The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 28, Number 5; May, 2001

Monitor Lizards in Captivity

Reprinted from the Pacific Northwest Herpetological Society Newsletter, Vol.16, No.3, March 2001.
Based on a presentation by Luke Campbell at their February meeting.

General info: Very active, high metabolism, very intelligent.

Breeding: In the last ten years great leaps have been made in the captive reproduction of monitors.

Buzzwords: Keep them hot and feed them a lot.

Why are monitors different from other lizards? They are very active. Most reptiles cannot run and breathe at the same time, because they share the same muscles for running and breathing. Monitors have developed a highly muscular area of the throat allowing them to breathe while running. Their lungs are subdivided, greatly increasing the surface area, allowing a greater intake of oxygen from the air they breathe.

Cardiovascular: Most lizards have a three chambered heart. Monitors have a modified three chambered heart that makes them very similar to mammal's and bird's four chamber hearts. This gives them the advantage of getting oxygen rich blood to their body more efficiently.

Thermoregulation: This is very important to the husbandry. The body temp for normal activity is the same as that of mammals. Since they are cold-blooded, we need to provide these high temps for them. Over 40°C basking areas. Heat the entire lizard also. Because of their size, they need the high temperatures to spread evenly over the whole body.

Building a proper burrow: Burrows are for security. Monitors like a nice tight space, where they can feel the space on both top and bottom. Thermoregulation of burrow. This is where they can escape from extremes in temperature. This is where they can hide from hot days, or warm up through cool periods. Burrows are also typically humid. When a monitor sleeps in a water dish it is a sign that their burrow may be too dry.

Feeding: High activity and high metabolism means they eat much more than other reptiles. A typical monitor will eat several small meals a day, with the occasional large meal. They need daily feeding. When they are resting, they run with a much lower metabolism then we mammals have. They can survive up to several seasons when temps are low, and they are less active. Keep them away from your other pets. They will eat anything they can fit in their mouth. Do not feed them by hand, as they have very powerful mouths and sharp teeth.

General behavior: Mostly active during the day. They are active in daylight hours basking. They are active foragers, searching for food on the ground and in the trees. They are quick learners, and will get into a feeding routine.

Gender differences: Males have a much larger range than females have. In general the males are more active than the females. This has led to a disproportionate amount of males in the pet trade. Wild caught animals tend to be males, as the males are the ones who are found wandering about much more frequently than the females. The home range is just big enough to eat and reproduce.

Sexing is difficult, even probing has only a 50% success rate. So, you are just as successful flipping a coin.

Having a monitor loose in the house: They will do damage to your house. They like to climb. Bookshelves and china cabinets are in danger. House plants will get dug up, climbed on, and generally destroyed. They are wonderful animals, but it is best not to keep them in the house loose.

CBN Editor's Note: I usually don't publish reports from other Societies' meetings, but this report had so much valuable information in it that I just couldn't resist.