Green Tree Monitor (Varanus prasinus), also known as the Emerald Tree Monitor
Popularity: Make good pets for only advanced keepers because they are delicate and have exacting care needs. Handling causes stress, so it should be kept to a minimum.
Origin: Papua New Guinea and nearby islands
Native habitat: tropical rain forest
Size: 28-39 inches
Lifespan: 15+ years
Appearance: It has unusual coloration, which consists of shades from green to turquoise topped with dark, transverse dorsal banding. It is one of the few brightly colored lizards. It has a long, prehensile tail.
Diet: primarily insects
Activities: It is arboreal and loves to climb.
Misc characteristics: It has a prehensile tail that wraps around tree branches to help with climbing. Special scales on its feet and long toes also help with climbing. It flicks its tongue like a snake to sense its surroundings. Males may fight if kept in the same enclosure, but will usually get along with females.
Green Tree Monitors are active and require a large amount of space. They are avid tree climbers, so a vertically oriented enclosure is essential. It’s a good idea to affix cork or some other material on to the side of the enclosure so the lizard can climb on it. The tank should be a minimum of 6-feet high, 4-feet wide, and 2-feet deep. Arrange climbing branches of over 4-inches in diameter vertically and horizontally, and there needs to be some hiding places. The substrate should help with humidity by retaining moisture without building up mold. A good substrate is a leaf litter type.
The Green Tree Monitor needs a hotter basking area than most lizards. It should be 115-120 degrees F. The main temperature should be in the low to high 80s. Use heat lamps to maintain the desired thermal gradient, and a regular lamp to heat the basking area. Maintain nighttime temperatures with ceramic heat emitters, which do not produce light. Position thermometers in the warmer and cooler areas at branch and ground level of the enclosure, as well as in the basking spot.
The humidity in the enclosure should never drop below 70-percent. Use a hygrometer to measure it. Daily misting with fresh chlorine-free water will maintain humidity and provide droplets that will keep the reptile hydrated. Large air vents and top screening should not be used on the enclosure, as they will prevent the humidity.
The lizard needs 12 hours per day of UVB lighting exposure to synthesize calcium. Use specialized reptile lighting should be used rather than plant or aquarium lighting. Glass blocks out UVB light, so overhead light sources should be kept behind a wire mesh cover, not a glass or acrylic tank top. A fluorescent light source should be within 12 inches of the animal. The reptile also needs a day/night cycle which can be provided by lamps and timers.
Green Tree Monitors need to eat every day. Small, frequent meals are better than infrequent large ones. The diet consists mainly of gut-loaded, dusted insects. These include commercially raised crickets, cockroaches, and mealworms. They will also take feeder mice, which you should offer now and then for variety. Per-day portion size should be 12-24 crickets (or appropriately sized feeder mouse) for adults, and 6-12 crickets for juveniles.
Like many lizards, Green Tree Monitors often will refuse water from a bowl, and instead drink by taking droplets from leaves and other surfaces. However, a bowl of fresh chlorine-free water should always be provided. It’s a good idea to mist a Green Tree Monitor before offering it food.