The subject of tortoise diet is extremely popular but it's rarely taken seriously in herpetoculture, especially in the United States. Mediterranean tortoises are no exception.
The diet of Hermann's, Greek, marginated, Russian and Egyptian tortoises (Testudo species) must be made up of 3 major components: low protein, high fiber and high calcium. Perhaps appropriate ratios for food items should be somewhere in the range of 15-20% (max) protein, less than 15% fat and above 15% in raw fibers with a calcium to phosphorus ratio of 2:1. Most foods in nature contain a much higher ratio with some exceeding a ratio of 20:1 and tortoises kept outdoors can safely consume foods with higher ratios on a more regular basis. This does not mean that these tortoises won’t willingly accept items that are made up of less than desirable ratios and in actuality, their willingness to eat such foods is why many of them end up deformed, grown improperly or suffer from liver diseases under captive conditions. Like humans, the food items that Testudo specimens are started on upon entering the world can imprint on them. If inappropriate foods are what is first offered, the animals may become stuck on them leading to a reluctance in accepting healthy choices later on. For this reason it is imperative to start neonates on a healthy, at least somewhat natural diet from the start. In captivity, we as keepers tend to load our tortoises up with supermarket produce or commercial feeds and this is often attributed to the lack of available natural food items in winter.
The truth is that these unnatural foods are not awful for the animals, but they must be used in moderation and only as part of a varied diet. Commonly used produce such as lettuces, tomato, squash, cucumber, sweet potato and various fruits have minimal benefits but when used excessively they can cause a fat build up, particularly in the liver and even under the skin. If fruit and vegetables are to be offered, spread them out and aim to use them no more than once weekly, if that. We prefer to stay away from fruits almost entirely with the exception of only occasionally offering watermelon rinds in the peak of summer for added hydration. Various berries like blackberry or blueberries are only sometimes provided as well. The animals may receive these items only a handful of times throughout the active season.
In the wild, Testudo graze on edibles that are low in nutritional value. These plants, which grow in soils that are calcium-packed, are loaded with vitamins, raw fiber and minerals, while being low in calories. The availability and level of growth changes seasonally and so this means the tortoises’ intakes also change. The animals typically graze or browse in the morning after warming up and again later in the day once the peak in heat has subsided some. They usually do not eat a plant in its entirety but instead move from item to item taking bites as they go. This enables them to consume a wide variety of plant life. They will eat what they are familiar with and as already stated, this was imprinted on them at a very young age. Leaves and flowers of appropriate plants, shoots, seeds and even roots are eaten. Select plants and weeds that grow naturally even in the USA are excellent staple food items for Mediterranean tortoises. These include but are not limited to pointed and Mediterranean plantain, sow thistle, mallow, dandelion, catsear (also known as flatweed), thorn lettuce, vetches, red clover and purple dead nettle. We are able to pick these foods for our tortoises throughout a good portion of the year with some still being available in the heart of winter in southern New Jersey. They also grow naturally in the tortoise pens, in which case the inhabitants can help themselves by grazing like they would in nature.
Various store-bought greens like curly endive, collard greens, turnip greens, chicory and escarole can be added to the diet of any Testudo but be sure to rotate them. In combination with a more naturalistic diet, they help keep things varied. The fact that tortoises are opportunistic feeders but primarily herbivorous, means they will openly accept a variety. This suggests they will even consume invertebrates. Like other tortoises, some Testudo specimens will eat earthworms, slugs and garden snails. These random prey choices do not cause the animals any harm because they are not the staple diet. In addition to this, the consumption of snails offers calcium through the ingestion of the snail’s shell which is of course a benefit. When living outdoors in naturally constructed pens, the tortoises will inevitably come across such prey and may or may not choose to eat them. Although Testudo species may eat invertebrates and even carrion in some cases, it is absolutely not advisable to offer them high-protein items such as dog or cat foods. While this may be acceptable to some degree for other species of tortoise such as red foot tortoises (Chelonoidis carbonaria), Mediterranean tortoises do not require protein-rich feed with regards to staying in optimal health.
The use of prepared commercial diets specially made for tortoises has reached an all time high in recent years. While some of these brands or formulas are not acceptable mainly due to a protein content that is much too high, others can safely be used in moderation. Mazuri tortoise diets are popular products in the United States. While the 5M21 original formula is a bit higher in protein than the LS form, it has proven to yield healthy animals if not used in excess. Many Testudo will refuse the LS formula but will eagerly accept the 5M21 formula. It’s important to remember that these commercial pellet feeds are not a natural food source for these creatures but they can be beneficial when used correctly. We use 5M21 once to twice weekly during the active season. It’s soaked in water until it becomes spongy and offered on terra cotta plates. Other products can be mixed in with Mazuri diets such as Zoo Med’s grassland tortoise diet (which is another product that many tortoises will ignore unless disguised with something else) or dried herbs.
Kapidolo Farms offers a variety of dried products that are excellent choices to add to the diet of any Testudo species. These items can also help coax a reluctant feeder into accepting food. Some imported tortoise specimens may only accept what they were familiar with during their time in nature. These animals are sometimes problematic when it comes to getting them onto a sufficient diet. Usually underweight and otherwise compromised from a long trip and less-than-desirable shipping conditions, it’s imperative to get them feeding well as quickly as possible. Offering more natural choices may spark a familiarity trigger and the tortoise might start to eat. Dried herbs and other items from Kapidolo Farms such as rose hips, dandelion, plantain loose leaf, mulberry leaves, hibiscus flowers, cactus chips, raspberry loose leaf, oat straw looseleaf and red clover loose leaf are just some good choices one can order. Visit kapidolofarms.com
For calcium intake, a common practice is to heavily sprinkle commercially made calcium powders directly onto the food. These products, often containing vitamin D3, can actually cause harm if overused or even when used if a tortoise is already suffering from a calcium deficiency. The practice of forcing vitamin D3 into our animals can have adverse effects and may even lead to death as the internal system becomes “confused”. Forcing calcium on tortoises can also lead to calcium deposits in the form of build ups as the blood looks to relieve itself of it by storing it in organs. This is yet another reason why an appropriate, varied diet is so crucial. Calcium powders may be safely used in moderation but letting the tortoises choose when to consume it seems to be the better option. In nature, they will eat discarded snail shells, bones, limestone rock pieces and egg shell pieces.
The shell or calcified skeleton of the cuttlefish, known as “cuttle-bone” is most commonly associated with being used for captive birds. This is actually an excellent and preferred source of calcium for tortoises. Cuttlebone can be purchased in bulk and randomly placed throughout a tortoise enclosure. The animals will nibble them when they feel the need. Even hatchlings will utilize them. Breaking off small pieces can be done for younger specimens while adults can easy manipulate a whole piece. You can also boil the shells of chicken eggs or collect empty shells of garden snails. These are more natural choices for calcium intake. If you are to use calcium powder, I have found that sprinkling it once monthly on food is enough, if you are offering a proper diet and the animals are exposed to natural sunlight for part of the year. Ready-made calcium blocks designed for reptiles are something I’ve chosen to stay away from. They are sometimes jam-packed with a content of minerals and vitamins that are unnecessary for Testudo species to consume regularly. Cuttlebone is without a doubt a reliable and safe source of calcium for the tortoises and if you find that your animals are not nibbling at it, you can occasionally shave some off by scraping a knife on it. It will make a fine powder that sticks to the food.
To conclude the dietary section of this article, I will emphasize a very interesting point. No matter what we do under captive conditions, we will never be able to completely replicate the natural diet of tortoises. This is particularly important to understand if you reside in the United States. We as responsible keepers must do our best to offer as close to a natural diet as we possibly can, but we also need to understand that the inevitable gaps we find in a captive diet have to be filled with something. These gaps, which are not an issue in nature, may deprive the animals of some necessary dietary components and so, variety is absolutely key. Moderation is a crucial term to take into account and when practiced, it can make some food items beneficial that typically would not be if used alone. Keep in mind that tortoises are opportunistic feeders with a survival instinct that has been imbedded in them since the time of the dinosaur. They eat to be able to stay alive and they know what they need to make that happen. By offering them a wide variety, we can be more assured that they are getting a better chance at consuming all the specifics required for a long and healthy life.