Slow and Steady for the Desert Tortoise

Slow and Steady for the Desert Tortoise

By: Cesar Sanchez

Habitat of the Mojave Desert Tortoise

The species of Desert Tortoise scientifically referred to as Gopherus agassizii, is found in the Mojave Desert located in the western parts of Arizona, southeastern California and southwestern Utah. 

Geographic Range of Mojave Desert Tortoise

   You will most likely not stumble upon a Desert Tortoise outside of its burrow, because it spends 95% of the year underground. While underground, the tortoise does not engage in much activity. This is to preserve the amount of water they use, and burrowing underground is a great way to escape the scorching sun and prevent evaporation of they water in and on their body. The sun can be seen as an opponent of the tortoise, and because of this it is essential that a tortoise can burrow underground. The claws on their front feet are especially made for digging into dirt that is friable enough to dig and strong enough to not collapse. 

Tortoise in habitat in Riverside, CA

Home Sweet Home!

FUN FACT

The Ground temperature in the Mojave Desert can reach up to 140 degrees Fahrenheit!

Description

The desert tortoise can range in length from 10 to 14 inches and heights from 4 to 6 inches. Males are typically larger due to the fact that they must compete with other males for mates. They also have a larger gular horns located on their throats and they have larger tails. The top part of their shells are higher domed for males, the reason for this, in the event of being turned over, a larger dome allows for a better chance of flipping over. Typically they are greenish-tan in color or dark brown. Perfect camouflage from predators. 

Female looking on in shock 

Two males fighting over her

Notice the horns on their neck. These are meant for these situations and made for flipping over an opponent.

Reproduction

Tortoises take about 15 to 20 years to reach reproductive maturity. So in this sense the can be considered k selected species. Tortoises mate during the Spring and Autumn seasons, and during this time, males develop two white glands beneath their chin to signify mating season.

Male desert tortoise enjoying a strawberry with white glands beneath his chin.
Signifying he is ready to mate

You may google the mating process if you feel it will expand your knowledge of the Mojave Desert Tortoise. But if you don't feel the need, then let us move on.


A female can lay up to 4 to 8 eggs in their burrows, and they take about 135 days to hatch. Offspring have a very high infant mortality rate, and because of this they can also be seen as r-selected species. An estimated 2 to 5% of hatchlings reach reproductive maturity. :'(

Diet

The diet of a desert tortoise consists of grass and seasonal flowers. They may also eat cacti growing in their area along with their fruit. Desert tortoise gets a majority of their water from the plants they eat because of the lack of rain in the desert. You are more likely to catch a tortoise outside of its burrow after it rains because this is the right time to drink as much water as they can from small 

puddles. 

As you can see the wild desert tortoise is not even phased
the spikes on a cactus

YUMM!

FUN FACT

The Desert Tortoise is the state reptile of California.

Geographic and Population Changes

Indirect impacts to desert tortoise populations and habitat are also known to occur in areas that interface with intense human activity. In some areas the number of desert tortoises have decreased by 90% since the 1980s. Declines seem to be most severe in the western part of the Mojave Desert. Recent estimates indicate there are about 100,000 desert tortoises left in the Mojave and Sonoran Deserts. 

Tortoise cleverly avoiding traffic

Getting Put on the List

The Mojave population of the Desert Tortoise was listed under the Endangered Species Act as a Threatened species on April 2, 1990. The areas where they are founded was also listed as Critical Habitat in 1994 along with the the recovery plan being published in June of 1994. The desert tortoise was seen as having a moderate degree of threat, but with a very low potential for recovery. Largely because of their slow birthing rates and high infant mortality rates mentioned earlier. 

Main Threats to the Tortoise

Since the 1800s the desert southwest has been subject to a variety of activities that result in habitat fragmentation, degradation and loss. some of the more obvious reasons include road and highway development, and habitat invasion by non-native species. Off-highway vehicle activity, roads, livestock grazing, agricultural uses, and other activities contribute to the spread of non-native species and the direct loss and degradation of habitats. 

Desert Tortoise approaching a non-native grass species

Despite legal protection under Federal and State laws, deliberate maiming or killing of tortoises and collection of desert tortoises by humans for food or as pets were cited as potential threats to the species. 

Desert tortoises, particularly hatchlings and juveniles, are preyed upon by several native species of mammals, reptiles, and birds. The common raven has been the most highly visible predator of small tortoises, while coyotes have been commonly implicated in deaths of adult tortoises.

Desert toals, reptiles, and birds. The common raven has been the most highly visible predator of small tortoises, while coyotes have been commonly implicated in deaths of adult tortoises.

Elevated mercury  have been associated with diseased tortoises in the wild. Necropsy and analyses of kidney, liver, and scute tissues suggested that tortoises from California with a variety of diseases had statistically significantly higher levels of several potentially toxic elements as compared to healthy tortoises. Illegal dumping of hazardous wastes in the California deserts may expose tortoises to increased levels and possible consumption of toxic substances and affect populations on a localized level where these activities are concentrated 

Description of Recovery Plan

One main focus of the recovery plan is to keep the adults alive and reproducing as long as possible. Once adults have reached reproductive maturity, they are more likely to survive in the wild. If they do live longer then the current trends are saying, then they have a higher chance of reproducing more offspring. 

In 2000, Congress enacted the State Wildlife Grants Program to fund activities that benefit species of concern and their habitats. All four states where the Mojave population of the desert tortoise occurs are currently implementing these strategies to guide species and habitat management through 2015. 

Improved grazing management has been put into place to ensure the stopping of invasive plant species. 

In March 2008, about 650 tortoises were moved by helicopter and vehicle, up to 35 km away. The Desert Tortoise Preserve Committee roughly 5,000 acres of desert tortoise habitat from human activity. This area includes 4,340 acres in Kern County, 710 acres in San Bernardino County, and 80 acres in Riverside County.

Personal Action.

One thing us citizens can do to help continue the recovery of this threatened species is to not pick them up and take them home as pets. I know these are adorable and it may be hard to resist, but it is what is best for their survival. Also if you stumble upon one in the middle of the road, the best ting to do is safely move the animal away form the highway. Pull over to the side of the road or create a small road barrier and let drivers know that this threatened species is making their way across the road. 

It is our duty as Californians to help with the recovery process of our very own state reptile!

Slow and steadily this tortoise is making his way to recovery.

Resources

http://ecos.fws.gov/docs/recovery_plan/RRP%20for%20the%20Mojave%20Desert%20Tortoise%20-%20May%202011_1.pdf

http://www.californiaherps.com/turtles/pages/g.agassizii.html

http://animaldiversity.org/accounts/Gopherus_agassizii/

http://www.defenders.org/desert-tortoise/basic-facts