Mountain Horned Lizards: An Introduction to Acanthosauria 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.

NATURAL HISTORY

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.

“Accanthosauria capra”

HOUSING

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 overtime, 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.

A well-designed habitat suitable for a pair or trio of Mountaini Horned Lizards

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!

Creative “living vivaria” are suitable for Mountain Horned Lizards of all sizes

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.

“Mowgli” – a captive-hatched Mountain Horned Lizard, surveys his domain.

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 timeconsuming. These alternate methods of providing moisture can be extra helpful if you live in an excessively hot or dry climate.

NUTRITION

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.

IN CLOSING

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 50^th!

Harness the Sun: Outdoor Housing of Bearded Dragons

By Jonathan Rheins

INTRODUCTION

The awesome power of the sun plays a tremendous role in the lifecycle of nearly all reptiles and amphibians.  While some species bask in its glory, even those that avoid its brilliance rely on day length as a seasonal clock. Whether in nature or in the terrarium, solar wavelengths and intensity play an integral role in basking behavior, brumation schedules, and reproduction among herps.

Indoors, we must make every possible effort to mimic outdoor conditions for our charges, doing our best to ensure that appropriate photoperiods and lighting type and intensity are provided.  However, in certain climactic zones, select species have proven quite content to enjoy the region’s outdoor weather.

Case in point is the Inland Bearded Dragon (Pogona vitticeps).  Perhaps the most popular and beloved pet herp across the globe, Bearded Dragons are personable, attractive, and love getting some sun!

Pugsley soaking up some rays.

HABITAT TYPES

During much of the year throughout most of the United States, Bearded Dragons will be maintained indoors, with outdoor housing reserved for impeccable weather.  However, in Mediterranean and desert climates, such as Southern California, ‘beardies’ will thrive outdoors from late spring into late summer if certain preparations are made.

Outdoor habitats for any species should first and foremost be secure.  It is our responsibility as the keeper to do everything in our power to ensure the well being of the animals under our care.  Protection against escape and rural predators should be high on the priority list.  Thoughtful habitat construction and careful husbandry routines will reduce the risk of either worst-case scenario.

Glass-walled enclosures or aquariums should never be placed in direct sunlight for any reason.  Animal overheating is likely to occur.  Even when outdoor ambient temperatures are relatively cool, the light of the sun can be magnified through the tank walls, creating a see-through oven!  Herps housed outdoors for anytime period should be in screen or mesh type enclosures.

Custom-built enclosures are an option, but one must consider the time, efficiency, and cost of such endeavors on a small scale.  Zoo Med Laboratories manufactures two fantastic products that are both equally well-suited for the occasional sunning or seasonal housing of one or two mature dragons.  Granted, they are geared towards keepers of tortoises, but Bearded Dragons are equally happy to make a summer home of either enclosure type.

The Zoo Med Tortoise Pen is a medium sized outdoor sunning enclosure that is ideal for getting one or two adult dragons outside when temperatures are acceptable.  A built-in shelter is provided to allow for thermoregulation so as to help prevent overheating.  The floor is open, which allows for placement over organically grown grasses and dark, leafy greens such as kale, dandelion, and romaine–all dragon favorites!

Also from Zoo Med is the Tortoise House, a slightly larger and expandable take on the Tortoise Pen.  With the Zoo Med Tortoise House, more Bearded Dragons can be kept per enclosure, and a solid floor is incorporated should escape by digging be of concern.  Additionally, these units can be combined in a linear fashion, and the built in shelter is larger, allowing for lay boxes or heating devices.

Some of the author’s Bearded Dragons basking in Reptarium Screen Cages

I have found that for small to moderately sized dragon collections, Reptarium brand mesh enclosures are quite acceptable, and perhaps preferable, when a larger number of animals are being maintained.   They are modular, easy to clean, and allow for a maximum amount of “leg room” for each dragon.  Furthermore, acceptable amounts of heat and UVB easily transfer through the heavy duty replaceable mesh cover.

HABITAT PLACEMENT

Once the overall design and attributes of the outdoor habitat have been determined, physical orientation to the sun must be taken into consideration.  A fair amount of observation, measures, and experimentation may be necessary before an acceptable configuration is adopted.

Obviously, it is important that the area selected for your outdoor enclosure receive a good amount of sunlight, but also offers the animal(s) some refuge from the heat of the sun.  I try to locate outdoor habitats in areas that receive nearly direct sunlight for a few hours in the morning and afternoon.  This correlates to the general activity patterns for most dragons.  And, during these hours, the sun is lower in the sky, providing a constant but not overly intense amount of exposure.

Natural features around your property can also be utilized as a natural shade cloth.  I have found that the citrus trees in my yard provide partial shade to my Reptariums during the hottest parts of the day, allowing dappled light to reach the enclosures.

No reptile of any species should ever be housed outdoors for any period of time without access to water and a shaded area.  Even though most reptiles like it hot, it is still vitally important that they have the ability to cool down if needed.

By ensuring that no outdoor habitat is placed in direct constant sunlight, both shaded and illuminated sections within the enclosure can be established at the same time.  This allows for easy thermoregulation of the dragons as they move in and out of shaded or sunny areas.

TEMPERATURE CONSIDERATIONS

While the primary reason for housing Bearded Dragons in the backyard is to allow access to natural sunlight and high levels of UV light, air temperature must be considered before animals are placed outdoors.  If Bearded Dragons are placed outside when the temperature is too cool, they may become stressed or ill.  Furthermore, reptiles can only effectively utilize the beneficial UV rays of the sun when they are within their preferred temperature range.

It should be noted that air temperatures and surface temperatures within the enclosure can vary greatly.  A high quality digital thermometer with a minimum/maximum feature should be included in every enclosure.  I also highly recommend the use of an infrared temperature gun that can be used to easily measure surface temps of basking surfaces and the animals themselves.  Temp guns are perhaps the most useful tool in herpeteculture today, and will prove truly invaluable when establishing outdoor housing for any herp.

When given a variety of basking and hiding areas, Bearded Dragons are incredibly adept at maintaining a body temperature between 90 and 100 degrees F, almost regardless of air temperature.  As long as ambient temperatures are above 75 F, dragons with access to full sun will quickly and efficiently achieve their preferred thermal range.

Only when conditions are optimal should animals be left outside overnight. Keep in mind that while wild dragons can and do thrive when nighttime temperatures drop into the 50’s F, pet dragons are usually not acclimated to such changes in temperature. It is good practice to bring your pet indoors after dark, unless lows hover around 70 degrees. In most cases, the threat of predators (such as cats and raccoons) and the risk of chill greatly outweigh the advantages to keeping Bearded Dragons outside over night.

Beardeds basking on wood inside a reptarium.

FURNISHINGS AND SUBSTRATE

Just as with any indoor habitat, some attention must be given to the choice of enclosure floor covering, as well as decorative and functional decor.  Outdoor habitats are subjected to different extremes in temperature and humidity, so what may work wonderfully indoors may or may not be an acceptable outdoors.

Products that are conducive to easy cleaning and replacement are ideal for use in backyard herp enclosures.  I have had much success keeping larger dragons on a substrate mix of cypress mulch and large grade redwood chips (Repti Bark).  These products combined are aesthetically pleasing, easy to spot clean, and hold up well when exposed to weather.

When housing small groups of hatchlings or juveniles outdoors, coconut husk type beddings are ideal.  The small particle size makes accidental ingestion practically a non-issue, and it has the same weather-resistant properties of other substrates.

All bearded dragons housed in outdoor enclosures must have multiple basking areas, either of wood, rock, or both, to ensure that each animal being housed has access to its own basking area.  Large pieces of driftwood,African mopani wood, and slate slabs work well.  One of the newer products to hit the market (and a personal favorite of mine) is bamboo root.  This all-natural product is very funky in appearance, having all sorts of angles and branches.  One main advantage of bamboo root is that unlike grapewood, it has no cracks or crevices in which crickets and other feeder insects might hide.  Additionally, when it comes to cleaning large numbers of enclosures, anything with a smooth surface is easier to clean and disinfect.

Whatever cage furniture tickles your fancy, make sure that you give your pet a couple of basking and shade options. A few pieces of strategically placed wood perches and a nice warm basking rock can turn a ho-hum screen cage into a comfy outdoor vacation spot for your scaly friend.

Ferrari, a translucent Italian leatherback.

IN CLOSING

Harnessing the power of the sun for herpeteculture is not only natural, but self-sustaining. While special UV and heating bulbs will likely constitute the majority of your pet’s basking media, take advantage of the terrific weather that we usually enjoy in southern California. Bearded Dragons are especially well suited for outdoor housing in the summer as they love to soak up the rays in what we would consider unusually hot weather.

When considering outdoor housing options, remember that your pet’s safety and comfort come first. Make sure that your pet is secure from escape as well as from your inquisitive pet tabby.

Placement of your enclosure is also equally important. Too much sun is as bad as too little. Make sure that it receives some direct sunlight, but also has a naturally shaded area, like that of a nearby tree, to give your pet a temperature gradient. Just like indoors, you want to give your pet the option to get away from the heat.

Appropriate furniture and substrate can help by providing lots of heating and cooling spots, which can also be aesthetically pleasing.

In the end, it is our responsibility to keep our herps happy, whether indoors, or out. With a little thought and creative use of resources, your Bearded Dragon can enjoy its own summer getaway spot right in your own backyard.