CAPTIVE REPRODUCTION OF THE ORNATE SPINY-TAILED LIZARD (Uromastyx ocellatus ornatus)
Randall L. Gray
Ornate spiny-tailed lizards (Uromastyx ocellatus ornatus) are members of the old world lizard family Agamidae. Adults are approximately 12 inches long and can weigh up to 300 gr. This species is sexually dichromatic, the males are green, lime green, rust, blue or a combination of these colors, whereas females are light tan or brown with usually only a little color.
They were originally described as a distinct species by Heyden (1827) but in the literature the taxonomic status of the ornate spiny-tailed lizard varies between subspecies and species distinction (Moody 1987). Presently several contemporary taxonomists recognize it as a subspecies of the ocellated spiny-tailed lizard (Uromastyx ocellatus) (Arnold 1986, Joger 1987, Wilms 1995). They are distributed from northwestern Saudi Arabia, southern Israel, and eastern Egypt along a band following the Red Sea (Joger 1987). This species inhabits rocky habitats with many holes and crevices, in areas with less than 2 inches (50 mm) of rainfall. They are usually inactive from December to February. In their habitat, summer maximum air temperatures are 102-105?F (38-41?C) and soil surface temperatures generally 113-122?F (45-50?C) and occasionally much higher. Summer den temperatures are around 95F? (35?C) and their activity body temperature is between 102-105?F (38-41?C). They live solitary or in small groups, but never with more than one adult male (Mendelssohn and Bouskila 1989).
Ornate spiny-tailed lizards are listed on Appendix II of the Conventional of International Trade of Endangered Species (CITES). Several thousand were imported into the United States from Egypt between 1992-1995. High mortality during importation and soon after arrival was common. The limited distribution of this species coupled with large scale importation may jeopardize this species in the wild. Egypt discontinued the exportation of Uromastyx spp. in 1995.
Ornate spiny-tailed lizards are heliothermic (heat loving), therefore I simulate a hot and arid desert environment in captivity. They are kept in 4 foot by 2 foot by 2 foot metal stock tanks with a washed sand substrate. Rocky crevices are approximated with concrete construction blocks (Gray 1995).
High wattage incandescent spotlights provide basking sites that exceed 130?F (54?C), thereby allowing the animal to select its optimum body temperature. The cage is maintained with a diurnal ambient temperature around 90?F (32?C) and allowed to drop to 65-70?F (18-21?F) at night. Full spectrum lights manufactured by ZOOMED (Reptisun ?) are used since they provide a relatively high UVA and UVB output. However it is unclear as to whether these bulbs provide adequate UVB radiation to stimulate vitamin D3 production which is needed for calcium absorption, therefore a supplement is added to the food at least once per week. Since they are a temperate species, an annual photoperiod cycle of 14 hours daylight during summer and 10 hours during the winter is provided.
Only one male is maintained per enclosure. More than one female can be kept together, however they often show aggressive behavior towards other females, as well as males, so the animals must be monitored for signs of stress. Aggression is particularly evident during the breeding season and while females are gravid. Weight loss or bite marks along the sides of the lizards indicate antagonistic behavior and the animals should be separated.
Ornate spiny-tailed lizards are omnivorous, meaning they eat primarily plant matter and some insects. Mendelssohn and Bouskila (1989) indicate that they eat primarily seeds. Probably their diet is dependent upon the season with more herbaceous matter being consumed following the limited rainfall, whereas seeds may be more available at other times of the year. In captivity the majority of calories are provided by peas, alfalfa, green beans, lentils, corn, carrots, sweet potatoes, kale, bird seed, and the greens from collard, mustard , turnip, and dandelions. Superworms, crickets and waxworms are fed once or twice per week. They have a tendency to become obese, especially in the spring, therefore the amount and frequency of feeding should be adjusted depending upon the animal's condition. As noted above, mixed vitamin and mineral supplements are added to the salad once per week. The exact amount of vitamin supplementation is unclear for most reptile species so caution must be exercised. There is some indication that this species may be sensitive to excessive amounts of vitamin D3 (de Vosjoli personal communication).
Newly imported animals are usually parasitized, therefore fecal samples should be tested and the appropriate treatment rendered (Klingenberg 1993). Rapid deterioration is often observed in newly acquired animals being hibernated, therefore only healthy and acclimated animals should be cooled down.
As discussed above, adult ornate spiny-tailed lizards are sexually dichromatic with the males often being spectacular in color and with larger femoral pores. Juvenile animals can often be sexed by the size of the femoral pores at 6 months of age. The difference in femoral pore size accentuates as the animals mature and the males begin to show color differences around one year which becomes increasing noticeable during the second year.
In 1996 four pairs of ornate spiny-tailed lizards laid eggs. All of the animals were obtained as wild caught 1994. One pair were wild caught hatchlings, therefore they reached sexual maturity at approximatley 18 months of age. Copulation followed a winter cool down period of three months. Unlike Moroccan spiny-tailed lizards (Uromastyx acanthinurus) and Mali spiny-tailed lizards (Uromastyx maliensis), ornate spiny-tailed lizards would remain active at temperatures as low as 55-60?F. I was concerned for their health so would often turn basking lights on for several days. In effect, the lizards were provide with only intermittent periods of high and low temperatures.
After hibernation the males would pursue the females, often biting them. During copulation the males hold on to the female's neck and wrap their tails underneath the female's tail , thereby positioning the hemipene to be inserted into the cloaca.
When the females appeared gravid, one third of the cage was dammed with a piece of wood so 3 to 4 inches of moist sand could be piled to provide an egg laying site. The females excavated burrows and deposited eggs. The eggs were removed to a styrofoam incubator and placed on a substrate of 4 parts vermiculite and 1 part water (by weight) and incubated at 90?F (32?C). Table 1 summarizes incubation data.
Table 1. Incubation data for Uromastyx ocellatus ornatus.
Female Date and (# Eggs Laid) Date and # Eggs Hatched Incubation Time (days)
1 June 6 (18) August 18 (13) 72-74
2 July 12 (12) None N/A
3 Died egg bound N/A N/A
4 July 4 (8) September 21 (7) 67
The hatchlings weighed approximately 4 grams and doubled their weight
within one week. At about one month of age they were separated because
of aggressive behavior towards each other. At 6 months of age, including
2 months of a partial cool down period, the weight varies from 30-52 grams.
The young are fed the same diet as adults.
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