The Dumeril’s monitor (Varanus dumerili) is also known as the brown rough-neck monitor. These are 4’ long, arboreal lizards native to southeast Asia. They prefer a forested habitat with ready access to a body of water, and are comfortable both in the trees and in the water.
Dumeril’s monitors have a long head and neck, nostrils placed close to the eyes, a slender body, prominent round scales on the back and nape of the neck, and a laterally-compressed tail. Coloring is brown and tan with a banded to spotted pattern.
Due to their housing and feeding requirements, Dumeril’s monitors are at least intermediate-level pet reptiles. When kept appropriately, they can be expected to live up to 20+ years.
Minimum enclosure size for Dumeril’s monitors
The absolute minimum enclosure size for a single Dumeril’s monitor is 8’L x 4’W x 6’H. This may seem huge, but keep in mind that these are large, active lizards that need opportunities for both climbing and soaking within their enclosure. Of course, if you can manage it, larger is always better!
Housing multiple Dumeril’s monitors in the same enclosure is not recommended.
Do Dumeril’s monitors need UVB?
Dumeril’s monitors have been shown to be able to survive without UVB lighting to some degree, but we still recommend providing it to your pet. UVB lighting helps provide a clear day/night cycle, provides all of the vitamin D that your pet needs, strengthens the immune system, facilitates better digestion, and other benefits.
Here are the best UVB bulbs for Dumeril’s monitors:
- Arcadia Desert 12%
- Zoo Med Reptisun T5 HO 10.0
For best results, use a bulb half the length of the enclosure, and house it in a reflective fixture by Arcadia or Vivarium Electronics. Position the lamp on the same side of the terrarium as the heat lamps. If the UVB is mounted over mesh, place the basking platform/branch so the lizard’s back will be 12-15” below the lamp. If the UVB is mounted inside the enclosure, place the basking surface so the lizard’s back is 16-18” below the lamp.
They are also likely to benefit from plant grow lights as part of their environment as well. Add a ~6500K LED or T5 HO fluorescent grow lamp to provide extra illumination, as well as help any live plants in the enclosure to thrive.
Lights should be on for 12 hours/day.
Best temperature for Dumeril’s monitors
Dumeril’s monitors should have a basking area temperature of 110-120°F, with a cool side temperature around 80-85°F, as measured by at least two digital probe thermometers. Temperatures can get as low as 68°F at night.
Provide heat for your Dumeril’s monitor with a cluster of halogen heat bulbs placed above the basking branch. You will need enough lamps to evenly heat an area at least the size of the lizard’s body. Halogen bulbs are the best way to imitate the warmth of sunlight indoors, and considered to be a superior form of reptile heating by experts. Do not use ceramic heat emitters (CHEs), red bulbs, or blue bulbs, as these are not as effective.
Best humidity levels for Dumeril’s monitors
Dumeril’s monitors are a tropical species, so the humidity inside their enclosure should be fairly high: around 80% on average. Humidity should be measured via digital probe hygrometer, with the probe placed in the middle of the terrarium.
Increase humidity by misting your monitor’s enclosure 1-2x/day with a large pressure sprayer or automatic misting system. Mist first thing in the morning and then again at night if needed. If you need more help maintaining humidity, install a cool mist humidifier connected to a humidistat.
Dumeril's monitors need more than just humidity to meet their water needs — they also require a pool of water that is deep and large enough for them to submerge and preferably also swim in. This means that it should be at least 12” deep, and occupy 1/2 to 1/3 of the enclosure’s floor space.
The pool water will need to be changed once weekly or whenever it gets soiled. Give the pool a good scrub with disinfectant before refilling. Using a siphon (or better yet, a powerful mechanical water pump) and a hose will make maintaining your lizard’s pool faster and easier.
Best substrate for Dumeril’s monitors
Although Dumeril’s monitors spend most of their time either in the trees or in their pool, they do occasionally spend time at ground level. Providing a layer of naturalistic substrate (“bedding”) in the enclosure will help maintain correct humidity, cushion your lizard against falls, provide a digging medium, and also help make your enclosure more attractive!
We recommend the following substrates for Dumeril’s monitors:
Layering clean, chemical-free leaf litter on top of the substrate can help with humidity as well as add enrichment value.
Substrate should be at least 4” deep and completely replaced every 3-4 months. Remove poop and urates daily, along with any contaminated substrate.
How to decorate a Dumeril’s monitor enclosure
An empty enclosure makes for a bored lizard, reducing its quality of life. Keep your pet entertained and engaged with its environment with the strategic use of décor items that encourage it to exercise natural behaviors!
Since Dumeril’s monitors have both arboreal and aquatic tendencies, at bare minimum you will need a large, sturdy branch for them to bask on and a sufficiently large pool for swimming. However, it’s best to include other items, such as:
- hideouts/caves
- more branches
- ledges
- live or artificial foliage
All climbing branches should be securely anchored into the walls/floor of the enclosure to prevent collapse.
Training and designing enrichment activities are also good ways to help keep your Dumeril’s monitor engaged, as well as provide a nice opportunity for bonding!
What to feed to a Dumeril’s monitor
Dumeril’s monitors are carnivorous, which means that they require a whole animal-based diet to get the nutrition that they need. How often they need to eat depends on life stage: Hatchlings and juveniles should be fed daily to every other day for older individuals, but once they near adulthood, reduce feedings to 3-4x/week. Each meal should be slightly smaller than the lizard’s skull.
Here are foods that are appropriate for a Dumeril’s monitor to eat:
- snails (captive-bred only)
- mealworms
- superworms
- dubia roaches
- grasshoppers
- hornworms
- crawfish
- crabs
- shrimp
- whole fish (tilapia, salmon, pollock)
- frozen rodents
- eggs
Young Dumeril’s monitors are more likely to be interested in insects than adults.
Supplements
You will also need calcium and vitamin supplements to help keep your Dumeril’s monitor healthy. We recommend Repashy Calcium Plus LoD, lightly dusted on all foods except whole prey. It’s okay to occasionally skip a dusting.
How to handle your Dumeril’s monitor
Reptiles generally don’t appreciate petting and handling in the same way that dogs and cats do. Regarding Dumeril’s monitors specifically, they generally tame down well and can become very personable pets.
If you want to build a trusting relationship with your pet Dumeril’s monitor, you will need to develop a foundation of positive interactions. Offering food from feeding tweezers works well as an initial bribe, and it’s best to get the lizard to come to you rather than simply grabbing it.
Here are some more tips for success:
- Don’t grab the lizard from above. Instead, scoop from below.
- Support as much of its body as possible.
- Start with short handling sessions at first, then gradually make them longer.
- Put the lizard back in its enclosure only when it’s calm.
*This care sheet contains only very basic information. Although it’s a good introduction, please further your research with high-quality sources. The more you know, the better you will be able to care for your pet!
"Dumeril's Monitor Lizard (Varanus dumerilii) (Photo by Xavier MALLERET)" by berniedup is licensed under CC BY-SA 2.0
