HEALTH CARE FOR TORTOISES

Health Care for the Desert Tortoise

General Information
Diet
Cold Weather Care
Warm Weather Care
Releasing Captive Tortoises
Reproduction
Diet at ASDM

General Information

The desert tortoise (Xerobates Agassizi Cooper) is a dry land turtle. It has tough skin, the legs are heavily scaled and the feet are tough and "elephant-like," rather webbed. Unlike other turtles, it does not swim. Its upper and lower shell (carapace and plastron) are light to medium brown and are fused (not hinged) at the sides. The carapace is made up of a series of plates of scales (tortoises are reptiles).

As the tortoise grows, new scales are produced beneath the old ones, causing them to "stack up" over a period of time, forming the tortoise's hard shell. Over the years, the outer scales are worn down, keeping the process in balance. An average adult tortoise may measure 5-6 lbs.; however, there is considerable variation in size.

Diet

The desert tortoise is herbivorous, feeding mostly on native grasses and leafy plants. In captivity they do well on a diet of grass or grass cuttings, and other garden plants, flowers and shrubs, greens (collard, kale, mustard, turnip) and carrots (see food value chart). Lettuce is not sufficiently nutritious and must be avoided. Cactus fruits and vegetables must be fed in small amounts (10-15% of meal) at most once a week.

Native grasses and other edible plants, Bermuda grass or alfalfa, must be offered daily. Greens and carrots must be clean and fresh and chopped, grated or scraped into small enough pieces for the tortoise to eat. The food must be served in a dish or on a feeding platform within the tortoise's reach to prevent the tortoise from ingesting gravel or sand with his food and getting impacted intestines. A shallow puddle of water inside the tortoise enclosure must be provided once a week during the months of activity.

Cold Weather Care

In Arizona, tortoises must be kept outdoors year round if at all feasible. As the weather turns cool in the fall, the tortoise will prepare to hibernate. Its appetite will decrease and it will gradually become less active. If it has eaten well during the summer months, it will have a fat reserve built up and must easily survive through the winter's hibernation. A den can be constructed above ground using concrete blocks, 3/4" plywood and an ample amount of fill dirt to completely bury it for insulation.

The den must have a southern exposure. A heavy, weatherproof tarp over the opening is recommended. If space does not permit this, the tortoise may be placed in a dark, well-insulated box buried with a thick layer of dry soil or leaves. A styrofoam ice chest works well for this purpose. This "burrow" must be protected from rain or leakage.

An alternative to the aforementioned method is to store the tortoise in a cool, dry place such as a garage or storeroom. A high-sided box (again the styrofoam ice chest works well) packed with dirt, straw, or leaves and covered with several layers of blankets or newspapers is recommended. The box must be kept up off the cement floor and away from drafts and rodents.

Remember, if the room is too warm the tortoise will not be able to hibernate. The temperature must remain between 10-14 C (50-55 degrees Fahrenheit). Dehydration is a potential problem during hibernation. Juveniles must be offered water every 4 weeks during this period, adults, every eight weeks. The tortoise must be quietly checked every 10-14 days to see that no health problems are developing. Otherwise, do not expose the tortoise to light or other disturbance.

If the tortoise cannot hibernate for some reason, e.g. health problems, underweight, the following recommendations are made for indoor care:

INDOOR CARE:

The tortoise must be kept in a terrarium or other suitable container with proper ventilation. The terrarium must maintain a constant daytime temperature of between 27-30 C (80-85 degrees Fahrenheit). This can be simply achieved by placing a light above the terrarium and mounting a wall thermometer inside. Different wattage may be tried until the desire temperature is achieved.

Always be certain your tortoise has fresh food and water daily. Daily sunlight is important, but shade must always be available. Maintain normal daily photoperiods--leaving the light on at night may result in hyperthyroidism, a glandular disorder.

Tortoises exhibiting obvious signs of illness or injury or those suspected of being ill must not be allowed to hibernate. During hibernation, the body temperature of tortoises decreases and their immune system becomes less capable of protecting the animal against disease. As a general rule, captive hatchlings must not be allowed to hibernate for their first one to two years of life.

Hibernation is not a necessary physiologic stage through which captive tortoises must pass each year. Hibernation is an adaptation of wild animals which allows them to avoid having to cope with adverse climatic conditions. Captive tortoises that are kept warm all winter will usually not hibernate completely. They can exhibit lethargy and refuse to eat on their own.

Warm Weather Care

As the weather warms up, tortoises become more active. At this time, allow a long drink or a soak in very shallow water. It will gradually (within a few weeks) begin to resume its warm weather routine of eating, basking and exercise. Normally, tortoises in southern Arizona must be fully active by early April.

Make certain the outdoor enclosure is well-fenced. Tortoises can travel as much as seven miles in a day and can easily escape. In warm weather a tortoise may dig a shallow burrow in the soil. This provides the tortoise some shelter from the summer sun. The tortoise may also sleep here at night. Provide water to captive tortoises once a week by turning the hose on the yard, allowing a puddle to form.

Releasing Captive Tortoises

Under no circumstances should a captive tortoise be released into the wild. Recent studies have demonstrated a 100% mortality of such tortoises.

Captive tortoises do not adapt well to the rigors of life in the wild and to feeding on the native plants and other vegetation.

Desert tortoises are territorial and may fight to the death when introduced into an established tortoise's range.

Captive tortoises may introduce diseases of captivity into the wild tortoise population for which wild tortoises have little or no immunity.

Reproduction

The subject of reproduction becomes an important one to keepers of healthy adult tortoises. With care, tortoises are easily bred and eggs incubated successfully in captivity. However, there are a number of factors to consider.

Sex Differentiation

First determine the sex of your adult tortoise. To do this, check the plastron (lower shell). If the hind portion is concave, it is a mature male. This concavity enables the male to fit the carapace (upper shell) of the female during mating. If the plastron is flat, the tortoise is a female.

NOTE: Immature tortoises of either sex will have a flat plastron. Therefore, age--best determined by size in the absence of an actual life history--is of considerable importance in determining sex.

The Reproductive Process in the Wild

The male tortoise begins to show interest in the female sometime in the early spring. He nods his head at her and eventually begins his attempts at mounting her, regardless of whether or not she appears receptive. Although she frequently ignores him, he will persist until she becomes receptive. Actual mating may only take a very short time or may continue for several hours. Both male and female may mate several times (with several mates) during one season. Eggs are laid in May or June and again in August or September.

The female is capable of laying fertile eggs for several seasons (up to four years) from only one mating. The number of fertile eggs per clutch will diminish with time. To lay her eggs, usually numbering between three and seven, the female digs a hole in the soil. After depositing the eggs, she covers them over with soil. From this time on she provides no care for the offspring but may remain by her nest for a period of time. In approximately 80 to 120 days the babies begin to crack the eggshell with an eggtooth--a temporary protrusion on the upper jaw which is lost soon after hatching. Alternating between periods of activity and rest, the baby eventually emerges from the egg and independently digs its way to the surface. At this point, the hatchling measures about the size of a silver dollar and its shell is still quite soft. If there is egg yolk attached to the baby's shell do not remove it but keep it clean and allow the baby to absorb the nutrients.

Captive Breeding and Incubation

If eggs are laid in an out door enclosure, the keeper may be unaware of their presence until they hatch. In most cases, it is best to leave the eggs in the nest to hatch. However, if their location is at risk and the keeper wants to attempt to incubate and hatch the eggs, the following procedure is recommended:

Before removing the eggs from their "nest" mark the top of each with a graphite pencil, being careful not to turn or move them. Carefully remove each egg from the nest and place it in the incubator in the exact position in which it was originally laid. Even the slightest rotation of the egg can prevent successful hatching by damaging sensitive membranes.

Choice of an incubator can be fairly simple. A commercial poultry incubator may be used--or you may construct your own from a styrofoam box. You will need a light for heat, a layer of slightly moist sand in the bottom of the box and a thermometer mounted on the side. Temperature is the most important factor for successful incubation of tortoise eggs. It must remain between 32-35C (85-90 degrees Fahrenheit). The light wattage required to maintain this temperature will vary according to the type of incubator used, thus some experimentation will be required. You may occasionally sprinkle the said (not the eggs) with a little water for humidity. Do not over water or the eggs will mold.

Care of the Hatchlings

Do not remove hatching tortoises from the eggshell--allow them to absorb the yolk (this takes two to four days). Some or all of the hatchlings may emerge with the yolk sac still attached to the plastron. This is the only food source they need until it is fully absorbed; therefore, it is vital to the development of the hatchlings and must not be disturbed. You can place the hatchling with the yolk sac on clean wax paper to keep it from sticking.

Once the sac is absorbed, the hatchlings may be placed in a shoe box or similar container. It must be clean and offer protection from insects. They may easily be tipped over onto their backs at this stage, so a low ceiling is recommended to prevent them from climbing. One hatchling per box is best to help prevent tipping over.

They should have a small water dish, both for drinking and for soaking. The hatchling's shell is relatively soft but will harden with proper diet. Its diet is basically the same as that of mature tortoises, taking care that the food is finely chopped or grated, and free of sand. Babies eat often, so fresh food must be offered several times a day. The diet staple must be clover, freshly cut grasses, globemallow, heronbill leaves, other native plants. Collard, kale, mustard, turnip greens, sprouting grasses, and grated carrots may be substituted on occasion. Do not leave stale food in their enclosure because they will not eat it and it is an invitation to insects.

Desert tortoises need certain beneficial bacteria in their intestinal tracts to aid in the breakdown and digestion of plant material. One source of this bacteria is feces from adult tortoises. Fresh droppings from healthy adult tortoises may be broken in the diet from time t time. It is also good idea to allow juvenile tortoises to spend time outdoors on a soil surface where they may ingest small amounts of soil containing these bacteria.

The physical environment for hatchlings must consist of a coarse gravel substrate (never sand or fine gravel). The daytime temperature must range between 27-32 C (80-85 degrees Fahrenheit) with a modes temperature drop at night to above 25 C (upper 70's Fahrenheit). A normal day or night light cycle must be maintained. They will require access to natural sunlight (not filtered through glass) or artificial full-spectrum light if they are kept indoors. It is essential to provide the hatchling with daily sunlight. This sunlight is necessary for healthy growth and proper hardening of the shell. Make certain there is also available shade for its protection, as they may dehydrate or overheat without shelter. The hatchling will also require shelter to sleep at night. They will often group together for this.

Tortoise Diets at ASDM

Provide the components as indicated on the following schedules:

Summer Schedule - Mid-March to early November (flexible according to season):

Diet A: six days weekly Edible native plants, grasses, fresh alfalfa hay including leafy material, trace mineral block shavings, grated carrot ad lib.
Diet B: one day weekly Shredded collard, kale, mustard or turnip greens mixed with grated carrot, fresh alfalfa leafy material.

Winter Schedule - Mid-November to mid-March (flexible according to season):

Ad lib - grasses or alfalfa hay only.

Hatchling Tortoise Feeding and Management

Summer diet schedule according to consumption, feed daily. Bermuda grass or native grasses are preferred over alfalfa for hatchling development.
Maintain on coarse gravel substrate.
Provide petri dish with soil for seeding intestinal flora. NO SAND! Fresh droppings from healthy adult tortoises can also serve this purpose.

This health care information for desert tortoises was compiled by Marilyn Lieb, D.V.M., from material gathered at the Arizona-Sonora Desert Museum in Tucson, Arizona, and permission to quote or reproduce details from it is granted when due acknowledgement is made.