Care of Desert Tortoises (Gopherus agassizii)
The Desert Tortoise is a long-lived fascinating creature well adapted to survive in the desert environment. It is found throughout the Sonoran Desert region and is commonly kept as a backyard family companion pet in southern Arizona. As a family pet, it is relatively a low-maintenance animal, but the Desert Tortoise does have some very specific requirements that will ensure its health and longevity.
Desert Tortoises are primarily herbivorous, and grasses comprise the bulk of their diet. In addition, these tortoises will eat, when they are available, wildflowers and cactus fruit. Wild tortoises will also eat, when the odd circumstance allows, insect or carrion food items. As desert animals, they are opportunistic eaters, which is to say they might eat anything that is edible when it becomes available… even if that item is unhealthful. Care must be taken to not offer unhealthful or toxic food items: animal fats, excessive protein, excessive fruits, oleander, chinaberry, toadstools, or other toxic items. Tortoises potentially can eat dangerous foods for long periods of time before they show the life-threatening effects of their diet. It is essential that the diet of a captive tortoise be properly managed.
In captivity, tortoises may be fed a large variety of foods, including:
Grasses (fresh and dried) Dandelion
Alfalfa Hibiscus Flowers
Clover Mulberry Leaves
Melons Rose Petals
Apples (without seeds) Nasturtiums
Peas Yellow Squash
Corn (raw with or without the cob) Romaine Lettuce
Zucchini Green Beans
Carrots (shredded) Cabbage (small amounts)
Dichondra Turnip Greens
Beet Greens Avocados
Oranges Frozen Mixed Vegetables (thawed)
Bean Sprouts Cauliflower
Plums Collared Greens
Mustard Greens Herbivorous Tortoise Diet (Mazuri)
Deer Grass Curly Mesquite
Arizona Cottontop Bamboo Muhly
In general, fruit should not comprise more than 10 to 20% of the tortoise’s diet (with the exception of cactus fruit). Excessive fruit sugars in the diet may contribute to bacterial overgrowth of the tortoise’s gut. Improper gut flora (bacteria) may lead to severe health problems. Herbivorous tortoises rely heavily on their bacterial flora to help in the digestion of their food. Without the proper bacteria, an herbivorous tortoise cannot properly digest its food. Desert Tortoises can be very selective—finicky-- with the food items that they choose to consume. All of the above food items are acceptable, but some tortoises may choose to eat only grasses to the exclusion of everything else. It is still important to try and offer variety… with some patience and persistence a tortoise may be induced to try a new food item. Usually, for a healthy tortoise in an outdoor environment, dietary supplementation with a reptile vitamin product is not necessary. Feeding of a pelleted diet, such as the Mazuri Herbivorous Tortoise Diet, is an easy and convenient way to enhance, vary, and supplement a Desert Tortoise’s diet (this pelleted diet is available through your veterinarian).
Maturity and Reproduction
In general, captive Desert Tortoises should not be allowed to reproduce. Currently, there are more captive tortoises than there are homes for captive tortoises. For a variety of reasons, among which are health threats to wild populations, captive Desert Tortoises may not be released back into the wild. So, backyard breeding of tortoises is something to be avoided. Male and female tortoises should be kept segregated. Male tortoises may be very territorial, and two males kept together will probably fight and create excessive behavioral stress (and subsequent health problems). Females may be kept together if approximately 120 square feet of space is provided per animal.
All this said, it is important to realize that despite all efforts, a single female tortoise might lay fertile or infertile eggs without the immediate or obvious benefit of a mate. The fertile eggs may be the result of “sperm storage”, a strange phenomenon whereby a mature female tortoise may carry viable sperm for up to four seasons… just in case she can’t find a good man. And when it comes time to deposit those eggs, they can be fertile.
Because tortoises are reptiles, which are very dependant on environmental temperatures for normal physiologic activity, they must become inactive and hibernate during cold weather months. This period of inactivity generally spans the winter months of October/November through March/April. It is during this period that a Desert Tortoise will crawl deep into its burrow and hibernate. Proper hibernation is essential to the overall health of a Desert Tortoise. It is also during this period of time that a tortoise is most vulnerable in terms of health and security.
Tortoises in captivity also need to hibernate. To do so properly, they will need a den (or burrow). Wild tortoises will often use dens that have existed for decades, if not centuries. Usually, a wild tortoise would not need to construct a den from scratch. In captivity, it is best to construct a basic den for your Desert Tortoise. The tortoise will further modify the den to suit its personal tastes.
A basic outdoor den should be large enough for a tortoise to enter and turn around. A den would be dug into the ground and covered with a sheet of wood, to lessen the likelihood of a cave-in. The wood should be then covered with 8 to 12 inches of soil to provide insulation. Because tortoises like to constantly modify their homes, it is important to monitor that the tortoise is not undermining the structures that prevent a cave-in. In addition, dens are most hospitable if their openings have an eastern, northeastern, or southern exposure. The opening should also be constructed in a way to allow for drainage from the den and prevent flooding in a heavy rain shower. It is also a good idea to build an access hatch at the far end of the den to allow for inspection of the tortoise and the den during hibernation.
It is also possible to hibernate tortoises indoors during the winter months. Typically, this would be accomplished in cool but sheltered areas such as a garage or storage shed. The area must be maintained at a temperature of approximately 55°F and 30 to 40% humidity. The tortoise may be placed in an insulated box with leaves and newspaper. The box should be placed in an area inaccessible to rodents and isolated from drafts.
Wherever they are over-wintered, tortoises should be checked on a routine basis of every two or three weeks. Some tortoises benefit from a half-hour long warm-water soak every three or four weeks. These soaks help maintain critical hydration. Towards the end of the hibernation period, warm-water soaks will helps restore a tortoise to activity by raising the hydration levels and the critical core temperature.
In general, sick or debilitated tortoises might be at risk during hibernation. If this is the case, your veterinarian may recommend avoiding hibernation by providing supplemental heat and lighting. A physical examination with a qualified veterinarian prior to hibernation is always recommended. It is during this examination that the tortoise’s overall health and body condition may be assessed. A microscopic examination of fresh feces is also recommended at this point to check for evidence of parasitism the digestive tract.
Common Health Problems
One of the more common Desert Tortoise health problems is an infection of the respiratory tract. Typically, these infections present as an upper respiratory infection (URI), but they can easily develop into a lower respiratory infection and pneumonia. Tortoise URIs are usually contagious and chronic in nature—they are very difficult to permanently clear, and they tend to spread within a group of tortoises. URIs tend to occur just before and just after hibernation periods. Early URI signs include puffy or swollen eyelids and eye membranes; ocular (eye) and nasal discharge; inactivity; loss of appetite. There are several treatment protocols for URIs in Desert Tortoises, some of which may be very successful, and your veterinarian can help determine which course of treatment would be best for your tortoise. Desert Tortoise URI is an active area of veterinary research, which will produce more effective techniques of diagnosis and treatment.
Indoor tortoises, especially young rapidly growing tortoises, often suffer health problems due to poor nutrition and/or improper lighting. The most common symptom is an improperly developing shell secondary to poor calcification. We have previously discussed diet. It is essential that tortoises have a source of direct ultraviolet (UV) lighting. In an indoor setting, this is accomplished through the utilization of fluorescent “full-spectrum” lights. Sunlight through glass or plastic is not adequate since the glass or plastic will filter out the UV spectrum of the light. Similarly, the UV light must be direct. Fluorescent UV lights are available under the brand names of Vitalite, Reptisun, and Chromolux (among others).
Desert Tortoises are potentially very long-lived animals, and many of their health problems may be avoided via the implementation of a good nutritional and preventative healthcare program. It is recommended that you have your tortoise examined by a veterinarian on an annual basis. It is through regular physical examinations that a veterinarian can detect health problems and identify health trends.
Michael S. Samuels, D.V.M.