Tiliqua – Blue-tongue Lizard or Skink
The Blue-tongue lizard is one of the most commonly seen and known reptiles in Australia, found in eastern and northern Australia in woodlands, grasslands and heath country. The Blue- tongue lizard readily adapts to urban and suburban gardens and parks, feeding on a variety of invertebrates and plant material with their favourites being slugs and snails.
Blue-tongue lizards can reach sizes of up to 60cms in length and are typically grey or pale brown with darker banding on the body and tail. The belly is cream or yellowish white and the lizard is characterised by its vivid Blue-tongue. The Blue-tongue lizard is harmless however it can bite if harassed but usually prefers to carry out a bluff performance that can involve opening its mouth to display its Blue-tongue and producing a hiss by forcing air from its lungs.
The Blue-tongue lizard gives birth to live young and is capable of producing litters of up to 30 lizards in late summer after mating in spring and early summer.
Multiple Blue-tongue lizards can be kept together however fighting can occur and Blue-tongue lizards can readily reproduce. For this reason, it is recommended that Blue-tongue lizards are not kept together in a school situation so that aggressive behaviour which can lead to injuries requiring veterinary treatment and unwanted breeding that produces an excess of unwanted offspring is avoided.
The ideal temperature range for a Blue-tongue lizard is 22 – 34°C. It is important to create a temperature gradient within enclosures, with the basking area being the hottest area of the enclosure and the opposite end of the enclosure having the lowest temperature. This allows animals to move around the enclosure and choose their preferred temperature as they would in their natural environment.
The heat source can be provided by a UV heat lamp above the basking area or alternatively a “UV Tube” is placed across the length of the enclosure and a “non UV” heat lamp such as a reflector globe is provided at one end of the enclosure for the animal’s basking area .
A temperature gun should be used to regularly monitor the temperature in different areas of the enclosure and ensure the enclosure is not becoming too hot or too cold. UV lights should be switched off at night to replicate the natural daylight hours. The use of a timer for lights is recommended.
Blue-tongue lizards will enter a dormant phase in the wild during the winter months. This is not a true hibernation as on warmers days the lizards will come out and bask for short periods of time however feeding does not normally take place. Lizards that are kept in enclosures should be kept at a constant temperature gradient throughout the year to avoid the dormant stage and encouraging the dormant stage in a school situation is not recommended.
Blue-tongue lizards require good ventilation. Lizards that are kept in outdoor enclosures or large open topped enclosures will have adequate ventilation. Lizards kept in indoor enclosures such as aquariums and tanks require a secure mesh top to provide adequate ventilation. It is essential that mesh tops are very secure to avoid animals escaping or objects falling into enclosures. A common way of securing a mesh top to an aquarium is by securing mesh to a metal frame that is fitted to the top of the tank.
Humidity is generally not a problem when keeping Blue-tongue lizards. A dry enclosure with a permanent water source such as a bowl and adequate ventilation will ensure an appropriate environment for this species.
Blue-tongue lizards kept in indoor enclosures require a heat lamp as well as a UV light tube. It is recommended to have timers fitted to lighting to ensure lights are turned off and on at appropriate times to replicate the natural light cycle that animals would experience in their natural environment. The UV heat lamp should be positioned to one side of the basking area, which should be at one end of the enclosure.
The location and positioning of outdoor enclosures needs to be well planned so that the lizards have access to direct sunlight during the day to allow the animals to bask and that objects will not block the sunlight as the sun moves. As it is impossible to control the temperature in outdoor enclosures it is essential that appropriate shelter is provided so the lizards can avoid temperature extremes (cold in winter and heat in summer as exposure to these both can potentially cause death). If the enclosure does not receive sun for a large portion of the day especially in winter the enclosure is unsuitable for housing Blue-tongues. UV lamps should not be required in an outdoor enclosure as they should receive enough UV from the sun. Close monitoring of outdoor enclosures should take place to ensure correct heating and lighting is provided. When constructing an outdoor enclosure, the basking area should be created in the area that receives sunlight for the longest period of time during the day.
Blue-tongued lizards can be housed in both indoor and outdoor enclosures as long as the enclosure is safe, secure, free from danger of predators and theft and their spatial requirements are met.
Outdoor enclosures are typically larger than indoor enclosures and can be more – suitable for multiple lizards. Both outdoor and indoor enclosures must provide the minimum spatial requirements for Blue-tongue lizards and are based on the extended length from snout to tail tip of the longest animal to be housed in the enclosure and written as L.
Enclosures must be no less than 4L2 (2L x 2L) with no dimension less than 0.75L. For example, if a lizard is 20cm in length, the enclosure must be a minimum of 40cm x 40cm.
It is always recommended to provide more space for Blue-tongue lizards if possible so they can move around as they would in their natural habitat. An adult Blue-tongue should never be kept in a tank less than 120cm in length and 60cm wide.
While some species of reptiles must have an appropriate sized enclosure for their current size, adult Blue-tongue-lizards can be kept in a larger enclosure than the minimum requirements state. However, it is preferable that juvenile and small animals are housed in smaller enclosures than larger adult animals.
Large glass aquariums/tanks make suitable indoor enclosures for Blue-tongue lizards. The top of the tank must be securely enclosed to prevent escapes and objects falling into the tank. A metal framework attached to the top of the tank with mesh secured over the frame is recommended. The enclosure must be inside a room that can be secured and locked to prevent escape, theft and attack by predators.
If housed in outdoor enclosures, adult Blue-tongued lizards can be content in a fairly large enclosure that replicates their natural habitat. Outdoor enclosures must be extremely secure as lizards can climb mesh, rocks and branches and other routes to escape. Outdoor enclosures must have a solid base, e.g. concrete and be completely enclosed on the sides. If there is any chance that the sides can be climbed then a roof that allows sunlight in, e.g. wire mesh needs to be fitted. Typical outdoor enclosures are constructed from a solid concrete base and sturdy, fine mesh with at least 2 solid sides. Other enclosures used to house lizards include open topped enclosures with smooth concrete walls that prevent climbing. These types of enclosures however must be within a secure compound and are often more expensive and difficult to construct.
Suitable substrates that can be used on the floor of enclosures include sandy soil, rocks and leaf litter. Glass aquariums can also be lined with paper however a more natural substrate is recommended if possible. The substrate should be kept dry to reduce humidity in the enclosure.
Blue-tongue lizards require plenty of hiding places in their enclosure. Small logs, hollow logs and boxes as well as rocks should be provided in the enclosure to replicate the natural environment. As Blue-tongue lizards climb and dig, it is essential that all furniture within the enclosure is secure and stable. Rocks and logs should be placed on the base of the enclosure rather than on top of the substrate to prevent lizards digging under furniture and causing collapses and injury.
It is also essential to provide a raised basking area under the heat lamp. Flat rocks, logs or other flat objects can be used to create the basking area platform. The rock or platform should be large enough for all lizards within the enclosure to stretch out on and large enough so that the lizards can also move to the edge of the basking area, away from the direct heat to find an appropriate temperature. The heat lamp should be placed to one side of the basking rock and the rock should be big enough so that lizards can choose to lay directly under the heat or to the side in a cooler area.
Nutrition and Water
Clean water must be provided at all times. A shallow water dish that lizards can easily get out of if they were to get in should be provided. Water must be checked twice daily and should be replaced once per day. Water dishes must be cleaned regularly. Juvenile lizards should be provided with a very small, shallow water dish to prevent drowning.
Blue-tongue lizards are omnivorous animals and eat a mix of vegetables and protein. A Blue-tongue lizard’s diet in the wild typically includes insects, snails and slugs, vegetation and flowers.
In captivity this species should be fed a variety of food items to achieve a high level of health and nutrition as not one single food item provides complete nutrition.
Suitable food items that can be included in the diet include:
- Wood cockroaches
- Boiled Egg whites
- Salad mix
- Greens + vegetables.
Blue-tongue lizards do not require a large amount of insects and their nutritional needs can be met by providing a mix of vegetables items and egg whites for protein however insects can be fed occasionally. Crickets and wood roaches are the most commercially available insect that can be purchased for reptiles and are available at most pet stores.
The diet should also be supplemented with calcium and multivitamins to ensure good health. Suitable multivitamin and calcium powders can also be purchased from pet and reptile stores and these should be incorporated into the diet by mixing the powder into the salad mix or dusting insects in multivitamin and calcium powder prior to feeding at the suggested ratio.
Juvenile lizards should be fed every day and adult lizards should be fed 3 times per week.
An example of an amount and type of food to feed an adult Blue-tongue lizard weekly is:
- 50 grams of ‘Salad mix’ three times per week on Monday, Wednesday and Friday.
- Occasionally (once per week) a small number of insects, five crickets or wood roaches dusted with multivitamin and calcium powder. It is recommended to hand feed off forceps most of the insects to the lizards and also to release some into the enclosure for the animals to feed on naturally.
This diet is an example only. Individual animals may require more or less depending on their body condition and age.
Any uneaten food or insects should be removed from the enclosure daily.
Food dishes that are used for salad mix and vegetables should be cleaned with detergent after every use and any food left in dishes should be removed daily.
Salad mix recipe
The mix should include the following:
- Chopped into bite-sized pieces:
- Bok choy
- Cos lettuce.
- Diced into very fine pieces:
- Sweet potatoes
Add alfalfa sprouts, mung beans and chopped hard-boiled egg and dust with calcium and multivitamin powder as per the product directions.
Indoor enclosures including tanks and aquariums must be spot cleaned daily to remove faeces and any uneaten food. Water dishes must be cleaned weekly and food dishes cleaned after each feeding day. Full tank cleans including complete soil/substrate changes should be carried out every term (10 weeks) or 1 – 3 months as required. A full tank clean should include a complete soil change, cleaning furniture if required and cleaning and disinfecting glass and other surfaces. If paper is used on the floor of the tank this should be replaced regularly, even daily if needed.
Outdoor enclosures must be spot cleaned regularly to remove faeces and uneaten food. While larger enclosures may not appear to need cleaning as frequently, it is good practice to still clean enclosures daily to reduce buildup of waste. Soil changes should be carried out if required.