Box Turtle Food Pyramid
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The pyramid is a guide to feed your box turtle. You do not have to follow the schedule exactly (see special considerations). It is based off of research on the macronutrient and calcium requirements of various types of reptiles outlined in the Merck Veterinary Manual as well as individual scientific studies about wild box turtles' diets. This pyramid is also based off of what experienced box turtle breeders have found to work for their animals.
The box turtle food pyramid is designed to be a user-friendly guide. The foods on the bottom are the most important, however all the food groups are necessary for a healthy box turtle. The key on the right side describes how many times to feed this food group per a week. When the pyramid level is broken in half, you can choose either food group. The larger the section, the more important it is. |
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Introduction: |
This guide is made to combat the incomplete knowledge of box turtle nutrition. It specifically refers to North American species of box turtle in the genus terrapene. Asian box turtle species can either be more herbivorous or carnivorous, depending on the species. Many new owners are confused about what to feed their pets while experienced owners are looking for the best diet possible.
There is no such thing as a complete guide to box turtle nutrition because there is no realistic way for the in-home keeper to formulate a total diet. It is conventional wisdom that variety is the key to combat an incomplete diet, but that isn’t always the case. For example, almost all the foods a box turtle is fed will be deficient in calcium and iodine. This is simply a product of commercial agriculture raising plants and insects so that they grow as cost effectively as possible. This guide will get you as close as possible to a complete diet without expensive scientific testing. The most important thing in any animal’s diet is feeding appropriate foods in appropriate ratios in order to get the correct balance of protein fat and carbohydrates. It will also help you understand other nutrients how to get them too. |
Key Food Groups:
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Insects:
Insects are the major source of box turtle nutrition. Klimstra and Newsome (1960) found that animal sourced foods made up about half the volume of the stomach contents of box turtles. Of this, about 20% was true insects and 10% was snails and slugs. This indicates the strong importance of these food sources. Additionally, Platt et al. (2009) also found snails and slugs to be a major component of the box turtle diet. However, snails may not be practical to feed in a captive setting. All nutrients that snails provide can be provided through other food sources in a captive diet. Earthworms are a good choice to replace snails but other insects can be used as well. Most commercially raised insects are deficient in several nutrients, including calcium, thiamin (vitamin B1), vitamin A and vitamin E. Since box turtles get a large amount of their nutrients from the plant portion of their diet it is less essential to dust or gut load insects than with a reptile that exclusively eats insects. However, it is a good idea to feed the insects a high calcium and vitamin A diet before feeding to your box turtle and/or to dust them with a calcium and vitamin supplement. The insects fed should also be low in fat content. Ideal insects include snails, slugs, beetles, crickets, roaches, hornworms, earthworms and soldier fly larva (reptiworms). Insects that should be fed more sparingly due to their fat content and lower nutritional value include mealworms , superworms and waxworms. Check out the nutritional analysis of some common feeder insects. Vegetables: This is the part of a box turtle’s diet that will bring in a diversity of nutrients and a ton of beta-carotene. Klimstra and Newsome (1960) found that about half the stomach content of wild box turtles consists of plant material. This should be replicated in captivity by feeding plenty of vegetables. Good vegetables are often bright in color and not too high in oxalates and phosphorus. Sometimes the healthiest foods are also the strangest, such as prickly pear leafs and hibiscus flowers. Some of the best vegetables include acorn squash, butternut squash, bell peppers, prickly pear leafs, hibiscus, common button mushroom, okra, and pumpkin. Other good vegetables include asparagus, broccoli, brussel sprouts, carrot, green beans, snap peas, tomato, yellow squash and cucumber. Check out the nutritional analysis of vegetables. Fruit: Fruit is a less essential part of the box turtle diet. Although they eat quite a bit of fruit in the wild (Platt et al. 2009), almost all fruit you can buy in the store is heavily domesticated and has little relation to the nutritional content of its wild relatives. Fruit should be used as a flavor enhancer more than a nutritional component of the food, but is great to feed in moderation. It is important to remember that box turtles are highly adaptable omnivores. They have adapted to eating many different kinds of foods by changing the transit time of their digestive system (Stone and Moll 2006). It is also important to remember that in the wild box turtles change their diet seasonally and have long periods where they do not eat fruit (Platt et al. 2009, Klimstra and Newsome 1960). Cutting out domesticated fruit that is extremely high in sugar and low in nutrients is more helpful than including fruit because it is "natural." Some healthy fruits include berries, cantelope, dates, figs, guava, kiwi, mango, oranges, papaya and pineapple. Greens: Greens are a powerful source of nutrition for box turtles and should not be skipped over. Wild box turtles eat leafy vegetation, but it is not a large portion of their diet (Platt et al. 2009) Greens generally can be divided into four categories, staple, occasional rare and never foods. To make a green a staple green it must be rich in nutrients like calcium, low in phosphorus and low in anti-nutrients like oxalates and goitrogens. Occasional greens are rich in nutrients, but contain too high a level of oxalates or goitrogens to be feed every day. Rare greens have very high oxalates and goitrogens. They should be avoided. Never greens have high phosphorus, low calcium and sometimes have high oxalates. Staple greens are escarole, endive, alfalfa and dandelion greens. Occasional greens are bok choy, collard greens, mustard greens, turnip greens, watercress Rare greens are kale, dark lettuces, parsley, swiss chard, spinach Never greens are iceburg lettuce, cabbage Vitamin/Mineral Supplement: Liberally sprinkle a vitamin supplement on the box turtle's food. A vitamin and mineral supplement is essential when feeding a home made diet to ensure no nutrients are missing, however there is quite a variety of supplements on the market. When looking for a supplement to a healthy box turtle diet, as outlined here, there are a few key nutrients one should consider. Most greens, fruits and vegetables are low in magnesium, iron and iodine. Make sure your supplement provides these nutrients as well as ample amounts of B vitamins. Often iodide is provided using kelp as an ingredient. Additionally, vitamin A should be provided in a retinol form because it is not know if these animals can synthesize vitamin A retinol from beta-carotene. Calcium Supplement: Gut load all insects with calcium and liberally dust on other foods. A calcium supplement should be purchased separately from a vitamin and mineral supplement. This is because calcium needs to be supplemented in a much higher level than any other mineral. Most foods for box turtles are deficient in calcium and calcium is required more than any other mineral in reptiles. Also be sure that you have proper UVB lighting or access to direct sunlight (not through a window). Without UVB, box turtles cannot have enough vitamin D in their system to process the calcium they are eating. Supplementing calcium is useless without UVB lights as dietary vitamin D is not absorbed by most reptiles. Sources: Klimstra, W. D. and Frances Newsome. Some Observations on the Food Coactions of the Common Box Turtle, Terrapene C. Carolina. Ecology. 41(4) 639-647 (1960). Platt, Steven G., Clint Hall, Hong Liu, Christopher K. Borg. Wet-season Food Habits and Intersexual Dietary Overlap of Florida Box Turtles (Terrapene Carolina Bauri) on National Key Deer Wildlife Refuge, Florida. Southeastern Naturalist. 8(2):335-346 (2009). Stone, Matt D. and Don Moll. Diet-Dependent Differences in Digestive Efficiency in Two Sympatric Species of Box Turtles, Terrapene carolina and Terrapene ornata. Journal of Herpetology. 40(3):364-371 (2006). |
Special Considerations:
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These dietary guidelines are designed for an average, healthy, box turtle. As with anything, if your reptiles are ill you need to consult a veterinarian for advice. That being said, there are some normal dietary considerations that apply to many box turtles. If your box turtle is sick, please check out our diagnostics page.
Brumation: Similar to hibernation, many reptiles go through a dormant cycle in the wintertime. Assuming your husbandry is correct, this is perfectly normal. Their appetites will decrease so they many not need to be fed as much or as often. The most important thing is to ensure that they remain hydrated during this time. Obesity: Many captive animals of all kinds suffer from obesity. The best thing you can do for an obese box turtle is feed only lean insect species and cut fruit out of the diet. Obesity is deadly. It can cause liver failure and many other issues. Supplementing with a very small amount of omega 3 fish oil is also wise to prevent liver disease in obese animals. Juveniles and Breeding Females: Young box turtles are growing fast and need more protein and calcium than older box turtles. It is also likely that very young box turtles will only eat live insects. Fatty insects are also a good source of energy for young animals. Make sure all insects fed are gut loaded with calcium. This also applies to females developing eggs, known as gravid females. Anorexia: Not eating is a common occurrence with many pet reptiles. Usually the issue is with the temperature of the enclosure, or another husbandry problem. Ensure that your tank is up to standards and visit a veterinarian. In the mean time, remember that eating any food is better than eating no food. Even if all your box turtle will eat is iceberg lettuce, this is better than not eating anything at all. Work on getting them to eat healthy foods, but again, unhealthy food is better than no food. For tips and tricks to get your animal to eat see our "appetite stimulation" page. |
Key Nutrients:
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There are many key nutrients in a box turtle’s diet. Calcium is a particularly important nutrient that many beginner keepers do not offer enough of. It is imperative to supplement your box turtle with calcium and provide proper UVB lighting.
The key nutrients are listed in alphabetical order. Anthocyanin Definition-natural plant flavonoid pigments that appear blue or purple Function-a weak antioxidant that enhances color Foods-acai, eggplant, blood orange, blackberry, raspberry, blueberry, purple grapes Beta-carotene Definition-a red-orange pigment in plants that can be converted by some animals to vitamin A Function-A vitamin A supplement for omnivores and herbivores that cannot be overdosed as well as an antioxidant that enhances color Foods-carrot, pumpkin, sweet potato, spinach Calcium Definition-an abundant chemical element that essential for life Function-building blocks for bones and teeth and an essential element for cell physiology Foods-calcium carbonate supplement, prickly pear leafs, collard greens, oranges, soldier fly larva, mustard greens, bell peppers Carbohydrates Definition-a biological molecule made of chemically linked sugars. Carbohydrates include, sugars, starch and fiber. Function-simple energy source for animals Foods-almost all foods, especially plants Copper Definition-a chemical element that is an essential mineral Function-Copper has many functions, including collagen formation, enzyme cofactors, incorporating iron into red blood cells and generation of energy from carbohydrates. It is usually abundant in foods for box turtle and inhibits zinc uptake, so copper intake needs to be limited. Foods-spinach, turnip greens. asparagus, beans, nuts, kale, mushroom, pumpkin Fats (lipids) Definition-a biological molecule that is found in plants and animals Function- a dense energy source and an energy storage method Foods-waxworms, superworms, mealworms, nuts, seeds Fiber - Click Here for More Information Definition-a type of complex carbohydrate in plants that cannot be digested Function-Fibers add bulk to the stool and are digested by gut bacteria in box turtle into essential fatty acids. Foods- all vegetables and fruit Goitrogens Definition-substances that disrupt the production of thyroid hormones Function-These anti-nutrients should be avoided in excess in order to maintain thyroid health of box turtles. They are less harmful when proper iodine supplementation is provided. Foods-cassava, soy, peanuts, strawberries, spinach, bok choy, broccoli, cabbage, kale, turnip Iodine Definition-a chemical element abundant in the ocean that is an essential mineral Function-key component of hormones made by the thyroid Foods-kelp, ocean fish, shrimp, spirulina, scallops, standard table salt Macronutrient Definition- A category of nutrients that makes up the bulk of foods. It includes protein, fat(lipids), carbohydrates and water. Function-each macronutrient has a different function, but protein, fat(lipids) and carbohydrates can all provide energy. The ratios of these nutrients in a diet is extremely important. Foods-all foods Minerals (dietary) Definition-a chemical element that is required by living organisms other than carbon, hydrogen, nitrogen and oxygen Function-builds bones, tissue, catalyzes biological reactions, transports oxygen and many more Foods-all foods have some mineral content Oxalates Definition-a specific organic acid found in plants and animals Function-binds with calcium to form kidney stones and prevents calcium from being used in the body Foods-soy, nuts, beans, spinach, swiss chard, beets, collard greens, okra, blueberries, grapes, raspberries Phytonutrients Definition-chemicals naturally produced by plants that are not of conventional nutritional value Function-functions vary but they are usually antioxidants, anti-inflammatory and promote liver health Foods-plants, especially ones rich in color Protein - Click Here for More Information Definition-a biological molecule made of chemically linked amino acids Function-maintains the structure of the body and excess can be used as an energy source Foods-all foods have some protein, with insects being especially high as well as a decent amount of protein in nuts, seeds and greens Phosphorus Definition- an abundant chemical element that essential for life Function-enables cell function and builds bones, but is easily consumed in excess in a box turtle diet. Excess consumption impairs calcium absorption and can cause muscle disorders. Foods-asparagus, beans, soy, seeds, cricket, mealworms, mushroom Vitamins Definition-A vital organic compound that an organism cannot synthesize on its own. They can be divided into fat soluble and water soluble. Function-each vitamin has its own function in the body Foods-all foods Vitamin A Definition-a group of related fat-soluble nutrients (carotenoids and retinoids) that are essential for the body. Function- Carotenoids come from plants and cannot be overdosed, so they are the safest form of vitamin A, however it is not known if box turtles can convert carotenoids to retinoids. Vitamin A is needed for immune responses, night vision and many other functions in the body. Foods-egg yolk, turkey liver Vitamin D Definition-a fat soluble vitamin derived from UVB light or dietary sources Function- needed to absorb calcium and other minerals from food Foods-UVB lighting should be provided for box turtles so that they can synthesize vitamin D, numerous studies have indicated that dietary supplementation is not an effective source of vitamin D in diurnal reptiles. Vitamin E Definition-a fat soluble vitamin that acts as a powerful antioxidant Function-protects against free radical damage, ageing and heart disease. It is especially crucial in a high fat diet. Most foods high in vitamin E are also high in fat, so a balance is difficult to achieve. Foods-sunflower seeds, greens. almonds, broccoli |
Science Behind the Pyramid:
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The proportions of the pyramid are based on macronutrient balancing. According to the Merck Veterinary Manual, omnivorous reptiles need a diet of 20-25% protein, 3-6% fat and 20-35% fiber on a dry matter basis. To achieve these macronutrient ratios the pyramid recommends how often to feed a portion of insects, greens, fruits or vegetables. There is a total of 18 portions of these food groups fed each week.
7 insect portions/17 total portions=41.2% insects 4 vegetable portions/17 total portions=23.5% vegetables 2 fruit portion/17 total portions=11.8% fruit 4 green portions/17 total portions=23.5% greens The most important macronutrient is protein. The diet aims to achieve a 20-25% dry matter protein content. Greens, vegetables, fruit and insects are typically 20%, 10%, 5% and 50% protein, respectively. Multiplying the % of protein by the proportion of portions gives us: .235x20% + .235x10% + .118x5% + .412x50%= 28.24% protein This protein content is slightly high, but considering the composition of the stomach contents of box turtles, it is highly likely that they have a natural protein consumption that is higher than the average reptilian omnivore. Therefor this food pyramid provides an adequate amount of protein. Using this same method fat and fiber can also be calculated. Greens, vegetables, fruit and insects are typically 2%, 2%, 2% and 18% fat, respectively. They are typically 25%, 25%,15% and 10% fiber, respectively. .235x2% + .235x2% + .118x2% + .412x18%= 8.6% fat (goal 3%-6%) .235x25% + .235x25% + .118x15% + .412x10%= 29.2% fiber (goal 20%-35%) |