Collared lizards emerge from hibernation during March and April. Follicular development has begun in females by early April (Ferguson, 1976). Orange to red bars and spots appear on her neck and sides. This coloration, which can appear overnight, is visual signal to the male lizards that the females are ready to mate. Around the same time, testes size in male lizards increases and continues to increase until early June (Trauth, 1979).
Collared lizards are very territorial. Male lizards defend 2 or 3 female lizards that share his territory. If a male lizard enters another males territory, the defending male arches its back, compress its sides in an attempt to appear large and fierce. He will then do a series of pushups. C. collaris ' pushups are so powerful that its front feet often come off the ground. If this doesn't deter the trespasser, the defending male chases the intruder off. Male lizards will approach a female and do a series of head bobs. The lizards circle each other, both of them bobbing their heads. The male will grab the female by the back of her neck and attempt to mate. The female becomes submissive if she is ready. If she is not ready or already gravid, she will twist her body and roll him off. Sometimes the female lizard climbs on the males back to subdue his advances.
The breeding season last until June. Once the eggs are laid, female lizards aggressively defend the nesting site. Her breeding coloration also fades. This coloration becomes vibrant again if there is another clutch. In the northern part of their range, female collared lizards produce only one clutch. In the south, they often produce two to four clutches. Clutch size ranges from one to thirteen. There is a positive correlation between body size and clutch size (Ballinger and Hipp, 1985). The average clutch size is about six. Eggs are usually deposited under rocks and will hatch in about 40 to 60 days.
Hatchlings appear from July to September. By late August to early September, adult lizards usually start their hibernation. This leaves the hatchlings with less competition. The young lizards eat anything that it can get their mouth around. This insures survival over the winter. Young male lizards often have orange bars across their dorsum similar to breeding females. This is to deter adult male aggression until the young lizard can find its own territory. Collard lizard are usually sexually mature during their first spring. Lizards from colder areas may not reproduce until their second season. Males reach their maximum size by the age of three. Females continue to grow very slowly their entire lives (Sexton, Andrews, and Bramble, 1992).
Collared lizards emerge each morning around 9 to 10 a.m. to bask on prominent rocks in their territory. Once they reach their preferred body temperature, they begin to forage for insects. They are very agile and can easily snag flying insects out of midair. Before rushing down on their prey they will often do a series of tail wags. Collared lizards occasionally feed on plant matter and vertebrate prey. Collared lizards have excellent eyesight and are difficult to approach. The best way to get close, is to scan boulders far ahead of you with binoculars. The lizards are usually already looking back at you by the time you spot them. When approaching these lizards, do so very slowly. You can get within a few feet if you move slow and don't startle them. If you get too close they'll dash under rocks, often running on their hind legs. Their tails are used to balance when running bipedally and it doesn't break off easily like most other lizards. It will only grow back if just the tip is broken off . When hiding under rocks or sleeping, they will coil their tail to keep from being pulled out by it. These lizards are very aggressive when corned. They will hiss and leap at you in an attempt to bite. Once they get a hold of you, they often hold on.
Collared lizards make excellent captives as long as their basic requirements are met. These lizards are very active and you can not give them enough room. Adult lizards should be kept in at least a forty gallon aquarium. These lizards are very territorial, no more than one male and two females should be kept together. Sand makes an excellent substrate. Collared lizards are saxicolous so rocks piles make natural basking sites. If more than one lizard is to be caged together, make several basking sites. Be careful that the rocks can not come down on the lizards when they dig around them. Like most lizards, collared lizards require ultraviolet light. Use a full-spectrum fluorescent bulb along with a incandescent bulb above the basking site. For healthy and colorful lizards, natural sunlight is a must. Collared lizards like it hot. Their basking site should be between 100 and 105 degrees. The rest of their cage should be in the high 80's to 90's during the day. Some individuals will drink from a water bowl, but most will only drink from water droplets. Mist the rocks and glass in their enclosure to stimulate drinking every few days. Collared lizards eat a lot and can be fed daily. Crickets are the most convenient food source available. It is best to feed them a variety of insects. It is always fun to watch them catch flying insects in midair. Some individuals will also eat lizards and pinkies.
Captive bred lizards do excellent as captives. Wild caught lizards don't always do as well. Many die from the stress of being taken from their natural environment. They are usually loaded ticks, chiggers, nematodes, and other parasites. Wild caught lizards will often rub their nose raw trying to escape. If the lizard doesn't adapt, it will go off feed until it is too weak to move. It will lose weight and wither away over a period of several weeks. Once this has started, it is almost impossible to turn them around. Collared lizards are fairly easy to breed in captivity. They must hibernate at least a month and can be left in this state for several months. Two weeks before hibernation, stop feeding them so their stomachs will be empty. Turn off the heat sources and slowly cool the lizards down to between 40 to 55 degrees. If your room doesn't stay cool enough to induce hibernation, you can hibernate them in the refrigerator. Use a thermometer to regulate the temperature. Because the refrigerator will dehydrate the lizards, I put them in plastic shoe boxes with damp sand as a substrate. I also keep a small bowl of water in with them. Check them every few days and mist the sand down as it dries.
After hibernation, slowly warm the lizards up by keeping them at room temperature for a day or so, then you can turn up the heat. Start feeding the lizards insects dusted with calcium. The females will especially need it for strong egg development. Within a few weeks the female lizards will develop their breeding coloration.
After the lizards have mated, the female will start to show bulges near its abdomen. At this time, keep a moist spot in the cage and the female will usually lay the eggs in this spot. When she is ready to lay the eggs, she will begin digging. Check her daily, because she will appear skinny after she has deposited the eggs. The eggs must be removed from the cage. Keep them right side up and place them in an incubator. An incubator can be made from a plastic shoe box with a hole, the size of a quarter, cut in the top for air circulation. Fill the shoe box with about three inches of vermiculite and keep the vermiculite moist but not wet. Put the shoe box in a place were the temperature wont drop below the high 70's and won't rise above the low 90's. Temperature fluctuations will insure that the hatchlings will be of both sexes.
As long as the eggs continue to grow they should be fine, even if they turn an off white to brown. In about 40 to 60 days the eggs should be ready to hatch. It take several hours to more than a day for the hatchling to break free from their eggs. Their umbilical cords will remain attached for several days. Hatchling lizards need natural sunlight in order to develop properly. Without it, they will likely perish. They can be fed week old crickets, but they will eat anything they can get their mouths around. Collared lizards grow very fast and within a matter of weeks they can be fed adult crickets.