Scattered through dry areas of Africa and Arabia are numerous species of herbivorous agamid lizard in the genus Uromastyx. Formerly included in the same genus are at least three species of Saara, which replaces Uromastyx in the Middle East and India. Commonly called spiny tailed lizards, they are mostly large lizards with distinctive thick, spiked tails which they use on defense, either by striking attackers with it or using it to block the entrance to their burrows.
The species on show at Bristol is Leptien’s Uromastyx. Depending on how they are classified, they are either a species in their own right or a subspecies of the widespread Egyptian Uromastyx, U aegyptia. They are found in the United Arab Emirates and Oman, with other related forms in Egypt and Arabia. These are some of the largest of the genus, reaching 75cm in length and a weight of 2kg.
These lizards are specialists in arid environments, living in rocky hillsides, gravel plains, or wadis. They are sociable animals, living in colonies of several adults and juveniles using burrows they have dug which in extreme cases may be 10m long and well over 1m deep. These burrows may be occupied for many years – they can take at least 4 years to reach maturity, and can live to well over 30.
They are diurnal animals, basking at the mouth of their burrows in the morning until they have reached their normal operating temperature, and then foraging for flowers, leaves, buds, and probably seeds of desert plants. They obtain all their water needs from their diet, although they will drink if it is available. In colder periods, or during summer droughts, they retreat to the depths of their burrows to survive inclement weather. In order to function normally, they need high temperatures – in captivity a basking spot well over 100 degrees Fahrenheit is required.
The breeding season starts in the spring, and after mating the females dig a burrow and lay anything up to 40 eggs, depending on the size of the female. The eggs take around 60 days to incubate, and the neonates are around 8-10 cm long. As with many herbivorous animals, neonates acquire the gut microorganisms they require to properly digest plants from the faeces of the adults, so it is important that they have access to this. The same problems may arise when an adult is treated with antibiotics – they may require similar re-exposure to a normal gut biota to recover full health.
Uromastyx of various species are widely kept. Unfortunately there is as a result a trade in wild caught specimens, which given their comparatively low reproductive rate and long life spans means they are at risk from local extinction, not least because they are also eaten by people and many natural predators. In Dubai, they are also at risk from overgrazing which destroys their habitat and off-road driving across the desert, especially close to cities.
Nest time, this series will end with the largest lizard kept at Bristol, the Rhinoceros Iguana
(Images are mine)