Uromastyx

Uromastyx is a genus of lizards in the family Agamidae, native to North and Northeast Africa and the Middle East as far east as Iran. Commonly called spiny-tailed lizards or dabb lizards, they are primarily herbivorous, though they occasionally eat insects and other small animals. They live in hilly, rocky areas with good shelter and plants to eat, spend most waking hours basking in the sun, and retreat to underground chambers at night or when danger appears. Sizes range from 25 cm for U. macfadyeni to 91 cm or more for U. aegyptia, and the thick, spiked tail can be swung at an attacker.

About the uromastyx

A uromastyx is a spiny-tailed lizard from the genus Uromastyx in the family Agamidae. These sturdy, mostly plant-eating lizards live in the deserts and rocky hills of North and Northeast Africa and the Middle East. They are also called mastigures or dabb lizards, and they are known for a thick, heavily spiked tail used in defense.

The name says it all. Uromastyx comes from the Ancient Greek words for "tail" and "whip," after the thick, spiked tail that every species shares. About 15 species are recognized, including the North African spiny-tailed lizard (U. acanthinura), the Egyptian spiny-tailed lizard (U. aegyptia), the ornate mastigure (U. ornata), the ocellated spinytail (U. ocellata) and Geyr's spiny-tailed lizard (U. geyri), sold in the pet trade as the Saharan yellow uromastyx. Three species once in this genus have been moved to a separate genus, Saara.

Size varies a lot across the group. The smallest species, U. macfadyeni, reaches about 25 cm (10 in), while the Egyptian spiny-tailed lizard grows to 91 cm (36 in) or more. A well-studied mid-sized species, the North African spiny-tailed lizard, reaches 40–43 cm (16–17 in) and around 450 g (16 oz), with a maximum near 600 g (21 oz). Hatchlings are tiny, about 5 cm (2 in) from snout to vent and weighing just 4–6 g (0.14–0.21 oz).

These lizards have a blunt head and a flattened body. Their color shifts with temperature and season. In cool weather they look dark and dull, which helps the skin soak up sunlight, and they turn lighter as they warm up while basking. Many species are strikingly colored. The North African spiny-tailed lizard can be mottled red, orange, green or yellow over a grey base, overlaid with curling dark spots, though juveniles are mostly grey and brown. Colors grow brightest at sexual maturity, around four years old. In many species males are more colorful than females; in the Mali uromastyx (U. dispar maliensis), males are mostly bright yellow with black mottling, while females are often light tan with black spots.

Behavior and diet

Uromastyx are sun-lovers. They are diurnal, spending most of their waking hours basking, and they retreat underground at night or whenever danger appears. The North African spiny-tailed lizard basks when outside temperatures are around 18–28 °C (64–82 °F). Its burrows can run more than 4 m (13 ft) deep, sometimes with several entrances, and they hold a steady 20–25 °C (68–77 °F) even when the surface swings from below freezing to 60 °C (140 °F). This species hibernates for two to five months in winter and becomes dormant during summer droughts.

The tail is the main weapon. It is muscular and heavy and can be swung at an attacker with great speed, usually along with hissing and an open-mouthed display of small teeth. Uromastyx sleep with the tail toward the burrow entrance to block intruders, and when grabbed inside a burrow they cling to the walls with their strong limbs. Juveniles have no burrows of their own; they shelter under stones and tend to freeze when approached.

The North African spiny-tailed lizard is solitary and fiercely territorial, defending areas of 10,000–50,000 square meters (about 2.5–12 acres). Fights involve biting the opponent's flanks, and even siblings kept together too long in captivity will attack each other. Males court with head-swinging and push-up displays and mark territory with scent from glands near the thighs and vent.

Uromastyx are mainly herbivores. They eat leaves, flowers, seeds and fruit, and they get most of the water they need from the plants they eat. Insects such as ants and beetles are an occasional addition, eaten more by young lizards and by some adults during hot spells when plants are scarce. Desert soils are salty, and so are many desert plants, so the North African spiny-tailed lizard has glands in its nostrils that get rid of excess salt without losing water. One unusual detail: newly hatched young eat their mother's droppings as a first meal to pick up the gut microbes they need to digest plants.

Females lay 5 to 40 eggs, depending on age and species, about 30 days after mating. Incubation takes roughly 70–80 days. In the North African spiny-tailed lizard, the female lays leathery eggs inside her burrow and guards them until they hatch, and the young stay in the burrow for a few weeks to a few months. A field study in Algeria found Moroccan spiny-tailed lizards grow about 5 cm (2 in) a year until around eight or nine years of age.

Range and habitat

The genus ranges across most of North and Northeast Africa and the Middle East, as far east as Iran. Species found farther east are now placed in Saara. Individual species have narrower ranges: the North African spiny-tailed lizard spans the Sahara from Morocco and Tunisia to Sudan, the Egyptian spiny-tailed lizard occurs in Egypt, Israel and the Arabian Peninsula, and several species, such as the Omani spiny-tailed lizard, are limited to parts of Oman or Yemen.

Uromastyx favor hilly, rocky areas with good shelter and plants to eat, at elevations from sea level to well over 900 m (3,000 ft). The North African species prefers rocky or semi-rocky sandy ground and only rarely open sand, digging burrows under bushes or using cracks in cliffs, dry riverbanks and stabilized dunes.

Conservation status

Because Uromastyx is a genus of many species, there is no single status. Every species in the genus is listed on CITES Appendix II, which means international trade is regulated. Individual species are assessed separately on the IUCN Red List, so no single status applies to the group.

The pet trade and trapping for food and medicine are the main pressures. In Morocco, uromastyx are taken from the wild without regulation for the pet and medicine trades, despite being protected there, and animals for sale are often kept in very poor, crowded conditions. The North African spiny-tailed lizard was at one time the most traded species in the genus, though captive breeding has since reduced demand for wild-caught animals. Enforcement is hard because species are easily confused and many are sold through underground markets.

People have also eaten these lizards for a long time. The Mali uromastyx, known as ḍabb, was historically eaten by some Bedouin of the Arabian Peninsula and was once considered a delicacy, and the lizards are sold in produce markets in parts of their range. Other threats include livestock grazing the plants the lizards depend on, and road traffic, since warm asphalt draws them in to bask.

In captivity, uromastyx once had poor survival because their diet and habitat needs were not well understood. Better knowledge of their care has since improved survival a great deal.