Desert tortoises, also known as gopher tortoises and desert turtles, are fascinating reptiles found in the southwestern United States and northern Mexico. As a federally-listed endangered species, it is illegal to remove these animals from the wild. They spend their days in burrows, under bushes, overhanging soil or rock formations, or in the open, emerging to forage during dawn and dusk. This article provides a comprehensive overview of the desert tortoise diet, covering essential nutritional needs, suitable food sources, and important considerations for both wild and captive tortoises.
Understanding the Desert Tortoise
Before diving into the specifics of their diet, it's essential to understand the basic aspects of desert tortoises.
- Habitat: Desert tortoises inhabit the Sonoran and Mojave deserts. The Agassiz's desert tortoise (Gopherus agassizi) lives in the Mojave deserts of California, Nevada, Utah, and Arizona west of the Colorado River.
- Lifespan: In captivity, desert tortoises can live up to 60 years or more with proper care.
- Sexing: Once they reach sexual maturity, desert tortoises can be sexed. Males have a concave plastron, while the female’s is flat.
- Conservation Status: Wild desert tortoise populations are threatened by development and destruction of natural habitat. Captive tortoises have the opposite problem and have become over-populated. Large numbers of tortoises now sit homeless in sanctuaries throughout the southwest US. Collecting a desert tortoise from the wild is illegal. Captive tortoises should not be released into the wild, as they can potentially carry a highly contagious and fatal upper respiratory disease to the wild population.
Nutritional Needs of Desert Tortoises
Desert tortoises are strictly herbivores and require a diet that is high in fiber, moderate in protein, low in fat, and rich in calcium. A proper diet is crucial for their overall health, growth, and longevity. The challenge is to provide these nutrients without giving excessive sodium, or giving more phosphorus than calcium.
- Fiber: Essential for healthy growth and digestion.
- Protein: Necessary for tissue repair and growth.
- Fat: Should be limited to prevent obesity and related health problems.
- Calcium: Crucial for bone development and overall health. UVB is essential for tortoises to synthesize Vitamin D, which is crucial to calcium metabolization.
Dietary Guidelines
The ideal desert tortoise diet should consist of:
- 85% Grasses, Weeds, and Dark, Leafy Greens: This forms the bulk of their diet.
- 15% Hard Vegetables: These can be offered in moderation.
Recommended Food Sources
Grasses and Weeds
These should constitute the majority of the tortoise's diet. Examples include:
Read also: Feeding Desert Iguanas
- Alfalfa hay
- Bermuda grass
- Fresh clover
- Clover hay
- Mallow
- Opuntia cactus pads (prickly pears) and flowers
- Rye grass
- Rice grass
- Sowthistle
- Timothy, Bermuda, or orchard grass hays.
Vegetables
Offer these in limited quantities:
- Edible shrubs and garden plants can also be planted in the enclosure, which many tortoises will relish.
- Weeds and native shrubs are especially important to growing, juvenile tortoises. Planting Dichondra along with their grass is an easy way to achieve this in outdoor habitats.
Fruits and Flowers
Feed sparingly as treats:
- Edible flowers
Commercial Diets
- Mazuri LS Tortoise Pellets can be given no more than weekly.
- Grassland Tortoise Food provides all the necessary nutrients and fiber. Soften Tortoise Food with water for 2 or 3 minutes using a ratio of about 1 part Tortoise Food to 11/2 parts water.
Foods to Avoid
Certain foods can be harmful or even fatal to desert tortoises. Avoid feeding them:
- Meat
- Insects
- Dog or cat foods
- Monkey biscuits
- Sweet fruit
- Corn
- Frozen vegetables (especially for young tortoises)
Harmful Substances
- Spinach: Although it contains nutrients, spinach also contains oxalic acid, which binds calcium, making it unavailable to the system.
- Broccoli, Kale, Collards, and Mustard Greens: These vegetables (of the cabbage family) have valuable nutrients but depress the thyroid.*Be sure, however, to provide some shade. Being too hot is just as dangerous as being too cold.
Water and Hydration
It is important to limit access to water. Instead of providing a water bowl we recommend soaking the tortoise in shallow warm water for 15-30 minutes 1-2 times weekly. Alternatively, water can be provided by flooding a small area of the pen or soaking your tortoise for 15-30 minutes in shallow warm water several times a week. It's preferable to not have water available at all times for this species. Always provide fresh water available for drinking. they can access but not accidentally tip into and possibly drown.
Nutritional Supplementation
Desert tortoises housed indoors or young, rapidly growing tortoises should have their diet supplemented with a calcium carbonate powder such as ReptiCal 2-3 times weekly. As we cannot replicate their natural diet, we must supplement their food with calcium. This can be in the form of a calcium carbonate powder that can be sprinkled on moistened food daily.
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Feeding Captive Desert Tortoises
Indoor Housing
If housing must be indoors, an all glass vivaria can be used. To make sure the tortoise has enough room to exercise, the enclosure should be at least 2x3 feet for one small tortoise. Increase the enclosure size as the number and size of animals increases. Males should be housed separately as they can fight and possibly get flipped onto their back, which can be fatal if no one is around to right him.
- Enclosure Size: To make sure the tortoise has enough room to exercise, the enclosure should be at least 2x3 feet for one small tortoise. Increase the enclosure size as the number and size of animals increases.
- Substrate: For an indoor enclosure, the bottom should be covered with something safe and easy to clean. Newspaper or indoor/outdoor carpeting are easy to change/clean and inexpensive. If you want something more aesthetically pleasing or natural looking, grass hay can be laid down, which should be removed when wet or spoiled, or sterile potting soil can be used, which can be spot cleaned every few days and changed every 6 weeks.
- Temperature: If housed indoors, the daytime temperature of the enclosure should be between 70F and 90F. One corner should have a 100W heat lamp positioned for basking at 95F. This will provide a temperature gradient with one side being warmer than the other. Under tank heaters are useful to gently raise the overall temperature of the tank, but should be used with a thermostat or rheostat to accommodate changing ambient temperatures. At night the temperature should drop to 70F-75F. When room temperatures are below 70F, use an under tank heater or a ceramic heat emitter. Obviously, at least two thermometers must be in use to monitor these temperatures, but digital thermometers that can measure ambient temperature are now readily available.
- Lighting: When housed indoors desert tortoise should be provided artificial UVB lighting to allow for proper calcium absorption form their diet. This should be provided through a commercially available fluorescent or mercury vapor reptile bulb specifically designed for this purpose.
Outdoor Housing
We recommend desert tortoises be housed outdoors whenever possible.
- Enclosure Size: Each side of the enclosure should be at minimum 6 times the length of the tortoise to allow for plenty of room to browse and exercise. The height should be twice the length of the tortoise and should be at least one foot underground to prevent escape via burrowing.
- Security: The area should be predator proof with a screen or wire mesh overhead and be fenced off from any pools or ponds. Make sure there are no poisonous plants, chemical pesticides or fertilizers in the enclosure. Pens can be constructed with solid walls which the tortoises cannot see through. Tortoises will try in vain for hours to walk through fences if they can see through to the other side. The walls should extend below the ground surface a minimum of 6-12 inches to discourage tortoises from digging under the walls. The enclosure must also provide protection from predators and other family pets, such as dogs, which could harm the tortoise.
- Substrate: Outdoor enclosures can have a planted soil substrate with a dry surface.
- Shade: Desert tortoises housed outside must have an area where they can get shade as direct sun can kill a tortoise in an hour or less on a hot day.
Hibernation
In late October when the days become cooler, the tortoise will eat less, bask less, and appear sluggish. In captivity you're taking a chance allowing your animals to hibernate in the back yard. A combination of wet and cold will kill a digging or burrowing chelonian, even though our California winters are temperate by the nation's standards. A cardboard box deep enough that the tortoise cannot climb out lined with newspaper is fine for hibernation. This can be put in a cool, dry place kept between 39F and 50F. The tortoise should be checked on periodically; it will move when touched if sleeping. In the spring when the days are warmer, the tortoise will become active in its box. A warm soak should be given at this time. Do not hibernate your tortoise if you suspect it is at all ill or injured, as this will exacerbate its symptoms. Bring your tortoise indoors and keep it at a warm temperature (75F-85F) to keep it active.
Read also: Feeding Your Desert Tortoise