all desert animals and habitats, stay on marked roads and avoid flicking cigarettes in the desert, since they can cause wildfires.