Psammobates pardalis

Leopard tortoises (Psammobates pardalis) are endemic to Africa, and their geographic range extends from Sudan to Ethiopia and from Natal in eastern Africa to southern Angola and South Africa. They are also diffusely distributed throughout portion of southwestern Africa. (Bartlett, et al., 2006; Douglas and Rall, 2006; McMaster and Downs, 2009)

Leopard tortoises occupy a variety of xeric and mesic habitats throughout their geographic range, ranging from dry arid plains to temperate grassland ecosystems. They are intolerant of damp or cold habitats. They have also been reported in mountainous terrain. These tortoises spend most of their time in shrub habitat with low lying vegetation, which serves as their primary food source. In the summer, they seek shelter under various low lying plants. (Bartlett, et al., 2006; Douglas and Rall, 2006)

Leopard tortoises are the fourth largest tortoise species in the world. They exhibit indeterminate growth and adults range in mass from 15 to 54 kg, with an average of 18 kg. Carapace length ranges from 30 to 70 cm, with an average carapace length of 45 cm. Females are often larger than males. It also is common for leopard tortoises to have moderate carapacial pyramiding, a shell deformity in which scutes exhibit pyramidal growth. Leopard tortoises differ from other members of the genus Geochelone due to their distinct shell markings. Base color of the carapace may be tan, yellow, or sometimes shades of dusty brown. The intensity of shell patterning varies. Blotches on the shell are most often black and are typically only present on juveniles. The head, feet, and tail vary in color but are usually tan to brown. Despite differences in appearance, the diet and habitat of tortoises in the genus Geochelone are usually similar. (Bartlett, et al., 2006; Leuteritz and Ekbia, 2008; Schmidt, 2006; Simang, et al., 2010)

Leopard tortoises are oviparous, and their eggs are initially leather-like but dry to become hard and brittle. The egg contains a large, nutrient-rich yolk, which the embryo feeds on during development. Sex determination is temperature dependent; females develop under average temperatures of 30 C or more and males develop under average temperatures of less than 30 C. Temperature-dependent sex determination suggests that the mother has some control over the sex ratio of her offspring. If she lays her eggs in a warm environment the sex ratio favors females, whereas a cool environment favors males. Eggs are roughly spherical and about 57.5 mm in diameter. Clutch size ranges from 7 to 20 eggs, and most eggs hatch within 47 to 180 days. After hatching, young tortoises grow very rapidly during the first few months of life. In general, hatchlings in this genus weigh around 100 grams and grow between 300 and 400 grams during their first year of life. (Bowman, 1966; Deeming and Ferguson, 1991; Spotila, et al., 1994; Stanford, 2010)

Leopard tortoises are monogamous, and both males and females become increasingly aggressive when searching for a mate. They fight for mates by butting and ramming rivals. During courtship, males follow their potential mate and repeatedly run into them until the females become immobilized. Males sometimes lift their mate off the ground by ramming them. Females become defensive and in some cases try to escape. During copulation, males mount the female and extend their necks and grunt during mating. (Ernst and Barbour, 1989; Leuteritz and Ravolanaivo, 2005)

Leopard tortoises breed from May to October. Males become reproductively mature by five years of age, and although the specific age of maturation is unknown, females are thought to become reproductively mature later than males. After mating, females dig a hole in the ground, ranging from 100 to 300 mm deep, in which to lay her eggs. The frail eggs are white and spherical. Gestation ranges from 9 to 12 months and varies according to location, temperature, and precipitation. Females lay 5 to 7 clutches during a single breeding season, with each clutch separated from the previous by about 3 to 4 weeks. Clutches range from 5 to 30 eggs, with larger female having larger clutches. (Ernst and Barbour, 1989; Leuteritz and Ravolanaivo, 2005)

Paternal care in leopard tortoises is non-existent, as males leave directly after copulation. Females dig a hole in which to lay their eggs, which ranges in depth from 100 to 300 mm. After the eggs are laid, she covers them and leaves. Hatchlings are immediately independent upon emerging. (Bartlett, et al., 2006; Ernst and Barbour, 1989)

In the wild, adult leopard tortoises may live for up to 100 years. No records are available regarding captive individuals. However, typical lifespan for other species of Geochelone tortoises in captivity is approximately 50 years. Factors that may limit the lifespan of leopard tortoises include human impacts through the pet trade and male aggression during courtship and mating. (Bartlett, et al., 2006; Ernst and Barbour, 1989; Wimberger, et al., 2009)

Auditory perception is important to leopard tortoise mating behavior, as males vocalize species-specific calls in an attempt to attract females. Males also vocalize during competition for mates. Male vocalizations include a variety of grunts and groans. Although tortoises do not audibly respond to vocalizations, most are visually responsive. Like most other tortoises, leopard tortoises are known for their hissing noises. When feeling threatened, tortoises quickly pull the head and feet into the shell, resulting in air being forced from the lungs and thus the distinctive hissing noise is produced. Males possess neck glands, which inform conspecifics of their willingness to mate or battle another male. Evidence suggests that, during mating season, male tortoises follow females for days or even weeks at a time before initiating courtship. In order to initiate contact, males bite the female on the head or feet. Social hierarchies are established via aggression, as dominance is established through a series of competitions. Social networks among the tortoises are fairly weak, with little intraspecific communication occurring. (Auffenberg, 1977)

There is no information available regarding the average home range size of leopard tortoises. (Ernst and Barbour, 1989)

Communication and perception within leopard tortoises is primarily visual, however, there is little evidence to suggest that tortoises are able to distinguish between different colors. A recent study proposed juvenile leopard tortoises most often approach colors such as red and different shades of green. In general, tortoises are particularly sensitive to sounds under 1,000 Hz. (Auffenberg, 1977; Simang, et al., 2010)

Leopard tortoises are primarily herbivorous, with plant material making up approximately 98% of their diet. They consume berries and other fruits when available. Bone fragments and ash may be consumed during times of decreased resource abundance. Although most tortoises consume mostly grasses, leopard tortoises primarily consume forbs. They feed primarily from the ground, particularly from areas within their habitat that produce low-lying forbs. (McMaster and Downs, 2008; Schmidt, 2006)

Leopard tortoises are well camouflaged and are difficult to capture given their thick, heavy shells. Tortoises suffer the highest predation rates prior to hatching due to predation on eggs. Nearly 80% of hatchlings may eaten by predators such as foxes, coyotes, and mongooses. Adult tortoises are preyed upon by humans and are usedful in creating medicine, tools, and are often used as a source of food. (Stanford, 2010)

Leopard tortoises are important seed predators and disperse seeds throughout their environment. They commonly forage on plants that are close to the ground and ingest a large number of seeds, which are redistributed throughout their geographic range via defecation. They also consume the seeds of berries and other fruits, which are redistributed after consumption as well. Leopard tortoises are vulnerable to tortoise ticks. There is no other information available regarding parasites of this species. (Horak, et al., 2006; Leuteritz and Ekbia, 2008; Schmidt, 2006)

Leopard tortoises are sometimes hunted for their meat and for the pet trade and are used to create traditional medicine. As an indigenous food source, they are cooked in their shells, however, this does not occur frequently and does not seem to significantly affect population abundance. According to Schedule 2 of the Western Cape Nature Conservation Laws Amendment Act of 2000, leopard tortoises are classified as "protected wildlife", which restricts trade of whole animals, dead or alive, and by-products of this species. (Leuteritz and Ekbia, 2008)

Psammobates pardalis is regarded as an agricultural pest (pumpkins, beans, and cowpeas) throughout its geographic range. (Kabigumila, 1998)

Although many species of tortoise are becoming increasingly threatened, leopard tortoises have not been evaluated by the International Union for the Conservation of Nature (IUCN). They are endemic to Africa and are currently listed under CITES' Appendix II. Although Tanzania has the largest recorded leopard tortoise population, with an estimated 5,990 individuals, it also has the highest mortality rate of any country containing leopard tortoises. Ethiopia is second, with only 500 individuals. Leopard tortoises are regarded as agricultural pests throughout their geographic range, and as a result, retaliatory killings are not uncommon. (Kabigumila, 1998; Leuteritz and Ekbia, 2008)