By Max Weissman
Varanus acanthurus is a species of monitor lizard found widely throughout most of Australia. Commonly referred to as Ackie Monitors or Spiny Tailed Monitors, they are found in arid regions or scrubland environments throughout Western Australia, Northern Territory, and parts of Queensland. They live near rocky outcroppings, and when frightened they retreat into small crevices of the rock. They will fill their bodies with air to wedge into the rocks and fold their hard, spiny tails in front of the rock face to discourage predators from trying to pull them out. They live in humid burrows that they dig deep into the ground to escape the midday heat and also to control their hydration and temperature levels. Ackie Monitors are a popular pet monitor species to own because they are inquisitive, active, and have great colors and patterns, and relatively small adult size.
Ackie Monitors grow to reach an average length of 24 – 28 inches, with males usually having a thicker, heavier set head and neck than the females. Ackie Monitors, like most monitors, can live a long time with an average life span of 15 to 20 years if properly housed and maintained.
When housing any Ackie Monitor keep in mind they actively hunt, explore, bask, and burrow. With this in mind I would recommend a 48” x 24” x 24” or larger glass terrarium from Creative Habitat, which we sell online and in our stores, or you can make a custom enclosure. It is best to give them a tall cage to give them a deep substrate to burrow into. Remember, if you ever question the size of your cage, bigger is always better with monitor species. Also, with cages that have screen lids you can add a cover made of acrylic, foil or a towel to help maintain humidity levels in the cage. However, if you keep at least 10 to 12 inches of moist substrate in the cage, and an appropriate size water bowl, humidity levels on the top level can dip very low as Ackie Monitors will retreat into their burrows to control hydration and shedding.
Happily peeking out of a burrow!
Since Ackie Monitors come from Australia, they should be provided with a basking zone surface temperature (which is best measured with a temp gun) of around 130 degrees Fahrenheit or hotter, while the air temperature measured by a probe thermometer is around 90 degrees Fahrenheit. You must maintain the cooler side’s air temperature at no lower than 70 degrees Fahrenheit and no warmer than 80 degrees Fahrenheit for your ackies to have optimal temperatures for thermoregulation.
This is critical since all reptiles are ectothermic and need to regulate their body temperatures by the temperatures of their environment. The best way to do this is by giving them as many areas of different temperatures as possible. Also, while some breeders have successfully kept and breed Ackie Monitors without UVB lighting, I highly recommend you use UVB lighting with your own monitors, since Ackie Monitors are basking lizards and in the wild they are exposed to UVB. Using a Mercury Vapor Bulb provides the animal with both UVB and heat all in one bulb. Deep Dome light fixtures are the best way to house your bulbs because they do not protrude out of the bottom of your fixture. Do not leave any visible light on at night as this can stress your animal; I recommend that you keep them on a 12-hour cycle (12 hours of light and 12 hours of darkness). This can be accomplished simply by turning the light on in the morning and turning it of at night, or by a use of a timer. With this being said, if you are an experienced monitor owner or feel comfortable in doing such you can try a more natural approach with cycling the lights. This means going down to as little as 8 hours a day through the winter months, as long as you maintain the proper temperatures, and as much as 14 hours a day in the summer months, again making sure you are constantly reading and maintaining the temperatures within an acceptable range. If the daylight heat bulb you are using does not reaching the optimal temperatures you can add ceramic heat emitters. The ceramic heat emitters do not produce any light but put off a good deal of heat. Lamp stands can also be a good way to help keep temperatures at a constant by keeping the light at just the right height.
Ackie Monitors love to burrow and need a substrate to hold humidity and the shape of the burrows. Compressed coconut substrate, when lightly packed in the cage, holds its shape and humidity nicely. And, if mixed with clay based substrates such as Zoo Med’s Excavator substrate makes a great combo at a ratio of 1 part excavator to 3 parts coconut substrate. Most coconut, cypress, and sterile plantation soils are all highly recommended. They make a great mix when added in with vermiculite and play sand in a ratio of 1 part vermiculite : 1 part play sand : 3 parts soil. Making the substrate layer thick and moist will aid in keeping your monitor hydrated and shedding properly. There are a variety of ways to provide hiding spots, which include cork bark stacks, half logs, flat pieces of wood, thick layers of bedding and moss,caves, and lots of cover in the form of fake plants. A monitor’s need to hide and stay warm can be duly accomplished in the form of providing a stack of cork bark or wood underneath the basking light, with the highest level being a few inches away and forming the hottest spot in the cage, with the lower levels being significantly cooler. This will allow your Ackie Monitor to thermoregulate its temperature and still feel secure. The key to success in a monitor’s cage is to offer the lizard as many choices as possible. The more options the monitor has to utilize for thermoregulating, the better it will do.
One of the author’s ackies enjoying some natural sunlight!
An effective way to keep an Ackie Monitor hydrated is to keep a water bowl large enough for the monitor to soak in within the cage, so that if it wants to climb in, it can. They tend to like the surface and air to be dry and their burrows to be moist. A good way to keep burrows moist is to add water into them when the animal is out and about and not in the burrow. Also misting the cage once or twice a day will help keep the humidity levels up and aid in proper shedding and hydration.
Ackie Monitors in captivity have been known to take a wide range of prey items, including but not limited to: mice, crickets, hissing cockroaches, dubia roaches,mealworms, Zoo Med’s canned food diets, snails, eggs (chicken and quail), and shrimp. It should be noted that just because a monitor can eat something, that does not mean that it is a suitable food. While a wide variety of food will be accepted, some foods are more readily eaten than others and some are far more appropriate as food items than others. While these monitors will eat dog and cat food, I do not recommend it as a part of the diet. Ideally, a diet consisting almost entirely of whole prey items with a small portion consisting of the raw turkey and egg diet, which was pioneered by the San Diego Zoo, is best.
Suitable whole prey items include hissing cockroaches, dubia roaches, lobster roaches; mice (avoid unweaned rodents as they are high in fat and low in calcium and other nutrients). All food items, with the exception of rodents, should be dusted with a high quality calcium and/or vitamin powder, such as Sticky Tongue Farms MinerAll Indoor Formula or Repashy’s Calcium Plus.Young monitors can be kept mainly on crickets, mealworms, and small roaches, while adult monitors can be fed the entire range of possible food items. Rodents should be fed in moderation, leaning on the side of fewer rodents than insects. Captive monitors rarely, if ever, get the same kind of exercise wild monitors do, and care should be taken to ensure that an adult monitor does not become obese.
Some of the author’s baby Ackies basking
In addition to being fascinating and hardy captives, Ackie Monitors are relatively easy to handle. With calm, confident handling on a regular (but not necessarily frequent) basis, these monitors can learn to tolerate and even enjoy human interaction. Care must be given to allow the monitor plenty of time to acclimate before any attempts at developing an owner-monitor bond are made. Once the monitor shows a healthy appetite and eats readily, and does so regularly, start handling it for just a few minutes at a time daily. If the monitor continues to eat and does not spend the time immediately after handling buried beneath the substrate, avoiding you at all costs, increase the handling time slowly but surely, until the monitor does not mind being out for extended periods of time. Always be sure to read your monitor’s behavior: If it hides and does not move for days on end after being handled, decrease handling time and frequency. With patience, eventually these monitors can and will become tame.