Spiny-Tailed Lizards Captive Care of the Genus UROMASTYX
By Randall L. Gray
Spiny-Tailed lizards have become popular in the pet trade during the last few years. They are commonly known as Uromastyx, but are also called “dabb lizards” or “mastigures,” depending on the part of the world from which they originate. For the purposes of this article, we will consider them all “spiny-tailed lizards.”
These unusual and interesting lizards make exciting additions to the desert vivarium; however, they can be difficult to maintain in captivity. Large numbers die during importation, and many of those that survive are very stressed and difficult for even the experienced herpetoculturists to get established. Once established, though, they can prove hardy and live for many years.
Spiny-tailed lizards are members of the genus Uromastyx, which belongs to the Old World lizard family known as Agamide. Scientific names allow scientists from all over the world to communicate correctly about the species in which they are interested, whereas common names can vary. There are approximately 13 species of Uromastyx distributed throughout arid regions of northwest India, southwestern Asia, the Arabian Peninsula and the Sahara of northern Africa. Even though only a few species are imported into the United States, the number of species available has increased in recent years.
The most commonly available spiny-tailed lizards are Egyptian spiny tail (Uromastyx aegyptis), the ornate spiny tail (U. ocellatus ornatus) and the ocellate spiny tail (U. ocellatus). (Many taxonomists consider the ornate spiny-tailed lizard to be a sub-species of the ocellate.)
Occasionally, Moroccan spiny-tailed lizards (U. acanthinurus; this is the species that's sometimes called a “dabb lizard”), Indian spiny tails (U. hardwickii) and Bent’s spiny tails (U. benti) are available. In 1995, a new species from Mali, Africa, was imported into the United States. It resembles the Moroccan spiny-tailed lizard, and some taxonomists have classified it as such. (However, as this writing, Dr. Ulrich Jogger of Germany plans to publish a paper later this year proposing a new scientific name for the species.) Males are generally yellow backed with black heads, legs , and tails and females are generally yellow-tan in color.
The Egyptian spiny-tailed lizard is the largest member of the genus,
reaching lengths of more than 30 inches and weighing several pounds. The
Moroccan and Mali spiny tails are the next largest members of the genus,
with about 16 inches of total length and weight approximately 1 pound.
Most of the other species that are imported into the United States
usually attain 12-inch lengths or less, and weigh only 100 to 200 grams .
All Uromastyx possess well-armored tails that are used as defensive weapons; a spiny-tailed lizard deters predators by blocking its burrow or crevice with its massive spiny tail.
Each species of spiny-tailed lizard behaves differently in captivity. Generally, ornate spiny tails become the most tame; however, individuals of any species may adapt well to the presence of people. Unfortunately, on the other hand, many will run for a hide spot whenever someone approaches their cage (this is especially true for the wild-caught animals).
Before acquiring any spiny-tailed lizard, be sure you understand the basic requirements for this group of lizards as outlined below.
Acquiring a Healthy Spiny Tail
When choosing a spiny-tailed lizard, always try to obtain a captive born animal whenever possible. This can be difficult, however, because there are very few captive-born spiny-tailed lizards available. I only know of one private breeder, Matt Moyle, who consistently reproduces the Moroccan spiny-tailed lizard each year. Except on a few rare occasions, none of the other species are consistently, if at all, produced in captivity; therefore, the vast majority of the young spiny-tails available in the pet trade are wild caught.
When selecting an animal, look for an active and robust individual. The eyes should be bright and alert, the base of the tail should be thick and round, and the lizard should be active and responsive to any attempts to pick it up. Pick the animal up and look for sores, blisters or broken appendages. An experienced herpetoculturist can determine if the animals weight is healthy just by lifting it up. Do not buy a sick animal with the hope you will be able to nurse it back to health you will be disappointed.
Spiny-tailed lizards are listed in Appendix II of the Convention for the International Trade of Endangered Species (CITES); therefore, they are afforded international protection. Only a few countries allow the exportation of spiny-tailed lizards. Some species, such as the Moroccan spiny tail, are probably smuggled out of their country of origin, and then legally imported into the United States through a third country by claiming the animals as captive born. When acquiring an spiny tail, make sure you keep a receipt and have the seller document in writing that the animal was legally imported or captive born in the United States. This documentation could help protect you. As mentioned whenever possible, insist upon captive-born animals, both to discourage large-scale importation and to ensure that your animal adapts to captivity with less trouble.
Determining the sex of an individual spiny-tailed lizard can be a challenge. Some species, such as the ornate spiny tail or the Mali spiny tail, are sexually dichromatic, which means you can see differences in color between males and females. As mentioned previously, male Mali spiny-tailed lizards have black heads and yellow backs, and the females are a more uniform yellow-tan; however, after the females lays her eggs, she takes on the darker coloration of the male. Ornate spiny-tailed males are spectacularly colored. They can be green, blue, lime, reddish, or any combination of colors, whereas the females are usually tan with only a little additional color evident.
Moroccan spiny-tailed lizards can be difficult to sex. The males and females are both colorful, and very similar in appearance. Adult males usually have larger femoral pores along the underside of the rear legs, as well as slightly larger heads with larger jowls. In addition, males appear to have cloacal openings that are a little larger than females’.
All of the preceding sexual characteristics are relative, and you will usually need several animals to compare. Then, just when you think you have them sexed, chances are you'll encounter another animal that is somewhere in between! Adult males are easier to distinguish in the spring, when hemipenal bulges appear along both sides of the lower base of the tail.
Other spiny tails are less difficult to sex than the Moroccans, but most are still not as easy to determine as ornate spiny-tailed lizards. In all cases, you should look at the head shapes, size of femoral pores, and the presence of hemipenal bulges. Probing spiny-tailed lizards-Moroccan spiny-tailed lizards, anyway does not seem to work.
Over time, while observing your animals, you may notice behavioral differences that can help determine sex. Of course, a clutch of eggs can prove you right or wrong!
Uromastyx lizards are territorial, which means that in the wild they will actively defend a piece of ground against other members of their species, especially those of the same sex. Males will often actively patrol an area and keep out all other adult males. Females will behave similarly toward other females, and even males.
In captivity, the ability of an individual to flee a dominant animal is restricted because of the confines of the cage; therefore, you must watch for signs of stress in submissive individuals. In most cases, it is best to keep only one male per enclosure. I have observed female Moroccan and ornate spiny-tailed lizards exhibit aggressive behavior toward individuals of the same sex, causing the submissive animal's health to rapidly decline. Be sure to watch for signs of aggressive behavior, evident by bytes on a lizards body particularly along the sides of the animal. If you see this, separate the submissive animal.
Mali and Moroccan spiny-tailed lizards exhibit interesting behavior characteristics: Females will occasionally roll over onto their backs when approached by a male. Whether this behavior is exhibited by submissive females, females that are receptive to breeding, or perhaps even submissive males is unknown. Hopefully, herpetoculturists will document behavioral observations so we can increase our knowledge about this species, which should also help us to more easily sex the animals and give us a better idea as to when they are reproductively receptive. (Unfortunately, some observers often jump to unwarranted conclusions about observations, and perpetuate misinformation.)
Behavioral interactions are part of the animals environment and should be encouraged when possible. For example, some herpetoculturists will temporarily introduce a second male into a breeding cage to stimulate the resident male to breed with the female. In this case , short-term aggressive behavior may be beneficial.
Caging for the spiny-tailed lizards can be simplistic or complicated, depending upon the personal preferences of a lizard's owner. The main criteria determining cage design should be ease of cleaning and temperature control, safety, and aesthetic taste of the keeper.
Spiny-tailed lizards can be set up in aquariums, metal livestock watering tanks or plastic tubs, all of which come in a variety of sizes. You may even choose to build your own cage out of wood and glass. If climate permits, spiny-tailed lizards can be kept outdoors in large natural cages.
Screened and washed plat sand makes an attractive and natural substrate. Although some lizard species can ingest sand, which can lead to health problems, I have not had this problem with spiny-tailed lizards. Dirty sand can be easily removed when cleaning fecal mater from the cage.
All of the larger spiny-tailed lizards, as well as hardwickii, dig burrows. The ocellate and ornate spiny tails, on the other hand, often live in rocky crevices or under exfoliating slabs of rocks. A retreat can be provided by using a small plastic box with a short tube leading into a hole cut in the side , or a large plastic plant saucer with a hole cut on the edge and then placed upside down in the cage. For smaller species, stacked cinderblocks with narrow openings recreate natural crevices. Be creative and design your own rocky outcrops or burrows, but make sure they are secure. Spiny-tailed lizards will burrow under them and can either become trapped or die if the rocks topple down on them.
Heating and Lighting
Spiny-tailed lizards live in desert environments; therefore, you should try to simulate these conditions in captivity. Deserts are areas of low rainfall and high temperatures. Moroccan spiny-tailed lizards are most active during the hottest part of the day, when many other reptiles have retreated to cool burrows. Cages should allow an animal to choose the temperature it requires. Providing a heat source at one end of the cage allows the animal to retreat to a cooler spot at the other end of the cage if it becomes overheated.
An excellent source of heat is an incandescent spotlight, such as a halogen bulb. The concentrated light can heat a basking spot to an extremely hot temperature, depending upon the elevation of the light and the wattage of the bulb (make sure that nothing flammable is located near the light).
Heating pads or other subsurface heating units can help control temperatures in different parts of the cage. During the early spring of late fall I place heating pads under my lizards sleeping areas to maintain somewhat higher temperatures during the night. When cooling the animals down for the winter, the heating pads are turned off.
Natural sunlight provides a wide spectrum of light bands. Certain ultra-violet light (i.e., UVB) is important for producing vitamin D3 in an animal which is necessary for calcium absorption. There is some controversy as to whether vitamin D3 can be properly supplemented by diet, so most herpetoculturists try to provide natural sunlight or use full spectrum fluorescent lights. Several of the reptile-specific full-spectrum bulbs now on the market generate ultraviolet light specifically UVB and UVA. However there is no scientific evidence these lights are necessary. In fact many herpetoculturists have had great success breeding many species of lizards without using them. I still prefer to use full-spectrum bulbs, though, primarily to play it safe concerning the need for ultraviolet light, and because my animals’ colors are more vivid under full-spectrum bulbs.
Diet, Nutrition and Water
Spiny-tailed lizards are omnivorous which means they eat both plant and animal matter. There have been very few field studies on the uromastyx genus, but we can glean from the literature that they eat primarily plants and will take insects when available.
The foundation of a good spiny-tail diet should be a salad made from a variety of nutritious fruits and vegetables. A mixture of collard, mustard and turnip greens, with peas, corn, lentils, green beans, alfalfa pellets and strawberries will provide the basis of the salad. It should be supplemented with a variety of beans, birdseed and other vegetables. When available, dandelion greens and flowers are eagerly consumed, as well. Once a week, a multivitamin/mineral supplement should be added to your lizard's salad.
Spiny-tailed lizards will eat crickets, wax worms and super worms. Individual lizards may show changing preferences for these food items, however, so vary the diet if yours seems to shun a specific food. Some Uromastyx, such as the Mali and ornate, show greater interest in insect food than others. Younger animals may consume insects more readily than adults, but as they mature, they usually slow down on eating animal foods. The young lizards’ preference for insects may be related to protein needs for growth. There is some debate as to the amount of protein that spiny-tailed lizards should be feed, although I have not had any adverse reactions feeding insects three to four times per week
Prior to being offered to your lizards, all insect food should be fed
the same nutritious salad as the spiny tails to increase their nutritive
value. In addition, insects can occasionally be coated with vitamins prior
to feeding them to the lizards.
I do not provide standing water to my spiny-tailed lizards; they get all their moisture from their diet. If you provide a water bowl, make sure it cannot overturn and raise the cage's humidity.
There has been some limited success in breeding spiny-tailed lizards in captivity. As of this writing, there are at least six documented records in the United States for breeding Uromastyx acanthinurus and U. aegyptius. In 1995, one herpetoculturist near Palm Springs, California, hatched ornate spiny tails in an outdoor enclosure. This year (1996), myself and several others have been successful in having our ornates produce fertile eggs, and are hopeful we will be able to hatch them this year. There have more recently been reports that one or two private herpetoculturists have bred ornate spiny-tailed lizards outside, in the desert regions of the United States. Ornate spiny tails have also been bred in outdoor enclosures in Israel. I hatched out Mali spiny-tailed lizards this year, as well as the Moroccan spiny-tailed lizard.
All documented instances of captive propagation followed a winter cooling period. The lizards were maintained at temperatures between the mid-50’s Fahrenheit and low 60’s for three to four months.
Spiny-tailed lizards usually breed in March or April, and lay their eggs one to two months later. The eggs are placed at the end of a short burrow and covered in dirt. In captivity, an egg-laying site (such as a large plastic box filled with moist sand and dirt) should be provided to induce lizards to lay eggs.
Eggs should be incubated at 88 to 90 degrees Fahrenheit in slightly moist vermiculite, with the humidity around 95 percent. Depending upon temperature and the species, the eggs will hatch in about 75 to 90 days. There are documented cases in which the eggs have taken more than 100 days to hatch.
Young Uromastyx should be housed separately from adults so they can be monitored for growth.
Spiny-tailed lizards are beautiful and interesting lizards. Unfortunately many die during importation or soon after entering the pet trade. You must select healthy animals and provide good husbandry. As previously mentioned, spiny-tailed lizards need hot and dry cage environments that offer secure places into which they retreat. A varied and nutritious diet is important to ensure good health and longevity. And even though few spiny-tailed lizards are currently being captive bred, we should work toward this end, both to ensure healthy animals for pets and to decrease the number of wild-caught lizards that are imported into the United States.