Depending on who you believe, red foot tortoises are either completely herbivorous (that is, vegetarian), or predominantly herbivorous but occasionally feasting on grubs, insects and other meats. Andy Highfield of the Tortoise Trust has argued quite convincingly that red foots should be given small amounts of animal-based protein (for instance, low-fat rehydrated cat food) once a week. His recent article in the Tortoise Trust Newsletter summarizes this point of view.
While a little bit of protein is thought to be beneficial, too much protein in a red foot's diet can cause shell deformation (pyramiding) and other debilitating conditions. Severe pyramiding can be seen in this picture taken by Darrell Senneke, Director of the World Chelonian Trust, of a red foot that was raised on a protein-rich diet of dog food (photo used by permission).
Every Friday evening, Basil gets about 3 grams of Medi Cal Weight Control cat food that has been rehydrated in water mixed with a pinch of Herptivite Multivitamins. For the rest of the week, Basil enjoys a wide variety of good greens, fruits and vegetables, mostly organic.
What do we mean by "good"? All tortoises require a diet with a positive calcium to phosphorous ratio. Too much phosphorous relative to calcium intake is believed to lead to shell deformities, bone problems and other serious metabolic difficulties. Therefore, we are careful to choose foods for Basil that have more calcium than phosphorous. We find nutritional information about various foods on the United States Department of Agriculture (USDA) Nutrient Database web page.
A high calcium to phosphorous ratio does not necessarily make a food totally appropriate. For instance, spinach contains high levels of oxalic acid, which "bind calcium into an insoluble compound that is of little use to the tortoise" (see Darrell Senneke, Nutrient Analysis of Replacement Tortoise Foods). It is therefore considered inadvisable to feed spinach or other high oxalic acid foods to tortoises. Melissa Kaplan has compiled a handy list of oxalate, calcium and phosphorus concentrations in a variety of common greens and vegetable. Although the list is oriented towards Iguana diets, the information is still relevant and useful for tutle caregivers.
Basil is fed a wide variety of organic greens and vegetables, including dandelion, romaine lettuce, collard, turnip and beet greens, portabello mushrooms, kale, watercress, celery, brocolli stems, and acorn squash (the last three chopped finely so that the pieces are smaller than Basil's head).
Why organic? We try to feed organic food to Basil, in the belief that pesticides, insecticides and fungicides would be harmful to her. We are fortunate to live in a large urban area where it is possible to buy organic produce.
You will often see in magazine articles or on Web sites that tortoises should only be fed fruit sparingly. Red foots, however, do not seem to fit this rule of thumb. The Tortoise Trust suggests that red foots in the wild can consume a diet in which fruit comprises "up to 70% of the total intake during the wet season and approximately 40% during the dry season," (see Highfield, Feeding Red-foot and Yellow-foot tortoises Geochelone carbonaria and G. denticulata). Basil enjoys pears, papayas, pineapple and stawberries (the latter only as a rare treat). We place a piece of cuttlefish bone in her tank to ensure that she gets sufficient calcium (we can often hear her crunching away on the cuttlefish). And once a week in the winter we add Herpcare Calcium and Vitamin D3 supplement to her food (in the summer we ensure that she gets outside for a daily dose of natural sunlight). Vitamin D3 is essential to the absorption of calcium in tortoises; however, being fat soluble, high doses of vitamin D3 can be toxic. It is important to consult a good book or your veterinarian for advice on how to use these or any other supplements.
Finally, plenty of fresh drinking water must be available at all times in order to keep the tortoise hydrated and digesting properly. However, red foots (as with all tortoises) cannot swim, so it is important that the water not be too deep or else your tortoise could drown.