The Desert Tortoise (Gopherus agassizii) is a rarely seen reptile whose range extends across the Mojave and Sonoran deserts of southern California, Nevada, Arizona and even Utah; as well as the arid regions of northern Mexico. The tortoise is a beautiful and elusive member of the Testudinidae family who differ from other reptiles due to their hard outer shell. With little access to water and the inhospitable nature of its surroundings, the desert tortoise perseveres with the help of adaptation.
Desert Tortoise - Life in the Desert: With desert ground temperatures often exceeding 140 degrees Fahrenheit, the tortoise has adopted a burrowing strategy to handle its harsh environment. Desert Tortoises can dig burrows up to 6 feet deep and will spend 95 percent of their time underground. The tortoise will emerge from its den to eat during the evening when the temperatures are cooler but even during their 'active' period - emergence is rare.
Desert Tortoise - Size and Shape: The desert tortoise is fairly oval-shaped with a dark brown shell often made to look lighter by the presence of sand. The can grow between 8 - 15 inches long and weigh up to 15 pounds. Their height can vary based on natural shell shape but can exceed 5 inches and will have an average 'ground clearance' of only 1-2 inches. Their lack of ground clearance causes their feet to drag in the sand - resulting in drag marks between foot impressions (see track). The desert tortoise has both an upper shell and a 'belly' shell referred to as the plastron.
The lesser-known plastron is found in both sexes and can also be used to tell them apart. In the male, the plastron is concave whereas in the female, the plastron lays flat. Another way to differentiate the sexes is through the gular horn. The gular horn is a pointed extension of the anterior plastron (lower shell) and while found in both sexes, the gular horn is much longer and more pronounced in males. In fact, the gular horn is used for tortoise-to-tortoise combat during mating season. The goal is to use one's gular horn to flip the other tortoise on its back resulting in victory.
Desert Tortoise - Diet, Age and Reproduction: The tortoise is an herbivore and feeds on shrubs, grasses, cacti, flowers and other plants. With regard to water, the tortoise is well adapted. Its metabolic rate is so low that it can tolerate lack of water for up to an entire year - a desirable trait for any desert dweller. However, the tortoise has a back up plan. Desert tortoises will dig 'catch basins' to collect rainwater. As a storm approaches, the tortoise will emerge from its burrow and can often be found waiting next to their catch basins for a drink.
Mating season occurs during the months of August through October with an incubation period of 90 -120 days. The desert tortoise lays eggs and the number of hatchlings can range greatly - but rarely exceeds a dozen. The tortoise will reach sexual maturity before the age of 20 and can live up to 80 years old in the wild yet averages between 50 - 70 years. Desert Tortoise - Endangered and Protected The desert tortoise is endangered and comes with local and federal protection. Always enjoy sightings from a distance and be sure to report them to your local or federal wilderness agency. Never handle a tortoise or disturb its borrow.