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Natural History

The Captive Breeding of Crotaphytus dickersonae

by Scott Patterson and Dr. Julio Lemos-Espinal
with Jim Winn and Randy Cordero

Our permit to collect these Mexican Collared Lizards was obtained for us by Dr. Richard Montanucci of Clemson University and Dr. Julio Lemos-Espinal of Mexico City, and the trip was partially funded by the Colorado Herpetological Society. On Saturday, May 3, 1997, Jim Winn drove his van from Los Angeles to the Phoenix airport to pick up Randy Cordero from Austin, Texas, and myself from Littleton, Colorado. We loaded up the van with provisions and headed south to the border at Nogales. We crossed the border at 3:00 PM and proceeded toward Hermosillo. We set up camp that afternoon, an hour outside of Hermosillo. That afternoon we were entertained by a pair of earless lizards that stayed active around the van until the sun went down.

Sunday morning, we drove to the Hermosillo Airport, picked up Dr. Lemos and headed for the Sonoran Desert. We reached a rocky area just prior to noon; it was 86 degrees. Dr. Lemos and Jim went to the west, Randy went north, and I traveled the eastern side of the hill. I saw zebratails, desert iguanas and whiptails in the sandy washes below the hill. The zebratails were much larger than the Callisaurus I was accustomed to seeing in the Mojave and Colorado deserts of California. The coloration was very similar, though. The whiptails and desert iguanas, I noticed, had a dark brown hue to them, however their size was similar to that of their American relatives. I spotted four chuckwallas on the rocks on my two hour hike. They were not particularly large or colorful. They were a dark brown and tan color with no trace of red, and were approximately 12-13 inches long. I made my way back to the van without seeing any dickersonae, even though the habitat seemed ideal.

I met with Randy, who had noosed a male dickersonae on a larger sized red rock halfway up the side of a rocky hill. After noosing the male, he captured a female on a smaller gray rock, approximately ten yards below the rock the male had been sunning on. The male was an aquamarine color and had a yellow tint on the hindlimbs. He had a snout-vent length of 4 inches and was 11 1/2 inches long. The female was smaller, around 9 1/2 inches, and showed no gravid coloration. She had black pigmentation on the dorsal side forming a third collar and had the customary butterscotch colored tail. Both lizards were found on a south facing slope.

Jim and Julio walked back to the campsite a few minutes later. They had captured a beautiful cobalt blue male dickersonae, SVL (snout vent length) of 4½ inches and total length of 12 inches. The coloring of the male dickersonae was not unusual except for the yellow tint on the hindlimbs. Everyone's observations on the chuckwallas, desert iguanas, zebratails, and whiptails were similar to mine.

After a quick lunch we drove 6 miles north to another rocky hillside and climbed up it. This time Jim was the only person to spot any dickersonae. He saw and captured another large male -- SVL, 4 inches, total length 11 3/4 inches. Cuts were beginning to appear on Randy's legs and mine also, mostly from one type of bush (must be in the paloverde family because of its green branches). It has a pretty light green color, but razor sharp edges.

We made camp at the beach and enjoyed a beef and baked potato dinner from Chef Jim. I walked the beach and gathered seashells for my kids back home. The water was surprisingly warm and we used it to bathe in. I was amazed at how close the zebratail and whiptail lizards came to the shore.

We woke up early Monday morning, and Jim tried his hand at fishing. He caught a sea bass and corvina, which added to our breakfast. We observed whiptails and zebratails scurrying around our campsite at 8:00 am. We packed up and hunted in the hills further north. At about 11:00 I spotted an adult female basking on a small white rock approximately half way up a south facing hill. She was about 9 1/2 inches long and seemed disinterested as I approached and noosed her. Once again the territory looked inviting, but we only caught the one female.

After lunch, Randy and I hunted west, and Jim and Julio hunted east. Randy and I saw zebratails, side blotched lizards, and desert iguanas, but no Crotaphytus. Jim and Julio came back with two adult male dickersonae. The males were the same size as Jim's male that he had caught the previous day, and had the same beautiful cobalt blue coloration, with a generous sprinkling of white dots. We contemplated the scarcity of these lizards. Were they naturally this scarce or had their numbers been depleted by illegal poaching?

We made camp for the night by the beach, but farther north than our previous campsite. Julio walked around the camp that evening and found a Lampropeltis shedded skin. This was the only sign of a snake that we saw on the trip, other than spotting a hawk from a distance with a limp serpent in its talons. As night fell, we watched kangaroo rats scurry around our campsite in the darkness. It made sleeping in our sleeping bags a little uneasy.

Tuesday was our warmest and most successful day, as the temperature climbed into the 90's. We drove further north to more rocky habitat at 9:00 AM. We spotted a male sunning himself on a medium size red rock on a south facing hill. This was the earliest we saw a dickersonae. We were so busy photographing him, that he caught us off guard by slipping into his hole into the rocky ledge. The morning hunt turned out to be successful as we caught three males and a female. We then had lunch and went to a nearby rocky hill, a bit further north. I noticed a female sunning on a rock approximately 15 feet up the hill (the lowest we had seen). Jim noosed her and we went back to the van for more refreshments.

We ventured out for a late afternoon hunt; at about 4:00 PM. Julio and Randy came across a bobcat lair with two cubs in it. We photographed them and walked away as they screamed at us. At 4:30 Jim and I spotted a beautiful blue male on a medium sized red rock near the top of a steep hill. After noosing him, we decided to scale down the hill. As I slid about half way down the hill, I disturbed a yearling female dickersonae that had been sunning on a small gray rock. She was the only pre-adult we saw, we noosed her and finished our descent off the hill. Altogether, Tuesday we caught four males and three females. We noticed on these "northern" captives that not only did the females have black pigmentation on their backs resembling a third collar, these males did also. The previous males caught in the more southern areas had no trace of black pigmentation on the dorsal side. The northern males lacked the yellow pigmentation on the hindlimbs that the southern captives had. Also noted was a mating attempt by a male on a female in the carrying cage.

Wednesday was a windy day and the temperature was cooler. We split up, Jim and Julio scaled the hills and worked the high areas, while Randy and I traversed the hills at mid-level. At 10:15 Jim and Julio spotted a female on a small rock, at the same time Randy and I noticed another female just ten yards away from the one Julio saw. Two adult females in that close proximity, yet the second female had bright orange mating colors and the first one had no sign of breeding color. Julio and Jim later caught a male, and that was all we saw that day.

We divided up the lizards per the Mexican permit, Jim, Randy and I took a male and two females and Julio kept the rest. We then took Julio to the airport, and we crossed the border and went our separate ways.

The male I brought home had a SVL of 95mm and had a total length of 287 mm. He was a young adult, probably two years old. Both females had a SVL of 87-88 mm, one was a young female about 2 years old and the other female was older, probably three years old. One female had orange breeding color and the other one didn't.

During the first week, I used olive oil to de-mite the lizards, as there were red mites in the postfemoral pockets and around the collar. The mite problem never recurred. The threesome was placed in a cage five feet long by two feet wide and two feet tall. I used play sand as a substrate and placed a couple rocks in the cage for the lizards to sun themselves on, and a hide box was put in the corner. I have spot lights at the middle of the cage and a Reptisun light inside the cage to give the lizards full spectrum and ultraviolet light. By the second day all three lizards were eating Zophoba worms, crickets, and grasshoppers, all dusted with Repcal calcium with vitamin D3. All three were vomiting their food, so they were given .02 Panicure and that cured that problem. Randy's male ate pinky mice voraciously though mine showed no interest in them. I noticed during the first week that the male did a lot of head bobbing in rapid succession and the females flattened themselves to offset his advances. I had seen this behavior in other species of collared lizards before. I never observed copulation, however by the end of the week, the second female developed her orange mating color. Both Jim and Randy noticed copulation with their pairs that lasted 1½ minutes to 2 minutes.

Unlike Randy and I, Jim kept his animals in an outdoor enclosure. It was a wood screen cage in the backyard measuring 2' wide x 4' long x 2' high. The cage contained a heated covered sandbox, which was used to provide shelter at night and on cool days.

During the second week I filled my lizards' hidebox (shoebox) with 3 to 4" of moist vermiculite. All three lizards took to it immediately. My reason for doing this was to get the females familiar enough with the box that they Would feel comfortable about laying eggs in it later! The lights were turned on every morning at 5:30 AM and were turned off at 6:00 PM every evening. In my collection, the dickersonae were the first lizards up in the morning and the first ones to retire in the evening, usually by 4:00 PM.

During weeks three and four, both females showed signs of being gravid, their appetites had increased, and they had gained weight. I had witnessed the male head bobbing and biting the necks of the females, but I still had not seen copulation. All three were getting comfortable with captivity, as they were drinking and eating more often. I noticed that the male's tail was becoming more round with the amount he was eating. He tried to jump out of the cage often, and his vertical leap was approximately 12 inches. The females' mating orange color was getting brighter. They had 6 horizontal orange bars on each side of the dorsal area, beginning right behind the head and ending just above the hips. Each orange bar went from the side of the belly almost to mid-dorsal. The Alpha female still had the sore on her lip that she had when we captured her. The Beta female was larger than the Alpha female and her orange bars were thicker. An interesting note is that as the females developed their orange mating bars, their dorsal color changed from brown and tan to a gray silver color.

During the fifth week, the male was still head-bobbing toward the females and doing "figure eights" on the rocks, marking his territory. The females were drinking more and digging around the cage. The females were staying up later, past 7:00 PM, warming their bellies on the rocks and sand. The Alpha females abrasion on her lip finally fell off and her lip had healed.

By the end of June, both females' appetites had started to diminish and they were drinking even more. I knew the eggs would be laid soon and I began moistening the vermiculite in the hidebox each day.

On July 3, by 6:00 AM, the Alpha female had laid 6 eggs in the egg laying box. Two were buried and four were not. All six were white. The eggs were placed in a Rubbermaid container filled with moist vermiculite. The ratio I used was 1.25:1 vermiculite to water. I then placed the container inside a ziplock baggy with sprinkled water in the bottom and then placed everything into a Hovabator incubator. I let the temperature in the incubator fluctuate between 82 and 88 degrees, and opened the baggy twice a day to give the eggs fresh air. After two weeks, I also put 2 holes in the baggy with a pin. These procedures were repeated for every clutch. The Alpha female had her breeding orange color when we caught her on May 6, so she had her breeding colors for at least 58 days before laying her eggs! By 7:00 AM, she was on a rock sunning herself, and she watched intently as I searched through the vermiculite for any other eggs. When I finished, she went back into the egg box, investigated, and then buried the area where her eggs were laid. The eggs measured 24 - 27 mm. just like Randy's pair had laid. Within 24 hours, five had hardened, the sixth egg was infertile. On July 5, by 6:00 AM the Beta female had laid 3 eggs in the same egg box in which the Alpha female had laid hers. By 7:00 AM, the fourth egg was laid. The Beta female noticed me searching the vermiculite, and like the Alpha female, she proceeded to bury the egg box. This burying of the egg box went on for four days. The Beta female ate 2 crickets and drank water the day she laid her eggs, the Alpha female drank, but wasn't observed eating the day she laid her eggs.

Seven days after laying the eggs, both females' appetites had gotten even stronger, and their breeding colors were as vibrant as ever. During these 7 days I observed the male making several unsuccessful mating attempts.

• At 15 days   Alpha's 5 eggs - white and fine
• At 13 days   Beta's 4 eggs - 2 white, 2 manila and fine
• At 30 days   Alpha's 5 eggs - white and fine
• At 28 days   Beta's 4 eggs - 2 white, 2 manila and fine

At 30 days, the females were definitely carrying second clutches, and I began moistening the vermiculite in the hide box. Two weeks later on August 16, the females stopped eating, signifying they were getting ready to lay their eggs. Both females were drinking water out of the syringe in the morning and in the evening.

On August 21, forty nine days after laying her first clutch, the Alpha female laid her second clutch. She laid 4 eggs in the hidebox, sunned herself under the spotlight, ate a Zophoba worm, returned to her egg box and laid a fifth egg. She apparently didn't mind her cage mates being there, as all three were in the box when the eggs were laid.

0n August 23, forty nine days after laying her first clutch, the Beta female laid her second clutch. The clutch of 4 eggs was laid in the same box that the Alpha female laid hers in two days prior. The Beta female, being the larger female, laid larger eggs, the largest egg being almost 3 cm. long. The females lost between 5 and 7 grams of weight with the egg laying activity.

By August 22, day 48 and 50 for the first clutches, the eggs were visibly beginning to collapse. I was concerned, as I did not recall eggs from other species of Crotaphytus doing this. When the eggs were given fresh air outside of the incubator, they reinflated. By August 24, the eggs were very deflated and my concern mounted. On August 25, day 53, two babies hatched out of their eggs from Alpha's clutch. SVL on the two hatchlings was 3 cm. and total length was 8 cm.. On August 26, the third hatchling appeared and was larger and stronger than his two siblings. His SVL was 3 1/4 cm.. On August 27 and 28, the last two hatched from Alpha's clutch, the final one was very weak and needed extensive care.

The Beta females eggs began to hatch on August 27, day 53, and were larger, reaching a SVL of 3.8 cm. and 9 cm. total length. The last one hatched on August 30, day 56. All nine eggs hatched, some with kinked tails, one very weak and one with possible neurological problems. All were silver with orange and black striping, and were drinking water out of a syringe the day they hatched, and daily afterwards. All babies were eating small crickets on their third and fourth days, except for the weak one, which I "assisted" through the first 2 weeks.

It was noted that there was posturing, but no open aggression between the babies during their first week. They were all similarly colored, having a silver dorsal color with orange on the head behind the ears. They each had 5 orange horizontal stripes across the back, the first stripe between the black collars and the final stripe just above the hind limbs. They each had a series of black dots between each set of orange stripes. Their heads were tan colored.

They were housed in 30 gallon terrariums, four hatchlings in one, five in the other. The cages had "playsand" as a substrate and basking rocks under spotlights, with full spectrum lights inside the cages. Crickets were covered with RepCal prior to being thrown into the lizard cages. The hatchlings' attempts to catch their prey during the first week was comical. There were more misses than catches, with many of the babies' lunges falling short of their prey. After three weeks, the orange coloring was fading on some of the hatchlings. Later I realized that these were the females. The males kept their bright orange color for weeks.

By early September, one egg from the second clutch had deflated and was getting moldy. I opened the egg up, and found that a tail had formed, and I could make out the eyes and the hind legs. I was surprised that so much had formed in 15 days. On September 20, day 30, a second egg deflated and got moldy. I opened it up and found an almost fully formed lizard. The seven remaining eggs still looked perfect. At 45 days it was still status quo, the eggs still perfect.

On October 8, day 48 Alpha's four eggs were all deflating. On day 51, Alpha's first egg hatched, on day 52 her other 3 eggs hatched. Beta's eggs began hatching on day 51, and her last two hatched on day 52 and day 53. Once again, Beta's eggs were larger and so were her hatchlings. The babies, like the first clutch, were very thirsty and drank two times a day.

During the first two months, the hatchlings from the first clutches were eating well and growing. They were being fed crickets, grasshoppers, moths, and Zophobas. I was giving them natural sunlight at least once a week for 2 hours. At two months old, the black pigment on their backs was disappearing. The males were a dark gray color, starting to turn blue, and the orange stripes were still bright. The females were a lighter gray, had smaller heads and the orange, while still present had paled considerably. By December 2, at the age of 14 weeks the males were getting more blue coloration and losing their orange color. They were also developing a dark blue color on the gular region and were 10 inches long.

While this project is still ongoing, Julio and I would like to thank Dr. Richard Montanucci for his guidance, and Jim Winn and Randy Cordero for their friendship, company and extensive contributions to the project. We would also like to thank the Colorado Herpetological Society for helping fund our project.

Through this project we found that Crotaphytus dickersonae is a more nervous and difficult captive than many of the American species of Crotaphytus. While certainly not for the beginner, with the proper care Crotaphytus dickersonae can be maintained and bred in captivity.

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