Marginated tortoise

Marginated tortoise（圖片來源：Bouke ten Cate，採用 CC BY 4.0 授權）

The marginated tortoise (Testudo marginata) is the largest tortoise species native to Europe, distributed mainly in Greece, Italy, and surrounding regions. Its carapace is elongated and oval, with the posterior marginal scutes expanding outward into a skirt-like shape, which gives the species its common name. Adult individuals can exceed 35 cm in body length and approach 5 kilograms in weight. Their lifespan is exceptionally long; many individuals live for more than a century, and some researchers have suggested that in the wild they may survive for up to 140 years. The shell is typically dark black with bright yellow markings. Under the Mediterranean sun, this coloration is highly conspicuous and also allows the tortoise to absorb heat efficiently, helping maintain body temperature. This characteristic is particularly beneficial for populations living in mountainous or high-elevation habitats.

In the wild, marginated tortoises inhabit Mediterranean-type environments, including rocky slopes, shrublands, and mountainous terrain up to elevations of about 1,600 meters. They typically begin their day by basking in the early morning to raise their body temperature, then move out to forage. During the hottest hours of the afternoon they retreat into rock crevices or beneath shrubs, becoming active again in the evening. This diurnal rhythm closely follows the climatic patterns of their native environment. During winter, marginated tortoises enter brumation, a state similar to hibernation in mammals, although the period of complete inactivity is usually shorter. This seasonal dormancy is an adaptation to the cool and dry winters of the Mediterranean region.

Marginated tortoises are herbivorous animals that primarily feed on wild grasses, tender leaves of shrubs, and wildflowers, occasionally consuming small amounts of vegetables or fruits. Hatchlings grow rapidly during their first several years of life, gaining several hundred grams of weight annually. Growth gradually slows after about twenty years of age. Their temperament is generally gentle. Although males may compete with each other in the wild, they are not considered aggressive animals overall. Because of their calm behavior, they have become popular in the pet trade. However, their extremely long lifespan means that anyone considering keeping one as a pet must carefully evaluate their long-term commitment. In many cases, care may eventually need to be passed on to the next generation.

Marginated tortoise（圖片來源：Konstantinos Kalaentzis，採用 CC BY-SA 4.0 授權）

Housing Requirements in Captivity

Under captive conditions, marginated tortoises require an environment that mimics the Mediterranean climate. Juveniles can be housed in plastic tubs or wooden reptile enclosures measuring approximately 90 × 60 cm, which allows easier control of humidity and temperature. As the tortoise grows, progressively larger enclosures are necessary. Adults require at least 2.4 × 1.2 meters of space. If keeping a pair or a small group, outdoor housing is generally more suitable.

For indoor housing, the substrate can be made from a mixture of soil, coconut fiber, and bark, with a depth of at least 10 cm so the tortoise can dig naturally. Outdoor enclosures should be built on well-drained ground, often with a mixture of soil and gravel to prevent excessive moisture that could lead to respiratory illness.

During the daytime, a localized basking area should be provided with temperatures around 35°C. The surrounding area should remain between 26 and 29°C, creating a temperature gradient that allows the tortoise to choose its preferred resting location. At night, temperatures can drop to around 21°C to replicate the natural day–night cycle.

Proper lighting is essential. Ultraviolet (UVB) lighting must be provided to allow the tortoise to synthesize vitamin D3, which supports calcium metabolism and healthy bone development. When kept outdoors under natural sunlight this requirement is usually met automatically. However, in Taiwan or other regions outside the species' native range, climate differences and seasonal adjustments must still be carefully considered.

Humidity should generally be maintained between 60% and 70%. This is especially important for juvenile tortoises, as excessively dry conditions may lead to shell deformities known as pyramiding. It is recommended to include a humid hide within the enclosure using moist moss or damp soil, allowing the tortoise to regulate its own humidity exposure.

Water should be provided in a shallow dish that does not exceed the height of the tortoise's shell to prevent drowning. Juveniles may also benefit from soaking in shallow water three to four times per week to promote hydration and proper digestion. Environmental enrichment such as rocks, logs, branches, and shrubs can provide hiding places that simulate natural habitat conditions and help reduce stress.

Feeding Conditions

The diet of marginated tortoises should be high in fiber and low in both protein and sugar. Caretakers should attempt to provide foods similar to those available in the wild. Suitable plants include dandelion leaves, clover, plantain, thistles, alfalfa, mulberry leaves, and various pesticide-free wild grasses.

In household settings where wild plants are difficult to obtain, leafy vegetables such as kale, mustard greens, arugula, chicory, and endive may serve as alternatives. However, a single vegetable should never be fed exclusively over long periods. Dietary variety is essential, and low-nutrient lettuce with high water content should not be relied upon as a staple food.

Small amounts of vegetables such as carrots, zucchini, and sweet peppers may occasionally be added. Fruit intake should be strictly limited because excessive sugar can lead to digestive problems and may encourage parasite proliferation.

Commercial tortoise diets and hay-based formulas are available, such as Mazuri tortoise feed, and can serve as supplementary food sources, especially during winter when fresh wild plants are scarce. Regardless of the food source, maintaining a diverse diet is strongly recommended to prevent nutritional imbalance.

Young and growing tortoises require higher calcium intake. Calcium powder or vitamin supplements may be sprinkled on food regularly. Adult tortoises usually require supplementation only once or twice per week. Another natural option is to provide cuttlebone, allowing the tortoise to chew on it and obtain calcium as needed.

Feeding should occur at a consistent time each day. Food should be chopped and placed in shallow dishes to prevent contamination with substrate such as soil or sand. All plant materials should be confirmed to be pesticide-free and uncontaminated. If plants are collected from the wild, they must be harvested far from roadsides and agricultural areas where chemicals may be used.

Any uneaten food should be removed on the same day to prevent bacterial growth. Observing feeding behavior is also an important indicator of health. If a tortoise refuses food for an extended period or shows noticeable weight loss, veterinary consultation should be sought promptly.

Breeding Conditions

When both males and females are kept together, breeding will often occur naturally. The most common mating season is spring. During courtship, males may chase females, bite their shells or limbs, and sometimes ram them forcefully. During copulation the male often produces low-pitched vocalizations.

After successful mating, females usually search for suitable soil in summer to dig nests and lay eggs. A single clutch typically contains between 6 and 15 eggs, and multiple clutches may be produced in a year.

Tortoise eggs are extremely sensitive to both humidity and orientation. After laying, eggs should be carefully collected and placed in incubation media such as vermiculite or sand. The eggs must remain in the same orientation as originally laid, because turning them may cause embryo death. Humidity should be maintained at 60–70%. Incubation temperatures between 29 and 31°C usually result in hatching within approximately 60 to 75 days.

The sex of marginated tortoise hatchlings is determined by incubation temperature. Higher temperatures tend to produce more females, while lower temperatures produce more males.

After hatching, the young tortoises often remain buried in the soil for several days to two weeks while absorbing nutrients from the yolk sac. During this period caretakers should avoid disturbing them. Regular husbandry can begin once the hatchlings emerge on their own.

If breeding is not intended, males and females should not be housed together. Marginated tortoises require substantial space, and breeding may produce multiple offspring that increase the caretaker's burden and potentially lead to abandonment. Careful planning is necessary before allowing reproduction.

Preventing Invasive Spread

The natural range of the marginated tortoise is limited to Greece and Italy. Because the species is widely traded in the international pet market, releasing or abandoning individuals in non-native regions may lead to invasive populations.

Tortoises have long lifespans and strong reproductive potential. Even a small number of released individuals can gradually establish a population, competing with native species for food and habitat and potentially causing unpredictable ecological damage.

For this reason, keepers must follow the principle of never abandoning or releasing captive animals. If circumstances make continued care impossible, appropriate rehoming options should be pursued, such as transferring the animal to another responsible keeper or to a legal animal shelter, rather than releasing it into the wild.

It must be emphasized again that marginated tortoises live for many decades and require large living spaces. They are not suitable pets for everyone. Anyone considering acquiring one should carefully evaluate their ability to provide long-term care. In some cases, arrangements may even need to be made for future generations to continue caring for the animal so that it can live out its full lifespan under proper care.

Author: Shui-Ye You