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Desert Tortoise Fact File

Gopherus agassizii

Weight

3.6-6.8kg

(8-15lbs)

Length

25-36cm

(10-14in)

Lifespan

Wild 35 years

Captive 100 years

Diet

Herbivore

Cacti and Grass

Conservation Status

IUCN

Vulnerable

The desert tortoise is native to the North American deserts where they escape the heat by creating a burrow where they may spend up to 95% of their life.

Their back features a large shell which protects them from threats such as coyotes and badgers.

Most of their diet is made up of plants such as cacti and grasses. They can go for as long as a year without water.

Read on to learn more about these reptiles.

Appearance

The desert tortoise, like all tortoises has a hard shell on its back which helps to protect the body. On top this shell is brown or grey with a potential center spot which is brown or tan. The underside may be yellow or brownish. Their shell is rounded on the top. The top of the shell features distinctive growth lines.

To protect themselves against attack they can withdraw their body inside the shell.

Further protection is afforded by the rough scales which cover the front legs.

Desert tortoises measure between 25 and 36cm (10 and 14in) long on average with a weight between 3.6 and 6.8kg (8-15lbs). They are 10-15cm (4-6in) tall.

Males differ from females in having a longer projection at the front of the plastron (lower shell).

Diet


The desert tortoise is primarily herbivorous. Their diet includes grasses, flowers, cactus pads and fruit.

These animals will dig a hole in the ground where water pools. After a storm they will return to these holes and drink the water.

Desert tortoises have been recorded to go up to a year without drinking. Water is stored in the bladder and will be reabsorbed if required. At times as much as 40% of their body weight comes from stored water.

When handled they may empty their bladder.

Desert tortoises help to re-establish plants in their environment through spreading the seeds of the plants they eat.

Desert Tortoise

Range

North America is the native home of the desert tortoise. Here they can be found in the South of the continent in Mexico and the United States.

Habitat

As their name suggests they are found in desert habitats.

Desert tortoises will use their strong forearms and tough nails to dig their own burrows under the ground. These tunnels may reach up to 10m (32ft) long.

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Reproduction

Egg-laying occurs from May to June. Each clutch will include between 2 and 15 eggs with as many as 3 clutches laid each year.


During the breeding season males will regularly fight one another. Small horns are present on the chest they can use to knock one another over. The loser is flipped on to its back. They can eventually wiggle themselves back on to their front.

Females may not lay their eggs immediately after mating. Instead they can store sperm and wait for optimal conditions to lay the golf ball sized eggs.


These clutches are incubated for between 90 and 135 days.


At hatching the young are fully independent and will set out to find food. A juvenile desert tortoise will measure between 4.2 and 4.5cm (1.6-1.7in) long.


Sexual maturity is reached between 15 and 20 years old. Less eggs are laid in years with little to no rainfall.

Behavior

As an ectotherm the desert tortoise must regulate its own body temperature and aim to reduce water loss. To achieve this they spend much of their time hiding in a burrow or rock shelter. As much as 95% of their life may be spent in the burrow.

During warm weather they will burrow alone. In winter groups burrow together to share body warmth.

Throughout winter they enter a period of brumation where they are inactive for much of this part of the year. In spring they will emerge and begin to bask in the sun to warm their body.

A range of vocalizations are made by the desert tortoise. These include a hiss, grunt and moan. They also use visual communication such as head bobs.

Desert Tortoise

Predators and Threats

Natural predators of the desert tortoise include birds of prey such as ravens, kit foxes and coyotes. Juveniles face additional predators including badgers, skunks, roadrunners and lizards such as the gila monster.

Over the last 20 years the desert tortoise population has declined by around 90%.

One threatening factor has been the use of off-road vehicles. These will destroy plants which the tortoises rely on for food. Some of these habitats can take up to 200 years to recover.

These vehicles may also run over burrows and bury the tortoise alive.

They may be outcompeted for food by domestic animals such as cattle.

Humans have increasingly developed their habitat or destroyed it during building projects.

Desert tortoises were given federal protection in the United States during 1989.

Quick facts

These animals are also known as the gopher tortoise as they live underground like gophers do.

They are referred to as the mojave desert tortoise.

The desert tortoise is recognized as the state reptile of California.

Desert Tortoise

Photo Credits

Top and Middle One

Public Domain

Middle Two and Bottom

Kurtab123, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

References

Burnie, D., 2011. Animal. 3rd ed. London: DK

Racinezoo.org. 2021. Desert Tortoise Fact Sheet | racinezoo.org. [online] Available at: <https://www.racinezoo.org/desert-tortoise-fact-sheet> [Accessed 27 May 2021].

Tortoise & Freshwater Turtle Specialist Group. 1996. Gopherus agassizii. The IUCN Red List of Threatened Species 1996: e.T9400A12983037. https://dx.doi.org/10.2305/IUCN.UK.1996.RLTS.T9400A12983037.en. Downloaded on 27 May 2021.

Animals. 2021. Desert Tortoise. [online] Available at: <https://kids.nationalgeographic.com/animals/reptiles/facts/deserttortoise> [Accessed 28 May 2021].

Service, U., 2021. Desert Tortoise Life History. [online] Fws.gov. Available at: <https://www.fws.gov/nevada/desert_tortoise/dt/dt_life.html> [Accessed 28 May 2021].

Animals.sandiegozoo.org. 2021. Desert Tortoise | San Diego Zoo Animals & Plants. [online] Available at: <https://animals.sandiegozoo.org/animals/desert-tortoise> [Accessed 28 May 2021].

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