Natural History

The desert of North Africa is a harsh but beautiful habitat that provided a crucible for the evolution of life adapted to these conditions. One of these species, which is also one of the largest lizards in northwestern Africa, is the Moroccan spiny-tail that belongs to the family Agamidae.

These lizards derive their name from the whorls of "spikes" that compose their tails. They can reach a total length of approximately 17 inches (43 cm) and weigh over 600 grams. They can take eight years to reach their full size, with males growing slightly faster than females (Scheleich, Kastle, and Kabisch 1996).

They can be red, orange, yellow, lime green, or a combination of these colors. Both the males and females are colorful. Colors are dependent upon the body temperature or stress level of the individual. In addition, their colors are not maximized until the third or fourth year of life

The species is distributed throughout North Africa, however the most colorful subspecies and the best known in herpetoculture is Uromastyx acanthinurus acanthinurus which is found in Morocco, Algeria, Tunisia, and Mauritania.

They occur in a variety of desert landscapes where the humidity is usually less than 30% and rainfall is infrequent and less than 2 inches (5 cm) per year. They are found on rocky slopes as well as open plains with only shrubs providing occasional cover. The average home range, which depends upon food supply and topography, varies from 2 to 12 acres (1 to 5 hectares). They dig burrows that can be 12 feet (4 meters) or more in length where they quickly treat at the first sign of predators.

These lizards live in hot desert environments and are active when most other species have retreated from the sun. Research indicates that their optimum body temperature ranges between 102F and 106F (39-41C) and they can withstand temperatures as high as 118F (48C) for short periods (Vernet, et al 1988).

During summers with extreme drought conditions they may estivate in their burrows. During the winter they will also hibernate in their burrows from two to five months depending upon the local climate (Schleich, Kastle, Kabisch 1996).

Legal Status

The genus Uromastyx is protected by the Convention in the International Trade Of Endangered Species (C.I.T.E.S). Moroccan spiny-tailed lizards have not been legally exported for many years. Occasionally wild caught animals are smuggled out of Morocco to Europe where they are sold as captive born. Some of these animals eventually end up in the United States. However the presence of parasites and a rough skin texture influenced by the extremes of the desert sun make recognition of these animals fairly easy.

Life Span

This species appears to live a long time. There is some evidence (Dick Bartlett, personal communication) that wild caught adults have lived 20 years in captivity. If so, these animals were probably 25 years or older when they died. I have one specimen in my collection that was obtained by the Ft. Worth Zoo as an adult in 1989 and must now be at least 14 years old and is probably closer to 18 years. This animal bred in both 1996 and 1997.

Husbandry

I keep Moroccan spiny-tailed lizards in 2ft by 4ft by 2ft (0.6 m by 1.2 m by 0.6m) high metal livestock water tanks which are relatively inexpensive and easy to clean. Washed play sand is used as a substrate. Concrete construction blocks are used for basking sites and plastic plant saucers placed upside down with a hole cut in the side are used as a hiding place.

Incandescent spot lights, wattage depending upon the time of the year, are used to generate heat and create a hot spot. The ambient temperature in the cage often exceeds 100F with the hot spot reaching temperatures well over 140F. I do not advocated such extreme ambient temperatures but the large number of cage lights and local summer temperatures where I live often produce this condition. Their body colors are most radiant at these high temperatures or when placed under natural sunlight.

I use Zoomedâ full spectrum fluorescent bulbs to provide UVA and UVB. However, there is little scientific evidence that full spectrum bulbs are necessary to maintain lizards in captivity. Some herpetoculturists have been successful breeding this species using regular fluorescent bulbs in conjunction with a black light and vitamin D3 supplementation. Richard Montanucci (1996) has raised chuckawallas, which are ecologically similar to spiny-tailed lizards, without any fluorescent bulbs but he supplements with vitamin D3 daily.

Water is not provided because it is seldom available to wild populations and because it will raise the humidity level of the cage. They obtain all their moisture from food.

Diseases

Metabolic bone disease is occasionally found in captives and should be treated under supervision of a veterinarian. However, calcium supplementation and unfiltered direct sunlight is beneficial.

Excessive humidity can possibly cause blister disease which is often observed on newly acquired specimens of Uromastyx. These blisters can become secondarily infected by bacteria. Many wild caught specimens of Uromastyx are often soaked to hydrate them after long periods in transport following removal from the wild. This may lead to blister disease if done excessively. In addition, high sugar solutions such as Gatoradeâ are used which can leave a residue of sugar on the skin therefore providing a medium for bacteria to grow on (Dr. Greg Moore, personal communication).

Herpetoculturists have reported a mouth crust on Moroccan spiny-tailed lizards. This condition does not appear to be deleterious but can cause distortion of the mouth and possibly a secondary infection if not treated. I do not know of any other species of Uromastyx where this has been observed. It appears as a build up of light brown colored material on the labial scales. Its origin is unknown and does not appear to be bacterial. Several veterinarians have hypothesized that its caused by too much or too little of some nutrient. It can be gently removed with tweezers and then treated with a dilute mixture of hydrogen peroxide to disinfect any tissue torn during the procedure.

Food and Supplementation

One field study of Morcoccan spiny-tailed lizards indicated that the diet was composed primarily of plants with only a few insects consumed. However, this study did not analyze the diet throughout the year or by age of the animal. It is probable that juvenile lizards eat a higher percentage of insects to obtain protein for growth.

My Moroccan spiny-tailed lizards are fed a salad every other day. The ingredients are equal parts of thawed frozen mixed vegetables (i.e., peas, green beans, carrots, lima beans), mustard or turnip greens, alfalfa pellets, and bird seed. A calcium and vitamin D3 supplement (Repcal) is added to the salad once a week.

Crickets and super worms are fed several times per week. The insects are "gut loaded" with the same salad fed to the lizards.

Reproduction

I cool my lizards from late November to mid to late February after at least two weeks without food. Temperatures are maintained between 55F and 60F. However, local climatic ambient temperatures sometimes raise the temperature beyond this preferred range. It is not conclusive that a cool down period is required to stimulate reproduction but all reproduction in this species that I am aware of was preceded by a cooling down period.

After the cooling period the lizards are rapidly brought back up to the high temperatures discussed above. Mating usually occurs in April.

Eggs are laid approximately 1 month following copulation. Prior to egg laying I pile moist sand in one end of the cage so they can dig nesting chambers. The eggs are removed from the enclosure and placed in slightly moist vermiculite which is approximately 4:1 (weight of vermiculite to weight of water). The eggs are then placed in an incubator set at 87F-89F.

At the above temperatures, incubation time is approximately 70-80 days.

The eggs may hatch over period of several days. The neonates weigh 4-6 grams and are about 2 inches (5 cm) snout to vent length. They rapidly gain weight during the first few weeks following hatching. They are fed the same diet as the adults with appropriately sized crickets being offered.

Growth Rates

A field study in Algeria indicates that Moroccan spiny-tailed lizards add approximately 1.5 to 2 inches (3.75 to 5 cm) of total growth each year until around the age of 8-9 years (Vernet, et al 1988). In captivity this rate can be exceeded due to a more reliable food source and probably better nutrition.

Growth rate in captivity is probably influenced by a variety of things such as nutritive value of food, temperature and possibly the presence of other lizards. For example, I compared the growth rate of eight individuals that hatched in 1996 with nine of their siblings that a friend raised. I kept the lizards separate from each other, ambient temperatures often exceeding 100F, and under full spectrum bulbs. The other nine were fed a similar diet and supplementation. However, they were all kept in the same cage, ambient temperatures were in the low 90Fs, and no full spectrum bulbs were used. Both setups provided incandescent spot lights to allow the animals to raise their body temperature above the ambient temperature. After 12 months the following data was collected.

Growth Rates of Siblings Raised Under Different Environmental Conditions
 

Measurements	Siblings In Isolation at higher Ambient Temperatures (n=8)	Siblings Raised as a Group at lower Ambient Temperatures (n=9)
Average Weight	122 grams	67 grams
Average Total Length	22.5 cm	18.6 cm

As the data indicates, there are significant differences between the two groups. My eight hatchlings were 21% longer in total length and weighed 82% more. Unfortunately, I can not determine which environmental factor was the cause of the difference or whether it was several factors in concert. However, I believe this data suggests that raising hatchlings separately at higher temperatures may increase growth.

Another interesting fact is the differential growth rates among individuals raised under exactly the same conditions. I have observed siblings in my own collection weigh twice as much after one and two years of growth. This can not be attributed to gender differences since I have observed it with both sexes.

In captivity Moroccan spiny-tailed lizards have bred as early as two years of age (Matt Moyle, personal communication) but three or four years of age is more common.

The hatchlings are usually brown and begin to show color at one year of age. Their colors continue to intensify for the next several years. Siblings from the same parents can be strikingly different in both their color and the intensity of color.

Social Interactions

Most lizards are solitary and actively defend a territory against other members of the same species. They usually only come in close contact when mating or defending territories. In captivity we usually put individuals in the same cage thus creating an unnatural situation. This can lead to outright conflicts. In addition, less dominant animals may suffer stress that can possibly lead to lower growth rates and greater susceptibility to disease.

Male Moroccan spiny-tailed lizards often fight in captivity. In addition, females can be very aggressive towards both males and other females. This is often observed after eggs are laid and the female defends her nest site. You should watch for this and separate aggressive animals.

Members of the genus Uromastyx usually bite along the sides. At first this can be observed by a hardening of tissue that is damaged during the bite. Eventually this material will be replaced by white scare tissue that no longer contains color pigments.

I raise my hatchling separately after three to four weeks of age because I have lost several hatchlings to wounds suffered from conflicts with siblings. They are fed the same diet as the adults but with a slightly higher level of calcium supplementation.

REFERENCES

Montanucci, Richard R. 1997. Captive management, behavior, and conservation of chuckawallas, Sauromalus obesus (Lacertilia: Iguanidae). Bulletin of the Chicago Herpetological Society, Volume 32 (6):121-137.

Vernet, Roland, Michel Lemire, Claude J. Grenot, and Jean-Marc Francaz. 1988. Ecophysiological comparisons between two large Saharan Lizards, Uromastix acanthinurus (Agamidae) and Varanus griseus (Varanidae). Journal of Arid Environments 14:187-200.

Scheleich, H. Hermann, Werner Kastle and Klaus Kabisch. 1996. Amphibians and Reptiles of North Africa. Koeltz Scientific Books, Koenigstein, Germany. 630 pp.