Mountain Horned Dragons An Introduction to Accanthosauria in the Terrarium
By Jonathan Rheins
MEET THE DRAGON
Mountain Horned lizards (Accanthosaura sp.), or Mountain Horned dragons, as they are sometimes referred, are moderately sized tropical lizards belonging to the family Agamidae. They have an extensive range throughout much of South-East Asia, the Malay Peninsula, and adjacent island chains. Locally abundant, these lizards are common in the pet trade, and make for incredibly fascinating and entertaining terrarium subjects.
All mountain horned lizards are of the genus Accanthosaura. Species accounts vary from one publication to another, but it is safe to assume that as many as 10 described species exist within the genus. Despite such a taxonomically diverse family tree, only a handful of species are ever encountered in the U.S pet trade. The most common is A. capra, with the occasional A. crucigera making its way into the hands of American hobbyists.
The vast majority of Mountain Horned lizards are collected in Asia and shipped to various markets throughout the world. However, A. capra have proven to be quite prolific in captivity, and private breeding efforts have increased the number of domestically produced dragons available.
All species of Accanthosaura are highly arboreal in nature, spending much of their time high in the dense canopies of both primary and secondary rainforests within their range. They are almost always encountered near permanent sources of running water.
Accanthosaura capra, the most often encountered species, seldom attain sizes of more than 12”, total length. Their arboreal nature dictates that the tail length is often equal or greater to snout-to-vent (SVL) length. While little is known about the longevity of wild individuals, captive born and raised animals can be expected to live in excess of 8 years, with 5-10 years being a reasonable goal.
Mountain Horned lizards typically perch motionless in the treetops, waiting for various invertebrate and vertebrate prey to cross their paths. Insects make up much of the diet in the wild, with earthworms being a favorite food, both in nature and in the terrarium. Some wild individuals have been reported to stalk and prey upon fish from overhanging perches.
When startled, these lizards will remain motionless until the threat has passed. If they continue to feel threatened, they will dash to the forest floor (or bottom of the terrarium) as a last resort to evade the perpetrator. As terrarium subjects, this behavior correlates to a very mild-mannered, easy to work with species.
There are many suitable enclosure types for Mountain Horned lizards. The most important aspects to consider are enclosure height and the ability of the enclosure to maintain adequate heat and humidity within.
All-glass terrariums with sliding screen lids work well, although the front-opening terrariums manufactured by Zoo Med and Exo Terra may be preferable. Front access tends to reduce stress of the inhabitants, while making feeding and maintenance less difficult. Molded plastic enclosures with sliding glass fronts (such as those made by Vision Products shown below) are simply the best at keeping heat and humidity at optimum levels.
Although not terribly active, size should still be a consideration when selecting a Mountain Horned lizard enclosure. A single adult should be allotted space equal to that of a standard 20-gallon “tall” terrarium, or front opening enclosure measuring 18x18x18”. If multiple animals are to be housed together, terrarium size should be increased.
Care should be taken to avoid housing multiple mature males together. They can become territorial over time, which can lead to stress, lack of appetite, and occasional physical altercations. Male-female pairs are communal, as are harem-type groups consisting of one male and multiple females.
FURNISHINGS & DÉCOR
Designing any reptile habitat should be fun and exciting. It is our opportunity to be creative and recreate a small piece of nature in our own homes. Mountain Horned lizards are not terribly picky about their surroundings, so long as multiple horizontal and vertical perches are provided.
Large pieces of grape wood, mopani wood, and vines should make up the bulk of the climbing structures within the terrarium. These most closely mimic the natural habitat of these lizards. Additionally, a multitude of both live and synthetic plants should be included, creating a dense, “canopy” feel in the enclosure.
The substrate used should be one that both promotes humidity and inhibits the growth of molds and fungus. Coconut husk beddings and cypress mulch are among the best for this type of application. Both products are available in a variety of forms and graded sizes, and both are excellent for maintaining the high levels of humidity required by these animals.
The use of planted vivaria has proven a highly successful and aesthetically pleasing means of keeping Mountain Horned lizards. The inclusion of multiple live plants, mosses, and a significant drainage layer produce high levels of humidity as well as an environment that is as close to nature as a lizard can get!
In addition to being quite beautiful to look at, living vivaria are also much easier to maintain than standard bedding-and-water bowl setups. When properly constructed and maintained, this type of habitat can go months, even years, without a total overhaul and cleaning. Furthermore, a nicely put-together vivarium can easily rival any tropical fish tank as a stunning living room center piece.
HEATING & LIGHTING
Compared to other tropical herps, Mountain Horned lizards seem to be less tolerant of extreme heat. Because they are found at high elevations, and often near bodies of water, they may simply be better adapted to cooler, more humid environments.
Ambient air temperature within the Mountain Horned lizard terrarium should be between 75 and 85 degrees, with 80 degrees being an ideal temperature. Under tank heat pads, infrared bulbs, and ceramic heat emitters are all excellent choices for maintaining a comfortable background temperature for these animals.
A basking bulb or spot light should be positioned over a section of the enclosure to produce a basking spot of approximately 90 degrees. This should be the absolute hottest part of the enclosure, and should not be allowed to climb much above that temperature. A series of analog or digital thermometers within the enclosures will prove an invaluable resource when keeping this, or any species of herp.
A moderate drop in temperature at night is acceptable, and is easily achieved by shutting off the basking bulb, while leaving all other heaters as-is. Temperatures dipping into the low 70’s or high 60’s should be considered a minimum nocturnal temperature.
In addition to being kept warm, Mountain Horned lizards also require full spectrum lighting if expected to thrive long-term. Full spectrum lighting, specifically light in the UVB wavelength, is produced naturally by the sun. As reptile keepers, we must rely on specially designed bulbs to mimic the sunlight. Linear fluorescent bulbs, as well as compact fluorescent bulbs work well in this capacity. UVB lights should be on during the same time as any light-emitting basking bulbs. 10-12 hours of daylight is recommended for these lizards year round.
WATER & HUMIDITY
Proper hydration is paramount to the successful maintenance of Mountain Horned lizards. Like many other arboreal herps, these lizards prefer to drink water directly off of leaves and other foliage, rather than seeking a pool of standing water. That said, a large water bowl should be provided for soaking, and also for producing added humidity within the enclosure.
In addition to a water dish, mountain horned lizard terraria should be misted heavily 2-3 times daily to ensure high levels of humidity (60-80%) as well as ample drinking water. Automated misting systems, waterfalls, and foggers all work well if manually spraying each enclosure becomes too tedious or time consuming. These alternate methods of providing moisture can be extra helpful if you live in an excessively hot or dry climate.
Mountain Horned lizards are not difficult to feed in captivity. They readily accept all manner of commercially produced crickets, mealworms, superworms, and cockroaches. Like true chameleons, these lizards have been known to become “bored” when provided a monotonous diet.
To avoid this issue, provide these lizards with the widest variety of foods possible. In addition to insect prey, many Mountain Horned lizards will relish the occasional pinky (newborn) mouse, handful of earthworms, or even minnows and goldfish!
All food items should be “gut-loaded,” that is fed a highly nutritious diet prior to being offered as food themselves. This maximizes the nutritional value of each individual food item, which helps to offset the relatively limited diet made available to most terrarium lizards.
In addition to variety and gut-loading, all food items offered to Mountain Horned lizards should be lightly dusted with an appropriate calcium and vitamin supplement. A high quality calcium powder with added vitamin D3 should be used at every feeding for young and growing lizards, or those suspected of carrying eggs. This will ensure proper bone growth and skeletal integrity.
In addition to calcium, a reptile multi-vitamin should be used as well, about once a week for animals of all ages. These products ensure that the animals are receiving all of the necessary fat and water-soluble vitamins they would normally encounter in their wild prey.
Mountain Horned lizards are in a class of their own when it comes to prehistoric-looking, yet readily available saurian companions. They are just different enough looking to catch even the seasoned herper off guard, but easily obtained and cared for. Their gentle disposition, range of colors, and inexpensive price make them one of the best choices for lizard keepers of all levels of experience.
When properly acclimated and housed, these lizards will no doubt provide endless hours of enjoyment and entertainment, whether it’s your first lizard, or your 50th!